diff --git a/lib/include/srslte/srslog/bundled/fmt/chrono.h b/lib/include/srslte/srslog/bundled/fmt/chrono.h
index 421d464ad..e70b8053a 100644
--- a/lib/include/srslte/srslog/bundled/fmt/chrono.h
+++ b/lib/include/srslte/srslog/bundled/fmt/chrono.h
@@ -48,7 +48,7 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
     // From fits in To without any problem.
   } else {
     // From does not always fit in To, resort to a dynamic check.
-    if (from < T::min() || from > T::max()) {
+    if (from < (T::min)() || from > (T::max)()) {
       // outside range.
       ec = 1;
       return {};
@@ -74,7 +74,7 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
 
   if (F::is_signed && !T::is_signed) {
     // From may be negative, not allowed!
-    if (fmt::internal::is_negative(from)) {
+    if (fmt::detail::is_negative(from)) {
       ec = 1;
       return {};
     }
@@ -84,7 +84,7 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
       // yes, From always fits in To.
     } else {
       // from may not fit in To, we have to do a dynamic check
-      if (from > static_cast<From>(T::max())) {
+      if (from > static_cast<From>((T::max)())) {
         ec = 1;
         return {};
       }
@@ -97,7 +97,7 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
       // yes, From always fits in To.
     } else {
       // from may not fit in To, we have to do a dynamic check
-      if (from > static_cast<From>(T::max())) {
+      if (from > static_cast<From>((T::max)())) {
         // outside range.
         ec = 1;
         return {};
@@ -141,7 +141,7 @@ FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
 
   // catch the only happy case
   if (std::isfinite(from)) {
-    if (from >= T::lowest() && from <= T::max()) {
+    if (from >= T::lowest() && from <= (T::max)()) {
       return static_cast<To>(from);
     }
     // not within range.
@@ -195,12 +195,13 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
   }
   // multiply with Factor::num without overflow or underflow
   if (Factor::num != 1) {
-    const auto max1 = internal::max_value<IntermediateRep>() / Factor::num;
+    const auto max1 = detail::max_value<IntermediateRep>() / Factor::num;
     if (count > max1) {
       ec = 1;
       return {};
     }
-    const auto min1 = std::numeric_limits<IntermediateRep>::min() / Factor::num;
+    const auto min1 =
+        (std::numeric_limits<IntermediateRep>::min)() / Factor::num;
     if (count < min1) {
       ec = 1;
       return {};
@@ -269,7 +270,7 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
 
   // multiply with Factor::num without overflow or underflow
   if (Factor::num != 1) {
-    constexpr auto max1 = internal::max_value<IntermediateRep>() /
+    constexpr auto max1 = detail::max_value<IntermediateRep>() /
                           static_cast<IntermediateRep>(Factor::num);
     if (count > max1) {
       ec = 1;
@@ -306,12 +307,12 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
 // Usage: f FMT_NOMACRO()
 #define FMT_NOMACRO
 
-namespace internal {
+namespace detail {
 inline null<> localtime_r FMT_NOMACRO(...) { return null<>(); }
 inline null<> localtime_s(...) { return null<>(); }
 inline null<> gmtime_r(...) { return null<>(); }
 inline null<> gmtime_s(...) { return null<>(); }
-}  // namespace internal
+}  // namespace detail
 
 // Thread-safe replacement for std::localtime
 inline std::tm localtime(std::time_t time) {
@@ -322,22 +323,22 @@ inline std::tm localtime(std::time_t time) {
     dispatcher(std::time_t t) : time_(t) {}
 
     bool run() {
-      using namespace fmt::internal;
+      using namespace fmt::detail;
       return handle(localtime_r(&time_, &tm_));
     }
 
     bool handle(std::tm* tm) { return tm != nullptr; }
 
-    bool handle(internal::null<>) {
-      using namespace fmt::internal;
+    bool handle(detail::null<>) {
+      using namespace fmt::detail;
       return fallback(localtime_s(&tm_, &time_));
     }
 
     bool fallback(int res) { return res == 0; }
 
 #if !FMT_MSC_VER
-    bool fallback(internal::null<>) {
-      using namespace fmt::internal;
+    bool fallback(detail::null<>) {
+      using namespace fmt::detail;
       std::tm* tm = std::localtime(&time_);
       if (tm) tm_ = *tm;
       return tm != nullptr;
@@ -359,21 +360,21 @@ inline std::tm gmtime(std::time_t time) {
     dispatcher(std::time_t t) : time_(t) {}
 
     bool run() {
-      using namespace fmt::internal;
+      using namespace fmt::detail;
       return handle(gmtime_r(&time_, &tm_));
     }
 
     bool handle(std::tm* tm) { return tm != nullptr; }
 
-    bool handle(internal::null<>) {
-      using namespace fmt::internal;
+    bool handle(detail::null<>) {
+      using namespace fmt::detail;
       return fallback(gmtime_s(&tm_, &time_));
     }
 
     bool fallback(int res) { return res == 0; }
 
 #if !FMT_MSC_VER
-    bool fallback(internal::null<>) {
+    bool fallback(detail::null<>) {
       std::tm* tm = std::gmtime(&time_);
       if (tm) tm_ = *tm;
       return tm != nullptr;
@@ -386,17 +387,17 @@ inline std::tm gmtime(std::time_t time) {
   return gt.tm_;
 }
 
-namespace internal {
-inline std::size_t strftime(char* str, std::size_t count, const char* format,
-                            const std::tm* time) {
+namespace detail {
+inline size_t strftime(char* str, size_t count, const char* format,
+                       const std::tm* time) {
   return std::strftime(str, count, format, time);
 }
 
-inline std::size_t strftime(wchar_t* str, std::size_t count,
-                            const wchar_t* format, const std::tm* time) {
+inline size_t strftime(wchar_t* str, size_t count, const wchar_t* format,
+                       const std::tm* time) {
   return std::wcsftime(str, count, format, time);
 }
-}  // namespace internal
+}  // namespace detail
 
 template <typename Char> struct formatter<std::tm, Char> {
   template <typename ParseContext>
@@ -405,7 +406,7 @@ template <typename Char> struct formatter<std::tm, Char> {
     if (it != ctx.end() && *it == ':') ++it;
     auto end = it;
     while (end != ctx.end() && *end != '}') ++end;
-    tm_format.reserve(internal::to_unsigned(end - it + 1));
+    tm_format.reserve(detail::to_unsigned(end - it + 1));
     tm_format.append(it, end);
     tm_format.push_back('\0');
     return end;
@@ -414,11 +415,10 @@ template <typename Char> struct formatter<std::tm, Char> {
   template <typename FormatContext>
   auto format(const std::tm& tm, FormatContext& ctx) -> decltype(ctx.out()) {
     basic_memory_buffer<Char> buf;
-    std::size_t start = buf.size();
+    size_t start = buf.size();
     for (;;) {
-      std::size_t size = buf.capacity() - start;
-      std::size_t count =
-          internal::strftime(&buf[start], size, &tm_format[0], &tm);
+      size_t size = buf.capacity() - start;
+      size_t count = detail::strftime(&buf[start], size, &tm_format[0], &tm);
       if (count != 0) {
         buf.resize(start + count);
         break;
@@ -430,7 +430,7 @@ template <typename Char> struct formatter<std::tm, Char> {
         // https://github.com/fmtlib/fmt/issues/367
         break;
       }
-      const std::size_t MIN_GROWTH = 10;
+      const size_t MIN_GROWTH = 10;
       buf.reserve(buf.capacity() + (size > MIN_GROWTH ? size : MIN_GROWTH));
     }
     return std::copy(buf.begin(), buf.end(), ctx.out());
@@ -439,7 +439,7 @@ template <typename Char> struct formatter<std::tm, Char> {
   basic_memory_buffer<Char> tm_format;
 };
 
-namespace internal {
+namespace detail {
 template <typename Period> FMT_CONSTEXPR const char* get_units() {
   return nullptr;
 }
@@ -768,19 +768,25 @@ OutputIt format_duration_value(OutputIt out, Rep val, int precision) {
   return format_to(out, std::is_floating_point<Rep>::value ? fp_f : format,
                    val);
 }
+template <typename Char, typename OutputIt>
+OutputIt copy_unit(string_view unit, OutputIt out, Char) {
+  return std::copy(unit.begin(), unit.end(), out);
+}
+
+template <typename OutputIt>
+OutputIt copy_unit(string_view unit, OutputIt out, wchar_t) {
+  // This works when wchar_t is UTF-32 because units only contain characters
+  // that have the same representation in UTF-16 and UTF-32.
+  utf8_to_utf16 u(unit);
+  return std::copy(u.c_str(), u.c_str() + u.size(), out);
+}
 
 template <typename Char, typename Period, typename OutputIt>
 OutputIt format_duration_unit(OutputIt out) {
-  if (const char* unit = get_units<Period>()) {
-    string_view s(unit);
-    if (const_check(std::is_same<Char, wchar_t>())) {
-      utf8_to_utf16 u(s);
-      return std::copy(u.c_str(), u.c_str() + u.size(), out);
-    }
-    return std::copy(s.begin(), s.end(), out);
-  }
+  if (const char* unit = get_units<Period>())
+    return copy_unit(string_view(unit), out, Char());
   const Char num_f[] = {'[', '{', '}', ']', 's', 0};
-  if (Period::den == 1) return format_to(out, num_f, Period::num);
+  if (const_check(Period::den == 1)) return format_to(out, num_f, Period::num);
   const Char num_def_f[] = {'[', '{', '}', '/', '{', '}', ']', 's', 0};
   return format_to(out, num_def_f, Period::num, Period::den);
 }
@@ -874,9 +880,9 @@ struct chrono_formatter {
     if (isnan(value)) return write_nan();
     uint32_or_64_or_128_t<int> n =
         to_unsigned(to_nonnegative_int(value, max_value<int>()));
-    int num_digits = internal::count_digits(n);
+    int num_digits = detail::count_digits(n);
     if (width > num_digits) out = std::fill_n(out, width - num_digits, '0');
-    out = format_decimal<char_type>(out, n, num_digits);
+    out = format_decimal<char_type>(out, n, num_digits).end;
   }
 
   void write_nan() { std::copy_n("nan", 3, out); }
@@ -1004,14 +1010,14 @@ struct chrono_formatter {
     out = format_duration_unit<char_type, Period>(out);
   }
 };
-}  // namespace internal
+}  // namespace detail
 
 template <typename Rep, typename Period, typename Char>
 struct formatter<std::chrono::duration<Rep, Period>, Char> {
  private:
   basic_format_specs<Char> specs;
   int precision;
-  using arg_ref_type = internal::arg_ref<Char>;
+  using arg_ref_type = detail::arg_ref<Char>;
   arg_ref_type width_ref;
   arg_ref_type precision_ref;
   mutable basic_string_view<Char> format_str;
@@ -1032,7 +1038,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
       return arg_ref_type(arg_id);
     }
 
-    FMT_CONSTEXPR arg_ref_type make_arg_ref(internal::auto_id) {
+    FMT_CONSTEXPR arg_ref_type make_arg_ref(detail::auto_id) {
       return arg_ref_type(context.next_arg_id());
     }
 
@@ -1062,17 +1068,17 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
     auto begin = ctx.begin(), end = ctx.end();
     if (begin == end || *begin == '}') return {begin, begin};
     spec_handler handler{*this, ctx, format_str};
-    begin = internal::parse_align(begin, end, handler);
+    begin = detail::parse_align(begin, end, handler);
     if (begin == end) return {begin, begin};
-    begin = internal::parse_width(begin, end, handler);
+    begin = detail::parse_width(begin, end, handler);
     if (begin == end) return {begin, begin};
     if (*begin == '.') {
       if (std::is_floating_point<Rep>::value)
-        begin = internal::parse_precision(begin, end, handler);
+        begin = detail::parse_precision(begin, end, handler);
       else
         handler.on_error("precision not allowed for this argument type");
     }
-    end = parse_chrono_format(begin, end, internal::chrono_format_checker());
+    end = parse_chrono_format(begin, end, detail::chrono_format_checker());
     return {begin, end};
   }
 
@@ -1083,7 +1089,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
       -> decltype(ctx.begin()) {
     auto range = do_parse(ctx);
     format_str = basic_string_view<Char>(
-        &*range.begin, internal::to_unsigned(range.end - range.begin));
+        &*range.begin, detail::to_unsigned(range.end - range.begin));
     return range.end;
   }
 
@@ -1094,23 +1100,21 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
     // is not specified.
     basic_memory_buffer<Char> buf;
     auto out = std::back_inserter(buf);
-    using range = internal::output_range<decltype(ctx.out()), Char>;
-    internal::basic_writer<range> w(range(ctx.out()));
-    internal::handle_dynamic_spec<internal::width_checker>(specs.width,
-                                                           width_ref, ctx);
-    internal::handle_dynamic_spec<internal::precision_checker>(
-        precision, precision_ref, ctx);
+    detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref,
+                                                       ctx);
+    detail::handle_dynamic_spec<detail::precision_checker>(precision,
+                                                           precision_ref, ctx);
     if (begin == end || *begin == '}') {
-      out = internal::format_duration_value<Char>(out, d.count(), precision);
-      internal::format_duration_unit<Char, Period>(out);
+      out = detail::format_duration_value<Char>(out, d.count(), precision);
+      detail::format_duration_unit<Char, Period>(out);
     } else {
-      internal::chrono_formatter<FormatContext, decltype(out), Rep, Period> f(
+      detail::chrono_formatter<FormatContext, decltype(out), Rep, Period> f(
           ctx, out, d);
       f.precision = precision;
       parse_chrono_format(begin, end, f);
     }
-    w.write(buf.data(), buf.size(), specs);
-    return w.out();
+    return detail::write(
+        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
   }
 };
 
diff --git a/lib/include/srslte/srslog/bundled/fmt/color.h b/lib/include/srslte/srslog/bundled/fmt/color.h
index 96d9ab6b4..b65f892af 100644
--- a/lib/include/srslte/srslog/bundled/fmt/color.h
+++ b/lib/include/srslte/srslog/bundled/fmt/color.h
@@ -198,7 +198,7 @@ struct rgb {
   uint8_t b;
 };
 
-namespace internal {
+namespace detail {
 
 // color is a struct of either a rgb color or a terminal color.
 struct color_type {
@@ -221,7 +221,7 @@ struct color_type {
     uint32_t rgb_color;
   } value;
 };
-}  // namespace internal
+}  // namespace detail
 
 // Experimental text formatting support.
 class text_style {
@@ -298,11 +298,11 @@ class text_style {
   FMT_CONSTEXPR bool has_emphasis() const FMT_NOEXCEPT {
     return static_cast<uint8_t>(ems) != 0;
   }
-  FMT_CONSTEXPR internal::color_type get_foreground() const FMT_NOEXCEPT {
+  FMT_CONSTEXPR detail::color_type get_foreground() const FMT_NOEXCEPT {
     FMT_ASSERT(has_foreground(), "no foreground specified for this style");
     return foreground_color;
   }
-  FMT_CONSTEXPR internal::color_type get_background() const FMT_NOEXCEPT {
+  FMT_CONSTEXPR detail::color_type get_background() const FMT_NOEXCEPT {
     FMT_ASSERT(has_background(), "no background specified for this style");
     return background_color;
   }
@@ -313,7 +313,7 @@ class text_style {
 
  private:
   FMT_CONSTEXPR text_style(bool is_foreground,
-                           internal::color_type text_color) FMT_NOEXCEPT
+                           detail::color_type text_color) FMT_NOEXCEPT
       : set_foreground_color(),
         set_background_color(),
         ems() {
@@ -326,23 +326,23 @@ class text_style {
     }
   }
 
-  friend FMT_CONSTEXPR_DECL text_style fg(internal::color_type foreground)
+  friend FMT_CONSTEXPR_DECL text_style fg(detail::color_type foreground)
       FMT_NOEXCEPT;
-  friend FMT_CONSTEXPR_DECL text_style bg(internal::color_type background)
+  friend FMT_CONSTEXPR_DECL text_style bg(detail::color_type background)
       FMT_NOEXCEPT;
 
-  internal::color_type foreground_color;
-  internal::color_type background_color;
+  detail::color_type foreground_color;
+  detail::color_type background_color;
   bool set_foreground_color;
   bool set_background_color;
   emphasis ems;
 };
 
-FMT_CONSTEXPR text_style fg(internal::color_type foreground) FMT_NOEXCEPT {
+FMT_CONSTEXPR text_style fg(detail::color_type foreground) FMT_NOEXCEPT {
   return text_style(/*is_foreground=*/true, foreground);
 }
 
-FMT_CONSTEXPR text_style bg(internal::color_type background) FMT_NOEXCEPT {
+FMT_CONSTEXPR text_style bg(detail::color_type background) FMT_NOEXCEPT {
   return text_style(/*is_foreground=*/false, background);
 }
 
@@ -350,21 +350,21 @@ FMT_CONSTEXPR text_style operator|(emphasis lhs, emphasis rhs) FMT_NOEXCEPT {
   return text_style(lhs) | rhs;
 }
 
-namespace internal {
+namespace detail {
 
 template <typename Char> struct ansi_color_escape {
-  FMT_CONSTEXPR ansi_color_escape(internal::color_type text_color,
+  FMT_CONSTEXPR ansi_color_escape(detail::color_type text_color,
                                   const char* esc) FMT_NOEXCEPT {
     // If we have a terminal color, we need to output another escape code
     // sequence.
     if (!text_color.is_rgb) {
-      bool is_background = esc == internal::data::background_color;
+      bool is_background = esc == detail::data::background_color;
       uint32_t value = text_color.value.term_color;
       // Background ASCII codes are the same as the foreground ones but with
       // 10 more.
       if (is_background) value += 10u;
 
-      std::size_t index = 0;
+      size_t index = 0;
       buffer[index++] = static_cast<Char>('\x1b');
       buffer[index++] = static_cast<Char>('[');
 
@@ -398,7 +398,7 @@ template <typename Char> struct ansi_color_escape {
     if (em_bits & static_cast<uint8_t>(emphasis::strikethrough))
       em_codes[3] = 9;
 
-    std::size_t index = 0;
+    size_t index = 0;
     for (int i = 0; i < 4; ++i) {
       if (!em_codes[i]) continue;
       buffer[index++] = static_cast<Char>('\x1b');
@@ -429,14 +429,14 @@ template <typename Char> struct ansi_color_escape {
 
 template <typename Char>
 FMT_CONSTEXPR ansi_color_escape<Char> make_foreground_color(
-    internal::color_type foreground) FMT_NOEXCEPT {
-  return ansi_color_escape<Char>(foreground, internal::data::foreground_color);
+    detail::color_type foreground) FMT_NOEXCEPT {
+  return ansi_color_escape<Char>(foreground, detail::data::foreground_color);
 }
 
 template <typename Char>
 FMT_CONSTEXPR ansi_color_escape<Char> make_background_color(
-    internal::color_type background) FMT_NOEXCEPT {
-  return ansi_color_escape<Char>(background, internal::data::background_color);
+    detail::color_type background) FMT_NOEXCEPT {
+  return ansi_color_escape<Char>(background, detail::data::background_color);
 }
 
 template <typename Char>
@@ -455,11 +455,11 @@ inline void fputs<wchar_t>(const wchar_t* chars, FILE* stream) FMT_NOEXCEPT {
 }
 
 template <typename Char> inline void reset_color(FILE* stream) FMT_NOEXCEPT {
-  fputs(internal::data::reset_color, stream);
+  fputs(detail::data::reset_color, stream);
 }
 
 template <> inline void reset_color<wchar_t>(FILE* stream) FMT_NOEXCEPT {
-  fputs(internal::data::wreset_color, stream);
+  fputs(detail::data::wreset_color, stream);
 }
 
 template <typename Char>
@@ -476,33 +476,31 @@ void vformat_to(basic_memory_buffer<Char>& buf, const text_style& ts,
   bool has_style = false;
   if (ts.has_emphasis()) {
     has_style = true;
-    auto emphasis = internal::make_emphasis<Char>(ts.get_emphasis());
+    auto emphasis = detail::make_emphasis<Char>(ts.get_emphasis());
     buf.append(emphasis.begin(), emphasis.end());
   }
   if (ts.has_foreground()) {
     has_style = true;
-    auto foreground =
-        internal::make_foreground_color<Char>(ts.get_foreground());
+    auto foreground = detail::make_foreground_color<Char>(ts.get_foreground());
     buf.append(foreground.begin(), foreground.end());
   }
   if (ts.has_background()) {
     has_style = true;
-    auto background =
-        internal::make_background_color<Char>(ts.get_background());
+    auto background = detail::make_background_color<Char>(ts.get_background());
     buf.append(background.begin(), background.end());
   }
-  internal::vformat_to(buf, format_str, args);
-  if (has_style) internal::reset_color<Char>(buf);
+  detail::vformat_to(buf, format_str, args);
+  if (has_style) detail::reset_color<Char>(buf);
 }
-}  // namespace internal
+}  // namespace detail
 
 template <typename S, typename Char = char_t<S>>
 void vprint(std::FILE* f, const text_style& ts, const S& format,
             basic_format_args<buffer_context<Char>> args) {
   basic_memory_buffer<Char> buf;
-  internal::vformat_to(buf, ts, to_string_view(format), args);
+  detail::vformat_to(buf, ts, to_string_view(format), args);
   buf.push_back(Char(0));
-  internal::fputs(buf.data(), f);
+  detail::fputs(buf.data(), f);
 }
 
 /**
@@ -513,10 +511,10 @@ void vprint(std::FILE* f, const text_style& ts, const S& format,
                "Elapsed time: {0:.2f} seconds", 1.23);
  */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_string<S>::value)>
 void print(std::FILE* f, const text_style& ts, const S& format_str,
            const Args&... args) {
-  internal::check_format_string<Args...>(format_str);
+  detail::check_format_string<Args...>(format_str);
   using context = buffer_context<char_t<S>>;
   format_arg_store<context, Args...> as{args...};
   vprint(f, ts, format_str, basic_format_args<context>(as));
@@ -530,7 +528,7 @@ void print(std::FILE* f, const text_style& ts, const S& format_str,
                "Elapsed time: {0:.2f} seconds", 1.23);
  */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_string<S>::value)>
 void print(const text_style& ts, const S& format_str, const Args&... args) {
   return print(stdout, ts, format_str, args...);
 }
@@ -540,7 +538,7 @@ inline std::basic_string<Char> vformat(
     const text_style& ts, const S& format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buf;
-  internal::vformat_to(buf, ts, to_string_view(format_str), args);
+  detail::vformat_to(buf, ts, to_string_view(format_str), args);
   return fmt::to_string(buf);
 }
 
@@ -560,7 +558,7 @@ template <typename S, typename... Args, typename Char = char_t<S>>
 inline std::basic_string<Char> format(const text_style& ts, const S& format_str,
                                       const Args&... args) {
   return vformat(ts, to_string_view(format_str),
-                 internal::make_args_checked<Args...>(format_str, args...));
+                 detail::make_args_checked<Args...>(format_str, args...));
 }
 
 FMT_END_NAMESPACE
diff --git a/lib/include/srslte/srslog/bundled/fmt/compile.h b/lib/include/srslte/srslog/bundled/fmt/compile.h
index e4b12f349..d7e6449eb 100644
--- a/lib/include/srslte/srslog/bundled/fmt/compile.h
+++ b/lib/include/srslte/srslog/bundled/fmt/compile.h
@@ -13,7 +13,33 @@
 #include "format.h"
 
 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {
+
+// A compile-time string which is compiled into fast formatting code.
+class compiled_string {};
+
+template <typename S>
+struct is_compiled_string : std::is_base_of<compiled_string, S> {};
+
+/**
+  \rst
+  Converts a string literal *s* into a format string that will be parsed at
+  compile time and converted into efficient formatting code. Requires C++17
+  ``constexpr if`` compiler support.
+
+  **Example**::
+
+    // Converts 42 into std::string using the most efficient method and no
+    // runtime format string processing.
+    std::string s = fmt::format(FMT_COMPILE("{}"), 42);
+  \endrst
+ */
+#define FMT_COMPILE(s) FMT_STRING_IMPL(s, fmt::detail::compiled_string)
+
+template <typename T, typename... Tail>
+const T& first(const T& value, const Tail&...) {
+  return value;
+}
 
 // Part of a compiled format string. It can be either literal text or a
 // replacement field.
@@ -62,13 +88,15 @@ template <typename Char> struct part_counter {
     if (begin != end) ++num_parts;
   }
 
-  FMT_CONSTEXPR void on_arg_id() { ++num_parts; }
-  FMT_CONSTEXPR void on_arg_id(int) { ++num_parts; }
-  FMT_CONSTEXPR void on_arg_id(basic_string_view<Char>) { ++num_parts; }
+  FMT_CONSTEXPR int on_arg_id() { return ++num_parts, 0; }
+  FMT_CONSTEXPR int on_arg_id(int) { return ++num_parts, 0; }
+  FMT_CONSTEXPR int on_arg_id(basic_string_view<Char>) {
+    return ++num_parts, 0;
+  }
 
-  FMT_CONSTEXPR void on_replacement_field(const Char*) {}
+  FMT_CONSTEXPR void on_replacement_field(int, const Char*) {}
 
-  FMT_CONSTEXPR const Char* on_format_specs(const Char* begin,
+  FMT_CONSTEXPR const Char* on_format_specs(int, const Char* begin,
                                             const Char* end) {
     // Find the matching brace.
     unsigned brace_counter = 0;
@@ -116,25 +144,28 @@ class format_string_compiler : public error_handler {
       handler_(part::make_text({begin, to_unsigned(end - begin)}));
   }
 
-  FMT_CONSTEXPR void on_arg_id() {
+  FMT_CONSTEXPR int on_arg_id() {
     part_ = part::make_arg_index(parse_context_.next_arg_id());
+    return 0;
   }
 
-  FMT_CONSTEXPR void on_arg_id(int id) {
+  FMT_CONSTEXPR int on_arg_id(int id) {
     parse_context_.check_arg_id(id);
     part_ = part::make_arg_index(id);
+    return 0;
   }
 
-  FMT_CONSTEXPR void on_arg_id(basic_string_view<Char> id) {
+  FMT_CONSTEXPR int on_arg_id(basic_string_view<Char> id) {
     part_ = part::make_arg_name(id);
+    return 0;
   }
 
-  FMT_CONSTEXPR void on_replacement_field(const Char* ptr) {
+  FMT_CONSTEXPR void on_replacement_field(int, const Char* ptr) {
     part_.arg_id_end = ptr;
     handler_(part_);
   }
 
-  FMT_CONSTEXPR const Char* on_format_specs(const Char* begin,
+  FMT_CONSTEXPR const Char* on_format_specs(int, const Char* begin,
                                             const Char* end) {
     auto repl = typename part::replacement();
     dynamic_specs_handler<basic_format_parse_context<Char>> handler(
@@ -160,23 +191,24 @@ FMT_CONSTEXPR void compile_format_string(basic_string_view<Char> format_str,
       format_string_compiler<Char, PartHandler>(format_str, handler));
 }
 
-template <typename Range, typename Context, typename Id>
+template <typename OutputIt, typename Context, typename Id>
 void format_arg(
-    basic_format_parse_context<typename Range::value_type>& parse_ctx,
+    basic_format_parse_context<typename Context::char_type>& parse_ctx,
     Context& ctx, Id arg_id) {
-  ctx.advance_to(
-      visit_format_arg(arg_formatter<Range>(ctx, &parse_ctx), ctx.arg(arg_id)));
+  ctx.advance_to(visit_format_arg(
+      arg_formatter<OutputIt, typename Context::char_type>(ctx, &parse_ctx),
+      ctx.arg(arg_id)));
 }
 
 // vformat_to is defined in a subnamespace to prevent ADL.
 namespace cf {
-template <typename Context, typename Range, typename CompiledFormat>
-auto vformat_to(Range out, CompiledFormat& cf, basic_format_args<Context> args)
-    -> typename Context::iterator {
+template <typename Context, typename OutputIt, typename CompiledFormat>
+auto vformat_to(OutputIt out, CompiledFormat& cf,
+                basic_format_args<Context> args) -> typename Context::iterator {
   using char_type = typename Context::char_type;
   basic_format_parse_context<char_type> parse_ctx(
       to_string_view(cf.format_str_));
-  Context ctx(out.begin(), args);
+  Context ctx(out, args);
 
   const auto& parts = cf.parts();
   for (auto part_it = std::begin(parts); part_it != std::end(parts);
@@ -197,12 +229,12 @@ auto vformat_to(Range out, CompiledFormat& cf, basic_format_args<Context> args)
 
     case format_part_t::kind::arg_index:
       advance_to(parse_ctx, part.arg_id_end);
-      internal::format_arg<Range>(parse_ctx, ctx, value.arg_index);
+      detail::format_arg<OutputIt>(parse_ctx, ctx, value.arg_index);
       break;
 
     case format_part_t::kind::arg_name:
       advance_to(parse_ctx, part.arg_id_end);
-      internal::format_arg<Range>(parse_ctx, ctx, value.str);
+      detail::format_arg<OutputIt>(parse_ctx, ctx, value.str);
       break;
 
     case format_part_t::kind::replacement: {
@@ -226,7 +258,9 @@ auto vformat_to(Range out, CompiledFormat& cf, basic_format_args<Context> args)
 
       advance_to(parse_ctx, part.arg_id_end);
       ctx.advance_to(
-          visit_format_arg(arg_formatter<Range>(ctx, nullptr, &specs), arg));
+          visit_format_arg(arg_formatter<OutputIt, typename Context::char_type>(
+                               ctx, nullptr, &specs),
+                           arg));
       break;
     }
     }
@@ -240,7 +274,7 @@ struct basic_compiled_format {};
 template <typename S, typename = void>
 struct compiled_format_base : basic_compiled_format {
   using char_type = char_t<S>;
-  using parts_container = std::vector<internal::format_part<char_type>>;
+  using parts_container = std::vector<detail::format_part<char_type>>;
 
   parts_container compiled_parts;
 
@@ -305,7 +339,7 @@ struct compiled_format_base<S, enable_if_t<is_compile_string<S>::value>>
   const parts_container& parts() const {
     static FMT_CONSTEXPR_DECL const auto compiled_parts =
         compile_to_parts<char_type, num_format_parts>(
-            internal::to_string_view(S()));
+            detail::to_string_view(S()));
     return compiled_parts.data;
   }
 };
@@ -318,8 +352,8 @@ class compiled_format : private compiled_format_base<S> {
  private:
   basic_string_view<char_type> format_str_;
 
-  template <typename Context, typename Range, typename CompiledFormat>
-  friend auto cf::vformat_to(Range out, CompiledFormat& cf,
+  template <typename Context, typename OutputIt, typename CompiledFormat>
+  friend auto cf::vformat_to(OutputIt out, CompiledFormat& cf,
                              basic_format_args<Context> args) ->
       typename Context::iterator;
 
@@ -359,8 +393,7 @@ template <typename Char> struct text {
 
   template <typename OutputIt, typename... Args>
   OutputIt format(OutputIt out, const Args&...) const {
-    // TODO: reserve
-    return copy_str<Char>(data.begin(), data.end(), out);
+    return write<Char>(out, data);
   }
 };
 
@@ -373,33 +406,6 @@ constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos,
   return {{&s[pos], size}};
 }
 
-template <typename Char, typename OutputIt, typename T,
-          std::enable_if_t<std::is_integral_v<T>, int> = 0>
-OutputIt format_default(OutputIt out, T value) {
-  // TODO: reserve
-  format_int fi(value);
-  return std::copy(fi.data(), fi.data() + fi.size(), out);
-}
-
-template <typename Char, typename OutputIt>
-OutputIt format_default(OutputIt out, double value) {
-  writer w(out);
-  w.write(value);
-  return w.out();
-}
-
-template <typename Char, typename OutputIt>
-OutputIt format_default(OutputIt out, Char value) {
-  *out++ = value;
-  return out;
-}
-
-template <typename Char, typename OutputIt>
-OutputIt format_default(OutputIt out, const Char* value) {
-  auto length = std::char_traits<Char>::length(value);
-  return copy_str<Char>(value, value + length, out);
-}
-
 // A replacement field that refers to argument N.
 template <typename Char, typename T, int N> struct field {
   using char_type = Char;
@@ -408,13 +414,30 @@ template <typename Char, typename T, int N> struct field {
   OutputIt format(OutputIt out, const Args&... args) const {
     // This ensures that the argument type is convertile to `const T&`.
     const T& arg = get<N>(args...);
-    return format_default<Char>(out, arg);
+    return write<Char>(out, arg);
   }
 };
 
 template <typename Char, typename T, int N>
 struct is_compiled_format<field<Char, T, N>> : std::true_type {};
 
+// A replacement field that refers to argument N and has format specifiers.
+template <typename Char, typename T, int N> struct spec_field {
+  using char_type = Char;
+  mutable formatter<T, Char> fmt;
+
+  template <typename OutputIt, typename... Args>
+  OutputIt format(OutputIt out, const Args&... args) const {
+    // This ensures that the argument type is convertile to `const T&`.
+    const T& arg = get<N>(args...);
+    basic_format_context<OutputIt, Char> ctx(out, {});
+    return fmt.format(arg, ctx);
+  }
+};
+
+template <typename Char, typename T, int N>
+struct is_compiled_format<spec_field<Char, T, N>> : std::true_type {};
+
 template <typename L, typename R> struct concat {
   L lhs;
   R rhs;
@@ -450,7 +473,8 @@ constexpr auto compile_format_string(S format_str);
 
 template <typename Args, size_t POS, int ID, typename T, typename S>
 constexpr auto parse_tail(T head, S format_str) {
-  if constexpr (POS != to_string_view(format_str).size()) {
+  if constexpr (POS !=
+                basic_string_view<typename S::char_type>(format_str).size()) {
     constexpr auto tail = compile_format_string<Args, POS, ID>(format_str);
     if constexpr (std::is_same<remove_cvref_t<decltype(tail)>,
                                unknown_format>())
@@ -462,6 +486,21 @@ constexpr auto parse_tail(T head, S format_str) {
   }
 }
 
+template <typename T, typename Char> struct parse_specs_result {
+  formatter<T, Char> fmt;
+  size_t end;
+};
+
+template <typename T, typename Char>
+constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
+                                                  size_t pos) {
+  str.remove_prefix(pos);
+  auto ctx = basic_format_parse_context<Char>(str);
+  auto f = formatter<T, Char>();
+  auto end = f.parse(ctx);
+  return {f, pos + (end - str.data()) + 1};
+}
+
 // Compiles a non-empty format string and returns the compiled representation
 // or unknown_format() on unrecognized input.
 template <typename Args, size_t POS, int ID, typename S>
@@ -475,12 +514,13 @@ constexpr auto compile_format_string(S format_str) {
       return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
     } else if constexpr (str[POS + 1] == '}') {
       using type = get_type<ID, Args>;
-      if constexpr (std::is_same<type, int>::value) {
-        return parse_tail<Args, POS + 2, ID + 1>(field<char_type, type, ID>(),
-                                                 format_str);
-      } else {
-        return unknown_format();
-      }
+      return parse_tail<Args, POS + 2, ID + 1>(field<char_type, type, ID>(),
+                                               format_str);
+    } else if constexpr (str[POS + 1] == ':') {
+      using type = get_type<ID, Args>;
+      constexpr auto result = parse_specs<type>(str, POS + 2);
+      return parse_tail<Args, result.end, ID + 1>(
+          spec_field<char_type, type, ID>{result.fmt}, format_str);
     } else {
       return unknown_format();
     }
@@ -494,100 +534,130 @@ constexpr auto compile_format_string(S format_str) {
                                      format_str);
   }
 }
-#endif  // __cpp_if_constexpr
-}  // namespace internal
 
-#if FMT_USE_CONSTEXPR
-#  ifdef __cpp_if_constexpr
 template <typename... Args, typename S,
-          FMT_ENABLE_IF(is_compile_string<S>::value)>
+          FMT_ENABLE_IF(is_compile_string<S>::value ||
+                        detail::is_compiled_string<S>::value)>
 constexpr auto compile(S format_str) {
   constexpr basic_string_view<typename S::char_type> str = format_str;
   if constexpr (str.size() == 0) {
-    return internal::make_text(str, 0, 0);
+    return detail::make_text(str, 0, 0);
   } else {
     constexpr auto result =
-        internal::compile_format_string<internal::type_list<Args...>, 0, 0>(
+        detail::compile_format_string<detail::type_list<Args...>, 0, 0>(
             format_str);
     if constexpr (std::is_same<remove_cvref_t<decltype(result)>,
-                               internal::unknown_format>()) {
-      return internal::compiled_format<S, Args...>(to_string_view(format_str));
+                               detail::unknown_format>()) {
+      return detail::compiled_format<S, Args...>(to_string_view(format_str));
     } else {
       return result;
     }
   }
 }
+#else
+template <typename... Args, typename S,
+          FMT_ENABLE_IF(is_compile_string<S>::value)>
+constexpr auto compile(S format_str) -> detail::compiled_format<S, Args...> {
+  return detail::compiled_format<S, Args...>(to_string_view(format_str));
+}
+#endif  // __cpp_if_constexpr
+
+// Compiles the format string which must be a string literal.
+template <typename... Args, typename Char, size_t N>
+auto compile(const Char (&format_str)[N])
+    -> detail::compiled_format<const Char*, Args...> {
+  return detail::compiled_format<const Char*, Args...>(
+      basic_string_view<Char>(format_str, N - 1));
+}
+}  // namespace detail
+
+// DEPRECATED! use FMT_COMPILE instead.
+template <typename... Args>
+FMT_DEPRECATED auto compile(const Args&... args)
+    -> decltype(detail::compile(args...)) {
+  return detail::compile(args...);
+}
+
+#if FMT_USE_CONSTEXPR
+#  ifdef __cpp_if_constexpr
 
 template <typename CompiledFormat, typename... Args,
           typename Char = typename CompiledFormat::char_type,
-          FMT_ENABLE_IF(internal::is_compiled_format<CompiledFormat>::value)>
-std::basic_string<Char> format(const CompiledFormat& cf, const Args&... args) {
+          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
+FMT_INLINE std::basic_string<Char> format(const CompiledFormat& cf,
+                                          const Args&... args) {
   basic_memory_buffer<Char> buffer;
-  cf.format(std::back_inserter(buffer), args...);
+  detail::buffer<Char>& base = buffer;
+  cf.format(std::back_inserter(base), args...);
   return to_string(buffer);
 }
 
 template <typename OutputIt, typename CompiledFormat, typename... Args,
-          FMT_ENABLE_IF(internal::is_compiled_format<CompiledFormat>::value)>
+          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
 OutputIt format_to(OutputIt out, const CompiledFormat& cf,
                    const Args&... args) {
   return cf.format(out, args...);
 }
-#  else
-template <typename... Args, typename S,
-          FMT_ENABLE_IF(is_compile_string<S>::value)>
-constexpr auto compile(S format_str) -> internal::compiled_format<S, Args...> {
-  return internal::compiled_format<S, Args...>(to_string_view(format_str));
-}
 #  endif  // __cpp_if_constexpr
 #endif    // FMT_USE_CONSTEXPR
 
-// Compiles the format string which must be a string literal.
-template <typename... Args, typename Char, size_t N>
-auto compile(const Char (&format_str)[N])
-    -> internal::compiled_format<const Char*, Args...> {
-  return internal::compiled_format<const Char*, Args...>(
-      basic_string_view<Char>(format_str, N - 1));
-}
-
 template <typename CompiledFormat, typename... Args,
           typename Char = typename CompiledFormat::char_type,
-          FMT_ENABLE_IF(std::is_base_of<internal::basic_compiled_format,
+          FMT_ENABLE_IF(std::is_base_of<detail::basic_compiled_format,
                                         CompiledFormat>::value)>
 std::basic_string<Char> format(const CompiledFormat& cf, const Args&... args) {
   basic_memory_buffer<Char> buffer;
-  using range = buffer_range<Char>;
   using context = buffer_context<Char>;
-  internal::cf::vformat_to<context>(range(buffer), cf,
-                                    make_format_args<context>(args...));
+  detail::buffer<Char>& base = buffer;
+  detail::cf::vformat_to<context>(std::back_inserter(base), cf,
+                                  make_format_args<context>(args...));
   return to_string(buffer);
 }
 
+template <typename S, typename... Args,
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
+                                                           Args&&... args) {
+  constexpr basic_string_view<typename S::char_type> str = S();
+  if (str.size() == 2 && str[0] == '{' && str[1] == '}')
+    return fmt::to_string(detail::first(args...));
+  constexpr auto compiled = detail::compile<Args...>(S());
+  return format(compiled, std::forward<Args>(args)...);
+}
+
 template <typename OutputIt, typename CompiledFormat, typename... Args,
-          FMT_ENABLE_IF(std::is_base_of<internal::basic_compiled_format,
+          FMT_ENABLE_IF(std::is_base_of<detail::basic_compiled_format,
                                         CompiledFormat>::value)>
 OutputIt format_to(OutputIt out, const CompiledFormat& cf,
                    const Args&... args) {
   using char_type = typename CompiledFormat::char_type;
-  using range = internal::output_range<OutputIt, char_type>;
   using context = format_context_t<OutputIt, char_type>;
-  return internal::cf::vformat_to<context>(range(out), cf,
-                                           make_format_args<context>(args...));
+  return detail::cf::vformat_to<context>(out, cf,
+                                         make_format_args<context>(args...));
 }
 
-template <typename OutputIt, typename CompiledFormat, typename... Args,
-          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value)>
+template <typename OutputIt, typename S, typename... Args,
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+OutputIt format_to(OutputIt out, const S&, const Args&... args) {
+  constexpr auto compiled = detail::compile<Args...>(S());
+  return format_to(out, compiled, args...);
+}
+
+template <
+    typename OutputIt, typename CompiledFormat, typename... Args,
+    FMT_ENABLE_IF(detail::is_output_iterator<OutputIt>::value&& std::is_base_of<
+                  detail::basic_compiled_format, CompiledFormat>::value)>
 format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n,
                                          const CompiledFormat& cf,
                                          const Args&... args) {
   auto it =
-      format_to(internal::truncating_iterator<OutputIt>(out, n), cf, args...);
+      format_to(detail::truncating_iterator<OutputIt>(out, n), cf, args...);
   return {it.base(), it.count()};
 }
 
 template <typename CompiledFormat, typename... Args>
-std::size_t formatted_size(const CompiledFormat& cf, const Args&... args) {
-  return format_to(internal::counting_iterator(), cf, args...).count();
+size_t formatted_size(const CompiledFormat& cf, const Args&... args) {
+  return format_to(detail::counting_iterator(), cf, args...).count();
 }
 
 FMT_END_NAMESPACE
diff --git a/lib/include/srslte/srslog/bundled/fmt/core.h b/lib/include/srslte/srslog/bundled/fmt/core.h
index 0e0824f5f..37799a3a0 100644
--- a/lib/include/srslte/srslog/bundled/fmt/core.h
+++ b/lib/include/srslte/srslog/bundled/fmt/core.h
@@ -18,32 +18,7 @@
 #include <vector>
 
 // The fmt library version in the form major * 10000 + minor * 100 + patch.
-#define FMT_VERSION 60201
-
-#ifdef __has_feature
-#  define FMT_HAS_FEATURE(x) __has_feature(x)
-#else
-#  define FMT_HAS_FEATURE(x) 0
-#endif
-
-#if defined(__has_include) && !defined(__INTELLISENSE__) && \
-    !(defined(__INTEL_COMPILER) && __INTEL_COMPILER < 1600)
-#  define FMT_HAS_INCLUDE(x) __has_include(x)
-#else
-#  define FMT_HAS_INCLUDE(x) 0
-#endif
-
-#ifdef __has_cpp_attribute
-#  define FMT_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
-#else
-#  define FMT_HAS_CPP_ATTRIBUTE(x) 0
-#endif
-
-#define FMT_HAS_CPP14_ATTRIBUTE(attribute) \
-  (__cplusplus >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))
-
-#define FMT_HAS_CPP17_ATTRIBUTE(attribute) \
-  (__cplusplus >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+#define FMT_VERSION 70003
 
 #ifdef __clang__
 #  define FMT_CLANG_VERSION (__clang_major__ * 100 + __clang_minor__)
@@ -57,6 +32,12 @@
 #  define FMT_GCC_VERSION 0
 #endif
 
+#if defined(__INTEL_COMPILER)
+#  define FMT_ICC_VERSION __INTEL_COMPILER
+#else
+#  define FMT_ICC_VERSION 0
+#endif
+
 #if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
 #  define FMT_HAS_GXX_CXX11 FMT_GCC_VERSION
 #else
@@ -71,17 +52,43 @@
 
 #ifdef _MSC_VER
 #  define FMT_MSC_VER _MSC_VER
+#  define FMT_SUPPRESS_MSC_WARNING(n) __pragma(warning(suppress : n))
 #else
 #  define FMT_MSC_VER 0
+#  define FMT_SUPPRESS_MSC_WARNING(n)
+#endif
+#ifdef __has_feature
+#  define FMT_HAS_FEATURE(x) __has_feature(x)
+#else
+#  define FMT_HAS_FEATURE(x) 0
 #endif
 
+#if defined(__has_include) && !defined(__INTELLISENSE__) && \
+    !(FMT_ICC_VERSION && FMT_ICC_VERSION < 1600)
+#  define FMT_HAS_INCLUDE(x) __has_include(x)
+#else
+#  define FMT_HAS_INCLUDE(x) 0
+#endif
+
+#ifdef __has_cpp_attribute
+#  define FMT_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
+#else
+#  define FMT_HAS_CPP_ATTRIBUTE(x) 0
+#endif
+
+#define FMT_HAS_CPP14_ATTRIBUTE(attribute) \
+  (__cplusplus >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+
+#define FMT_HAS_CPP17_ATTRIBUTE(attribute) \
+  (__cplusplus >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+
 // Check if relaxed C++14 constexpr is supported.
 // GCC doesn't allow throw in constexpr until version 6 (bug 67371).
 #ifndef FMT_USE_CONSTEXPR
 #  define FMT_USE_CONSTEXPR                                           \
     (FMT_HAS_FEATURE(cxx_relaxed_constexpr) || FMT_MSC_VER >= 1910 || \
      (FMT_GCC_VERSION >= 600 && __cplusplus >= 201402L)) &&           \
-        !FMT_NVCC
+        !FMT_NVCC && !FMT_ICC_VERSION
 #endif
 #if FMT_USE_CONSTEXPR
 #  define FMT_CONSTEXPR constexpr
@@ -141,14 +148,6 @@
 #  define FMT_NORETURN
 #endif
 
-#ifndef FMT_MAYBE_UNUSED
-#  if FMT_HAS_CPP17_ATTRIBUTE(maybe_unused)
-#    define FMT_MAYBE_UNUSED [[maybe_unused]]
-#  else
-#    define FMT_MAYBE_UNUSED
-#  endif
-#endif
-
 #ifndef FMT_DEPRECATED
 #  if FMT_HAS_CPP14_ATTRIBUTE(deprecated) || FMT_MSC_VER >= 1900
 #    define FMT_DEPRECATED [[deprecated]]
@@ -164,12 +163,20 @@
 #endif
 
 // Workaround broken [[deprecated]] in the Intel, PGI and NVCC compilers.
-#if defined(__INTEL_COMPILER) || defined(__PGI) || FMT_NVCC
+#if FMT_ICC_VERSION || defined(__PGI) || FMT_NVCC
 #  define FMT_DEPRECATED_ALIAS
 #else
 #  define FMT_DEPRECATED_ALIAS FMT_DEPRECATED
 #endif
 
+#ifndef FMT_INLINE
+#  if FMT_GCC_VERSION || FMT_CLANG_VERSION
+#    define FMT_INLINE inline __attribute__((always_inline))
+#  else
+#    define FMT_INLINE inline
+#  endif
+#endif
+
 #ifndef FMT_BEGIN_NAMESPACE
 #  if FMT_HAS_FEATURE(cxx_inline_namespaces) || FMT_GCC_VERSION >= 404 || \
       FMT_MSC_VER >= 1900
@@ -181,39 +188,29 @@
 #    define FMT_INLINE_NAMESPACE namespace
 #    define FMT_END_NAMESPACE \
       }                       \
-      using namespace v6;     \
+      using namespace v7;     \
       }
 #  endif
 #  define FMT_BEGIN_NAMESPACE \
     namespace fmt {           \
-    FMT_INLINE_NAMESPACE v6 {
+    FMT_INLINE_NAMESPACE v7 {
 #endif
 
 #if !defined(FMT_HEADER_ONLY) && defined(_WIN32)
-#  if FMT_MSC_VER
-#    define FMT_NO_W4275 __pragma(warning(suppress : 4275))
-#  else
-#    define FMT_NO_W4275
-#  endif
-#  define FMT_CLASS_API FMT_NO_W4275
+#  define FMT_CLASS_API FMT_SUPPRESS_MSC_WARNING(4275)
 #  ifdef FMT_EXPORT
 #    define FMT_API __declspec(dllexport)
+#    define FMT_EXTERN_TEMPLATE_API FMT_API
+#    define FMT_EXPORTED
 #  elif defined(FMT_SHARED)
 #    define FMT_API __declspec(dllimport)
 #    define FMT_EXTERN_TEMPLATE_API FMT_API
 #  endif
-#endif
-#ifndef FMT_CLASS_API
+#else
 #  define FMT_CLASS_API
 #endif
 #ifndef FMT_API
-#  if FMT_GCC_VERSION || FMT_CLANG_VERSION
-#    define FMT_API __attribute__((visibility("default")))
-#    define FMT_EXTERN_TEMPLATE_API FMT_API
-#    define FMT_INSTANTIATION_DEF_API
-#  else
-#    define FMT_API
-#  endif
+#  define FMT_API
 #endif
 #ifndef FMT_EXTERN_TEMPLATE_API
 #  define FMT_EXTERN_TEMPLATE_API
@@ -270,14 +267,11 @@ struct monostate {};
 // to workaround a bug in MSVC 2019 (see #1140 and #1186).
 #define FMT_ENABLE_IF(...) enable_if_t<(__VA_ARGS__), int> = 0
 
-namespace internal {
+namespace detail {
 
 // A helper function to suppress bogus "conditional expression is constant"
 // warnings.
-template <typename T> FMT_CONSTEXPR T const_check(T value) { return value; }
-
-// A workaround for gcc 4.8 to make void_t work in a SFINAE context.
-template <typename... Ts> struct void_t_impl { using type = void; };
+template <typename T> constexpr T const_check(T value) { return value; }
 
 FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
                                       const char* message);
@@ -290,7 +284,7 @@ FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
 #    define FMT_ASSERT(condition, message)                                    \
       ((condition) /* void() fails with -Winvalid-constexpr on clang 4.0.1 */ \
            ? (void)0                                                          \
-           : ::fmt::internal::assert_fail(__FILE__, __LINE__, (message)))
+           : ::fmt::detail::assert_fail(__FILE__, __LINE__, (message)))
 #  endif
 #endif
 
@@ -305,7 +299,7 @@ template <typename T> struct std_string_view {};
 
 #ifdef FMT_USE_INT128
 // Do nothing.
-#elif defined(__SIZEOF_INT128__) && !FMT_NVCC
+#elif defined(__SIZEOF_INT128__) && !FMT_NVCC && !(FMT_CLANG_VERSION && FMT_MSC_VER)
 #  define FMT_USE_INT128 1
 using int128_t = __int128_t;
 using uint128_t = __uint128_t;
@@ -324,7 +318,7 @@ FMT_CONSTEXPR typename std::make_unsigned<Int>::type to_unsigned(Int value) {
   return static_cast<typename std::make_unsigned<Int>::type>(value);
 }
 
-constexpr unsigned char micro[] = "\u00B5";
+FMT_SUPPRESS_MSC_WARNING(4566) constexpr unsigned char micro[] = "\u00B5";
 
 template <typename Char> constexpr bool is_unicode() {
   return FMT_UNICODE || sizeof(Char) != 1 ||
@@ -336,10 +330,11 @@ using char8_type = char8_t;
 #else
 enum char8_type : unsigned char {};
 #endif
-}  // namespace internal
+}  // namespace detail
 
-template <typename... Ts>
-using void_t = typename internal::void_t_impl<Ts...>::type;
+#ifdef FMT_USE_INTERNAL
+namespace internal = detail;  // DEPRECATED
+#endif
 
 /**
   An implementation of ``std::basic_string_view`` for pre-C++17. It provides a
@@ -354,14 +349,13 @@ template <typename Char> class basic_string_view {
   size_t size_;
 
  public:
-  using char_type FMT_DEPRECATED_ALIAS = Char;
   using value_type = Char;
   using iterator = const Char*;
 
-  FMT_CONSTEXPR basic_string_view() FMT_NOEXCEPT : data_(nullptr), size_(0) {}
+  constexpr basic_string_view() FMT_NOEXCEPT : data_(nullptr), size_(0) {}
 
   /** Constructs a string reference object from a C string and a size. */
-  FMT_CONSTEXPR basic_string_view(const Char* s, size_t count) FMT_NOEXCEPT
+  constexpr basic_string_view(const Char* s, size_t count) FMT_NOEXCEPT
       : data_(s),
         size_(count) {}
 
@@ -384,22 +378,21 @@ template <typename Char> class basic_string_view {
       : data_(s.data()),
         size_(s.size()) {}
 
-  template <
-      typename S,
-      FMT_ENABLE_IF(std::is_same<S, internal::std_string_view<Char>>::value)>
+  template <typename S, FMT_ENABLE_IF(std::is_same<
+                                      S, detail::std_string_view<Char>>::value)>
   FMT_CONSTEXPR basic_string_view(S s) FMT_NOEXCEPT : data_(s.data()),
                                                       size_(s.size()) {}
 
   /** Returns a pointer to the string data. */
-  FMT_CONSTEXPR const Char* data() const { return data_; }
+  constexpr const Char* data() const { return data_; }
 
   /** Returns the string size. */
-  FMT_CONSTEXPR size_t size() const { return size_; }
+  constexpr size_t size() const { return size_; }
 
-  FMT_CONSTEXPR iterator begin() const { return data_; }
-  FMT_CONSTEXPR iterator end() const { return data_ + size_; }
+  constexpr iterator begin() const { return data_; }
+  constexpr iterator end() const { return data_ + size_; }
 
-  FMT_CONSTEXPR const Char& operator[](size_t pos) const { return data_[pos]; }
+  constexpr const Char& operator[](size_t pos) const { return data_[pos]; }
 
   FMT_CONSTEXPR void remove_prefix(size_t n) {
     data_ += n;
@@ -438,16 +431,11 @@ template <typename Char> class basic_string_view {
 using string_view = basic_string_view<char>;
 using wstring_view = basic_string_view<wchar_t>;
 
-#ifndef __cpp_char8_t
-// char8_t is deprecated; use char instead.
-using char8_t FMT_DEPRECATED_ALIAS = internal::char8_type;
-#endif
-
 /** Specifies if ``T`` is a character type. Can be specialized by users. */
 template <typename T> struct is_char : std::false_type {};
 template <> struct is_char<char> : std::true_type {};
 template <> struct is_char<wchar_t> : std::true_type {};
-template <> struct is_char<internal::char8_type> : std::true_type {};
+template <> struct is_char<detail::char8_type> : std::true_type {};
 template <> struct is_char<char16_t> : std::true_type {};
 template <> struct is_char<char32_t> : std::true_type {};
 
@@ -484,14 +472,13 @@ inline basic_string_view<Char> to_string_view(basic_string_view<Char> s) {
 }
 
 template <typename Char,
-          FMT_ENABLE_IF(!std::is_empty<internal::std_string_view<Char>>::value)>
-inline basic_string_view<Char> to_string_view(
-    internal::std_string_view<Char> s) {
+          FMT_ENABLE_IF(!std::is_empty<detail::std_string_view<Char>>::value)>
+inline basic_string_view<Char> to_string_view(detail::std_string_view<Char> s) {
   return s;
 }
 
 // A base class for compile-time strings. It is defined in the fmt namespace to
-// make formatting functions visible via ADL, e.g. format(fmt("{}"), 42).
+// make formatting functions visible via ADL, e.g. format(FMT_STRING("{}"), 42).
 struct compile_string {};
 
 template <typename S>
@@ -502,9 +489,9 @@ constexpr basic_string_view<typename S::char_type> to_string_view(const S& s) {
   return s;
 }
 
-namespace internal {
+namespace detail {
 void to_string_view(...);
-using fmt::v6::to_string_view;
+using fmt::v7::to_string_view;
 
 // Specifies whether S is a string type convertible to fmt::basic_string_view.
 // It should be a constexpr function but MSVC 2017 fails to compile it in
@@ -520,16 +507,16 @@ template <typename S> struct char_t_impl<S, enable_if_t<is_string<S>::value>> {
 };
 
 struct error_handler {
-  FMT_CONSTEXPR error_handler() = default;
-  FMT_CONSTEXPR error_handler(const error_handler&) = default;
+  constexpr error_handler() = default;
+  constexpr error_handler(const error_handler&) = default;
 
   // This function is intentionally not constexpr to give a compile-time error.
   FMT_NORETURN FMT_API void on_error(const char* message);
 };
-}  // namespace internal
+}  // namespace detail
 
 /** String's character type. */
-template <typename S> using char_t = typename internal::char_t_impl<S>::type;
+template <typename S> using char_t = typename detail::char_t_impl<S>::type;
 
 /**
   \rst
@@ -547,7 +534,7 @@ template <typename S> using char_t = typename internal::char_t_impl<S>::type;
   +-----------------------+-------------------------------------+
   \endrst
  */
-template <typename Char, typename ErrorHandler = internal::error_handler>
+template <typename Char, typename ErrorHandler = detail::error_handler>
 class basic_format_parse_context : private ErrorHandler {
  private:
   basic_string_view<Char> format_str_;
@@ -557,26 +544,24 @@ class basic_format_parse_context : private ErrorHandler {
   using char_type = Char;
   using iterator = typename basic_string_view<Char>::iterator;
 
-  explicit FMT_CONSTEXPR basic_format_parse_context(
-      basic_string_view<Char> format_str, ErrorHandler eh = ErrorHandler())
+  explicit constexpr basic_format_parse_context(
+      basic_string_view<Char> format_str, ErrorHandler eh = {})
       : ErrorHandler(eh), format_str_(format_str), next_arg_id_(0) {}
 
   /**
     Returns an iterator to the beginning of the format string range being
     parsed.
    */
-  FMT_CONSTEXPR iterator begin() const FMT_NOEXCEPT {
-    return format_str_.begin();
-  }
+  constexpr iterator begin() const FMT_NOEXCEPT { return format_str_.begin(); }
 
   /**
     Returns an iterator past the end of the format string range being parsed.
    */
-  FMT_CONSTEXPR iterator end() const FMT_NOEXCEPT { return format_str_.end(); }
+  constexpr iterator end() const FMT_NOEXCEPT { return format_str_.end(); }
 
   /** Advances the begin iterator to ``it``. */
   FMT_CONSTEXPR void advance_to(iterator it) {
-    format_str_.remove_prefix(internal::to_unsigned(it - begin()));
+    format_str_.remove_prefix(detail::to_unsigned(it - begin()));
   }
 
   /**
@@ -584,6 +569,8 @@ class basic_format_parse_context : private ErrorHandler {
     the next argument index and switches to the automatic indexing.
    */
   FMT_CONSTEXPR int next_arg_id() {
+    // Don't check if the argument id is valid to avoid overhead and because it
+    // will be checked during formatting anyway.
     if (next_arg_id_ >= 0) return next_arg_id_++;
     on_error("cannot switch from manual to automatic argument indexing");
     return 0;
@@ -606,20 +593,15 @@ class basic_format_parse_context : private ErrorHandler {
     ErrorHandler::on_error(message);
   }
 
-  FMT_CONSTEXPR ErrorHandler error_handler() const { return *this; }
+  constexpr ErrorHandler error_handler() const { return *this; }
 };
 
 using format_parse_context = basic_format_parse_context<char>;
 using wformat_parse_context = basic_format_parse_context<wchar_t>;
 
-template <typename Char, typename ErrorHandler = internal::error_handler>
-using basic_parse_context FMT_DEPRECATED_ALIAS =
-    basic_format_parse_context<Char, ErrorHandler>;
-using parse_context FMT_DEPRECATED_ALIAS = basic_format_parse_context<char>;
-using wparse_context FMT_DEPRECATED_ALIAS = basic_format_parse_context<wchar_t>;
-
 template <typename Context> class basic_format_arg;
 template <typename Context> class basic_format_args;
+template <typename Context> class dynamic_format_arg_store;
 
 // A formatter for objects of type T.
 template <typename T, typename Char = char, typename Enable = void>
@@ -628,43 +610,44 @@ struct formatter {
   formatter() = delete;
 };
 
-template <typename T, typename Char, typename Enable = void>
-struct FMT_DEPRECATED convert_to_int
-    : bool_constant<!std::is_arithmetic<T>::value &&
-                    std::is_convertible<T, int>::value> {};
-
 // Specifies if T has an enabled formatter specialization. A type can be
 // formattable even if it doesn't have a formatter e.g. via a conversion.
 template <typename T, typename Context>
 using has_formatter =
     std::is_constructible<typename Context::template formatter_type<T>>;
 
-namespace internal {
+namespace detail {
 
-/** A contiguous memory buffer with an optional growing ability. */
+/**
+  \rst
+  A contiguous memory buffer with an optional growing ability. It is an internal
+  class and shouldn't be used directly, only via `~fmt::basic_memory_buffer`.
+  \endrst
+ */
 template <typename T> class buffer {
  private:
   T* ptr_;
-  std::size_t size_;
-  std::size_t capacity_;
+  size_t size_;
+  size_t capacity_;
 
  protected:
   // Don't initialize ptr_ since it is not accessed to save a few cycles.
-  buffer(std::size_t sz) FMT_NOEXCEPT : size_(sz), capacity_(sz) {}
+  FMT_SUPPRESS_MSC_WARNING(26495)
+  buffer(size_t sz) FMT_NOEXCEPT : size_(sz), capacity_(sz) {}
 
-  buffer(T* p = nullptr, std::size_t sz = 0, std::size_t cap = 0) FMT_NOEXCEPT
+  buffer(T* p = nullptr, size_t sz = 0, size_t cap = 0) FMT_NOEXCEPT
       : ptr_(p),
         size_(sz),
         capacity_(cap) {}
 
   /** Sets the buffer data and capacity. */
-  void set(T* buf_data, std::size_t buf_capacity) FMT_NOEXCEPT {
+  void set(T* buf_data, size_t buf_capacity) FMT_NOEXCEPT {
     ptr_ = buf_data;
     capacity_ = buf_capacity;
   }
 
   /** Increases the buffer capacity to hold at least *capacity* elements. */
-  virtual void grow(std::size_t capacity) = 0;
+  virtual void grow(size_t capacity) = 0;
 
  public:
   using value_type = T;
@@ -681,10 +664,10 @@ template <typename T> class buffer {
   const T* end() const FMT_NOEXCEPT { return ptr_ + size_; }
 
   /** Returns the size of this buffer. */
-  std::size_t size() const FMT_NOEXCEPT { return size_; }
+  size_t size() const FMT_NOEXCEPT { return size_; }
 
   /** Returns the capacity of this buffer. */
-  std::size_t capacity() const FMT_NOEXCEPT { return capacity_; }
+  size_t capacity() const FMT_NOEXCEPT { return capacity_; }
 
   /** Returns a pointer to the buffer data. */
   T* data() FMT_NOEXCEPT { return ptr_; }
@@ -695,7 +678,7 @@ template <typename T> class buffer {
   /**
     Resizes the buffer. If T is a POD type new elements may not be initialized.
    */
-  void resize(std::size_t new_size) {
+  void resize(size_t new_size) {
     reserve(new_size);
     size_ = new_size;
   }
@@ -704,7 +687,7 @@ template <typename T> class buffer {
   void clear() { size_ = 0; }
 
   /** Reserves space to store at least *capacity* elements. */
-  void reserve(std::size_t new_capacity) {
+  void reserve(size_t new_capacity) {
     if (new_capacity > capacity_) grow(new_capacity);
   }
 
@@ -729,7 +712,7 @@ class container_buffer : public buffer<typename Container::value_type> {
   Container& container_;
 
  protected:
-  void grow(std::size_t capacity) FMT_OVERRIDE {
+  void grow(size_t capacity) FMT_OVERRIDE {
     container_.resize(capacity);
     this->set(&container_[0], capacity);
   }
@@ -760,12 +743,78 @@ template <typename T, typename Context>
 using has_fallback_formatter =
     std::is_constructible<fallback_formatter<T, typename Context::char_type>>;
 
-template <typename Char> struct named_arg_base;
-template <typename T, typename Char> struct named_arg;
+struct view {};
+
+template <typename Char, typename T> struct named_arg : view {
+  const Char* name;
+  const T& value;
+  named_arg(const Char* n, const T& v) : name(n), value(v) {}
+};
+
+template <typename Char> struct named_arg_info {
+  const Char* name;
+  int id;
+};
+
+template <typename T, typename Char, size_t NUM_ARGS, size_t NUM_NAMED_ARGS>
+struct arg_data {
+  // args_[0].named_args points to named_args_ to avoid bloating format_args.
+  T args_[1 + (NUM_ARGS != 0 ? NUM_ARGS : 1)];
+  named_arg_info<Char> named_args_[NUM_NAMED_ARGS];
+
+  template <typename... U>
+  arg_data(const U&... init) : args_{T(named_args_, NUM_NAMED_ARGS), init...} {}
+  arg_data(const arg_data& other) = delete;
+  const T* args() const { return args_ + 1; }
+  named_arg_info<Char>* named_args() { return named_args_; }
+};
+
+template <typename T, typename Char, size_t NUM_ARGS>
+struct arg_data<T, Char, NUM_ARGS, 0> {
+  T args_[NUM_ARGS != 0 ? NUM_ARGS : 1];
+
+  template <typename... U>
+  FMT_INLINE arg_data(const U&... init) : args_{init...} {}
+  FMT_INLINE const T* args() const { return args_; }
+  FMT_INLINE std::nullptr_t named_args() { return nullptr; }
+};
+
+template <typename Char>
+inline void init_named_args(named_arg_info<Char>*, int, int) {}
+
+template <typename Char, typename T, typename... Tail>
+void init_named_args(named_arg_info<Char>* named_args, int arg_count,
+                     int named_arg_count, const T&, const Tail&... args) {
+  init_named_args(named_args, arg_count + 1, named_arg_count, args...);
+}
+
+template <typename Char, typename T, typename... Tail>
+void init_named_args(named_arg_info<Char>* named_args, int arg_count,
+                     int named_arg_count, const named_arg<Char, T>& arg,
+                     const Tail&... args) {
+  named_args[named_arg_count++] = {arg.name, arg_count};
+  init_named_args(named_args, arg_count + 1, named_arg_count, args...);
+}
+
+template <typename... Args>
+FMT_INLINE void init_named_args(std::nullptr_t, int, int, const Args&...) {}
+
+template <typename T> struct is_named_arg : std::false_type {};
+
+template <typename T, typename Char>
+struct is_named_arg<named_arg<Char, T>> : std::true_type {};
+
+template <bool B = false> constexpr size_t count() { return B ? 1 : 0; }
+template <bool B1, bool B2, bool... Tail> constexpr size_t count() {
+  return (B1 ? 1 : 0) + count<B2, Tail...>();
+}
+
+template <typename... Args> constexpr size_t count_named_args() {
+  return count<is_named_arg<Args>::value...>();
+}
 
 enum class type {
   none_type,
-  named_arg_type,
   // Integer types should go first,
   int_type,
   uint_type,
@@ -796,7 +845,6 @@ struct type_constant : std::integral_constant<type, type::custom_type> {};
   struct type_constant<Type, Char>        \
       : std::integral_constant<type, type::constant> {}
 
-FMT_TYPE_CONSTANT(const named_arg_base<Char>&, named_arg_type);
 FMT_TYPE_CONSTANT(int, int_type);
 FMT_TYPE_CONSTANT(unsigned, uint_type);
 FMT_TYPE_CONSTANT(long long, long_long_type);
@@ -812,26 +860,28 @@ FMT_TYPE_CONSTANT(const Char*, cstring_type);
 FMT_TYPE_CONSTANT(basic_string_view<Char>, string_type);
 FMT_TYPE_CONSTANT(const void*, pointer_type);
 
-FMT_CONSTEXPR bool is_integral_type(type t) {
-  FMT_ASSERT(t != type::named_arg_type, "invalid argument type");
+constexpr bool is_integral_type(type t) {
   return t > type::none_type && t <= type::last_integer_type;
 }
 
-FMT_CONSTEXPR bool is_arithmetic_type(type t) {
-  FMT_ASSERT(t != type::named_arg_type, "invalid argument type");
+constexpr bool is_arithmetic_type(type t) {
   return t > type::none_type && t <= type::last_numeric_type;
 }
 
 template <typename Char> struct string_value {
   const Char* data;
-  std::size_t size;
+  size_t size;
+};
+
+template <typename Char> struct named_arg_value {
+  const named_arg_info<Char>* data;
+  size_t size;
 };
 
 template <typename Context> struct custom_value {
-  using parse_context = basic_format_parse_context<typename Context::char_type>;
+  using parse_context = typename Context::parse_context_type;
   const void* value;
-  void (*format)(const void* arg,
-                 typename Context::parse_context_type& parse_ctx, Context& ctx);
+  void (*format)(const void* arg, parse_context& parse_ctx, Context& ctx);
 };
 
 // A formatting argument value.
@@ -854,28 +904,30 @@ template <typename Context> class value {
     const void* pointer;
     string_value<char_type> string;
     custom_value<Context> custom;
-    const named_arg_base<char_type>* named_arg;
+    named_arg_value<char_type> named_args;
   };
 
-  FMT_CONSTEXPR value(int val = 0) : int_value(val) {}
-  FMT_CONSTEXPR value(unsigned val) : uint_value(val) {}
-  value(long long val) : long_long_value(val) {}
-  value(unsigned long long val) : ulong_long_value(val) {}
-  value(int128_t val) : int128_value(val) {}
-  value(uint128_t val) : uint128_value(val) {}
-  value(float val) : float_value(val) {}
-  value(double val) : double_value(val) {}
-  value(long double val) : long_double_value(val) {}
-  value(bool val) : bool_value(val) {}
-  value(char_type val) : char_value(val) {}
-  value(const char_type* val) { string.data = val; }
-  value(basic_string_view<char_type> val) {
+  constexpr FMT_INLINE value(int val = 0) : int_value(val) {}
+  constexpr FMT_INLINE value(unsigned val) : uint_value(val) {}
+  FMT_INLINE value(long long val) : long_long_value(val) {}
+  FMT_INLINE value(unsigned long long val) : ulong_long_value(val) {}
+  FMT_INLINE value(int128_t val) : int128_value(val) {}
+  FMT_INLINE value(uint128_t val) : uint128_value(val) {}
+  FMT_INLINE value(float val) : float_value(val) {}
+  FMT_INLINE value(double val) : double_value(val) {}
+  FMT_INLINE value(long double val) : long_double_value(val) {}
+  FMT_INLINE value(bool val) : bool_value(val) {}
+  FMT_INLINE value(char_type val) : char_value(val) {}
+  FMT_INLINE value(const char_type* val) { string.data = val; }
+  FMT_INLINE value(basic_string_view<char_type> val) {
     string.data = val.data();
     string.size = val.size();
   }
-  value(const void* val) : pointer(val) {}
+  FMT_INLINE value(const void* val) : pointer(val) {}
+  FMT_INLINE value(const named_arg_info<char_type>* args, size_t size)
+      : named_args{args, size} {}
 
-  template <typename T> value(const T& val) {
+  template <typename T> FMT_INLINE value(const T& val) {
     custom.value = &val;
     // Get the formatter type through the context to allow different contexts
     // have different extension points, e.g. `formatter<T>` for `format` and
@@ -886,8 +938,6 @@ template <typename Context> class value {
                          fallback_formatter<T, char_type>>>;
   }
 
-  value(const named_arg_base<char_type>& val) { named_arg = &val; }
-
  private:
   // Formats an argument of a custom type, such as a user-defined class.
   template <typename T, typename Formatter>
@@ -973,6 +1023,14 @@ template <typename Context> struct arg_mapper {
     static_assert(std::is_same<char_type, char>::value, "invalid string type");
     return reinterpret_cast<const char*>(val);
   }
+  FMT_CONSTEXPR const char* map(signed char* val) {
+    const auto* const_val = val;
+    return map(const_val);
+  }
+  FMT_CONSTEXPR const char* map(unsigned char* val) {
+    const auto* const_val = val;
+    return map(const_val);
+  }
 
   FMT_CONSTEXPR const void* map(void* val) { return val; }
   FMT_CONSTEXPR const void* map(const void* val) { return val; }
@@ -1004,11 +1062,9 @@ template <typename Context> struct arg_mapper {
   }
 
   template <typename T>
-  FMT_CONSTEXPR const named_arg_base<char_type>& map(
-      const named_arg<T, char_type>& val) {
-    auto arg = make_arg<Context>(val.value);
-    std::memcpy(val.data, &arg, sizeof(arg));
-    return val;
+  FMT_CONSTEXPR auto map(const named_arg<char_type, T>& val)
+      -> decltype(std::declval<arg_mapper>().map(val.value)) {
+    return map(val.value);
   }
 
   int map(...) {
@@ -1028,23 +1084,22 @@ using mapped_type_constant =
     type_constant<decltype(arg_mapper<Context>().map(std::declval<const T&>())),
                   typename Context::char_type>;
 
-enum { packed_arg_bits = 5 };
+enum { packed_arg_bits = 4 };
 // Maximum number of arguments with packed types.
-enum { max_packed_args = 63 / packed_arg_bits };
+enum { max_packed_args = 62 / packed_arg_bits };
 enum : unsigned long long { is_unpacked_bit = 1ULL << 63 };
-
-template <typename Context> class arg_map;
-}  // namespace internal
+enum : unsigned long long { has_named_args_bit = 1ULL << 62 };
+}  // namespace detail
 
 // A formatting argument. It is a trivially copyable/constructible type to
 // allow storage in basic_memory_buffer.
 template <typename Context> class basic_format_arg {
  private:
-  internal::value<Context> value_;
-  internal::type type_;
+  detail::value<Context> value_;
+  detail::type type_;
 
   template <typename ContextType, typename T>
-  friend FMT_CONSTEXPR basic_format_arg<ContextType> internal::make_arg(
+  friend FMT_CONSTEXPR basic_format_arg<ContextType> detail::make_arg(
       const T& value);
 
   template <typename Visitor, typename Ctx>
@@ -1053,14 +1108,20 @@ template <typename Context> class basic_format_arg {
       -> decltype(vis(0));
 
   friend class basic_format_args<Context>;
-  friend class internal::arg_map<Context>;
+  friend class dynamic_format_arg_store<Context>;
 
   using char_type = typename Context::char_type;
 
+  template <typename T, typename Char, size_t NUM_ARGS, size_t NUM_NAMED_ARGS>
+  friend struct detail::arg_data;
+
+  basic_format_arg(const detail::named_arg_info<char_type>* args, size_t size)
+      : value_(args, size) {}
+
  public:
   class handle {
    public:
-    explicit handle(internal::custom_value<Context> custom) : custom_(custom) {}
+    explicit handle(detail::custom_value<Context> custom) : custom_(custom) {}
 
     void format(typename Context::parse_context_type& parse_ctx,
                 Context& ctx) const {
@@ -1068,19 +1129,19 @@ template <typename Context> class basic_format_arg {
     }
 
    private:
-    internal::custom_value<Context> custom_;
+    detail::custom_value<Context> custom_;
   };
 
-  FMT_CONSTEXPR basic_format_arg() : type_(internal::type::none_type) {}
+  constexpr basic_format_arg() : type_(detail::type::none_type) {}
 
-  FMT_CONSTEXPR explicit operator bool() const FMT_NOEXCEPT {
-    return type_ != internal::type::none_type;
+  constexpr explicit operator bool() const FMT_NOEXCEPT {
+    return type_ != detail::type::none_type;
   }
 
-  internal::type type() const { return type_; }
+  detail::type type() const { return type_; }
 
-  bool is_integral() const { return internal::is_integral_type(type_); }
-  bool is_arithmetic() const { return internal::is_arithmetic_type(type_); }
+  bool is_integral() const { return detail::is_integral_type(type_); }
+  bool is_arithmetic() const { return detail::is_arithmetic_type(type_); }
 };
 
 /**
@@ -1091,92 +1152,73 @@ template <typename Context> class basic_format_arg {
   \endrst
  */
 template <typename Visitor, typename Context>
-FMT_CONSTEXPR auto visit_format_arg(Visitor&& vis,
-                                    const basic_format_arg<Context>& arg)
-    -> decltype(vis(0)) {
+FMT_CONSTEXPR_DECL FMT_INLINE auto visit_format_arg(
+    Visitor&& vis, const basic_format_arg<Context>& arg) -> decltype(vis(0)) {
   using char_type = typename Context::char_type;
   switch (arg.type_) {
-  case internal::type::none_type:
+  case detail::type::none_type:
     break;
-  case internal::type::named_arg_type:
-    FMT_ASSERT(false, "invalid argument type");
-    break;
-  case internal::type::int_type:
+  case detail::type::int_type:
     return vis(arg.value_.int_value);
-  case internal::type::uint_type:
+  case detail::type::uint_type:
     return vis(arg.value_.uint_value);
-  case internal::type::long_long_type:
+  case detail::type::long_long_type:
     return vis(arg.value_.long_long_value);
-  case internal::type::ulong_long_type:
+  case detail::type::ulong_long_type:
     return vis(arg.value_.ulong_long_value);
 #if FMT_USE_INT128
-  case internal::type::int128_type:
+  case detail::type::int128_type:
     return vis(arg.value_.int128_value);
-  case internal::type::uint128_type:
+  case detail::type::uint128_type:
     return vis(arg.value_.uint128_value);
 #else
-  case internal::type::int128_type:
-  case internal::type::uint128_type:
+  case detail::type::int128_type:
+  case detail::type::uint128_type:
     break;
 #endif
-  case internal::type::bool_type:
+  case detail::type::bool_type:
     return vis(arg.value_.bool_value);
-  case internal::type::char_type:
+  case detail::type::char_type:
     return vis(arg.value_.char_value);
-  case internal::type::float_type:
+  case detail::type::float_type:
     return vis(arg.value_.float_value);
-  case internal::type::double_type:
+  case detail::type::double_type:
     return vis(arg.value_.double_value);
-  case internal::type::long_double_type:
+  case detail::type::long_double_type:
     return vis(arg.value_.long_double_value);
-  case internal::type::cstring_type:
+  case detail::type::cstring_type:
     return vis(arg.value_.string.data);
-  case internal::type::string_type:
+  case detail::type::string_type:
     return vis(basic_string_view<char_type>(arg.value_.string.data,
                                             arg.value_.string.size));
-  case internal::type::pointer_type:
+  case detail::type::pointer_type:
     return vis(arg.value_.pointer);
-  case internal::type::custom_type:
+  case detail::type::custom_type:
     return vis(typename basic_format_arg<Context>::handle(arg.value_.custom));
   }
   return vis(monostate());
 }
 
-namespace internal {
-// A map from argument names to their values for named arguments.
-template <typename Context> class arg_map {
- private:
-  using char_type = typename Context::char_type;
-
-  struct entry {
-    basic_string_view<char_type> name;
-    basic_format_arg<Context> arg;
-  };
+// Checks whether T is a container with contiguous storage.
+template <typename T> struct is_contiguous : std::false_type {};
+template <typename Char>
+struct is_contiguous<std::basic_string<Char>> : std::true_type {};
+template <typename Char>
+struct is_contiguous<detail::buffer<Char>> : std::true_type {};
 
-  entry* map_;
-  unsigned size_;
+namespace detail {
 
-  void push_back(value<Context> val) {
-    const auto& named = *val.named_arg;
-    map_[size_] = {named.name, named.template deserialize<Context>()};
-    ++size_;
-  }
+template <typename OutputIt>
+struct is_back_insert_iterator : std::false_type {};
+template <typename Container>
+struct is_back_insert_iterator<std::back_insert_iterator<Container>>
+    : std::true_type {};
 
- public:
-  arg_map(const arg_map&) = delete;
-  void operator=(const arg_map&) = delete;
-  arg_map() : map_(nullptr), size_(0) {}
-  void init(const basic_format_args<Context>& args);
-  ~arg_map() { delete[] map_; }
-
-  basic_format_arg<Context> find(basic_string_view<char_type> name) const {
-    // The list is unsorted, so just return the first matching name.
-    for (entry *it = map_, *end = map_ + size_; it != end; ++it) {
-      if (it->name == name) return it->arg;
-    }
-    return {};
-  }
-};
+template <typename OutputIt>
+struct is_contiguous_back_insert_iterator : std::false_type {};
+template <typename Container>
+struct is_contiguous_back_insert_iterator<std::back_insert_iterator<Container>>
+    : is_contiguous<Container> {};
 
 // A type-erased reference to an std::locale to avoid heavy <locale> include.
 class locale_ref {
@@ -1224,10 +1266,14 @@ inline basic_format_arg<Context> make_arg(const T& value) {
 }
 
 template <typename T> struct is_reference_wrapper : std::false_type {};
-
 template <typename T>
 struct is_reference_wrapper<std::reference_wrapper<T>> : std::true_type {};
 
+template <typename T> const T& unwrap(const T& v) { return v; }
+template <typename T> const T& unwrap(const std::reference_wrapper<T>& v) {
+  return static_cast<const T&>(v);
+}
+
 class dynamic_arg_list {
   // Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
   // templates it doesn't complain about inability to deduce single translation
@@ -1252,14 +1298,14 @@ class dynamic_arg_list {
 
  public:
   template <typename T, typename Arg> const T& push(const Arg& arg) {
-    auto node = std::unique_ptr<typed_node<T>>(new typed_node<T>(arg));
-    auto& value = node->value;
-    node->next = std::move(head_);
-    head_ = std::move(node);
+    auto new_node = std::unique_ptr<typed_node<T>>(new typed_node<T>(arg));
+    auto& value = new_node->value;
+    new_node->next = std::move(head_);
+    head_ = std::move(new_node);
     return value;
   }
 };
-}  // namespace internal
+}  // namespace detail
 
 // Formatting context.
 template <typename OutputIt, typename Char> class basic_format_context {
@@ -1270,8 +1316,7 @@ template <typename OutputIt, typename Char> class basic_format_context {
  private:
   OutputIt out_;
   basic_format_args<basic_format_context> args_;
-  internal::arg_map<basic_format_context> map_;
-  internal::locale_ref loc_;
+  detail::locale_ref loc_;
 
  public:
   using iterator = OutputIt;
@@ -1287,34 +1332,38 @@ template <typename OutputIt, typename Char> class basic_format_context {
    */
   basic_format_context(OutputIt out,
                        basic_format_args<basic_format_context> ctx_args,
-                       internal::locale_ref loc = internal::locale_ref())
+                       detail::locale_ref loc = detail::locale_ref())
       : out_(out), args_(ctx_args), loc_(loc) {}
 
   format_arg arg(int id) const { return args_.get(id); }
+  format_arg arg(basic_string_view<char_type> name) { return args_.get(name); }
+  int arg_id(basic_string_view<char_type> name) { return args_.get_id(name); }
+  const basic_format_args<basic_format_context>& args() const { return args_; }
 
-  // Checks if manual indexing is used and returns the argument with the
-  // specified name.
-  format_arg arg(basic_string_view<char_type> name);
-
-  internal::error_handler error_handler() { return {}; }
+  detail::error_handler error_handler() { return {}; }
   void on_error(const char* message) { error_handler().on_error(message); }
 
   // Returns an iterator to the beginning of the output range.
   iterator out() { return out_; }
 
   // Advances the begin iterator to ``it``.
-  void advance_to(iterator it) { out_ = it; }
+  void advance_to(iterator it) {
+    if (!detail::is_back_insert_iterator<iterator>()) out_ = it;
+  }
 
-  internal::locale_ref locale() { return loc_; }
+  detail::locale_ref locale() { return loc_; }
 };
 
 template <typename Char>
 using buffer_context =
-    basic_format_context<std::back_insert_iterator<internal::buffer<Char>>,
-                         Char>;
+    basic_format_context<std::back_insert_iterator<detail::buffer<Char>>, Char>;
 using format_context = buffer_context<char>;
 using wformat_context = buffer_context<wchar_t>;
 
+// Workaround a bug in gcc: https://stackoverflow.com/q/62767544/471164.
+#define FMT_BUFFER_CONTEXT(Char) \
+  basic_format_context<std::back_insert_iterator<detail::buffer<Char>>, Char>
+
 /**
   \rst
   An array of references to arguments. It can be implicitly converted into
@@ -1331,29 +1380,35 @@ class format_arg_store
 {
  private:
   static const size_t num_args = sizeof...(Args);
-  static const bool is_packed = num_args < internal::max_packed_args;
+  static const size_t num_named_args = detail::count_named_args<Args...>();
+  static const bool is_packed = num_args <= detail::max_packed_args;
 
-  using value_type = conditional_t<is_packed, internal::value<Context>,
+  using value_type = conditional_t<is_packed, detail::value<Context>,
                                    basic_format_arg<Context>>;
 
-  // If the arguments are not packed, add one more element to mark the end.
-  value_type data_[num_args + (num_args == 0 ? 1 : 0)];
+  detail::arg_data<value_type, typename Context::char_type, num_args,
+                   num_named_args>
+      data_;
 
   friend class basic_format_args<Context>;
 
- public:
-  static constexpr unsigned long long types =
-      is_packed ? internal::encode_types<Context, Args...>()
-                : internal::is_unpacked_bit | num_args;
+  static constexpr unsigned long long desc =
+      (is_packed ? detail::encode_types<Context, Args...>()
+                 : detail::is_unpacked_bit | num_args) |
+      (num_named_args != 0
+           ? static_cast<unsigned long long>(detail::has_named_args_bit)
+           : 0);
 
+ public:
   format_arg_store(const Args&... args)
       :
 #if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
         basic_format_args<Context>(*this),
 #endif
-        data_{internal::make_arg<
+        data_{detail::make_arg<
             is_packed, Context,
-            internal::mapped_type_constant<Args, Context>::value>(args)...} {
+            detail::mapped_type_constant<Args, Context>::value>(args)...} {
+    detail::init_named_args(data_.named_args(), 0, 0, args...);
   }
 };
 
@@ -1373,8 +1428,24 @@ inline format_arg_store<Context, Args...> make_format_args(
 
 /**
   \rst
-  A dynamic version of `fmt::format_arg_store<>`.
-  It's equipped with a storage to potentially temporary objects which lifetime
+  Returns a named argument to be used in a formatting function. It should only
+  be used in a call to a formatting function.
+
+  **Example**::
+
+    fmt::print("Elapsed time: {s:.2f} seconds", fmt::arg("s", 1.23));
+  \endrst
+ */
+template <typename Char, typename T>
+inline detail::named_arg<Char, T> arg(const Char* name, const T& arg) {
+  static_assert(!detail::is_named_arg<T>(), "nested named arguments");
+  return {name, arg};
+}
+
+/**
+  \rst
+  A dynamic version of `fmt::format_arg_store`.
+  It's equipped with a storage to potentially temporary objects which lifetimes
   could be shorter than the format arguments object.
 
   It can be implicitly converted into `~fmt::basic_format_args` for passing
@@ -1392,49 +1463,73 @@ class dynamic_format_arg_store
   using char_type = typename Context::char_type;
 
   template <typename T> struct need_copy {
-    static constexpr internal::type mapped_type =
-        internal::mapped_type_constant<T, Context>::value;
+    static constexpr detail::type mapped_type =
+        detail::mapped_type_constant<T, Context>::value;
 
     enum {
-      value = !(internal::is_reference_wrapper<T>::value ||
+      value = !(detail::is_reference_wrapper<T>::value ||
                 std::is_same<T, basic_string_view<char_type>>::value ||
-                std::is_same<T, internal::std_string_view<char_type>>::value ||
-                (mapped_type != internal::type::cstring_type &&
-                 mapped_type != internal::type::string_type &&
-                 mapped_type != internal::type::custom_type &&
-                 mapped_type != internal::type::named_arg_type))
+                std::is_same<T, detail::std_string_view<char_type>>::value ||
+                (mapped_type != detail::type::cstring_type &&
+                 mapped_type != detail::type::string_type &&
+                 mapped_type != detail::type::custom_type))
     };
   };
 
   template <typename T>
-  using stored_type = conditional_t<internal::is_string<T>::value,
+  using stored_type = conditional_t<detail::is_string<T>::value,
                                     std::basic_string<char_type>, T>;
 
   // Storage of basic_format_arg must be contiguous.
   std::vector<basic_format_arg<Context>> data_;
+  std::vector<detail::named_arg_info<char_type>> named_info_;
 
   // Storage of arguments not fitting into basic_format_arg must grow
   // without relocation because items in data_ refer to it.
-  internal::dynamic_arg_list dynamic_args_;
+  detail::dynamic_arg_list dynamic_args_;
 
   friend class basic_format_args<Context>;
 
   unsigned long long get_types() const {
-    return internal::is_unpacked_bit | data_.size();
+    return detail::is_unpacked_bit | data_.size() |
+           (named_info_.empty()
+                ? 0ULL
+                : static_cast<unsigned long long>(detail::has_named_args_bit));
+  }
+
+  const basic_format_arg<Context>* data() const {
+    return named_info_.empty() ? data_.data() : data_.data() + 1;
   }
 
   template <typename T> void emplace_arg(const T& arg) {
-    data_.emplace_back(internal::make_arg<Context>(arg));
+    data_.emplace_back(detail::make_arg<Context>(arg));
+  }
+
+  template <typename T>
+  void emplace_arg(const detail::named_arg<char_type, T>& arg) {
+    if (named_info_.empty()) {
+      constexpr const detail::named_arg_info<char_type>* zero_ptr{nullptr};
+      data_.insert(data_.begin(), {zero_ptr, 0});
+    }
+    data_.emplace_back(detail::make_arg<Context>(detail::unwrap(arg.value)));
+    auto pop_one = [](std::vector<basic_format_arg<Context>>* data) {
+      data->pop_back();
+    };
+    std::unique_ptr<std::vector<basic_format_arg<Context>>, decltype(pop_one)>
+        guard{&data_, pop_one};
+    named_info_.push_back({arg.name, static_cast<int>(data_.size() - 2u)});
+    data_[0].value_.named_args = {named_info_.data(), named_info_.size()};
+    guard.release();
   }
 
  public:
   /**
     \rst
-    Adds an argument into the dynamic store for later passing to a formating
+    Adds an argument into the dynamic store for later passing to a formatting
     function.
 
-    Note that custom types and string types (but not string views!) are copied
-    into the store with dynamic memory (in addition to resizing vector).
+    Note that custom types and string types (but not string views) are copied
+    into the store dynamically allocating memory if necessary.
 
     **Example**::
 
@@ -1446,25 +1541,78 @@ class dynamic_format_arg_store
     \endrst
   */
   template <typename T> void push_back(const T& arg) {
-    static_assert(
-        !std::is_base_of<internal::named_arg_base<char_type>, T>::value,
-        "named arguments are not supported yet");
-    if (internal::const_check(need_copy<T>::value))
+    if (detail::const_check(need_copy<T>::value))
       emplace_arg(dynamic_args_.push<stored_type<T>>(arg));
     else
-      emplace_arg(arg);
+      emplace_arg(detail::unwrap(arg));
   }
 
   /**
+    \rst
     Adds a reference to the argument into the dynamic store for later passing to
-    a formating function.
+    a formatting function. Supports named arguments wrapped in
+    ``std::reference_wrapper`` via ``std::ref()``/``std::cref()``.
+
+    **Example**::
+
+      fmt::dynamic_format_arg_store<fmt::format_context> store;
+      char str[] = "1234567890";
+      store.push_back(std::cref(str));
+      int a1_val{42};
+      auto a1 = fmt::arg("a1_", a1_val);
+      store.push_back(std::cref(a1));
+
+      // Changing str affects the output but only for string and custom types.
+      str[0] = 'X';
+
+      std::string result = fmt::vformat("{} and {a1_}");
+      assert(result == "X234567890 and 42");
+    \endrst
   */
   template <typename T> void push_back(std::reference_wrapper<T> arg) {
     static_assert(
-        need_copy<T>::value,
+        detail::is_named_arg<typename std::remove_cv<T>::type>::value ||
+            need_copy<T>::value,
         "objects of built-in types and string views are always copied");
     emplace_arg(arg.get());
   }
+
+  /**
+    Adds named argument into the dynamic store for later passing to a formatting
+    function. ``std::reference_wrapper`` is supported to avoid copying of the
+    argument.
+  */
+  template <typename T>
+  void push_back(const detail::named_arg<char_type, T>& arg) {
+    const char_type* arg_name =
+        dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str();
+    if (detail::const_check(need_copy<T>::value)) {
+      emplace_arg(
+          fmt::arg(arg_name, dynamic_args_.push<stored_type<T>>(arg.value)));
+    } else {
+      emplace_arg(fmt::arg(arg_name, arg.value));
+    }
+  }
+
+  /** Erase all elements from the store */
+  void clear() {
+    data_.clear();
+    named_info_.clear();
+    dynamic_args_ = detail::dynamic_arg_list();
+  }
+
+  /**
+    \rst
+    Reserves space to store at least *new_cap* arguments including
+    *new_cap_named* named arguments.
+    \endrst
+  */
+  void reserve(size_t new_cap, size_t new_cap_named) {
+    FMT_ASSERT(new_cap >= new_cap_named,
+               "Set of arguments includes set of named arguments");
+    data_.reserve(new_cap);
+    named_info_.reserve(new_cap_named);
+  }
 };
 
 /**
@@ -1483,49 +1631,40 @@ template <typename Context> class basic_format_args {
   using format_arg = basic_format_arg<Context>;
 
  private:
-  // To reduce compiled code size per formatting function call, types of first
-  // max_packed_args arguments are passed in the types_ field.
-  unsigned long long types_;
+  // A descriptor that contains information about formatting arguments.
+  // If the number of arguments is less or equal to max_packed_args then
+  // argument types are passed in the descriptor. This reduces binary code size
+  // per formatting function call.
+  unsigned long long desc_;
   union {
-    // If the number of arguments is less than max_packed_args, the argument
-    // values are stored in values_, otherwise they are stored in args_.
-    // This is done to reduce compiled code size as storing larger objects
+    // If is_packed() returns true then argument values are stored in values_;
+    // otherwise they are stored in args_. This is done to improve cache
+    // locality and reduce compiled code size since storing larger objects
     // may require more code (at least on x86-64) even if the same amount of
     // data is actually copied to stack. It saves ~10% on the bloat test.
-    const internal::value<Context>* values_;
+    const detail::value<Context>* values_;
     const format_arg* args_;
   };
 
-  bool is_packed() const { return (types_ & internal::is_unpacked_bit) == 0; }
-
-  internal::type type(int index) const {
-    int shift = index * internal::packed_arg_bits;
-    unsigned int mask = (1 << internal::packed_arg_bits) - 1;
-    return static_cast<internal::type>((types_ >> shift) & mask);
+  bool is_packed() const { return (desc_ & detail::is_unpacked_bit) == 0; }
+  bool has_named_args() const {
+    return (desc_ & detail::has_named_args_bit) != 0;
   }
 
-  friend class internal::arg_map<Context>;
-
-  void set_data(const internal::value<Context>* values) { values_ = values; }
-  void set_data(const format_arg* args) { args_ = args; }
-
-  format_arg do_get(int index) const {
-    format_arg arg;
-    if (!is_packed()) {
-      auto num_args = max_size();
-      if (index < num_args) arg = args_[index];
-      return arg;
-    }
-    if (index > internal::max_packed_args) return arg;
-    arg.type_ = type(index);
-    if (arg.type_ == internal::type::none_type) return arg;
-    internal::value<Context>& val = arg.value_;
-    val = values_[index];
-    return arg;
+  detail::type type(int index) const {
+    int shift = index * detail::packed_arg_bits;
+    unsigned int mask = (1 << detail::packed_arg_bits) - 1;
+    return static_cast<detail::type>((desc_ >> shift) & mask);
   }
 
+  basic_format_args(unsigned long long desc,
+                    const detail::value<Context>* values)
+      : desc_(desc), values_(values) {}
+  basic_format_args(unsigned long long desc, const format_arg* args)
+      : desc_(desc), args_(args) {}
+
  public:
-  basic_format_args() : types_(0) {}
+  basic_format_args() : desc_(0) {}
 
   /**
    \rst
@@ -1533,10 +1672,8 @@ template <typename Context> class basic_format_args {
    \endrst
    */
   template <typename... Args>
-  basic_format_args(const format_arg_store<Context, Args...>& store)
-      : types_(store.types) {
-    set_data(store.data_);
-  }
+  FMT_INLINE basic_format_args(const format_arg_store<Context, Args...>& store)
+      : basic_format_args(store.desc, store.data_.args()) {}
 
   /**
    \rst
@@ -1544,10 +1681,8 @@ template <typename Context> class basic_format_args {
    `~fmt::dynamic_format_arg_store`.
    \endrst
    */
-  basic_format_args(const dynamic_format_arg_store<Context>& store)
-      : types_(store.get_types()) {
-    set_data(store.data_.data());
-  }
+  FMT_INLINE basic_format_args(const dynamic_format_arg_store<Context>& store)
+      : basic_format_args(store.get_types(), store.data()) {}
 
   /**
    \rst
@@ -1555,22 +1690,42 @@ template <typename Context> class basic_format_args {
    \endrst
    */
   basic_format_args(const format_arg* args, int count)
-      : types_(internal::is_unpacked_bit | internal::to_unsigned(count)) {
-    set_data(args);
-  }
+      : basic_format_args(detail::is_unpacked_bit | detail::to_unsigned(count),
+                          args) {}
 
-  /** Returns the argument at specified index. */
-  format_arg get(int index) const {
-    format_arg arg = do_get(index);
-    if (arg.type_ == internal::type::named_arg_type)
-      arg = arg.value_.named_arg->template deserialize<Context>();
+  /** Returns the argument with the specified id. */
+  format_arg get(int id) const {
+    format_arg arg;
+    if (!is_packed()) {
+      if (id < max_size()) arg = args_[id];
+      return arg;
+    }
+    if (id >= detail::max_packed_args) return arg;
+    arg.type_ = type(id);
+    if (arg.type_ == detail::type::none_type) return arg;
+    arg.value_ = values_[id];
     return arg;
   }
 
+  template <typename Char> format_arg get(basic_string_view<Char> name) const {
+    int id = get_id(name);
+    return id >= 0 ? get(id) : format_arg();
+  }
+
+  template <typename Char> int get_id(basic_string_view<Char> name) const {
+    if (!has_named_args()) return -1;
+    const auto& named_args =
+        (is_packed() ? values_[-1] : args_[-1].value_).named_args;
+    for (size_t i = 0; i < named_args.size; ++i) {
+      if (named_args.data[i].name == name) return named_args.data[i].id;
+    }
+    return -1;
+  }
+
   int max_size() const {
-    unsigned long long max_packed = internal::max_packed_args;
+    unsigned long long max_packed = detail::max_packed_args;
     return static_cast<int>(is_packed() ? max_packed
-                                        : types_ & ~internal::is_unpacked_bit);
+                                        : desc_ & ~detail::is_unpacked_bit);
   }
 };
 
@@ -1578,93 +1733,48 @@ template <typename Context> class basic_format_args {
 // It is a separate type rather than an alias to make symbols readable.
 struct format_args : basic_format_args<format_context> {
   template <typename... Args>
-  format_args(Args&&... args)
-      : basic_format_args<format_context>(static_cast<Args&&>(args)...) {}
+  FMT_INLINE format_args(const Args&... args) : basic_format_args(args...) {}
 };
 struct wformat_args : basic_format_args<wformat_context> {
-  template <typename... Args>
-  wformat_args(Args&&... args)
-      : basic_format_args<wformat_context>(static_cast<Args&&>(args)...) {}
+  using basic_format_args::basic_format_args;
 };
 
-template <typename Container> struct is_contiguous : std::false_type {};
-
-template <typename Char>
-struct is_contiguous<std::basic_string<Char>> : std::true_type {};
-
-template <typename Char>
-struct is_contiguous<internal::buffer<Char>> : std::true_type {};
-
-namespace internal {
-
-template <typename OutputIt>
-struct is_contiguous_back_insert_iterator : std::false_type {};
-template <typename Container>
-struct is_contiguous_back_insert_iterator<std::back_insert_iterator<Container>>
-    : is_contiguous<Container> {};
-
-template <typename Char> struct named_arg_base {
-  basic_string_view<Char> name;
-
-  // Serialized value<context>.
-  mutable char data[sizeof(basic_format_arg<buffer_context<Char>>)];
-
-  named_arg_base(basic_string_view<Char> nm) : name(nm) {}
-
-  template <typename Context> basic_format_arg<Context> deserialize() const {
-    basic_format_arg<Context> arg;
-    std::memcpy(&arg, data, sizeof(basic_format_arg<Context>));
-    return arg;
-  }
-};
-
-struct view {};
-
-template <typename T, typename Char>
-struct named_arg : view, named_arg_base<Char> {
-  const T& value;
-
-  named_arg(basic_string_view<Char> name, const T& val)
-      : named_arg_base<Char>(name), value(val) {}
-};
+namespace detail {
 
+// Reports a compile-time error if S is not a valid format string.
 template <typename..., typename S, FMT_ENABLE_IF(!is_compile_string<S>::value)>
-inline void check_format_string(const S&) {
-#if defined(FMT_ENFORCE_COMPILE_STRING)
+FMT_INLINE void check_format_string(const S&) {
+#ifdef FMT_ENFORCE_COMPILE_STRING
   static_assert(is_compile_string<S>::value,
-                "FMT_ENFORCE_COMPILE_STRING requires all format strings to "
-                "utilize FMT_STRING() or fmt().");
+                "FMT_ENFORCE_COMPILE_STRING requires all format strings to use "
+                "FMT_STRING.");
 #endif
 }
 template <typename..., typename S, FMT_ENABLE_IF(is_compile_string<S>::value)>
 void check_format_string(S);
 
-template <bool...> struct bool_pack;
-template <bool... Args>
-using all_true =
-    std::is_same<bool_pack<Args..., true>, bool_pack<true, Args...>>;
-
 template <typename... Args, typename S, typename Char = char_t<S>>
 inline format_arg_store<buffer_context<Char>, remove_reference_t<Args>...>
 make_args_checked(const S& format_str,
                   const remove_reference_t<Args>&... args) {
-  static_assert(
-      all_true<(!std::is_base_of<view, remove_reference_t<Args>>::value ||
-                !std::is_reference<Args>::value)...>::value,
-      "passing views as lvalues is disallowed");
+  static_assert(count<(std::is_base_of<view, remove_reference_t<Args>>::value &&
+                       std::is_reference<Args>::value)...>() == 0,
+                "passing views as lvalues is disallowed");
   check_format_string<Args...>(format_str);
   return {args...};
 }
 
-template <typename Char>
+template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
 std::basic_string<Char> vformat(
     basic_string_view<Char> format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args);
 
+FMT_API std::string vformat(string_view format_str, format_args args);
+
 template <typename Char>
-typename buffer_context<Char>::iterator vformat_to(
+typename FMT_BUFFER_CONTEXT(Char)::iterator vformat_to(
     buffer<Char>& buf, basic_string_view<Char> format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args);
+    basic_format_args<FMT_BUFFER_CONTEXT(type_identity_t<Char>)> args);
 
 template <typename Char, typename Args,
           FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
@@ -1674,58 +1784,38 @@ FMT_API void vprint_mojibake(std::FILE*, string_view, format_args);
 #ifndef _WIN32
 inline void vprint_mojibake(std::FILE*, string_view, format_args) {}
 #endif
-}  // namespace internal
-
-/**
-  \rst
-  Returns a named argument to be used in a formatting function. It should only
-  be used in a call to a formatting function.
-
-  **Example**::
-
-    fmt::print("Elapsed time: {s:.2f} seconds", fmt::arg("s", 1.23));
-  \endrst
- */
-template <typename S, typename T, typename Char = char_t<S>>
-inline internal::named_arg<T, Char> arg(const S& name, const T& arg) {
-  static_assert(internal::is_string<S>::value, "");
-  return {name, arg};
-}
-
-// Disable nested named arguments, e.g. ``arg("a", arg("b", 42))``.
-template <typename S, typename T, typename Char>
-void arg(S, internal::named_arg<T, Char>) = delete;
+}  // namespace detail
 
 /** Formats a string and writes the output to ``out``. */
 // GCC 8 and earlier cannot handle std::back_insert_iterator<Container> with
 // vformat_to<ArgFormatter>(...) overload, so SFINAE on iterator type instead.
-template <typename OutputIt, typename S, typename Char = char_t<S>,
-          FMT_ENABLE_IF(
-              internal::is_contiguous_back_insert_iterator<OutputIt>::value)>
+template <
+    typename OutputIt, typename S, typename Char = char_t<S>,
+    FMT_ENABLE_IF(detail::is_contiguous_back_insert_iterator<OutputIt>::value)>
 OutputIt vformat_to(
     OutputIt out, const S& format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  using container = remove_reference_t<decltype(internal::get_container(out))>;
-  internal::container_buffer<container> buf((internal::get_container(out)));
-  internal::vformat_to(buf, to_string_view(format_str), args);
+  auto& c = detail::get_container(out);
+  detail::container_buffer<remove_reference_t<decltype(c)>> buf(c);
+  detail::vformat_to(buf, to_string_view(format_str), args);
   return out;
 }
 
 template <typename Container, typename S, typename... Args,
           FMT_ENABLE_IF(
-              is_contiguous<Container>::value&& internal::is_string<S>::value)>
+              is_contiguous<Container>::value&& detail::is_string<S>::value)>
 inline std::back_insert_iterator<Container> format_to(
     std::back_insert_iterator<Container> out, const S& format_str,
     Args&&... args) {
   return vformat_to(out, to_string_view(format_str),
-                    internal::make_args_checked<Args...>(format_str, args...));
+                    detail::make_args_checked<Args...>(format_str, args...));
 }
 
 template <typename S, typename Char = char_t<S>>
-inline std::basic_string<Char> vformat(
+FMT_INLINE std::basic_string<Char> vformat(
     const S& format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  return internal::vformat(to_string_view(format_str), args);
+  return detail::vformat(to_string_view(format_str), args);
 }
 
 /**
@@ -1741,10 +1831,9 @@ inline std::basic_string<Char> vformat(
 // Pass char_t as a default template parameter instead of using
 // std::basic_string<char_t<S>> to reduce the symbol size.
 template <typename S, typename... Args, typename Char = char_t<S>>
-inline std::basic_string<Char> format(const S& format_str, Args&&... args) {
-  return internal::vformat(
-      to_string_view(format_str),
-      internal::make_args_checked<Args...>(format_str, args...));
+FMT_INLINE std::basic_string<Char> format(const S& format_str, Args&&... args) {
+  const auto& vargs = detail::make_args_checked<Args...>(format_str, args...);
+  return detail::vformat(to_string_view(format_str), vargs);
 }
 
 FMT_API void vprint(string_view, format_args);
@@ -1763,12 +1852,10 @@ FMT_API void vprint(std::FILE*, string_view, format_args);
  */
 template <typename S, typename... Args, typename Char = char_t<S>>
 inline void print(std::FILE* f, const S& format_str, Args&&... args) {
-  return internal::is_unicode<Char>()
-             ? vprint(f, to_string_view(format_str),
-                      internal::make_args_checked<Args...>(format_str, args...))
-             : internal::vprint_mojibake(
-                   f, to_string_view(format_str),
-                   internal::make_args_checked<Args...>(format_str, args...));
+  const auto& vargs = detail::make_args_checked<Args...>(format_str, args...);
+  return detail::is_unicode<Char>()
+             ? vprint(f, to_string_view(format_str), vargs)
+             : detail::vprint_mojibake(f, to_string_view(format_str), vargs);
 }
 
 /**
@@ -1784,12 +1871,11 @@ inline void print(std::FILE* f, const S& format_str, Args&&... args) {
  */
 template <typename S, typename... Args, typename Char = char_t<S>>
 inline void print(const S& format_str, Args&&... args) {
-  return internal::is_unicode<Char>()
-             ? vprint(to_string_view(format_str),
-                      internal::make_args_checked<Args...>(format_str, args...))
-             : internal::vprint_mojibake(
-                   stdout, to_string_view(format_str),
-                   internal::make_args_checked<Args...>(format_str, args...));
+  const auto& vargs = detail::make_args_checked<Args...>(format_str, args...);
+  return detail::is_unicode<Char>()
+             ? vprint(to_string_view(format_str), vargs)
+             : detail::vprint_mojibake(stdout, to_string_view(format_str),
+                                       vargs);
 }
 FMT_END_NAMESPACE
 
diff --git a/lib/include/srslte/srslog/bundled/fmt/format-inl.h b/lib/include/srslte/srslog/bundled/fmt/format-inl.h
index f632714d8..d8c9c8a5e 100644
--- a/lib/include/srslte/srslog/bundled/fmt/format-inl.h
+++ b/lib/include/srslte/srslog/bundled/fmt/format-inl.h
@@ -15,6 +15,7 @@
 #include <cstdarg>
 #include <cstring>  // for std::memmove
 #include <cwchar>
+#include <exception>
 
 #include "format.h"
 #if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
@@ -22,8 +23,16 @@
 #endif
 
 #ifdef _WIN32
+#  if !defined(NOMINMAX) && !defined(WIN32_LEAN_AND_MEAN)
+#    define NOMINMAX
+#    define WIN32_LEAN_AND_MEAN
+#    include <windows.h>
+#    undef WIN32_LEAN_AND_MEAN
+#    undef NOMINMAX
+#  else
+#    include <windows.h>
+#  endif
 #  include <io.h>
-#  include <windows.h>
 #endif
 
 #ifdef _MSC_VER
@@ -33,15 +42,19 @@
 
 // Dummy implementations of strerror_r and strerror_s called if corresponding
 // system functions are not available.
-inline fmt::internal::null<> strerror_r(int, char*, ...) { return {}; }
-inline fmt::internal::null<> strerror_s(char*, std::size_t, ...) { return {}; }
+inline fmt::detail::null<> strerror_r(int, char*, ...) { return {}; }
+inline fmt::detail::null<> strerror_s(char*, size_t, ...) { return {}; }
 
 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {
 
 FMT_FUNC void assert_fail(const char* file, int line, const char* message) {
-  print(stderr, "{}:{}: assertion failed: {}", file, line, message);
-  std::abort();
+  // Use unchecked std::fprintf to avoid triggering another assertion when
+  // writing to stderr fails
+  std::fprintf(stderr, "%s:%d: assertion failed: %s", file, line, message);
+  // Chosen instead of std::abort to satisfy Clang in CUDA mode during device
+  // code pass.
+  std::terminate();
 }
 
 #ifndef _MSC_VER
@@ -67,14 +80,14 @@ inline int fmt_snprintf(char* buffer, size_t size, const char* format, ...) {
 //   other  - failure
 // Buffer should be at least of size 1.
 FMT_FUNC int safe_strerror(int error_code, char*& buffer,
-                           std::size_t buffer_size) FMT_NOEXCEPT {
+                           size_t buffer_size) FMT_NOEXCEPT {
   FMT_ASSERT(buffer != nullptr && buffer_size != 0, "invalid buffer");
 
   class dispatcher {
    private:
     int error_code_;
     char*& buffer_;
-    std::size_t buffer_size_;
+    size_t buffer_size_;
 
     // A noop assignment operator to avoid bogus warnings.
     void operator=(const dispatcher&) {}
@@ -97,7 +110,7 @@ FMT_FUNC int safe_strerror(int error_code, char*& buffer,
 
     // Handle the case when strerror_r is not available.
     FMT_MAYBE_UNUSED
-    int handle(internal::null<>) {
+    int handle(detail::null<>) {
       return fallback(strerror_s(buffer_, buffer_size_, error_code_));
     }
 
@@ -111,7 +124,7 @@ FMT_FUNC int safe_strerror(int error_code, char*& buffer,
 
 #if !FMT_MSC_VER
     // Fallback to strerror if strerror_r and strerror_s are not available.
-    int fallback(internal::null<>) {
+    int fallback(detail::null<>) {
       errno = 0;
       buffer_ = strerror(error_code_);
       return errno;
@@ -119,7 +132,7 @@ FMT_FUNC int safe_strerror(int error_code, char*& buffer,
 #endif
 
    public:
-    dispatcher(int err_code, char*& buf, std::size_t buf_size)
+    dispatcher(int err_code, char*& buf, size_t buf_size)
         : error_code_(err_code), buffer_(buf), buffer_size_(buf_size) {}
 
     int run() { return handle(strerror_r(error_code_, buffer_, buffer_size_)); }
@@ -127,7 +140,7 @@ FMT_FUNC int safe_strerror(int error_code, char*& buffer,
   return dispatcher(error_code, buffer, buffer_size).run();
 }
 
-FMT_FUNC void format_error_code(internal::buffer<char>& out, int error_code,
+FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
                                 string_view message) FMT_NOEXCEPT {
   // Report error code making sure that the output fits into
   // inline_buffer_size to avoid dynamic memory allocation and potential
@@ -136,20 +149,17 @@ FMT_FUNC void format_error_code(internal::buffer<char>& out, int error_code,
   static const char SEP[] = ": ";
   static const char ERROR_STR[] = "error ";
   // Subtract 2 to account for terminating null characters in SEP and ERROR_STR.
-  std::size_t error_code_size = sizeof(SEP) + sizeof(ERROR_STR) - 2;
+  size_t error_code_size = sizeof(SEP) + sizeof(ERROR_STR) - 2;
   auto abs_value = static_cast<uint32_or_64_or_128_t<int>>(error_code);
-  if (internal::is_negative(error_code)) {
+  if (detail::is_negative(error_code)) {
     abs_value = 0 - abs_value;
     ++error_code_size;
   }
-  error_code_size += internal::to_unsigned(internal::count_digits(abs_value));
-  internal::writer w(out);
-  if (message.size() <= inline_buffer_size - error_code_size) {
-    w.write(message);
-    w.write(SEP);
-  }
-  w.write(ERROR_STR);
-  w.write(error_code);
+  error_code_size += detail::to_unsigned(detail::count_digits(abs_value));
+  auto it = std::back_inserter(out);
+  if (message.size() <= inline_buffer_size - error_code_size)
+    format_to(it, "{}{}", message, SEP);
+  format_to(it, "{}{}", ERROR_STR, error_code);
   assert(out.size() <= inline_buffer_size);
 }
 
@@ -168,10 +178,10 @@ FMT_FUNC void fwrite_fully(const void* ptr, size_t size, size_t count,
   size_t written = std::fwrite(ptr, size, count, stream);
   if (written < count) FMT_THROW(system_error(errno, "cannot write to file"));
 }
-}  // namespace internal
+}  // namespace detail
 
 #if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
-namespace internal {
+namespace detail {
 
 template <typename Locale>
 locale_ref::locale_ref(const Locale& loc) : locale_(&loc) {
@@ -194,18 +204,16 @@ template <typename Char> FMT_FUNC Char decimal_point_impl(locale_ref loc) {
   return std::use_facet<std::numpunct<Char>>(loc.get<std::locale>())
       .decimal_point();
 }
-}  // namespace internal
+}  // namespace detail
 #else
 template <typename Char>
-FMT_FUNC std::string internal::grouping_impl(locale_ref) {
+FMT_FUNC std::string detail::grouping_impl(locale_ref) {
   return "\03";
 }
-template <typename Char>
-FMT_FUNC Char internal::thousands_sep_impl(locale_ref) {
+template <typename Char> FMT_FUNC Char detail::thousands_sep_impl(locale_ref) {
   return FMT_STATIC_THOUSANDS_SEPARATOR;
 }
-template <typename Char>
-FMT_FUNC Char internal::decimal_point_impl(locale_ref) {
+template <typename Char> FMT_FUNC Char detail::decimal_point_impl(locale_ref) {
   return '.';
 }
 #endif
@@ -222,9 +230,9 @@ FMT_FUNC void system_error::init(int err_code, string_view format_str,
   base = std::runtime_error(to_string(buffer));
 }
 
-namespace internal {
+namespace detail {
 
-template <> FMT_FUNC int count_digits<4>(internal::fallback_uintptr n) {
+template <> FMT_FUNC int count_digits<4>(detail::fallback_uintptr n) {
   // fallback_uintptr is always stored in little endian.
   int i = static_cast<int>(sizeof(void*)) - 1;
   while (i > 0 && n.value[i] == 0) --i;
@@ -233,12 +241,27 @@ template <> FMT_FUNC int count_digits<4>(internal::fallback_uintptr n) {
 }
 
 template <typename T>
-const char basic_data<T>::digits[] =
-    "0001020304050607080910111213141516171819"
-    "2021222324252627282930313233343536373839"
-    "4041424344454647484950515253545556575859"
-    "6061626364656667686970717273747576777879"
-    "8081828384858687888990919293949596979899";
+const typename basic_data<T>::digit_pair basic_data<T>::digits[] = {
+    {'0', '0'},  {'0', '1'},  {'0', '2'},  {'0', '3'},  {'0', '4'},
+    {'0', '5'},  {'0', '6'},  {'0', '7'},  {'0', '8'},  {'0', '9'},
+    {'1', '0'},  {'1', '1'},  {'1', '2'},  {'1', '3'},  {'1', '4'},
+    {'1', '5'},  {'1', '6'},  {'1', '7'},  {'1', '8'},  {'1', '9'},
+    {'2', '0'},  {'2', '1'},  {'2', '2'},  {'2', '3'},  {'2', '4'},
+    {'2', '5'},  {'2', '6'},  {'2', '7'},  {'2', '8'},  {'2', '9'},
+    {'3', '0'},  {'3', '1'},  {'3', '2'},  {'3', '3'},  {'3', '4'},
+    {'3', '5'},  {'3', '6'},  {'3', '7'},  {'3', '8'},  {'3', '9'},
+    {'4', '0'},  {'4', '1'},  {'4', '2'},  {'4', '3'},  {'4', '4'},
+    {'4', '5'},  {'4', '6'},  {'4', '7'},  {'4', '8'},  {'4', '9'},
+    {'5', '0'},  {'5', '1'},  {'5', '2'},  {'5', '3'},  {'5', '4'},
+    {'5', '5'},  {'5', '6'},  {'5', '7'},  {'5', '8'},  {'5', '9'},
+    {'6', '0'},  {'6', '1'},  {'6', '2'},  {'6', '3'},  {'6', '4'},
+    {'6', '5'},  {'6', '6'},  {'6', '7'},  {'6', '8'},  {'6', '9'},
+    {'7', '0'},  {'7', '1'},  {'7', '2'},  {'7', '3'},  {'7', '4'},
+    {'7', '5'},  {'7', '6'},  {'7', '7'},  {'7', '8'},  {'7', '9'},
+    {'8', '0'},  {'8', '1'},  {'8', '2'},  {'8', '3'},  {'8', '4'},
+    {'8', '5'},  {'8', '6'},  {'8', '7'},  {'8', '8'},  {'8', '9'},
+    {'9', '0'},  {'9', '1'},  {'9', '2'},  {'9', '3'},  {'9', '4'},
+    {'9', '5'},  {'9', '6'},  {'9', '7'},  {'9', '8'},  {'9', '9'}};
 
 template <typename T>
 const char basic_data<T>::hex_digits[] = "0123456789abcdef";
@@ -317,6 +340,10 @@ const char basic_data<T>::background_color[] = "\x1b[48;2;";
 template <typename T> const char basic_data<T>::reset_color[] = "\x1b[0m";
 template <typename T> const wchar_t basic_data<T>::wreset_color[] = L"\x1b[0m";
 template <typename T> const char basic_data<T>::signs[] = {0, '-', '+', ' '};
+template <typename T>
+const char basic_data<T>::left_padding_shifts[] = {31, 31, 0, 1, 0};
+template <typename T>
+const char basic_data<T>::right_padding_shifts[] = {0, 31, 0, 1, 0};
 
 template <typename T> struct bits {
   static FMT_CONSTEXPR_DECL const int value =
@@ -576,9 +603,10 @@ class bigint {
   void operator=(const bigint&) = delete;
 
   void assign(const bigint& other) {
-    bigits_.resize(other.bigits_.size());
+    auto size = other.bigits_.size();
+    bigits_.resize(size);
     auto data = other.bigits_.data();
-    std::copy(data, data + other.bigits_.size(), bigits_.data());
+    std::copy(data, data + size, make_checked(bigits_.data(), size));
     exp_ = other.exp_;
   }
 
@@ -594,7 +622,7 @@ class bigint {
 
   int num_bigits() const { return static_cast<int>(bigits_.size()) + exp_; }
 
-  bigint& operator<<=(int shift) {
+  FMT_NOINLINE bigint& operator<<=(int shift) {
     assert(shift >= 0);
     exp_ += shift / bigit_bits;
     shift %= bigit_bits;
@@ -1125,7 +1153,7 @@ int snprintf_float(T value, int precision, float_specs specs,
     precision = (precision >= 0 ? precision : 6) - 1;
 
   // Build the format string.
-  enum { max_format_size = 7 };  // Ths longest format is "%#.*Le".
+  enum { max_format_size = 7 };  // The longest format is "%#.*Le".
   char format[max_format_size];
   char* format_ptr = format;
   *format_ptr++ = '%';
@@ -1145,13 +1173,13 @@ int snprintf_float(T value, int precision, float_specs specs,
   for (;;) {
     auto begin = buf.data() + offset;
     auto capacity = buf.capacity() - offset;
-#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+#ifdef FMT_FUZZ
     if (precision > 100000)
       throw std::runtime_error(
           "fuzz mode - avoid large allocation inside snprintf");
 #endif
     // Suppress the warning about a nonliteral format string.
-    // Cannot use auto becase of a bug in MinGW (#1532).
+    // Cannot use auto because of a bug in MinGW (#1532).
     int (*snprintf_ptr)(char*, size_t, const char*, ...) = FMT_SNPRINTF;
     int result = precision >= 0
                      ? snprintf_ptr(begin, capacity, format, precision, value)
@@ -1268,14 +1296,14 @@ FMT_FUNC const char* utf8_decode(const char* buf, uint32_t* c, int* e) {
 
   return next;
 }
-}  // namespace internal
+}  // namespace detail
 
-template <> struct formatter<internal::bigint> {
+template <> struct formatter<detail::bigint> {
   format_parse_context::iterator parse(format_parse_context& ctx) {
     return ctx.begin();
   }
 
-  format_context::iterator format(const internal::bigint& n,
+  format_context::iterator format(const detail::bigint& n,
                                   format_context& ctx) {
     auto out = ctx.out();
     bool first = true;
@@ -1289,12 +1317,12 @@ template <> struct formatter<internal::bigint> {
       out = format_to(out, "{:08x}", value);
     }
     if (n.exp_ > 0)
-      out = format_to(out, "p{}", n.exp_ * internal::bigint::bigit_bits);
+      out = format_to(out, "p{}", n.exp_ * detail::bigint::bigit_bits);
     return out;
   }
 };
 
-FMT_FUNC internal::utf8_to_utf16::utf8_to_utf16(string_view s) {
+FMT_FUNC detail::utf8_to_utf16::utf8_to_utf16(string_view s) {
   auto transcode = [this](const char* p) {
     auto cp = uint32_t();
     auto error = 0;
@@ -1325,7 +1353,7 @@ FMT_FUNC internal::utf8_to_utf16::utf8_to_utf16(string_view s) {
   buffer_.push_back(0);
 }
 
-FMT_FUNC void format_system_error(internal::buffer<char>& out, int error_code,
+FMT_FUNC void format_system_error(detail::buffer<char>& out, int error_code,
                                   string_view message) FMT_NOEXCEPT {
   FMT_TRY {
     memory_buffer buf;
@@ -1333,12 +1361,9 @@ FMT_FUNC void format_system_error(internal::buffer<char>& out, int error_code,
     for (;;) {
       char* system_message = &buf[0];
       int result =
-          internal::safe_strerror(error_code, system_message, buf.size());
+          detail::safe_strerror(error_code, system_message, buf.size());
       if (result == 0) {
-        internal::writer w(out);
-        w.write(message);
-        w.write(": ");
-        w.write(system_message);
+        format_to(std::back_inserter(out), "{}: {}", message, system_message);
         return;
       }
       if (result != ERANGE)
@@ -1350,7 +1375,7 @@ FMT_FUNC void format_system_error(internal::buffer<char>& out, int error_code,
   format_error_code(out, error_code, message);
 }
 
-FMT_FUNC void internal::error_handler::on_error(const char* message) {
+FMT_FUNC void detail::error_handler::on_error(const char* message) {
   FMT_THROW(format_error(message));
 }
 
@@ -1359,14 +1384,39 @@ FMT_FUNC void report_system_error(int error_code,
   report_error(format_system_error, error_code, message);
 }
 
+struct stringifier {
+  template <typename T> FMT_INLINE std::string operator()(T value) const {
+    return to_string(value);
+  }
+  std::string operator()(basic_format_arg<format_context>::handle h) const {
+    memory_buffer buf;
+    detail::buffer<char>& base = buf;
+    format_parse_context parse_ctx({});
+    format_context format_ctx(std::back_inserter(base), {}, {});
+    h.format(parse_ctx, format_ctx);
+    return to_string(buf);
+  }
+};
+
+FMT_FUNC std::string detail::vformat(string_view format_str, format_args args) {
+  if (format_str.size() == 2 && equal2(format_str.data(), "{}")) {
+    auto arg = args.get(0);
+    if (!arg) error_handler().on_error("argument not found");
+    return visit_format_arg(stringifier(), arg);
+  }
+  memory_buffer buffer;
+  detail::vformat_to(buffer, format_str, args);
+  return to_string(buffer);
+}
+
 FMT_FUNC void vprint(std::FILE* f, string_view format_str, format_args args) {
   memory_buffer buffer;
-  internal::vformat_to(buffer, format_str,
-                       basic_format_args<buffer_context<char>>(args));
+  detail::vformat_to(buffer, format_str,
+                     basic_format_args<buffer_context<char>>(args));
 #ifdef _WIN32
   auto fd = _fileno(f);
   if (_isatty(fd)) {
-    internal::utf8_to_utf16 u16(string_view(buffer.data(), buffer.size()));
+    detail::utf8_to_utf16 u16(string_view(buffer.data(), buffer.size()));
     auto written = DWORD();
     if (!WriteConsoleW(reinterpret_cast<HANDLE>(_get_osfhandle(fd)),
                        u16.c_str(), static_cast<DWORD>(u16.size()), &written,
@@ -1376,16 +1426,16 @@ FMT_FUNC void vprint(std::FILE* f, string_view format_str, format_args args) {
     return;
   }
 #endif
-  internal::fwrite_fully(buffer.data(), 1, buffer.size(), f);
+  detail::fwrite_fully(buffer.data(), 1, buffer.size(), f);
 }
 
 #ifdef _WIN32
 // Print assuming legacy (non-Unicode) encoding.
-FMT_FUNC void internal::vprint_mojibake(std::FILE* f, string_view format_str,
-                                        format_args args) {
+FMT_FUNC void detail::vprint_mojibake(std::FILE* f, string_view format_str,
+                                      format_args args) {
   memory_buffer buffer;
-  internal::vformat_to(buffer, format_str,
-                       basic_format_args<buffer_context<char>>(args));
+  detail::vformat_to(buffer, format_str,
+                     basic_format_args<buffer_context<char>>(args));
   fwrite_fully(buffer.data(), 1, buffer.size(), f);
 }
 #endif
diff --git a/lib/include/srslte/srslog/bundled/fmt/format.h b/lib/include/srslte/srslog/bundled/fmt/format.h
index 4e96539fa..17509b7b4 100644
--- a/lib/include/srslte/srslog/bundled/fmt/format.h
+++ b/lib/include/srslte/srslog/bundled/fmt/format.h
@@ -43,10 +43,6 @@
 
 #include "core.h"
 
-#ifdef FMT_DEPRECATED_INCLUDE_OS
-#  include "os.h"
-#endif
-
 #ifdef __INTEL_COMPILER
 #  define FMT_ICC_VERSION __INTEL_COMPILER
 #elif defined(__ICL)
@@ -76,7 +72,8 @@
 #if __cplusplus == 201103L || __cplusplus == 201402L
 #  if defined(__clang__)
 #    define FMT_FALLTHROUGH [[clang::fallthrough]]
-#  elif FMT_GCC_VERSION >= 700 && !defined(__PGI)
+#  elif FMT_GCC_VERSION >= 700 && !defined(__PGI) && \
+      (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= 520)
 #    define FMT_FALLTHROUGH [[gnu::fallthrough]]
 #  else
 #    define FMT_FALLTHROUGH
@@ -88,20 +85,28 @@
 #  define FMT_FALLTHROUGH
 #endif
 
+#ifndef FMT_MAYBE_UNUSED
+#  if FMT_HAS_CPP17_ATTRIBUTE(maybe_unused)
+#    define FMT_MAYBE_UNUSED [[maybe_unused]]
+#  else
+#    define FMT_MAYBE_UNUSED
+#  endif
+#endif
+
 #ifndef FMT_THROW
 #  if FMT_EXCEPTIONS
 #    if FMT_MSC_VER || FMT_NVCC
 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {
 template <typename Exception> inline void do_throw(const Exception& x) {
   // Silence unreachable code warnings in MSVC and NVCC because these
   // are nearly impossible to fix in a generic code.
   volatile bool b = true;
   if (b) throw x;
 }
-}  // namespace internal
+}  // namespace detail
 FMT_END_NAMESPACE
-#      define FMT_THROW(x) internal::do_throw(x)
+#      define FMT_THROW(x) detail::do_throw(x)
 #    else
 #      define FMT_THROW(x) throw x
 #    endif
@@ -123,11 +128,10 @@ FMT_END_NAMESPACE
 #endif
 
 #ifndef FMT_USE_USER_DEFINED_LITERALS
-// For Intel and NVIDIA compilers both they and the system gcc/msc support UDLs.
-#  if (FMT_HAS_FEATURE(cxx_user_literals) || FMT_GCC_VERSION >= 407 ||      \
-       FMT_MSC_VER >= 1900) &&                                              \
-      (!(FMT_ICC_VERSION || FMT_CUDA_VERSION) || FMT_ICC_VERSION >= 1500 || \
-       FMT_CUDA_VERSION >= 700)
+// EDG based compilers (Intel, NVIDIA, Elbrus, etc), GCC and MSVC support UDLs.
+#  if (FMT_HAS_FEATURE(cxx_user_literals) || FMT_GCC_VERSION >= 407 || \
+       FMT_MSC_VER >= 1900) &&                                         \
+      (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= /* UDL feature */ 480)
 #    define FMT_USE_USER_DEFINED_LITERALS 1
 #  else
 #    define FMT_USE_USER_DEFINED_LITERALS 0
@@ -135,12 +139,11 @@ FMT_END_NAMESPACE
 #endif
 
 #ifndef FMT_USE_UDL_TEMPLATE
-// EDG front end based compilers (icc, nvcc) and GCC < 6.4 do not propertly
+// EDG frontend based compilers (icc, nvcc, etc) and GCC < 6.4 do not properly
 // support UDL templates and GCC >= 9 warns about them.
-#  if FMT_USE_USER_DEFINED_LITERALS && FMT_ICC_VERSION == 0 && \
-      FMT_CUDA_VERSION == 0 &&                                 \
-      ((FMT_GCC_VERSION >= 604 && FMT_GCC_VERSION <= 900 &&    \
-        __cplusplus >= 201402L) ||                             \
+#  if FMT_USE_USER_DEFINED_LITERALS &&                         \
+      (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= 501) && \
+      ((FMT_GCC_VERSION >= 604 && __cplusplus >= 201402L) ||   \
        FMT_CLANG_VERSION >= 304)
 #    define FMT_USE_UDL_TEMPLATE 1
 #  else
@@ -176,7 +179,7 @@ FMT_END_NAMESPACE
 #  include <intrin.h>  // _BitScanReverse, _BitScanReverse64
 
 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {
 // Avoid Clang with Microsoft CodeGen's -Wunknown-pragmas warning.
 #  ifndef __clang__
 #    pragma intrinsic(_BitScanReverse)
@@ -189,10 +192,10 @@ inline uint32_t clz(uint32_t x) {
   // Static analysis complains about using uninitialized data
   // "r", but the only way that can happen is if "x" is 0,
   // which the callers guarantee to not happen.
-#  pragma warning(suppress : 6102)
+  FMT_SUPPRESS_MSC_WARNING(6102)
   return 31 - r;
 }
-#  define FMT_BUILTIN_CLZ(n) internal::clz(n)
+#  define FMT_BUILTIN_CLZ(n) detail::clz(n)
 
 #  if defined(_WIN64) && !defined(__clang__)
 #    pragma intrinsic(_BitScanReverse64)
@@ -214,26 +217,21 @@ inline uint32_t clzll(uint64_t x) {
   // Static analysis complains about using uninitialized data
   // "r", but the only way that can happen is if "x" is 0,
   // which the callers guarantee to not happen.
-#  pragma warning(suppress : 6102)
+  FMT_SUPPRESS_MSC_WARNING(6102)
   return 63 - r;
 }
-#  define FMT_BUILTIN_CLZLL(n) internal::clzll(n)
-}  // namespace internal
+#  define FMT_BUILTIN_CLZLL(n) detail::clzll(n)
+}  // namespace detail
 FMT_END_NAMESPACE
 #endif
 
 // Enable the deprecated numeric alignment.
-#ifndef FMT_NUMERIC_ALIGN
-#  define FMT_NUMERIC_ALIGN 1
-#endif
-
-// Enable the deprecated percent specifier.
-#ifndef FMT_DEPRECATED_PERCENT
-#  define FMT_DEPRECATED_PERCENT 0
+#ifndef FMT_DEPRECATED_NUMERIC_ALIGN
+#  define FMT_DEPRECATED_NUMERIC_ALIGN 0
 #endif
 
 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {
 
 // An equivalent of `*reinterpret_cast<Dest*>(&source)` that doesn't have
 // undefined behavior (e.g. due to type aliasing).
@@ -285,14 +283,31 @@ template <typename T> constexpr T max_value() {
 template <typename T> constexpr int num_bits() {
   return std::numeric_limits<T>::digits;
 }
+// std::numeric_limits<T>::digits may return 0 for 128-bit ints.
+template <> constexpr int num_bits<int128_t>() { return 128; }
+template <> constexpr int num_bits<uint128_t>() { return 128; }
 template <> constexpr int num_bits<fallback_uintptr>() {
   return static_cast<int>(sizeof(void*) *
                           std::numeric_limits<unsigned char>::digits);
 }
 
+FMT_INLINE void assume(bool condition) {
+  (void)condition;
+#if FMT_HAS_BUILTIN(__builtin_assume)
+  __builtin_assume(condition);
+#endif
+}
+
+// A workaround for gcc 4.8 to make void_t work in a SFINAE context.
+template <typename... Ts> struct void_t_impl { using type = void; };
+
+template <typename... Ts>
+using void_t = typename detail::void_t_impl<Ts...>::type;
+
 // An approximation of iterator_t for pre-C++20 systems.
 template <typename T>
 using iterator_t = decltype(std::begin(std::declval<T&>()));
+template <typename T> using sentinel_t = decltype(std::end(std::declval<T&>()));
 
 // Detect the iterator category of *any* given type in a SFINAE-friendly way.
 // Unfortunately, older implementations of std::iterator_traits are not safe
@@ -339,25 +354,39 @@ inline typename Container::value_type* get_data(Container& c) {
 #if defined(_SECURE_SCL) && _SECURE_SCL
 // Make a checked iterator to avoid MSVC warnings.
 template <typename T> using checked_ptr = stdext::checked_array_iterator<T*>;
-template <typename T> checked_ptr<T> make_checked(T* p, std::size_t size) {
+template <typename T> checked_ptr<T> make_checked(T* p, size_t size) {
   return {p, size};
 }
 #else
 template <typename T> using checked_ptr = T*;
-template <typename T> inline T* make_checked(T* p, std::size_t) { return p; }
+template <typename T> inline T* make_checked(T* p, size_t) { return p; }
 #endif
 
 template <typename Container, FMT_ENABLE_IF(is_contiguous<Container>::value)>
-inline checked_ptr<typename Container::value_type> reserve(
-    std::back_insert_iterator<Container>& it, std::size_t n) {
+#if FMT_CLANG_VERSION
+__attribute__((no_sanitize("undefined")))
+#endif
+inline checked_ptr<typename Container::value_type>
+reserve(std::back_insert_iterator<Container> it, size_t n) {
   Container& c = get_container(it);
-  std::size_t size = c.size();
+  size_t size = c.size();
   c.resize(size + n);
   return make_checked(get_data(c) + size, n);
 }
 
+template <typename Iterator> inline Iterator& reserve(Iterator& it, size_t) {
+  return it;
+}
+
+template <typename Container, FMT_ENABLE_IF(is_contiguous<Container>::value)>
+inline std::back_insert_iterator<Container> base_iterator(
+    std::back_insert_iterator<Container>& it,
+    checked_ptr<typename Container::value_type>) {
+  return it;
+}
+
 template <typename Iterator>
-inline Iterator& reserve(Iterator& it, std::size_t) {
+inline Iterator base_iterator(Iterator, Iterator it) {
   return it;
 }
 
@@ -365,7 +394,7 @@ inline Iterator& reserve(Iterator& it, std::size_t) {
 // discards them.
 class counting_iterator {
  private:
-  std::size_t count_;
+  size_t count_;
 
  public:
   using iterator_category = std::output_iterator_tag;
@@ -380,7 +409,7 @@ class counting_iterator {
 
   counting_iterator() : count_(0) {}
 
-  std::size_t count() const { return count_; }
+  size_t count() const { return count_; }
 
   counting_iterator& operator++() {
     ++count_;
@@ -399,10 +428,10 @@ class counting_iterator {
 template <typename OutputIt> class truncating_iterator_base {
  protected:
   OutputIt out_;
-  std::size_t limit_;
-  std::size_t count_;
+  size_t limit_;
+  size_t count_;
 
-  truncating_iterator_base(OutputIt out, std::size_t limit)
+  truncating_iterator_base(OutputIt out, size_t limit)
       : out_(out), limit_(limit), count_(0) {}
 
  public:
@@ -415,7 +444,7 @@ template <typename OutputIt> class truncating_iterator_base {
       truncating_iterator_base;  // Mark iterator as checked.
 
   OutputIt base() const { return out_; }
-  std::size_t count() const { return count_; }
+  size_t count() const { return count_; }
 };
 
 // An output iterator that truncates the output and counts the number of objects
@@ -433,7 +462,7 @@ class truncating_iterator<OutputIt, std::false_type>
  public:
   using value_type = typename truncating_iterator_base<OutputIt>::value_type;
 
-  truncating_iterator(OutputIt out, std::size_t limit)
+  truncating_iterator(OutputIt out, size_t limit)
       : truncating_iterator_base<OutputIt>(out, limit) {}
 
   truncating_iterator& operator++() {
@@ -456,7 +485,7 @@ template <typename OutputIt>
 class truncating_iterator<OutputIt, std::true_type>
     : public truncating_iterator_base<OutputIt> {
  public:
-  truncating_iterator(OutputIt out, std::size_t limit)
+  truncating_iterator(OutputIt out, size_t limit)
       : truncating_iterator_base<OutputIt>(out, limit) {}
 
   template <typename T> truncating_iterator& operator=(T val) {
@@ -469,22 +498,6 @@ class truncating_iterator<OutputIt, std::true_type>
   truncating_iterator& operator*() { return *this; }
 };
 
-// A range with the specified output iterator and value type.
-template <typename OutputIt, typename T = typename OutputIt::value_type>
-class output_range {
- private:
-  OutputIt it_;
-
- public:
-  using value_type = T;
-  using iterator = OutputIt;
-  struct sentinel {};
-
-  explicit output_range(OutputIt it) : it_(it) {}
-  OutputIt begin() const { return it_; }
-  sentinel end() const { return {}; }  // Sentinel is not used yet.
-};
-
 template <typename Char>
 inline size_t count_code_points(basic_string_view<Char> s) {
   return s.size();
@@ -523,8 +536,6 @@ inline size_t code_point_index(basic_string_view<char8_type> s, size_t n) {
   return s.size();
 }
 
-inline char8_type to_char8_t(char c) { return static_cast<char8_type>(c); }
-
 template <typename InputIt, typename OutChar>
 using needs_conversion = bool_constant<
     std::is_same<typename std::iterator_traits<InputIt>::value_type,
@@ -540,7 +551,8 @@ OutputIt copy_str(InputIt begin, InputIt end, OutputIt it) {
 template <typename OutChar, typename InputIt, typename OutputIt,
           FMT_ENABLE_IF(needs_conversion<InputIt, OutChar>::value)>
 OutputIt copy_str(InputIt begin, InputIt end, OutputIt it) {
-  return std::transform(begin, end, it, to_char8_t);
+  return std::transform(begin, end, it,
+                        [](char c) { return static_cast<char8_type>(c); });
 }
 
 #ifndef FMT_USE_GRISU
@@ -555,43 +567,13 @@ template <typename T> constexpr bool use_grisu() {
 template <typename T>
 template <typename U>
 void buffer<T>::append(const U* begin, const U* end) {
-  std::size_t new_size = size_ + to_unsigned(end - begin);
+  size_t new_size = size_ + to_unsigned(end - begin);
   reserve(new_size);
-  std::uninitialized_copy(begin, end, make_checked(ptr_, capacity_) + size_);
+  std::uninitialized_copy(begin, end,
+                          make_checked(ptr_ + size_, capacity_ - size_));
   size_ = new_size;
 }
-}  // namespace internal
-
-// A range with an iterator appending to a buffer.
-template <typename T>
-class buffer_range : public internal::output_range<
-                         std::back_insert_iterator<internal::buffer<T>>, T> {
- public:
-  using iterator = std::back_insert_iterator<internal::buffer<T>>;
-  using internal::output_range<iterator, T>::output_range;
-  buffer_range(internal::buffer<T>& buf)
-      : internal::output_range<iterator, T>(std::back_inserter(buf)) {}
-};
-
-class FMT_DEPRECATED u8string_view
-    : public basic_string_view<internal::char8_type> {
- public:
-  u8string_view(const char* s)
-      : basic_string_view<internal::char8_type>(
-            reinterpret_cast<const internal::char8_type*>(s)) {}
-  u8string_view(const char* s, size_t count) FMT_NOEXCEPT
-      : basic_string_view<internal::char8_type>(
-            reinterpret_cast<const internal::char8_type*>(s), count) {}
-};
-
-#if FMT_USE_USER_DEFINED_LITERALS
-inline namespace literals {
-FMT_DEPRECATED inline basic_string_view<internal::char8_type> operator"" _u(
-    const char* s, std::size_t n) {
-  return {reinterpret_cast<const internal::char8_type*>(s), n};
-}
-}  // namespace literals
-#endif
+}  // namespace detail
 
 // The number of characters to store in the basic_memory_buffer object itself
 // to avoid dynamic memory allocation.
@@ -626,27 +608,30 @@ enum { inline_buffer_size = 500 };
   The output can be converted to an ``std::string`` with ``to_string(out)``.
   \endrst
  */
-template <typename T, std::size_t SIZE = inline_buffer_size,
+template <typename T, size_t SIZE = inline_buffer_size,
           typename Allocator = std::allocator<T>>
-class basic_memory_buffer : private Allocator, public internal::buffer<T> {
+class basic_memory_buffer : public detail::buffer<T> {
  private:
   T store_[SIZE];
 
+  // Don't inherit from Allocator avoid generating type_info for it.
+  Allocator alloc_;
+
   // Deallocate memory allocated by the buffer.
   void deallocate() {
     T* data = this->data();
-    if (data != store_) Allocator::deallocate(data, this->capacity());
+    if (data != store_) alloc_.deallocate(data, this->capacity());
   }
 
  protected:
-  void grow(std::size_t size) FMT_OVERRIDE;
+  void grow(size_t size) FMT_OVERRIDE;
 
  public:
   using value_type = T;
   using const_reference = const T&;
 
   explicit basic_memory_buffer(const Allocator& alloc = Allocator())
-      : Allocator(alloc) {
+      : alloc_(alloc) {
     this->set(store_, SIZE);
   }
   ~basic_memory_buffer() FMT_OVERRIDE { deallocate(); }
@@ -654,14 +639,13 @@ class basic_memory_buffer : private Allocator, public internal::buffer<T> {
  private:
   // Move data from other to this buffer.
   void move(basic_memory_buffer& other) {
-    Allocator &this_alloc = *this, &other_alloc = other;
-    this_alloc = std::move(other_alloc);
+    alloc_ = std::move(other.alloc_);
     T* data = other.data();
-    std::size_t size = other.size(), capacity = other.capacity();
+    size_t size = other.size(), capacity = other.capacity();
     if (data == other.store_) {
       this->set(store_, capacity);
       std::uninitialized_copy(other.store_, other.store_ + size,
-                              internal::make_checked(store_, capacity));
+                              detail::make_checked(store_, capacity));
     } else {
       this->set(data, capacity);
       // Set pointer to the inline array so that delete is not called
@@ -693,32 +677,37 @@ class basic_memory_buffer : private Allocator, public internal::buffer<T> {
   }
 
   // Returns a copy of the allocator associated with this buffer.
-  Allocator get_allocator() const { return *this; }
+  Allocator get_allocator() const { return alloc_; }
 };
 
-template <typename T, std::size_t SIZE, typename Allocator>
-void basic_memory_buffer<T, SIZE, Allocator>::grow(std::size_t size) {
-#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
-  if (size > 1000) throw std::runtime_error("fuzz mode - won't grow that much");
+template <typename T, size_t SIZE, typename Allocator>
+void basic_memory_buffer<T, SIZE, Allocator>::grow(size_t size) {
+#ifdef FMT_FUZZ
+  if (size > 5000) throw std::runtime_error("fuzz mode - won't grow that much");
 #endif
-  std::size_t old_capacity = this->capacity();
-  std::size_t new_capacity = old_capacity + old_capacity / 2;
+  size_t old_capacity = this->capacity();
+  size_t new_capacity = old_capacity + old_capacity / 2;
   if (size > new_capacity) new_capacity = size;
   T* old_data = this->data();
-  T* new_data = std::allocator_traits<Allocator>::allocate(*this, new_capacity);
+  T* new_data =
+      std::allocator_traits<Allocator>::allocate(alloc_, new_capacity);
   // The following code doesn't throw, so the raw pointer above doesn't leak.
   std::uninitialized_copy(old_data, old_data + this->size(),
-                          internal::make_checked(new_data, new_capacity));
+                          detail::make_checked(new_data, new_capacity));
   this->set(new_data, new_capacity);
   // deallocate must not throw according to the standard, but even if it does,
   // the buffer already uses the new storage and will deallocate it in
   // destructor.
-  if (old_data != store_) Allocator::deallocate(old_data, old_capacity);
+  if (old_data != store_) alloc_.deallocate(old_data, old_capacity);
 }
 
 using memory_buffer = basic_memory_buffer<char>;
 using wmemory_buffer = basic_memory_buffer<wchar_t>;
 
+template <typename T, size_t SIZE, typename Allocator>
+struct is_contiguous<basic_memory_buffer<T, SIZE, Allocator>> : std::true_type {
+};
+
 /** A formatting error such as invalid format string. */
 FMT_CLASS_API
 class FMT_API format_error : public std::runtime_error {
@@ -733,15 +722,20 @@ class FMT_API format_error : public std::runtime_error {
   ~format_error() FMT_NOEXCEPT FMT_OVERRIDE;
 };
 
-namespace internal {
+namespace detail {
+
+template <typename T>
+using is_signed =
+    std::integral_constant<bool, std::numeric_limits<T>::is_signed ||
+                                     std::is_same<T, int128_t>::value>;
 
 // Returns true if value is negative, false otherwise.
 // Same as `value < 0` but doesn't produce warnings if T is an unsigned type.
-template <typename T, FMT_ENABLE_IF(std::numeric_limits<T>::is_signed)>
+template <typename T, FMT_ENABLE_IF(is_signed<T>::value)>
 FMT_CONSTEXPR bool is_negative(T value) {
   return value < 0;
 }
-template <typename T, FMT_ENABLE_IF(!std::numeric_limits<T>::is_signed)>
+template <typename T, FMT_ENABLE_IF(!is_signed<T>::value)>
 FMT_CONSTEXPR bool is_negative(T) {
   return false;
 }
@@ -756,9 +750,9 @@ FMT_CONSTEXPR bool is_supported_floating_point(T) {
 // Smallest of uint32_t, uint64_t, uint128_t that is large enough to
 // represent all values of T.
 template <typename T>
-using uint32_or_64_or_128_t = conditional_t<
-    std::numeric_limits<T>::digits <= 32, uint32_t,
-    conditional_t<std::numeric_limits<T>::digits <= 64, uint64_t, uint128_t>>;
+using uint32_or_64_or_128_t =
+    conditional_t<num_bits<T>() <= 32, uint32_t,
+                  conditional_t<num_bits<T>() <= 64, uint64_t, uint128_t>>;
 
 // Static data is placed in this class template for the header-only config.
 template <typename T = void> struct FMT_EXTERN_TEMPLATE_API basic_data {
@@ -767,16 +761,22 @@ template <typename T = void> struct FMT_EXTERN_TEMPLATE_API basic_data {
   static const uint64_t zero_or_powers_of_10_64[];
   static const uint64_t pow10_significands[];
   static const int16_t pow10_exponents[];
-  static const char digits[];
+  // GCC generates slightly better code for pairs than chars.
+  using digit_pair = char[2];
+  static const digit_pair digits[];
   static const char hex_digits[];
   static const char foreground_color[];
   static const char background_color[];
   static const char reset_color[5];
   static const wchar_t wreset_color[5];
   static const char signs[];
+  static const char left_padding_shifts[5];
+  static const char right_padding_shifts[5];
 };
 
+#ifndef FMT_EXPORTED
 FMT_EXTERN template struct basic_data<void>;
+#endif
 
 // This is a struct rather than an alias to avoid shadowing warnings in gcc.
 struct data : basic_data<> {};
@@ -834,7 +834,7 @@ template <unsigned BITS, typename UInt> inline int count_digits(UInt n) {
   return num_digits;
 }
 
-template <> int count_digits<4>(internal::fallback_uintptr n);
+template <> int count_digits<4>(detail::fallback_uintptr n);
 
 #if FMT_GCC_VERSION || FMT_CLANG_VERSION
 #  define FMT_ALWAYS_INLINE inline __attribute__((always_inline))
@@ -850,6 +850,12 @@ inline int count_digits(uint32_t n) {
 }
 #endif
 
+template <typename Int> constexpr int digits10() FMT_NOEXCEPT {
+  return std::numeric_limits<Int>::digits10;
+}
+template <> constexpr int digits10<int128_t>() FMT_NOEXCEPT { return 38; }
+template <> constexpr int digits10<uint128_t>() FMT_NOEXCEPT { return 38; }
+
 template <typename Char> FMT_API std::string grouping_impl(locale_ref loc);
 template <typename Char> inline std::string grouping(locale_ref loc) {
   return grouping_impl<char>(loc);
@@ -874,57 +880,61 @@ template <> inline wchar_t decimal_point(locale_ref loc) {
   return decimal_point_impl<wchar_t>(loc);
 }
 
-// Formats a decimal unsigned integer value writing into buffer.
-// add_thousands_sep is called after writing each char to add a thousands
-// separator if necessary.
-template <typename UInt, typename Char, typename F>
-inline Char* format_decimal(Char* buffer, UInt value, int num_digits,
-                            F add_thousands_sep) {
-  FMT_ASSERT(num_digits >= 0, "invalid digit count");
-  buffer += num_digits;
-  Char* end = buffer;
+// Compares two characters for equality.
+template <typename Char> bool equal2(const Char* lhs, const char* rhs) {
+  return lhs[0] == rhs[0] && lhs[1] == rhs[1];
+}
+inline bool equal2(const char* lhs, const char* rhs) {
+  return memcmp(lhs, rhs, 2) == 0;
+}
+
+// Copies two characters from src to dst.
+template <typename Char> void copy2(Char* dst, const char* src) {
+  *dst++ = static_cast<Char>(*src++);
+  *dst = static_cast<Char>(*src);
+}
+inline void copy2(char* dst, const char* src) { memcpy(dst, src, 2); }
+
+template <typename Iterator> struct format_decimal_result {
+  Iterator begin;
+  Iterator end;
+};
+
+// Formats a decimal unsigned integer value writing into out pointing to a
+// buffer of specified size. The caller must ensure that the buffer is large
+// enough.
+template <typename Char, typename UInt>
+inline format_decimal_result<Char*> format_decimal(Char* out, UInt value,
+                                                   int size) {
+  FMT_ASSERT(size >= count_digits(value), "invalid digit count");
+  out += size;
+  Char* end = out;
   while (value >= 100) {
     // Integer division is slow so do it for a group of two digits instead
     // of for every digit. The idea comes from the talk by Alexandrescu
     // "Three Optimization Tips for C++". See speed-test for a comparison.
-    auto index = static_cast<unsigned>((value % 100) * 2);
+    out -= 2;
+    copy2(out, data::digits[value % 100]);
     value /= 100;
-    *--buffer = static_cast<Char>(data::digits[index + 1]);
-    add_thousands_sep(buffer);
-    *--buffer = static_cast<Char>(data::digits[index]);
-    add_thousands_sep(buffer);
   }
   if (value < 10) {
-    *--buffer = static_cast<Char>('0' + value);
-    return end;
+    *--out = static_cast<Char>('0' + value);
+    return {out, end};
   }
-  auto index = static_cast<unsigned>(value * 2);
-  *--buffer = static_cast<Char>(data::digits[index + 1]);
-  add_thousands_sep(buffer);
-  *--buffer = static_cast<Char>(data::digits[index]);
-  return end;
+  out -= 2;
+  copy2(out, data::digits[value]);
+  return {out, end};
 }
 
-template <typename Int> constexpr int digits10() FMT_NOEXCEPT {
-  return std::numeric_limits<Int>::digits10;
-}
-template <> constexpr int digits10<int128_t>() FMT_NOEXCEPT { return 38; }
-template <> constexpr int digits10<uint128_t>() FMT_NOEXCEPT { return 38; }
-
-template <typename Char, typename UInt, typename Iterator, typename F>
-inline Iterator format_decimal(Iterator out, UInt value, int num_digits,
-                               F add_thousands_sep) {
-  FMT_ASSERT(num_digits >= 0, "invalid digit count");
+template <typename Char, typename UInt, typename Iterator,
+          FMT_ENABLE_IF(!std::is_pointer<remove_cvref_t<Iterator>>::value)>
+inline format_decimal_result<Iterator> format_decimal(Iterator out, UInt value,
+                                                      int num_digits) {
   // Buffer should be large enough to hold all digits (<= digits10 + 1).
   enum { max_size = digits10<UInt>() + 1 };
   Char buffer[2 * max_size];
-  auto end = format_decimal(buffer, value, num_digits, add_thousands_sep);
-  return internal::copy_str<Char>(buffer, end, out);
-}
-
-template <typename Char, typename It, typename UInt>
-inline It format_decimal(It out, UInt value, int num_digits) {
-  return format_decimal<Char>(out, value, num_digits, [](Char*) {});
+  auto end = format_decimal(buffer, value, num_digits).end;
+  return {out, detail::copy_str<Char>(buffer, end, out)};
 }
 
 template <unsigned BASE_BITS, typename Char, typename UInt>
@@ -942,7 +952,7 @@ inline Char* format_uint(Char* buffer, UInt value, int num_digits,
 }
 
 template <unsigned BASE_BITS, typename Char>
-Char* format_uint(Char* buffer, internal::fallback_uintptr n, int num_digits,
+Char* format_uint(Char* buffer, detail::fallback_uintptr n, int num_digits,
                   bool = false) {
   auto char_digits = std::numeric_limits<unsigned char>::digits / 4;
   int start = (num_digits + char_digits - 1) / char_digits - 1;
@@ -968,7 +978,7 @@ inline It format_uint(It out, UInt value, int num_digits, bool upper = false) {
   // Buffer should be large enough to hold all digits (digits / BASE_BITS + 1).
   char buffer[num_bits<UInt>() / BASE_BITS + 1];
   format_uint<BASE_BITS>(buffer, value, num_digits, upper);
-  return internal::copy_str<Char>(buffer, buffer + num_digits, out);
+  return detail::copy_str<Char>(buffer, buffer + num_digits, out);
 }
 
 // A converter from UTF-8 to UTF-16.
@@ -1019,7 +1029,7 @@ template <typename Char> struct fill_t {
     return fill;
   }
 };
-}  // namespace internal
+}  // namespace detail
 
 // We cannot use enum classes as bit fields because of a gcc bug
 // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61414.
@@ -1041,7 +1051,7 @@ template <typename Char> struct basic_format_specs {
   align_t align : 4;
   sign_t sign : 3;
   bool alt : 1;  // Alternate form ('#').
-  internal::fill_t<Char> fill;
+  detail::fill_t<Char> fill;
 
   constexpr basic_format_specs()
       : width(0),
@@ -1050,12 +1060,12 @@ template <typename Char> struct basic_format_specs {
         align(align::none),
         sign(sign::none),
         alt(false),
-        fill(internal::fill_t<Char>::make()) {}
+        fill(detail::fill_t<Char>::make()) {}
 };
 
 using format_specs = basic_format_specs<char>;
 
-namespace internal {
+namespace detail {
 
 // A floating-point presentation format.
 enum class float_format : unsigned char {
@@ -1071,7 +1081,6 @@ struct float_specs {
   sign_t sign : 8;
   bool upper : 1;
   bool locale : 1;
-  bool percent : 1;
   bool binary32 : 1;
   bool use_grisu : 1;
   bool showpoint : 1;
@@ -1087,12 +1096,12 @@ template <typename Char, typename It> It write_exponent(int exp, It it) {
     *it++ = static_cast<Char>('+');
   }
   if (exp >= 100) {
-    const char* top = data::digits + (exp / 100) * 2;
+    const char* top = data::digits[exp / 100];
     if (exp >= 1000) *it++ = static_cast<Char>(top[0]);
     *it++ = static_cast<Char>(top[1]);
     exp %= 100;
   }
-  const char* d = data::digits + exp * 2;
+  const char* d = data::digits[exp];
   *it++ = static_cast<Char>(d[0]);
   *it++ = static_cast<Char>(d[1]);
   return it;
@@ -1134,8 +1143,8 @@ template <typename Char> class float_writer {
             *it++ = static_cast<Char>('0');
           return it;
         }
-#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
-        if (num_zeros > 1000)
+#ifdef FMT_FUZZ
+        if (num_zeros > 5000)
           throw std::runtime_error("fuzz mode - avoiding excessive cpu use");
 #endif
         it = std::fill_n(it, num_zeros, static_cast<Char>('0'));
@@ -1198,11 +1207,10 @@ template <typename Char> class float_writer {
   }
 
   size_t size() const { return size_; }
-  size_t width() const { return size(); }
 
-  template <typename It> void operator()(It&& it) {
+  template <typename It> It operator()(It it) const {
     if (specs_.sign) *it++ = static_cast<Char>(data::signs[specs_.sign]);
-    it = prettify(it);
+    return prettify(it);
   }
 };
 
@@ -1235,10 +1243,15 @@ FMT_CONSTEXPR void handle_int_type_spec(char spec, Handler&& handler) {
   case 'o':
     handler.on_oct();
     break;
+#ifdef FMT_DEPRECATED_N_SPECIFIER
   case 'n':
+#endif
   case 'L':
     handler.on_num();
     break;
+  case 'c':
+    handler.on_chr();
+    break;
   default:
     handler.on_error();
   }
@@ -1274,19 +1287,16 @@ FMT_CONSTEXPR float_specs parse_float_type_spec(
     result.format = float_format::fixed;
     result.showpoint |= specs.precision != 0;
     break;
-#if FMT_DEPRECATED_PERCENT
-  case '%':
-    result.format = float_format::fixed;
-    result.percent = true;
-    break;
-#endif
   case 'A':
     result.upper = true;
     FMT_FALLTHROUGH;
   case 'a':
     result.format = float_format::hex;
     break;
+#ifdef FMT_DEPRECATED_N_SPECIFIER
   case 'n':
+#endif
+  case 'L':
     result.locale = true;
     break;
   default:
@@ -1335,6 +1345,7 @@ template <typename ErrorHandler> class int_type_checker : private ErrorHandler {
   FMT_CONSTEXPR void on_bin() {}
   FMT_CONSTEXPR void on_oct() {}
   FMT_CONSTEXPR void on_num() {}
+  FMT_CONSTEXPR void on_chr() {}
 
   FMT_CONSTEXPR void on_error() {
     ErrorHandler::on_error("invalid type specifier");
@@ -1366,38 +1377,6 @@ class cstring_type_checker : public ErrorHandler {
   FMT_CONSTEXPR void on_pointer() {}
 };
 
-template <typename Context>
-void arg_map<Context>::init(const basic_format_args<Context>& args) {
-  if (map_) return;
-  map_ = new entry[internal::to_unsigned(args.max_size())];
-  if (args.is_packed()) {
-    for (int i = 0;; ++i) {
-      internal::type arg_type = args.type(i);
-      if (arg_type == internal::type::none_type) return;
-      if (arg_type == internal::type::named_arg_type)
-        push_back(args.values_[i]);
-    }
-  }
-  for (int i = 0, n = args.max_size(); i < n; ++i) {
-    auto type = args.args_[i].type_;
-    if (type == internal::type::named_arg_type) push_back(args.args_[i].value_);
-  }
-}
-
-template <typename Char> struct nonfinite_writer {
-  sign_t sign;
-  const char* str;
-  static constexpr size_t str_size = 3;
-
-  size_t size() const { return str_size + (sign ? 1 : 0); }
-  size_t width() const { return size(); }
-
-  template <typename It> void operator()(It&& it) const {
-    if (sign) *it++ = static_cast<Char>(data::signs[sign]);
-    it = copy_str<Char>(str, str + str_size, it);
-  }
-};
-
 template <typename OutputIt, typename Char>
 FMT_NOINLINE OutputIt fill(OutputIt it, size_t n, const fill_t<Char>& fill) {
   auto fill_size = fill.size();
@@ -1406,375 +1385,474 @@ FMT_NOINLINE OutputIt fill(OutputIt it, size_t n, const fill_t<Char>& fill) {
   return it;
 }
 
-// This template provides operations for formatting and writing data into a
-// character range.
-template <typename Range> class basic_writer {
- public:
-  using char_type = typename Range::value_type;
-  using iterator = typename Range::iterator;
-  using format_specs = basic_format_specs<char_type>;
-
- private:
-  iterator out_;  // Output iterator.
-  locale_ref locale_;
-
-  // Attempts to reserve space for n extra characters in the output range.
-  // Returns a pointer to the reserved range or a reference to out_.
-  auto reserve(std::size_t n) -> decltype(internal::reserve(out_, n)) {
-    return internal::reserve(out_, n);
-  }
-
-  template <typename F> struct padded_int_writer {
-    size_t size_;
-    string_view prefix;
-    char_type fill;
-    std::size_t padding;
-    F f;
-
-    size_t size() const { return size_; }
-    size_t width() const { return size_; }
-
-    template <typename It> void operator()(It&& it) const {
-      if (prefix.size() != 0)
-        it = copy_str<char_type>(prefix.begin(), prefix.end(), it);
-      it = std::fill_n(it, padding, fill);
-      f(it);
-    }
-  };
-
-  // Writes an integer in the format
-  //   <left-padding><prefix><numeric-padding><digits><right-padding>
-  // where <digits> are written by f(it).
-  template <typename F>
-  void write_int(int num_digits, string_view prefix, format_specs specs, F f) {
-    std::size_t size = prefix.size() + to_unsigned(num_digits);
-    char_type fill = specs.fill[0];
-    std::size_t padding = 0;
+// Writes the output of f, padded according to format specifications in specs.
+// size: output size in code units.
+// width: output display width in (terminal) column positions.
+template <align::type align = align::left, typename OutputIt, typename Char,
+          typename F>
+inline OutputIt write_padded(OutputIt out,
+                             const basic_format_specs<Char>& specs, size_t size,
+                             size_t width, const F& f) {
+  static_assert(align == align::left || align == align::right, "");
+  unsigned spec_width = to_unsigned(specs.width);
+  size_t padding = spec_width > width ? spec_width - width : 0;
+  auto* shifts = align == align::left ? data::left_padding_shifts
+                                      : data::right_padding_shifts;
+  size_t left_padding = padding >> shifts[specs.align];
+  auto it = reserve(out, size + padding * specs.fill.size());
+  it = fill(it, left_padding, specs.fill);
+  it = f(it);
+  it = fill(it, padding - left_padding, specs.fill);
+  return base_iterator(out, it);
+}
+
+template <align::type align = align::left, typename OutputIt, typename Char,
+          typename F>
+inline OutputIt write_padded(OutputIt out,
+                             const basic_format_specs<Char>& specs, size_t size,
+                             const F& f) {
+  return write_padded<align>(out, specs, size, size, f);
+}
+
+template <typename Char, typename OutputIt>
+OutputIt write_bytes(OutputIt out, string_view bytes,
+                     const basic_format_specs<Char>& specs) {
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded(out, specs, bytes.size(), [bytes](iterator it) {
+    const char* data = bytes.data();
+    return copy_str<Char>(data, data + bytes.size(), it);
+  });
+}
+
+// Data for write_int that doesn't depend on output iterator type. It is used to
+// avoid template code bloat.
+template <typename Char> struct write_int_data {
+  size_t size;
+  size_t padding;
+
+  write_int_data(int num_digits, string_view prefix,
+                 const basic_format_specs<Char>& specs)
+      : size(prefix.size() + to_unsigned(num_digits)), padding(0) {
     if (specs.align == align::numeric) {
-      auto unsiged_width = to_unsigned(specs.width);
-      if (unsiged_width > size) {
-        padding = unsiged_width - size;
-        size = unsiged_width;
+      auto width = to_unsigned(specs.width);
+      if (width > size) {
+        padding = width - size;
+        size = width;
       }
     } else if (specs.precision > num_digits) {
       size = prefix.size() + to_unsigned(specs.precision);
       padding = to_unsigned(specs.precision - num_digits);
-      fill = static_cast<char_type>('0');
     }
-    if (specs.align == align::none) specs.align = align::right;
-    write_padded(specs, padded_int_writer<F>{size, prefix, fill, padding, f});
   }
+};
 
-  // Writes a decimal integer.
-  template <typename Int> void write_decimal(Int value) {
-    auto abs_value = static_cast<uint32_or_64_or_128_t<Int>>(value);
-    bool negative = is_negative(value);
-    // Don't do -abs_value since it trips unsigned-integer-overflow sanitizer.
-    if (negative) abs_value = ~abs_value + 1;
-    int num_digits = count_digits(abs_value);
-    auto&& it = reserve((negative ? 1 : 0) + static_cast<size_t>(num_digits));
-    if (negative) *it++ = static_cast<char_type>('-');
-    it = format_decimal<char_type>(it, abs_value, num_digits);
-  }
-
-  // The handle_int_type_spec handler that writes an integer.
-  template <typename Int, typename Specs> struct int_writer {
-    using unsigned_type = uint32_or_64_or_128_t<Int>;
-
-    basic_writer<Range>& writer;
-    const Specs& specs;
-    unsigned_type abs_value;
-    char prefix[4];
-    unsigned prefix_size;
-
-    string_view get_prefix() const { return string_view(prefix, prefix_size); }
-
-    int_writer(basic_writer<Range>& w, Int value, const Specs& s)
-        : writer(w),
-          specs(s),
-          abs_value(static_cast<unsigned_type>(value)),
-          prefix_size(0) {
-      if (is_negative(value)) {
-        prefix[0] = '-';
-        ++prefix_size;
-        abs_value = 0 - abs_value;
-      } else if (specs.sign != sign::none && specs.sign != sign::minus) {
-        prefix[0] = specs.sign == sign::plus ? '+' : ' ';
-        ++prefix_size;
-      }
+// Writes an integer in the format
+//   <left-padding><prefix><numeric-padding><digits><right-padding>
+// where <digits> are written by f(it).
+template <typename OutputIt, typename Char, typename F>
+OutputIt write_int(OutputIt out, int num_digits, string_view prefix,
+                   const basic_format_specs<Char>& specs, F f) {
+  auto data = write_int_data<Char>(num_digits, prefix, specs);
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded<align::right>(out, specs, data.size, [=](iterator it) {
+    if (prefix.size() != 0)
+      it = copy_str<Char>(prefix.begin(), prefix.end(), it);
+    it = std::fill_n(it, data.padding, static_cast<Char>('0'));
+    return f(it);
+  });
+}
+
+template <typename StrChar, typename Char, typename OutputIt>
+OutputIt write(OutputIt out, basic_string_view<StrChar> s,
+               const basic_format_specs<Char>& specs) {
+  auto data = s.data();
+  auto size = s.size();
+  if (specs.precision >= 0 && to_unsigned(specs.precision) < size)
+    size = code_point_index(s, to_unsigned(specs.precision));
+  auto width = specs.width != 0
+                   ? count_code_points(basic_string_view<StrChar>(data, size))
+                   : 0;
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded(out, specs, size, width, [=](iterator it) {
+    return copy_str<Char>(data, data + size, it);
+  });
+}
+
+// The handle_int_type_spec handler that writes an integer.
+template <typename OutputIt, typename Char, typename UInt> struct int_writer {
+  OutputIt out;
+  locale_ref locale;
+  const basic_format_specs<Char>& specs;
+  UInt abs_value;
+  char prefix[4];
+  unsigned prefix_size;
+
+  using iterator =
+      remove_reference_t<decltype(reserve(std::declval<OutputIt&>(), 0))>;
+
+  string_view get_prefix() const { return string_view(prefix, prefix_size); }
+
+  template <typename Int>
+  int_writer(OutputIt output, locale_ref loc, Int value,
+             const basic_format_specs<Char>& s)
+      : out(output),
+        locale(loc),
+        specs(s),
+        abs_value(static_cast<UInt>(value)),
+        prefix_size(0) {
+    static_assert(std::is_same<uint32_or_64_or_128_t<Int>, UInt>::value, "");
+    if (is_negative(value)) {
+      prefix[0] = '-';
+      ++prefix_size;
+      abs_value = 0 - abs_value;
+    } else if (specs.sign != sign::none && specs.sign != sign::minus) {
+      prefix[0] = specs.sign == sign::plus ? '+' : ' ';
+      ++prefix_size;
     }
+  }
 
-    struct dec_writer {
-      unsigned_type abs_value;
-      int num_digits;
-
-      template <typename It> void operator()(It&& it) const {
-        it = internal::format_decimal<char_type>(it, abs_value, num_digits);
-      }
-    };
+  void on_dec() {
+    auto num_digits = count_digits(abs_value);
+    out = write_int(
+        out, num_digits, get_prefix(), specs, [this, num_digits](iterator it) {
+          return format_decimal<Char>(it, abs_value, num_digits).end;
+        });
+  }
 
-    void on_dec() {
-      int num_digits = count_digits(abs_value);
-      writer.write_int(num_digits, get_prefix(), specs,
-                       dec_writer{abs_value, num_digits});
+  void on_hex() {
+    if (specs.alt) {
+      prefix[prefix_size++] = '0';
+      prefix[prefix_size++] = specs.type;
     }
-
-    struct hex_writer {
-      int_writer& self;
-      int num_digits;
-
-      template <typename It> void operator()(It&& it) const {
-        it = format_uint<4, char_type>(it, self.abs_value, num_digits,
-                                       self.specs.type != 'x');
-      }
-    };
-
-    void on_hex() {
-      if (specs.alt) {
-        prefix[prefix_size++] = '0';
-        prefix[prefix_size++] = specs.type;
-      }
-      int num_digits = count_digits<4>(abs_value);
-      writer.write_int(num_digits, get_prefix(), specs,
-                       hex_writer{*this, num_digits});
+    int num_digits = count_digits<4>(abs_value);
+    out = write_int(out, num_digits, get_prefix(), specs,
+                    [this, num_digits](iterator it) {
+                      return format_uint<4, Char>(it, abs_value, num_digits,
+                                                  specs.type != 'x');
+                    });
+  }
+
+  void on_bin() {
+    if (specs.alt) {
+      prefix[prefix_size++] = '0';
+      prefix[prefix_size++] = static_cast<char>(specs.type);
     }
-
-    template <int BITS> struct bin_writer {
-      unsigned_type abs_value;
-      int num_digits;
-
-      template <typename It> void operator()(It&& it) const {
-        it = format_uint<BITS, char_type>(it, abs_value, num_digits);
-      }
-    };
-
-    void on_bin() {
-      if (specs.alt) {
-        prefix[prefix_size++] = '0';
-        prefix[prefix_size++] = static_cast<char>(specs.type);
-      }
-      int num_digits = count_digits<1>(abs_value);
-      writer.write_int(num_digits, get_prefix(), specs,
-                       bin_writer<1>{abs_value, num_digits});
+    int num_digits = count_digits<1>(abs_value);
+    out = write_int(out, num_digits, get_prefix(), specs,
+                    [this, num_digits](iterator it) {
+                      return format_uint<1, Char>(it, abs_value, num_digits);
+                    });
+  }
+
+  void on_oct() {
+    int num_digits = count_digits<3>(abs_value);
+    if (specs.alt && specs.precision <= num_digits && abs_value != 0) {
+      // Octal prefix '0' is counted as a digit, so only add it if precision
+      // is not greater than the number of digits.
+      prefix[prefix_size++] = '0';
     }
+    out = write_int(out, num_digits, get_prefix(), specs,
+                    [this, num_digits](iterator it) {
+                      return format_uint<3, Char>(it, abs_value, num_digits);
+                    });
+  }
 
-    void on_oct() {
-      int num_digits = count_digits<3>(abs_value);
-      if (specs.alt && specs.precision <= num_digits && abs_value != 0) {
-        // Octal prefix '0' is counted as a digit, so only add it if precision
-        // is not greater than the number of digits.
-        prefix[prefix_size++] = '0';
-      }
-      writer.write_int(num_digits, get_prefix(), specs,
-                       bin_writer<3>{abs_value, num_digits});
-    }
+  enum { sep_size = 1 };
 
-    enum { sep_size = 1 };
-
-    struct num_writer {
-      unsigned_type abs_value;
-      int size;
-      const std::string& groups;
-      char_type sep;
-
-      template <typename It> void operator()(It&& it) const {
-        basic_string_view<char_type> s(&sep, sep_size);
-        // Index of a decimal digit with the least significant digit having
-        // index 0.
-        int digit_index = 0;
-        std::string::const_iterator group = groups.cbegin();
-        it = format_decimal<char_type>(
-            it, abs_value, size,
-            [this, s, &group, &digit_index](char_type*& buffer) {
-              if (*group <= 0 || ++digit_index % *group != 0 ||
-                  *group == max_value<char>())
-                return;
-              if (group + 1 != groups.cend()) {
-                digit_index = 0;
-                ++group;
-              }
-              buffer -= s.size();
-              std::uninitialized_copy(s.data(), s.data() + s.size(),
-                                      make_checked(buffer, s.size()));
-            });
-      }
-    };
-
-    void on_num() {
-      std::string groups = grouping<char_type>(writer.locale_);
-      if (groups.empty()) return on_dec();
-      auto sep = thousands_sep<char_type>(writer.locale_);
-      if (!sep) return on_dec();
-      int num_digits = count_digits(abs_value);
-      int size = num_digits;
-      std::string::const_iterator group = groups.cbegin();
-      while (group != groups.cend() && num_digits > *group && *group > 0 &&
-             *group != max_value<char>()) {
-        size += sep_size;
-        num_digits -= *group;
+  void on_num() {
+    std::string groups = grouping<Char>(locale);
+    if (groups.empty()) return on_dec();
+    auto sep = thousands_sep<Char>(locale);
+    if (!sep) return on_dec();
+    int num_digits = count_digits(abs_value);
+    int size = num_digits, n = num_digits;
+    std::string::const_iterator group = groups.cbegin();
+    while (group != groups.cend() && n > *group && *group > 0 &&
+           *group != max_value<char>()) {
+      size += sep_size;
+      n -= *group;
+      ++group;
+    }
+    if (group == groups.cend()) size += sep_size * ((n - 1) / groups.back());
+    char digits[40];
+    format_decimal(digits, abs_value, num_digits);
+    basic_memory_buffer<Char> buffer;
+    size += prefix_size;
+    buffer.resize(size);
+    basic_string_view<Char> s(&sep, sep_size);
+    // Index of a decimal digit with the least significant digit having index 0.
+    int digit_index = 0;
+    group = groups.cbegin();
+    auto p = buffer.data() + size;
+    for (int i = num_digits - 1; i >= 0; --i) {
+      *--p = static_cast<Char>(digits[i]);
+      if (*group <= 0 || ++digit_index % *group != 0 ||
+          *group == max_value<char>())
+        continue;
+      if (group + 1 != groups.cend()) {
+        digit_index = 0;
         ++group;
       }
-      if (group == groups.cend())
-        size += sep_size * ((num_digits - 1) / groups.back());
-      writer.write_int(size, get_prefix(), specs,
-                       num_writer{abs_value, size, groups, sep});
+      p -= s.size();
+      std::uninitialized_copy(s.data(), s.data() + s.size(),
+                              make_checked(p, s.size()));
     }
+    if (prefix_size != 0) p[-1] = static_cast<Char>('-');
+    using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+    auto data = buffer.data();
+    out = write_padded<align::right>(out, specs, size, size, [=](iterator it) {
+      return copy_str<Char>(data, data + size, it);
+    });
+  }
 
-    FMT_NORETURN void on_error() {
-      FMT_THROW(format_error("invalid type specifier"));
-    }
-  };
-
-  template <typename Char> struct str_writer {
-    const Char* s;
-    size_t size_;
+  void on_chr() { *out++ = static_cast<Char>(abs_value); }
 
-    size_t size() const { return size_; }
-    size_t width() const {
-      return count_code_points(basic_string_view<Char>(s, size_));
-    }
+  FMT_NORETURN void on_error() {
+    FMT_THROW(format_error("invalid type specifier"));
+  }
+};
 
-    template <typename It> void operator()(It&& it) const {
-      it = copy_str<char_type>(s, s + size_, it);
-    }
+template <typename Char, typename OutputIt>
+OutputIt write_nonfinite(OutputIt out, bool isinf,
+                         const basic_format_specs<Char>& specs,
+                         const float_specs& fspecs) {
+  auto str =
+      isinf ? (fspecs.upper ? "INF" : "inf") : (fspecs.upper ? "NAN" : "nan");
+  constexpr size_t str_size = 3;
+  auto sign = fspecs.sign;
+  auto size = str_size + (sign ? 1 : 0);
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded(out, specs, size, [=](iterator it) {
+    if (sign) *it++ = static_cast<Char>(data::signs[sign]);
+    return copy_str<Char>(str, str + str_size, it);
+  });
+}
+
+template <typename Char, typename OutputIt, typename T,
+          FMT_ENABLE_IF(std::is_floating_point<T>::value)>
+OutputIt write(OutputIt out, T value, basic_format_specs<Char> specs,
+               locale_ref loc = {}) {
+  if (const_check(!is_supported_floating_point(value))) return out;
+  float_specs fspecs = parse_float_type_spec(specs);
+  fspecs.sign = specs.sign;
+  if (std::signbit(value)) {  // value < 0 is false for NaN so use signbit.
+    fspecs.sign = sign::minus;
+    value = -value;
+  } else if (fspecs.sign == sign::minus) {
+    fspecs.sign = sign::none;
+  }
+
+  if (!std::isfinite(value))
+    return write_nonfinite(out, std::isinf(value), specs, fspecs);
+
+  if (specs.align == align::numeric && fspecs.sign) {
+    auto it = reserve(out, 1);
+    *it++ = static_cast<Char>(data::signs[fspecs.sign]);
+    out = base_iterator(out, it);
+    fspecs.sign = sign::none;
+    if (specs.width != 0) --specs.width;
+  }
+
+  memory_buffer buffer;
+  if (fspecs.format == float_format::hex) {
+    if (fspecs.sign) buffer.push_back(data::signs[fspecs.sign]);
+    snprintf_float(promote_float(value), specs.precision, fspecs, buffer);
+    return write_bytes(out, {buffer.data(), buffer.size()}, specs);
+  }
+  int precision = specs.precision >= 0 || !specs.type ? specs.precision : 6;
+  if (fspecs.format == float_format::exp) {
+    if (precision == max_value<int>())
+      FMT_THROW(format_error("number is too big"));
+    else
+      ++precision;
+  }
+  if (const_check(std::is_same<T, float>())) fspecs.binary32 = true;
+  fspecs.use_grisu = use_grisu<T>();
+  int exp = format_float(promote_float(value), precision, fspecs, buffer);
+  fspecs.precision = precision;
+  Char point =
+      fspecs.locale ? decimal_point<Char>(loc) : static_cast<Char>('.');
+  float_writer<Char> w(buffer.data(), static_cast<int>(buffer.size()), exp,
+                       fspecs, point);
+  return write_padded<align::right>(out, specs, w.size(), w);
+}
+
+template <typename Char, typename OutputIt, typename T,
+          FMT_ENABLE_IF(std::is_floating_point<T>::value)>
+OutputIt write(OutputIt out, T value) {
+  if (const_check(!is_supported_floating_point(value))) return out;
+  auto fspecs = float_specs();
+  if (std::signbit(value)) {  // value < 0 is false for NaN so use signbit.
+    fspecs.sign = sign::minus;
+    value = -value;
+  }
+
+  auto specs = basic_format_specs<Char>();
+  if (!std::isfinite(value))
+    return write_nonfinite(out, std::isinf(value), specs, fspecs);
+
+  memory_buffer buffer;
+  int precision = -1;
+  if (const_check(std::is_same<T, float>())) fspecs.binary32 = true;
+  fspecs.use_grisu = use_grisu<T>();
+  int exp = format_float(promote_float(value), precision, fspecs, buffer);
+  fspecs.precision = precision;
+  float_writer<Char> w(buffer.data(), static_cast<int>(buffer.size()), exp,
+                       fspecs, static_cast<Char>('.'));
+  return base_iterator(out, w(reserve(out, w.size())));
+}
+
+template <typename Char, typename OutputIt>
+OutputIt write_char(OutputIt out, Char value,
+                    const basic_format_specs<Char>& specs) {
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded(out, specs, 1, [=](iterator it) {
+    *it++ = value;
+    return it;
+  });
+}
+
+template <typename Char, typename OutputIt, typename UIntPtr>
+OutputIt write_ptr(OutputIt out, UIntPtr value,
+                   const basic_format_specs<Char>* specs) {
+  int num_digits = count_digits<4>(value);
+  auto size = to_unsigned(num_digits) + size_t(2);
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  auto write = [=](iterator it) {
+    *it++ = static_cast<Char>('0');
+    *it++ = static_cast<Char>('x');
+    return format_uint<4, Char>(it, value, num_digits);
   };
+  return specs ? write_padded<align::right>(out, *specs, size, write)
+               : base_iterator(out, write(reserve(out, size)));
+}
 
-  struct bytes_writer {
-    string_view bytes;
+template <typename T> struct is_integral : std::is_integral<T> {};
+template <> struct is_integral<int128_t> : std::true_type {};
+template <> struct is_integral<uint128_t> : std::true_type {};
 
-    size_t size() const { return bytes.size(); }
-    size_t width() const { return bytes.size(); }
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, monostate) {
+  FMT_ASSERT(false, "");
+  return out;
+}
 
-    template <typename It> void operator()(It&& it) const {
-      const char* data = bytes.data();
-      it = copy_str<char>(data, data + size(), it);
-    }
-  };
+template <typename Char, typename OutputIt,
+          FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
+OutputIt write(OutputIt out, string_view value) {
+  auto it = reserve(out, value.size());
+  it = copy_str<Char>(value.begin(), value.end(), it);
+  return base_iterator(out, it);
+}
 
-  template <typename UIntPtr> struct pointer_writer {
-    UIntPtr value;
-    int num_digits;
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, basic_string_view<Char> value) {
+  auto it = reserve(out, value.size());
+  it = std::copy(value.begin(), value.end(), it);
+  return base_iterator(out, it);
+}
 
-    size_t size() const { return to_unsigned(num_digits) + 2; }
-    size_t width() const { return size(); }
+template <typename Char, typename OutputIt, typename T,
+          FMT_ENABLE_IF(is_integral<T>::value &&
+                        !std::is_same<T, bool>::value &&
+                        !std::is_same<T, Char>::value)>
+OutputIt write(OutputIt out, T value) {
+  auto abs_value = static_cast<uint32_or_64_or_128_t<T>>(value);
+  bool negative = is_negative(value);
+  // Don't do -abs_value since it trips unsigned-integer-overflow sanitizer.
+  if (negative) abs_value = ~abs_value + 1;
+  int num_digits = count_digits(abs_value);
+  auto it = reserve(out, (negative ? 1 : 0) + static_cast<size_t>(num_digits));
+  if (negative) *it++ = static_cast<Char>('-');
+  it = format_decimal<Char>(it, abs_value, num_digits).end;
+  return base_iterator(out, it);
+}
 
-    template <typename It> void operator()(It&& it) const {
-      *it++ = static_cast<char_type>('0');
-      *it++ = static_cast<char_type>('x');
-      it = format_uint<4, char_type>(it, value, num_digits);
-    }
-  };
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, bool value) {
+  return write<Char>(out, string_view(value ? "true" : "false"));
+}
 
- public:
-  explicit basic_writer(Range out, locale_ref loc = locale_ref())
-      : out_(out.begin()), locale_(loc) {}
-
-  iterator out() const { return out_; }
-
-  // Writes a value in the format
-  //   <left-padding><value><right-padding>
-  // where <value> is written by f(it).
-  template <typename F> void write_padded(const format_specs& specs, F&& f) {
-    // User-perceived width (in code points).
-    unsigned width = to_unsigned(specs.width);
-    size_t size = f.size();  // The number of code units.
-    size_t num_code_points = width != 0 ? f.width() : size;
-    if (width <= num_code_points) return f(reserve(size));
-    size_t padding = width - num_code_points;
-    size_t fill_size = specs.fill.size();
-    auto&& it = reserve(size + padding * fill_size);
-    if (specs.align == align::right) {
-      it = fill(it, padding, specs.fill);
-      f(it);
-    } else if (specs.align == align::center) {
-      std::size_t left_padding = padding / 2;
-      it = fill(it, left_padding, specs.fill);
-      f(it);
-      it = fill(it, padding - left_padding, specs.fill);
-    } else {
-      f(it);
-      it = fill(it, padding, specs.fill);
-    }
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, Char value) {
+  auto it = reserve(out, 1);
+  *it++ = value;
+  return base_iterator(out, it);
+}
+
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, const Char* value) {
+  if (!value) {
+    FMT_THROW(format_error("string pointer is null"));
+  } else {
+    auto length = std::char_traits<Char>::length(value);
+    out = write(out, basic_string_view<Char>(value, length));
   }
+  return out;
+}
 
-  void write(int value) { write_decimal(value); }
-  void write(long value) { write_decimal(value); }
-  void write(long long value) { write_decimal(value); }
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, const void* value) {
+  return write_ptr<Char>(out, to_uintptr(value), nullptr);
+}
 
-  void write(unsigned value) { write_decimal(value); }
-  void write(unsigned long value) { write_decimal(value); }
-  void write(unsigned long long value) { write_decimal(value); }
+template <typename Char, typename OutputIt, typename T>
+auto write(OutputIt out, const T& value) -> typename std::enable_if<
+    mapped_type_constant<T, basic_format_context<OutputIt, Char>>::value ==
+        type::custom_type,
+    OutputIt>::type {
+  basic_format_context<OutputIt, Char> ctx(out, {}, {});
+  return formatter<T>().format(value, ctx);
+}
 
-#if FMT_USE_INT128
-  void write(int128_t value) { write_decimal(value); }
-  void write(uint128_t value) { write_decimal(value); }
-#endif
+// An argument visitor that formats the argument and writes it via the output
+// iterator. It's a class and not a generic lambda for compatibility with C++11.
+template <typename OutputIt, typename Char> struct default_arg_formatter {
+  using context = basic_format_context<OutputIt, Char>;
 
-  template <typename T, typename Spec>
-  void write_int(T value, const Spec& spec) {
-    handle_int_type_spec(spec.type, int_writer<T, Spec>(*this, value, spec));
+  OutputIt out;
+  basic_format_args<context> args;
+  locale_ref loc;
+
+  template <typename T> OutputIt operator()(T value) {
+    return write<Char>(out, value);
   }
 
-  template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
-  void write(T value, format_specs specs = {}) {
-    if (const_check(!is_supported_floating_point(value))) {
-      return;
-    }
-    float_specs fspecs = parse_float_type_spec(specs);
-    fspecs.sign = specs.sign;
-    if (std::signbit(value)) {  // value < 0 is false for NaN so use signbit.
-      fspecs.sign = sign::minus;
-      value = -value;
-    } else if (fspecs.sign == sign::minus) {
-      fspecs.sign = sign::none;
-    }
+  OutputIt operator()(typename basic_format_arg<context>::handle handle) {
+    basic_format_parse_context<Char> parse_ctx({});
+    basic_format_context<OutputIt, Char> format_ctx(out, args, loc);
+    handle.format(parse_ctx, format_ctx);
+    return format_ctx.out();
+  }
+};
 
-    if (!std::isfinite(value)) {
-      auto str = std::isinf(value) ? (fspecs.upper ? "INF" : "inf")
-                                   : (fspecs.upper ? "NAN" : "nan");
-      return write_padded(specs, nonfinite_writer<char_type>{fspecs.sign, str});
-    }
+template <typename OutputIt, typename Char,
+          typename ErrorHandler = error_handler>
+class arg_formatter_base {
+ public:
+  using iterator = OutputIt;
+  using char_type = Char;
+  using format_specs = basic_format_specs<Char>;
 
-    if (specs.align == align::none) {
-      specs.align = align::right;
-    } else if (specs.align == align::numeric) {
-      if (fspecs.sign) {
-        auto&& it = reserve(1);
-        *it++ = static_cast<char_type>(data::signs[fspecs.sign]);
-        fspecs.sign = sign::none;
-        if (specs.width != 0) --specs.width;
-      }
-      specs.align = align::right;
-    }
+ private:
+  iterator out_;
+  locale_ref locale_;
+  format_specs* specs_;
 
-    memory_buffer buffer;
-    if (fspecs.format == float_format::hex) {
-      if (fspecs.sign) buffer.push_back(data::signs[fspecs.sign]);
-      snprintf_float(promote_float(value), specs.precision, fspecs, buffer);
-      write_padded(specs, str_writer<char>{buffer.data(), buffer.size()});
-      return;
-    }
-    int precision = specs.precision >= 0 || !specs.type ? specs.precision : 6;
-    if (fspecs.format == float_format::exp) {
-      if (precision == max_value<int>())
-        FMT_THROW(format_error("number is too big"));
-      else
-        ++precision;
-    }
-    if (const_check(std::is_same<T, float>())) fspecs.binary32 = true;
-    fspecs.use_grisu = use_grisu<T>();
-    if (const_check(FMT_DEPRECATED_PERCENT) && fspecs.percent) value *= 100;
-    int exp = format_float(promote_float(value), precision, fspecs, buffer);
-    if (const_check(FMT_DEPRECATED_PERCENT) && fspecs.percent) {
-      buffer.push_back('%');
-      --exp;  // Adjust decimal place position.
-    }
-    fspecs.precision = precision;
-    char_type point = fspecs.locale ? decimal_point<char_type>(locale_)
-                                    : static_cast<char_type>('.');
-    write_padded(specs, float_writer<char_type>(buffer.data(),
-                                                static_cast<int>(buffer.size()),
-                                                exp, fspecs, point));
+  // Attempts to reserve space for n extra characters in the output range.
+  // Returns a pointer to the reserved range or a reference to out_.
+  auto reserve(size_t n) -> decltype(detail::reserve(out_, n)) {
+    return detail::reserve(out_, n);
+  }
+
+  using reserve_iterator = remove_reference_t<decltype(
+      detail::reserve(std::declval<iterator&>(), 0))>;
+
+  template <typename T> void write_int(T value, const format_specs& spec) {
+    using uint_type = uint32_or_64_or_128_t<T>;
+    int_writer<iterator, Char, uint_type> w(out_, locale_, value, spec);
+    handle_int_type_spec(spec.type, w);
+    out_ = w.out;
   }
 
   void write(char value) {
@@ -1782,198 +1860,151 @@ template <typename Range> class basic_writer {
     *it++ = value;
   }
 
-  template <typename Char, FMT_ENABLE_IF(std::is_same<Char, char_type>::value)>
-  void write(Char value) {
-    auto&& it = reserve(1);
-    *it++ = value;
+  template <typename Ch, FMT_ENABLE_IF(std::is_same<Ch, Char>::value)>
+  void write(Ch value) {
+    out_ = detail::write<Char>(out_, value);
   }
 
   void write(string_view value) {
     auto&& it = reserve(value.size());
-    it = copy_str<char_type>(value.begin(), value.end(), it);
+    it = copy_str<Char>(value.begin(), value.end(), it);
   }
   void write(wstring_view value) {
-    static_assert(std::is_same<char_type, wchar_t>::value, "");
+    static_assert(std::is_same<Char, wchar_t>::value, "");
     auto&& it = reserve(value.size());
     it = std::copy(value.begin(), value.end(), it);
   }
 
-  template <typename Char>
-  void write(const Char* s, std::size_t size, const format_specs& specs) {
-    write_padded(specs, str_writer<Char>{s, size});
-  }
-
-  template <typename Char>
-  void write(basic_string_view<Char> s, const format_specs& specs = {}) {
-    const Char* data = s.data();
-    std::size_t size = s.size();
-    if (specs.precision >= 0 && to_unsigned(specs.precision) < size)
-      size = code_point_index(s, to_unsigned(specs.precision));
-    write(data, size, specs);
+  template <typename Ch>
+  void write(const Ch* s, size_t size, const format_specs& specs) {
+    auto width = specs.width != 0
+                     ? count_code_points(basic_string_view<Ch>(s, size))
+                     : 0;
+    out_ = write_padded(out_, specs, size, width, [=](reserve_iterator it) {
+      return copy_str<Char>(s, s + size, it);
+    });
   }
 
-  void write_bytes(string_view bytes, const format_specs& specs) {
-    write_padded(specs, bytes_writer{bytes});
+  template <typename Ch>
+  void write(basic_string_view<Ch> s, const format_specs& specs = {}) {
+    out_ = detail::write(out_, s, specs);
   }
 
-  template <typename UIntPtr>
-  void write_pointer(UIntPtr value, const format_specs* specs) {
-    int num_digits = count_digits<4>(value);
-    auto pw = pointer_writer<UIntPtr>{value, num_digits};
-    if (!specs) return pw(reserve(to_unsigned(num_digits) + 2));
-    format_specs specs_copy = *specs;
-    if (specs_copy.align == align::none) specs_copy.align = align::right;
-    write_padded(specs_copy, pw);
+  void write_pointer(const void* p) {
+    out_ = write_ptr<char_type>(out_, to_uintptr(p), specs_);
   }
-};
 
-using writer = basic_writer<buffer_range<char>>;
-
-template <typename T> struct is_integral : std::is_integral<T> {};
-template <> struct is_integral<int128_t> : std::true_type {};
-template <> struct is_integral<uint128_t> : std::true_type {};
+  struct char_spec_handler : ErrorHandler {
+    arg_formatter_base& formatter;
+    Char value;
 
-template <typename Range, typename ErrorHandler = internal::error_handler>
-class arg_formatter_base {
- public:
-  using char_type = typename Range::value_type;
-  using iterator = typename Range::iterator;
-  using format_specs = basic_format_specs<char_type>;
+    char_spec_handler(arg_formatter_base& f, Char val)
+        : formatter(f), value(val) {}
 
- private:
-  using writer_type = basic_writer<Range>;
-  writer_type writer_;
-  format_specs* specs_;
+    void on_int() {
+      // char is only formatted as int if there are specs.
+      formatter.write_int(static_cast<int>(value), *formatter.specs_);
+    }
+    void on_char() {
+      if (formatter.specs_)
+        formatter.out_ = write_char(formatter.out_, value, *formatter.specs_);
+      else
+        formatter.write(value);
+    }
+  };
 
-  struct char_writer {
-    char_type value;
+  struct cstring_spec_handler : error_handler {
+    arg_formatter_base& formatter;
+    const Char* value;
 
-    size_t size() const { return 1; }
-    size_t width() const { return 1; }
+    cstring_spec_handler(arg_formatter_base& f, const Char* val)
+        : formatter(f), value(val) {}
 
-    template <typename It> void operator()(It&& it) const { *it++ = value; }
+    void on_string() { formatter.write(value); }
+    void on_pointer() { formatter.write_pointer(value); }
   };
 
-  void write_char(char_type value) {
-    if (specs_)
-      writer_.write_padded(*specs_, char_writer{value});
-    else
-      writer_.write(value);
-  }
-
-  void write_pointer(const void* p) {
-    writer_.write_pointer(internal::to_uintptr(p), specs_);
-  }
-
  protected:
-  writer_type& writer() { return writer_; }
-  FMT_DEPRECATED format_specs* spec() { return specs_; }
+  iterator out() { return out_; }
   format_specs* specs() { return specs_; }
-  iterator out() { return writer_.out(); }
 
   void write(bool value) {
-    string_view sv(value ? "true" : "false");
-    specs_ ? writer_.write(sv, *specs_) : writer_.write(sv);
+    if (specs_)
+      write(string_view(value ? "true" : "false"), *specs_);
+    else
+      out_ = detail::write<Char>(out_, value);
   }
 
-  void write(const char_type* value) {
+  void write(const Char* value) {
     if (!value) {
       FMT_THROW(format_error("string pointer is null"));
     } else {
       auto length = std::char_traits<char_type>::length(value);
       basic_string_view<char_type> sv(value, length);
-      specs_ ? writer_.write(sv, *specs_) : writer_.write(sv);
+      specs_ ? write(sv, *specs_) : write(sv);
     }
   }
 
  public:
-  arg_formatter_base(Range r, format_specs* s, locale_ref loc)
-      : writer_(r, loc), specs_(s) {}
+  arg_formatter_base(OutputIt out, format_specs* s, locale_ref loc)
+      : out_(out), locale_(loc), specs_(s) {}
 
   iterator operator()(monostate) {
     FMT_ASSERT(false, "invalid argument type");
-    return out();
+    return out_;
   }
 
   template <typename T, FMT_ENABLE_IF(is_integral<T>::value)>
-  iterator operator()(T value) {
+  FMT_INLINE iterator operator()(T value) {
     if (specs_)
-      writer_.write_int(value, *specs_);
+      write_int(value, *specs_);
     else
-      writer_.write(value);
-    return out();
+      out_ = detail::write<Char>(out_, value);
+    return out_;
   }
 
-  iterator operator()(char_type value) {
-    internal::handle_char_specs(
-        specs_, char_spec_handler(*this, static_cast<char_type>(value)));
-    return out();
+  iterator operator()(Char value) {
+    handle_char_specs(specs_,
+                      char_spec_handler(*this, static_cast<Char>(value)));
+    return out_;
   }
 
   iterator operator()(bool value) {
     if (specs_ && specs_->type) return (*this)(value ? 1 : 0);
     write(value != 0);
-    return out();
+    return out_;
   }
 
   template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
   iterator operator()(T value) {
+    auto specs = specs_ ? *specs_ : format_specs();
     if (const_check(is_supported_floating_point(value)))
-      writer_.write(value, specs_ ? *specs_ : format_specs());
+      out_ = detail::write(out_, value, specs, locale_);
     else
       FMT_ASSERT(false, "unsupported float argument type");
-    return out();
+    return out_;
   }
 
-  struct char_spec_handler : ErrorHandler {
-    arg_formatter_base& formatter;
-    char_type value;
-
-    char_spec_handler(arg_formatter_base& f, char_type val)
-        : formatter(f), value(val) {}
-
-    void on_int() {
-      if (formatter.specs_)
-        formatter.writer_.write_int(value, *formatter.specs_);
-      else
-        formatter.writer_.write(value);
-    }
-    void on_char() { formatter.write_char(value); }
-  };
-
-  struct cstring_spec_handler : internal::error_handler {
-    arg_formatter_base& formatter;
-    const char_type* value;
-
-    cstring_spec_handler(arg_formatter_base& f, const char_type* val)
-        : formatter(f), value(val) {}
-
-    void on_string() { formatter.write(value); }
-    void on_pointer() { formatter.write_pointer(value); }
-  };
-
-  iterator operator()(const char_type* value) {
-    if (!specs_) return write(value), out();
-    internal::handle_cstring_type_spec(specs_->type,
-                                       cstring_spec_handler(*this, value));
-    return out();
+  iterator operator()(const Char* value) {
+    if (!specs_) return write(value), out_;
+    handle_cstring_type_spec(specs_->type, cstring_spec_handler(*this, value));
+    return out_;
   }
 
-  iterator operator()(basic_string_view<char_type> value) {
+  iterator operator()(basic_string_view<Char> value) {
     if (specs_) {
-      internal::check_string_type_spec(specs_->type, internal::error_handler());
-      writer_.write(value, *specs_);
+      check_string_type_spec(specs_->type, error_handler());
+      write(value, *specs_);
     } else {
-      writer_.write(value);
+      write(value);
     }
-    return out();
+    return out_;
   }
 
   iterator operator()(const void* value) {
-    if (specs_)
-      check_pointer_type_spec(specs_->type, internal::error_handler());
+    if (specs_) check_pointer_type_spec(specs_->type, error_handler());
     write_pointer(value);
-    return out();
+    return out_;
   }
 };
 
@@ -2109,7 +2140,7 @@ template <typename Char> class specs_setter {
 
 template <typename ErrorHandler> class numeric_specs_checker {
  public:
-  FMT_CONSTEXPR numeric_specs_checker(ErrorHandler& eh, internal::type arg_type)
+  FMT_CONSTEXPR numeric_specs_checker(ErrorHandler& eh, detail::type arg_type)
       : error_handler_(eh), arg_type_(arg_type) {}
 
   FMT_CONSTEXPR void require_numeric_argument() {
@@ -2132,18 +2163,24 @@ template <typename ErrorHandler> class numeric_specs_checker {
 
  private:
   ErrorHandler& error_handler_;
-  internal::type arg_type_;
+  detail::type arg_type_;
 };
 
 // A format specifier handler that checks if specifiers are consistent with the
 // argument type.
 template <typename Handler> class specs_checker : public Handler {
+ private:
+  numeric_specs_checker<Handler> checker_;
+
+  // Suppress an MSVC warning about using this in initializer list.
+  FMT_CONSTEXPR Handler& error_handler() { return *this; }
+
  public:
-  FMT_CONSTEXPR specs_checker(const Handler& handler, internal::type arg_type)
-      : Handler(handler), checker_(*this, arg_type) {}
+  FMT_CONSTEXPR specs_checker(const Handler& handler, detail::type arg_type)
+      : Handler(handler), checker_(error_handler(), arg_type) {}
 
   FMT_CONSTEXPR specs_checker(const specs_checker& other)
-      : Handler(other), checker_(*this, other.arg_type_) {}
+      : Handler(other), checker_(error_handler(), other.arg_type_) {}
 
   FMT_CONSTEXPR void on_align(align_t align) {
     if (align == align::numeric) checker_.require_numeric_argument();
@@ -2176,9 +2213,6 @@ template <typename Handler> class specs_checker : public Handler {
   }
 
   FMT_CONSTEXPR void end_precision() { checker_.check_precision(); }
-
- private:
-  numeric_specs_checker<Handler> checker_;
 };
 
 template <template <typename> class Handler, typename FormatArg,
@@ -2191,10 +2225,10 @@ FMT_CONSTEXPR int get_dynamic_spec(FormatArg arg, ErrorHandler eh) {
 
 struct auto_id {};
 
-template <typename Context>
-FMT_CONSTEXPR typename Context::format_arg get_arg(Context& ctx, int id) {
+template <typename Context, typename ID>
+FMT_CONSTEXPR typename Context::format_arg get_arg(Context& ctx, ID id) {
   auto arg = ctx.arg(id);
-  if (!arg) ctx.on_error("argument index out of range");
+  if (!arg) ctx.on_error("argument not found");
   return arg;
 }
 
@@ -2227,17 +2261,17 @@ class specs_handler : public specs_setter<typename Context::char_type> {
   using format_arg = typename Context::format_arg;
 
   FMT_CONSTEXPR format_arg get_arg(auto_id) {
-    return internal::get_arg(context_, parse_context_.next_arg_id());
+    return detail::get_arg(context_, parse_context_.next_arg_id());
   }
 
   FMT_CONSTEXPR format_arg get_arg(int arg_id) {
     parse_context_.check_arg_id(arg_id);
-    return internal::get_arg(context_, arg_id);
+    return detail::get_arg(context_, arg_id);
   }
 
   FMT_CONSTEXPR format_arg get_arg(basic_string_view<char_type> arg_id) {
     parse_context_.check_arg_id(arg_id);
-    return context_.arg(arg_id);
+    return detail::get_arg(context_, arg_id);
   }
 
   ParseContext& parse_context_;
@@ -2424,7 +2458,7 @@ FMT_CONSTEXPR const Char* parse_align(const Char* begin, const Char* end,
     case '>':
       align = align::right;
       break;
-#if FMT_NUMERIC_ALIGN
+#if FMT_DEPRECATED_NUMERIC_ALIGN
     case '=':
       align = align::numeric;
       break;
@@ -2555,26 +2589,75 @@ template <>
 inline bool find<false, char>(const char* first, const char* last, char value,
                               const char*& out) {
   out = static_cast<const char*>(
-      std::memchr(first, value, internal::to_unsigned(last - first)));
+      std::memchr(first, value, detail::to_unsigned(last - first)));
   return out != nullptr;
 }
 
 template <typename Handler, typename Char> struct id_adapter {
-  FMT_CONSTEXPR void operator()() { handler.on_arg_id(); }
-  FMT_CONSTEXPR void operator()(int id) { handler.on_arg_id(id); }
+  Handler& handler;
+  int arg_id;
+
+  FMT_CONSTEXPR void operator()() { arg_id = handler.on_arg_id(); }
+  FMT_CONSTEXPR void operator()(int id) { arg_id = handler.on_arg_id(id); }
   FMT_CONSTEXPR void operator()(basic_string_view<Char> id) {
-    handler.on_arg_id(id);
+    arg_id = handler.on_arg_id(id);
   }
   FMT_CONSTEXPR void on_error(const char* message) {
     handler.on_error(message);
   }
-  Handler& handler;
 };
 
+template <typename Char, typename Handler>
+FMT_CONSTEXPR const Char* parse_replacement_field(const Char* begin,
+                                                  const Char* end,
+                                                  Handler&& handler) {
+  ++begin;
+  if (begin == end) return handler.on_error("invalid format string"), end;
+  if (static_cast<char>(*begin) == '}') {
+    handler.on_replacement_field(handler.on_arg_id(), begin);
+  } else if (*begin == '{') {
+    handler.on_text(begin, begin + 1);
+  } else {
+    auto adapter = id_adapter<Handler, Char>{handler, 0};
+    begin = parse_arg_id(begin, end, adapter);
+    Char c = begin != end ? *begin : Char();
+    if (c == '}') {
+      handler.on_replacement_field(adapter.arg_id, begin);
+    } else if (c == ':') {
+      begin = handler.on_format_specs(adapter.arg_id, begin + 1, end);
+      if (begin == end || *begin != '}')
+        return handler.on_error("unknown format specifier"), end;
+    } else {
+      return handler.on_error("missing '}' in format string"), end;
+    }
+  }
+  return begin + 1;
+}
+
 template <bool IS_CONSTEXPR, typename Char, typename Handler>
-FMT_CONSTEXPR void parse_format_string(basic_string_view<Char> format_str,
-                                       Handler&& handler) {
-  struct pfs_writer {
+FMT_CONSTEXPR_DECL FMT_INLINE void parse_format_string(
+    basic_string_view<Char> format_str, Handler&& handler) {
+  auto begin = format_str.data();
+  auto end = begin + format_str.size();
+  if (end - begin < 32) {
+    // Use a simple loop instead of memchr for small strings.
+    const Char* p = begin;
+    while (p != end) {
+      auto c = *p++;
+      if (c == '{') {
+        handler.on_text(begin, p - 1);
+        begin = p = parse_replacement_field(p - 1, end, handler);
+      } else if (c == '}') {
+        if (p == end || *p != '}')
+          return handler.on_error("unmatched '}' in format string");
+        handler.on_text(begin, p);
+        begin = ++p;
+      }
+    }
+    handler.on_text(begin, end);
+    return;
+  }
+  struct writer {
     FMT_CONSTEXPR void operator()(const Char* begin, const Char* end) {
       if (begin == end) return;
       for (;;) {
@@ -2590,8 +2673,6 @@ FMT_CONSTEXPR void parse_format_string(basic_string_view<Char> format_str,
     }
     Handler& handler_;
   } write{handler};
-  auto begin = format_str.data();
-  auto end = begin + format_str.size();
   while (begin != end) {
     // Doing two passes with memchr (one for '{' and another for '}') is up to
     // 2.5x faster than the naive one-pass implementation on big format strings.
@@ -2599,27 +2680,7 @@ FMT_CONSTEXPR void parse_format_string(basic_string_view<Char> format_str,
     if (*begin != '{' && !find<IS_CONSTEXPR>(begin + 1, end, '{', p))
       return write(begin, end);
     write(begin, p);
-    ++p;
-    if (p == end) return handler.on_error("invalid format string");
-    if (static_cast<char>(*p) == '}') {
-      handler.on_arg_id();
-      handler.on_replacement_field(p);
-    } else if (*p == '{') {
-      handler.on_text(p, p + 1);
-    } else {
-      p = parse_arg_id(p, end, id_adapter<Handler, Char>{handler});
-      Char c = p != end ? *p : Char();
-      if (c == '}') {
-        handler.on_replacement_field(p);
-      } else if (c == ':') {
-        p = handler.on_format_specs(p + 1, end);
-        if (p == end || *p != '}')
-          return handler.on_error("unknown format specifier");
-      } else {
-        return handler.on_error("missing '}' in format string");
-      }
-    }
-    begin = p + 1;
+    begin = parse_replacement_field(p, end, handler);
   }
 }
 
@@ -2629,44 +2690,121 @@ FMT_CONSTEXPR const typename ParseContext::char_type* parse_format_specs(
   using char_type = typename ParseContext::char_type;
   using context = buffer_context<char_type>;
   using mapped_type =
-      conditional_t<internal::mapped_type_constant<T, context>::value !=
+      conditional_t<detail::mapped_type_constant<T, context>::value !=
                         type::custom_type,
                     decltype(arg_mapper<context>().map(std::declval<T>())), T>;
   auto f = conditional_t<has_formatter<mapped_type, context>::value,
                          formatter<mapped_type, char_type>,
-                         internal::fallback_formatter<T, char_type>>();
+                         detail::fallback_formatter<T, char_type>>();
   return f.parse(ctx);
 }
 
+template <typename ArgFormatter, typename Char, typename Context>
+struct format_handler : detail::error_handler {
+  basic_format_parse_context<Char> parse_context;
+  Context context;
+
+  format_handler(typename ArgFormatter::iterator out,
+                 basic_string_view<Char> str,
+                 basic_format_args<Context> format_args, detail::locale_ref loc)
+      : parse_context(str), context(out, format_args, loc) {}
+
+  void on_text(const Char* begin, const Char* end) {
+    auto size = to_unsigned(end - begin);
+    auto out = context.out();
+    auto&& it = reserve(out, size);
+    it = std::copy_n(begin, size, it);
+    context.advance_to(out);
+  }
+
+  int on_arg_id() { return parse_context.next_arg_id(); }
+  int on_arg_id(int id) { return parse_context.check_arg_id(id), id; }
+  int on_arg_id(basic_string_view<Char> id) {
+    int arg_id = context.arg_id(id);
+    if (arg_id < 0) on_error("argument not found");
+    return arg_id;
+  }
+
+  FMT_INLINE void on_replacement_field(int id, const Char*) {
+    auto arg = get_arg(context, id);
+    context.advance_to(visit_format_arg(
+        default_arg_formatter<typename ArgFormatter::iterator, Char>{
+            context.out(), context.args(), context.locale()},
+        arg));
+  }
+
+  const Char* on_format_specs(int id, const Char* begin, const Char* end) {
+    advance_to(parse_context, begin);
+    auto arg = get_arg(context, id);
+    custom_formatter<Context> f(parse_context, context);
+    if (visit_format_arg(f, arg)) return parse_context.begin();
+    basic_format_specs<Char> specs;
+    using parse_context_t = basic_format_parse_context<Char>;
+    specs_checker<specs_handler<parse_context_t, Context>> handler(
+        specs_handler<parse_context_t, Context>(specs, parse_context, context),
+        arg.type());
+    begin = parse_format_specs(begin, end, handler);
+    if (begin == end || *begin != '}') on_error("missing '}' in format string");
+    advance_to(parse_context, begin);
+    context.advance_to(
+        visit_format_arg(ArgFormatter(context, &parse_context, &specs), arg));
+    return begin;
+  }
+};
+
+// A parse context with extra argument id checks. It is only used at compile
+// time because adding checks at runtime would introduce substantial overhead
+// and would be redundant since argument ids are checked when arguments are
+// retrieved anyway.
+template <typename Char, typename ErrorHandler = error_handler>
+class compile_parse_context
+    : public basic_format_parse_context<Char, ErrorHandler> {
+ private:
+  int num_args_;
+  using base = basic_format_parse_context<Char, ErrorHandler>;
+
+ public:
+  explicit FMT_CONSTEXPR compile_parse_context(
+      basic_string_view<Char> format_str, int num_args = max_value<int>(),
+      ErrorHandler eh = {})
+      : base(format_str, eh), num_args_(num_args) {}
+
+  FMT_CONSTEXPR int next_arg_id() {
+    int id = base::next_arg_id();
+    if (id >= num_args_) this->on_error("argument not found");
+    return id;
+  }
+
+  FMT_CONSTEXPR void check_arg_id(int id) {
+    base::check_arg_id(id);
+    if (id >= num_args_) this->on_error("argument not found");
+  }
+  using base::check_arg_id;
+};
+
 template <typename Char, typename ErrorHandler, typename... Args>
 class format_string_checker {
  public:
   explicit FMT_CONSTEXPR format_string_checker(
       basic_string_view<Char> format_str, ErrorHandler eh)
-      : arg_id_(-1),
-        context_(format_str, eh),
+      : context_(format_str, num_args, eh),
         parse_funcs_{&parse_format_specs<Args, parse_context_type>...} {}
 
   FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
 
-  FMT_CONSTEXPR void on_arg_id() {
-    arg_id_ = context_.next_arg_id();
-    check_arg_id();
-  }
-  FMT_CONSTEXPR void on_arg_id(int id) {
-    arg_id_ = id;
-    context_.check_arg_id(id);
-    check_arg_id();
-  }
-  FMT_CONSTEXPR void on_arg_id(basic_string_view<Char>) {
+  FMT_CONSTEXPR int on_arg_id() { return context_.next_arg_id(); }
+  FMT_CONSTEXPR int on_arg_id(int id) { return context_.check_arg_id(id), id; }
+  FMT_CONSTEXPR int on_arg_id(basic_string_view<Char>) {
     on_error("compile-time checks don't support named arguments");
+    return 0;
   }
 
-  FMT_CONSTEXPR void on_replacement_field(const Char*) {}
+  FMT_CONSTEXPR void on_replacement_field(int, const Char*) {}
 
-  FMT_CONSTEXPR const Char* on_format_specs(const Char* begin, const Char*) {
+  FMT_CONSTEXPR const Char* on_format_specs(int id, const Char* begin,
+                                            const Char*) {
     advance_to(context_, begin);
-    return arg_id_ < num_args ? parse_funcs_[arg_id_](context_) : begin;
+    return id < num_args ? parse_funcs_[id](context_) : begin;
   }
 
   FMT_CONSTEXPR void on_error(const char* message) {
@@ -2674,35 +2812,66 @@ class format_string_checker {
   }
 
  private:
-  using parse_context_type = basic_format_parse_context<Char, ErrorHandler>;
+  using parse_context_type = compile_parse_context<Char, ErrorHandler>;
   enum { num_args = sizeof...(Args) };
 
-  FMT_CONSTEXPR void check_arg_id() {
-    if (arg_id_ >= num_args) context_.on_error("argument index out of range");
-  }
-
   // Format specifier parsing function.
   using parse_func = const Char* (*)(parse_context_type&);
 
-  int arg_id_;
   parse_context_type context_;
   parse_func parse_funcs_[num_args > 0 ? num_args : 1];
 };
 
-template <typename Char, typename ErrorHandler, typename... Args>
-FMT_CONSTEXPR bool do_check_format_string(basic_string_view<Char> s,
-                                          ErrorHandler eh = ErrorHandler()) {
-  format_string_checker<Char, ErrorHandler, Args...> checker(s, eh);
-  parse_format_string<true>(s, checker);
-  return true;
+// Converts string literals to basic_string_view.
+template <typename Char, size_t N>
+FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
+    const Char (&s)[N]) {
+  // Remove trailing null character if needed. Won't be present if this is used
+  // with raw character array (i.e. not defined as a string).
+  return {s,
+          N - ((std::char_traits<Char>::to_int_type(s[N - 1]) == 0) ? 1 : 0)};
+}
+
+// Converts string_view to basic_string_view.
+template <typename Char>
+FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
+    const std_string_view<Char>& s) {
+  return {s.data(), s.size()};
 }
 
+#define FMT_STRING_IMPL(s, base)                                  \
+  [] {                                                            \
+    /* Use a macro-like name to avoid shadowing warnings. */      \
+    struct FMT_COMPILE_STRING : base {                            \
+      using char_type = fmt::remove_cvref_t<decltype(s[0])>;      \
+      FMT_MAYBE_UNUSED FMT_CONSTEXPR                              \
+      operator fmt::basic_string_view<char_type>() const {        \
+        return fmt::detail::compile_string_to_view<char_type>(s); \
+      }                                                           \
+    };                                                            \
+    return FMT_COMPILE_STRING();                                  \
+  }()
+
+/**
+  \rst
+  Constructs a compile-time format string from a string literal *s*.
+
+  **Example**::
+
+    // A compile-time error because 'd' is an invalid specifier for strings.
+    std::string s = fmt::format(FMT_STRING("{:d}"), "foo");
+  \endrst
+ */
+#define FMT_STRING(s) FMT_STRING_IMPL(s, fmt::compile_string)
+
 template <typename... Args, typename S,
           enable_if_t<(is_compile_string<S>::value), int>>
 void check_format_string(S format_str) {
-  FMT_CONSTEXPR_DECL bool invalid_format = internal::do_check_format_string<
-      typename S::char_type, internal::error_handler,
-      remove_const_t<remove_reference_t<Args>>...>(to_string_view(format_str));
+  FMT_CONSTEXPR_DECL auto s = to_string_view(format_str);
+  using checker = format_string_checker<typename S::char_type, error_handler,
+                                        remove_cvref_t<Args>...>;
+  FMT_CONSTEXPR_DECL bool invalid_format =
+      (parse_format_string<true>(s, checker(s, {})), true);
   (void)invalid_format;
 }
 
@@ -2713,44 +2882,37 @@ void handle_dynamic_spec(int& value, arg_ref<typename Context::char_type> ref,
   case arg_id_kind::none:
     break;
   case arg_id_kind::index:
-    value = internal::get_dynamic_spec<Handler>(ctx.arg(ref.val.index),
-                                                ctx.error_handler());
+    value = detail::get_dynamic_spec<Handler>(ctx.arg(ref.val.index),
+                                              ctx.error_handler());
     break;
   case arg_id_kind::name:
-    value = internal::get_dynamic_spec<Handler>(ctx.arg(ref.val.name),
-                                                ctx.error_handler());
+    value = detail::get_dynamic_spec<Handler>(ctx.arg(ref.val.name),
+                                              ctx.error_handler());
     break;
   }
 }
 
-using format_func = void (*)(internal::buffer<char>&, int, string_view);
+using format_func = void (*)(detail::buffer<char>&, int, string_view);
 
 FMT_API void format_error_code(buffer<char>& out, int error_code,
                                string_view message) FMT_NOEXCEPT;
 
 FMT_API void report_error(format_func func, int error_code,
                           string_view message) FMT_NOEXCEPT;
-}  // namespace internal
-
-template <typename Range>
-using basic_writer FMT_DEPRECATED_ALIAS = internal::basic_writer<Range>;
-using writer FMT_DEPRECATED_ALIAS = internal::writer;
-using wwriter FMT_DEPRECATED_ALIAS =
-    internal::basic_writer<buffer_range<wchar_t>>;
 
 /** The default argument formatter. */
-template <typename Range>
-class arg_formatter : public internal::arg_formatter_base<Range> {
+template <typename OutputIt, typename Char>
+class arg_formatter : public arg_formatter_base<OutputIt, Char> {
  private:
-  using char_type = typename Range::value_type;
-  using base = internal::arg_formatter_base<Range>;
-  using context_type = basic_format_context<typename base::iterator, char_type>;
+  using char_type = Char;
+  using base = arg_formatter_base<OutputIt, Char>;
+  using context_type = basic_format_context<OutputIt, Char>;
 
   context_type& ctx_;
   basic_format_parse_context<char_type>* parse_ctx_;
+  const Char* ptr_;
 
  public:
-  using range = Range;
   using iterator = typename base::iterator;
   using format_specs = typename base::format_specs;
 
@@ -2764,19 +2926,26 @@ class arg_formatter : public internal::arg_formatter_base<Range> {
   explicit arg_formatter(
       context_type& ctx,
       basic_format_parse_context<char_type>* parse_ctx = nullptr,
-      format_specs* specs = nullptr)
-      : base(Range(ctx.out()), specs, ctx.locale()),
+      format_specs* specs = nullptr, const Char* ptr = nullptr)
+      : base(ctx.out(), specs, ctx.locale()),
         ctx_(ctx),
-        parse_ctx_(parse_ctx) {}
+        parse_ctx_(parse_ctx),
+        ptr_(ptr) {}
 
   using base::operator();
 
   /** Formats an argument of a user-defined type. */
   iterator operator()(typename basic_format_arg<context_type>::handle handle) {
+    if (ptr_) advance_to(*parse_ctx_, ptr_);
     handle.format(*parse_ctx_, ctx_);
     return ctx_.out();
   }
 };
+}  // namespace detail
+
+template <typename OutputIt, typename Char>
+using arg_formatter FMT_DEPRECATED_ALIAS =
+  detail::arg_formatter<OutputIt, Char>;
 
 /**
  An error returned by an operating system or a language runtime,
@@ -2841,7 +3010,7 @@ class FMT_API system_error : public std::runtime_error {
   may look like "Unknown error -1" and is platform-dependent.
   \endrst
  */
-FMT_API void format_system_error(internal::buffer<char>& out, int error_code,
+FMT_API void format_system_error(detail::buffer<char>& out, int error_code,
                                  string_view message) FMT_NOEXCEPT;
 
 // Reports a system error without throwing an exception.
@@ -2858,47 +3027,32 @@ class format_int {
   mutable char buffer_[buffer_size];
   char* str_;
 
-  // Formats value in reverse and returns a pointer to the beginning.
-  char* format_decimal(unsigned long long value) {
-    char* ptr = buffer_ + (buffer_size - 1);  // Parens to workaround MSVC bug.
-    while (value >= 100) {
-      // Integer division is slow so do it for a group of two digits instead
-      // of for every digit. The idea comes from the talk by Alexandrescu
-      // "Three Optimization Tips for C++". See speed-test for a comparison.
-      auto index = static_cast<unsigned>((value % 100) * 2);
-      value /= 100;
-      *--ptr = internal::data::digits[index + 1];
-      *--ptr = internal::data::digits[index];
-    }
-    if (value < 10) {
-      *--ptr = static_cast<char>('0' + value);
-      return ptr;
-    }
-    auto index = static_cast<unsigned>(value * 2);
-    *--ptr = internal::data::digits[index + 1];
-    *--ptr = internal::data::digits[index];
-    return ptr;
+  template <typename UInt> char* format_unsigned(UInt value) {
+    auto n = static_cast<detail::uint32_or_64_or_128_t<UInt>>(value);
+    return detail::format_decimal(buffer_, n, buffer_size - 1).begin;
   }
 
-  void format_signed(long long value) {
-    auto abs_value = static_cast<unsigned long long>(value);
+  template <typename Int> char* format_signed(Int value) {
+    auto abs_value = static_cast<detail::uint32_or_64_or_128_t<Int>>(value);
     bool negative = value < 0;
     if (negative) abs_value = 0 - abs_value;
-    str_ = format_decimal(abs_value);
-    if (negative) *--str_ = '-';
+    auto begin = format_unsigned(abs_value);
+    if (negative) *--begin = '-';
+    return begin;
   }
 
  public:
-  explicit format_int(int value) { format_signed(value); }
-  explicit format_int(long value) { format_signed(value); }
-  explicit format_int(long long value) { format_signed(value); }
-  explicit format_int(unsigned value) : str_(format_decimal(value)) {}
-  explicit format_int(unsigned long value) : str_(format_decimal(value)) {}
-  explicit format_int(unsigned long long value) : str_(format_decimal(value)) {}
+  explicit format_int(int value) : str_(format_signed(value)) {}
+  explicit format_int(long value) : str_(format_signed(value)) {}
+  explicit format_int(long long value) : str_(format_signed(value)) {}
+  explicit format_int(unsigned value) : str_(format_unsigned(value)) {}
+  explicit format_int(unsigned long value) : str_(format_unsigned(value)) {}
+  explicit format_int(unsigned long long value)
+      : str_(format_unsigned(value)) {}
 
   /** Returns the number of characters written to the output buffer. */
-  std::size_t size() const {
-    return internal::to_unsigned(buffer_ - str_ + buffer_size - 1);
+  size_t size() const {
+    return detail::to_unsigned(buffer_ - str_ + buffer_size - 1);
   }
 
   /**
@@ -2924,75 +3078,71 @@ class format_int {
   std::string str() const { return std::string(str_, size()); }
 };
 
-// A formatter specialization for the core types corresponding to internal::type
+// A formatter specialization for the core types corresponding to detail::type
 // constants.
 template <typename T, typename Char>
 struct formatter<T, Char,
-                 enable_if_t<internal::type_constant<T, Char>::value !=
-                             internal::type::custom_type>> {
+                 enable_if_t<detail::type_constant<T, Char>::value !=
+                             detail::type::custom_type>> {
   FMT_CONSTEXPR formatter() = default;
 
   // Parses format specifiers stopping either at the end of the range or at the
   // terminating '}'.
   template <typename ParseContext>
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    using handler_type = internal::dynamic_specs_handler<ParseContext>;
-    auto type = internal::type_constant<T, Char>::value;
-    internal::specs_checker<handler_type> handler(handler_type(specs_, ctx),
-                                                  type);
+    using handler_type = detail::dynamic_specs_handler<ParseContext>;
+    auto type = detail::type_constant<T, Char>::value;
+    detail::specs_checker<handler_type> handler(handler_type(specs_, ctx),
+                                                type);
     auto it = parse_format_specs(ctx.begin(), ctx.end(), handler);
     auto eh = ctx.error_handler();
     switch (type) {
-    case internal::type::none_type:
-    case internal::type::named_arg_type:
+    case detail::type::none_type:
       FMT_ASSERT(false, "invalid argument type");
       break;
-    case internal::type::int_type:
-    case internal::type::uint_type:
-    case internal::type::long_long_type:
-    case internal::type::ulong_long_type:
-    case internal::type::int128_type:
-    case internal::type::uint128_type:
-    case internal::type::bool_type:
+    case detail::type::int_type:
+    case detail::type::uint_type:
+    case detail::type::long_long_type:
+    case detail::type::ulong_long_type:
+    case detail::type::int128_type:
+    case detail::type::uint128_type:
+    case detail::type::bool_type:
       handle_int_type_spec(specs_.type,
-                           internal::int_type_checker<decltype(eh)>(eh));
+                           detail::int_type_checker<decltype(eh)>(eh));
       break;
-    case internal::type::char_type:
+    case detail::type::char_type:
       handle_char_specs(
-          &specs_, internal::char_specs_checker<decltype(eh)>(specs_.type, eh));
+          &specs_, detail::char_specs_checker<decltype(eh)>(specs_.type, eh));
       break;
-    case internal::type::float_type:
-      if (internal::const_check(FMT_USE_FLOAT)) {
-        internal::parse_float_type_spec(specs_, eh);
-      } else {
+    case detail::type::float_type:
+      if (detail::const_check(FMT_USE_FLOAT))
+        detail::parse_float_type_spec(specs_, eh);
+      else
         FMT_ASSERT(false, "float support disabled");
-      }
       break;
-    case internal::type::double_type:
-      if (internal::const_check(FMT_USE_DOUBLE)) {
-        internal::parse_float_type_spec(specs_, eh);
-      } else {
+    case detail::type::double_type:
+      if (detail::const_check(FMT_USE_DOUBLE))
+        detail::parse_float_type_spec(specs_, eh);
+      else
         FMT_ASSERT(false, "double support disabled");
-      }
       break;
-    case internal::type::long_double_type:
-      if (internal::const_check(FMT_USE_LONG_DOUBLE)) {
-        internal::parse_float_type_spec(specs_, eh);
-      } else {
+    case detail::type::long_double_type:
+      if (detail::const_check(FMT_USE_LONG_DOUBLE))
+        detail::parse_float_type_spec(specs_, eh);
+      else
         FMT_ASSERT(false, "long double support disabled");
-      }
       break;
-    case internal::type::cstring_type:
-      internal::handle_cstring_type_spec(
-          specs_.type, internal::cstring_type_checker<decltype(eh)>(eh));
+    case detail::type::cstring_type:
+      detail::handle_cstring_type_spec(
+          specs_.type, detail::cstring_type_checker<decltype(eh)>(eh));
       break;
-    case internal::type::string_type:
-      internal::check_string_type_spec(specs_.type, eh);
+    case detail::type::string_type:
+      detail::check_string_type_spec(specs_.type, eh);
       break;
-    case internal::type::pointer_type:
-      internal::check_pointer_type_spec(specs_.type, eh);
+    case detail::type::pointer_type:
+      detail::check_pointer_type_spec(specs_.type, eh);
       break;
-    case internal::type::custom_type:
+    case detail::type::custom_type:
       // Custom format specifiers should be checked in parse functions of
       // formatter specializations.
       break;
@@ -3002,19 +3152,18 @@ struct formatter<T, Char,
 
   template <typename FormatContext>
   auto format(const T& val, FormatContext& ctx) -> decltype(ctx.out()) {
-    internal::handle_dynamic_spec<internal::width_checker>(
-        specs_.width, specs_.width_ref, ctx);
-    internal::handle_dynamic_spec<internal::precision_checker>(
+    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
+                                                       specs_.width_ref, ctx);
+    detail::handle_dynamic_spec<detail::precision_checker>(
         specs_.precision, specs_.precision_ref, ctx);
-    using range_type =
-        internal::output_range<typename FormatContext::iterator,
-                               typename FormatContext::char_type>;
-    return visit_format_arg(arg_formatter<range_type>(ctx, nullptr, &specs_),
-                            internal::make_arg<FormatContext>(val));
+    using af = detail::arg_formatter<typename FormatContext::iterator,
+                                     typename FormatContext::char_type>;
+    return visit_format_arg(af(ctx, nullptr, &specs_),
+                            detail::make_arg<FormatContext>(val));
   }
 
  private:
-  internal::dynamic_format_specs<Char> specs_;
+  detail::dynamic_format_specs<Char> specs_;
 };
 
 #define FMT_FORMAT_AS(Type, Base)                                             \
@@ -3035,7 +3184,7 @@ FMT_FORMAT_AS(unsigned long, unsigned long long);
 FMT_FORMAT_AS(Char*, const Char*);
 FMT_FORMAT_AS(std::basic_string<Char>, basic_string_view<Char>);
 FMT_FORMAT_AS(std::nullptr_t, const void*);
-FMT_FORMAT_AS(internal::std_string_view<Char>, basic_string_view<Char>);
+FMT_FORMAT_AS(detail::std_string_view<Char>, basic_string_view<Char>);
 
 template <typename Char>
 struct formatter<void*, Char> : formatter<const void*, Char> {
@@ -3065,7 +3214,7 @@ struct formatter<Char[N], Char> : formatter<basic_string_view<Char>, Char> {
 //   };
 template <typename Char = char> class dynamic_formatter {
  private:
-  struct null_handler : internal::error_handler {
+  struct null_handler : detail::error_handler {
     void on_align(align_t) {}
     void on_plus() {}
     void on_minus() {}
@@ -3078,16 +3227,15 @@ template <typename Char = char> class dynamic_formatter {
   auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
     format_str_ = ctx.begin();
     // Checks are deferred to formatting time when the argument type is known.
-    internal::dynamic_specs_handler<ParseContext> handler(specs_, ctx);
+    detail::dynamic_specs_handler<ParseContext> handler(specs_, ctx);
     return parse_format_specs(ctx.begin(), ctx.end(), handler);
   }
 
   template <typename T, typename FormatContext>
   auto format(const T& val, FormatContext& ctx) -> decltype(ctx.out()) {
     handle_specs(ctx);
-    internal::specs_checker<null_handler> checker(
-        null_handler(),
-        internal::mapped_type_constant<T, FormatContext>::value);
+    detail::specs_checker<null_handler> checker(
+        null_handler(), detail::mapped_type_constant<T, FormatContext>::value);
     checker.on_align(specs_.align);
     switch (specs_.sign) {
     case sign::none:
@@ -3104,104 +3252,47 @@ template <typename Char = char> class dynamic_formatter {
     }
     if (specs_.alt) checker.on_hash();
     if (specs_.precision >= 0) checker.end_precision();
-    using range = internal::output_range<typename FormatContext::iterator,
-                                         typename FormatContext::char_type>;
-    visit_format_arg(arg_formatter<range>(ctx, nullptr, &specs_),
-                     internal::make_arg<FormatContext>(val));
+    using af = detail::arg_formatter<typename FormatContext::iterator,
+                                     typename FormatContext::char_type>;
+    visit_format_arg(af(ctx, nullptr, &specs_),
+                     detail::make_arg<FormatContext>(val));
     return ctx.out();
   }
 
  private:
   template <typename Context> void handle_specs(Context& ctx) {
-    internal::handle_dynamic_spec<internal::width_checker>(
-        specs_.width, specs_.width_ref, ctx);
-    internal::handle_dynamic_spec<internal::precision_checker>(
+    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
+                                                       specs_.width_ref, ctx);
+    detail::handle_dynamic_spec<detail::precision_checker>(
         specs_.precision, specs_.precision_ref, ctx);
   }
 
-  internal::dynamic_format_specs<Char> specs_;
+  detail::dynamic_format_specs<Char> specs_;
   const Char* format_str_;
 };
 
-template <typename Range, typename Char>
-typename basic_format_context<Range, Char>::format_arg
-basic_format_context<Range, Char>::arg(basic_string_view<char_type> name) {
-  map_.init(args_);
-  format_arg arg = map_.find(name);
-  if (arg.type() == internal::type::none_type)
-    this->on_error("argument not found");
-  return arg;
-}
-
 template <typename Char, typename ErrorHandler>
 FMT_CONSTEXPR void advance_to(
     basic_format_parse_context<Char, ErrorHandler>& ctx, const Char* p) {
   ctx.advance_to(ctx.begin() + (p - &*ctx.begin()));
 }
 
-template <typename ArgFormatter, typename Char, typename Context>
-struct format_handler : internal::error_handler {
-  using range = typename ArgFormatter::range;
-
-  format_handler(range r, basic_string_view<Char> str,
-                 basic_format_args<Context> format_args,
-                 internal::locale_ref loc)
-      : parse_context(str), context(r.begin(), format_args, loc) {}
-
-  void on_text(const Char* begin, const Char* end) {
-    auto size = internal::to_unsigned(end - begin);
-    auto out = context.out();
-    auto&& it = internal::reserve(out, size);
-    it = std::copy_n(begin, size, it);
-    context.advance_to(out);
-  }
-
-  void get_arg(int id) { arg = internal::get_arg(context, id); }
-
-  void on_arg_id() { get_arg(parse_context.next_arg_id()); }
-  void on_arg_id(int id) {
-    parse_context.check_arg_id(id);
-    get_arg(id);
-  }
-  void on_arg_id(basic_string_view<Char> id) { arg = context.arg(id); }
-
-  void on_replacement_field(const Char* p) {
-    advance_to(parse_context, p);
-    context.advance_to(
-        visit_format_arg(ArgFormatter(context, &parse_context), arg));
-  }
-
-  const Char* on_format_specs(const Char* begin, const Char* end) {
-    advance_to(parse_context, begin);
-    internal::custom_formatter<Context> f(parse_context, context);
-    if (visit_format_arg(f, arg)) return parse_context.begin();
-    basic_format_specs<Char> specs;
-    using internal::specs_handler;
-    using parse_context_t = basic_format_parse_context<Char>;
-    internal::specs_checker<specs_handler<parse_context_t, Context>> handler(
-        specs_handler<parse_context_t, Context>(specs, parse_context, context),
-        arg.type());
-    begin = parse_format_specs(begin, end, handler);
-    if (begin == end || *begin != '}') on_error("missing '}' in format string");
-    advance_to(parse_context, begin);
-    context.advance_to(
-        visit_format_arg(ArgFormatter(context, &parse_context, &specs), arg));
-    return begin;
-  }
-
-  basic_format_parse_context<Char> parse_context;
-  Context context;
-  basic_format_arg<Context> arg;
-};
-
 /** Formats arguments and writes the output to the range. */
 template <typename ArgFormatter, typename Char, typename Context>
 typename Context::iterator vformat_to(
-    typename ArgFormatter::range out, basic_string_view<Char> format_str,
+    typename ArgFormatter::iterator out, basic_string_view<Char> format_str,
     basic_format_args<Context> args,
-    internal::locale_ref loc = internal::locale_ref()) {
-  format_handler<ArgFormatter, Char, Context> h(out, format_str, args, loc);
-  internal::parse_format_string<false>(format_str, h);
+    detail::locale_ref loc = detail::locale_ref()) {
+  if (format_str.size() == 2 && detail::equal2(format_str.data(), "{}")) {
+    auto arg = args.get(0);
+    if (!arg) detail::error_handler().on_error("argument not found");
+    using iterator = typename ArgFormatter::iterator;
+    return visit_format_arg(
+        detail::default_arg_formatter<iterator, Char>{out, args, loc}, arg);
+  }
+  detail::format_handler<ArgFormatter, Char, Context> h(out, format_str, args,
+                                                        loc);
+  detail::parse_format_string<false>(format_str, h);
   return h.context.out();
 }
 
@@ -3228,44 +3319,42 @@ class bytes {
 template <> struct formatter<bytes> {
   template <typename ParseContext>
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    using handler_type = internal::dynamic_specs_handler<ParseContext>;
-    internal::specs_checker<handler_type> handler(handler_type(specs_, ctx),
-                                                  internal::type::string_type);
+    using handler_type = detail::dynamic_specs_handler<ParseContext>;
+    detail::specs_checker<handler_type> handler(handler_type(specs_, ctx),
+                                                detail::type::string_type);
     auto it = parse_format_specs(ctx.begin(), ctx.end(), handler);
-    internal::check_string_type_spec(specs_.type, ctx.error_handler());
+    detail::check_string_type_spec(specs_.type, ctx.error_handler());
     return it;
   }
 
   template <typename FormatContext>
   auto format(bytes b, FormatContext& ctx) -> decltype(ctx.out()) {
-    internal::handle_dynamic_spec<internal::width_checker>(
-        specs_.width, specs_.width_ref, ctx);
-    internal::handle_dynamic_spec<internal::precision_checker>(
+    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
+                                                       specs_.width_ref, ctx);
+    detail::handle_dynamic_spec<detail::precision_checker>(
         specs_.precision, specs_.precision_ref, ctx);
-    using range_type =
-        internal::output_range<typename FormatContext::iterator, char>;
-    internal::basic_writer<range_type> writer(range_type(ctx.out()));
-    writer.write_bytes(b.data_, specs_);
-    return writer.out();
+    return detail::write_bytes(ctx.out(), b.data_, specs_);
   }
 
  private:
-  internal::dynamic_format_specs<char> specs_;
+  detail::dynamic_format_specs<char> specs_;
 };
 
-template <typename It, typename Char> struct arg_join : internal::view {
+template <typename It, typename Sentinel, typename Char>
+struct arg_join : detail::view {
   It begin;
-  It end;
+  Sentinel end;
   basic_string_view<Char> sep;
 
-  arg_join(It b, It e, basic_string_view<Char> s) : begin(b), end(e), sep(s) {}
+  arg_join(It b, Sentinel e, basic_string_view<Char> s)
+      : begin(b), end(e), sep(s) {}
 };
 
-template <typename It, typename Char>
-struct formatter<arg_join<It, Char>, Char>
+template <typename It, typename Sentinel, typename Char>
+struct formatter<arg_join<It, Sentinel, Char>, Char>
     : formatter<typename std::iterator_traits<It>::value_type, Char> {
   template <typename FormatContext>
-  auto format(const arg_join<It, Char>& value, FormatContext& ctx)
+  auto format(const arg_join<It, Sentinel, Char>& value, FormatContext& ctx)
       -> decltype(ctx.out()) {
     using base = formatter<typename std::iterator_traits<It>::value_type, Char>;
     auto it = value.begin;
@@ -3286,13 +3375,13 @@ struct formatter<arg_join<It, Char>, Char>
   Returns an object that formats the iterator range `[begin, end)` with elements
   separated by `sep`.
  */
-template <typename It>
-arg_join<It, char> join(It begin, It end, string_view sep) {
+template <typename It, typename Sentinel>
+arg_join<It, Sentinel, char> join(It begin, Sentinel end, string_view sep) {
   return {begin, end, sep};
 }
 
-template <typename It>
-arg_join<It, wchar_t> join(It begin, It end, wstring_view sep) {
+template <typename It, typename Sentinel>
+arg_join<It, Sentinel, wchar_t> join(It begin, Sentinel end, wstring_view sep) {
   return {begin, end, sep};
 }
 
@@ -3313,14 +3402,15 @@ arg_join<It, wchar_t> join(It begin, It end, wstring_view sep) {
   \endrst
  */
 template <typename Range>
-arg_join<internal::iterator_t<const Range>, char> join(const Range& range,
-                                                       string_view sep) {
+arg_join<detail::iterator_t<const Range>, detail::sentinel_t<const Range>, char>
+join(const Range& range, string_view sep) {
   return join(std::begin(range), std::end(range), sep);
 }
 
 template <typename Range>
-arg_join<internal::iterator_t<const Range>, wchar_t> join(const Range& range,
-                                                          wstring_view sep) {
+arg_join<detail::iterator_t<const Range>, detail::sentinel_t<const Range>,
+         wchar_t>
+join(const Range& range, wstring_view sep) {
   return join(std::begin(range), std::end(range), sep);
 }
 
@@ -3335,8 +3425,21 @@ arg_join<internal::iterator_t<const Range>, wchar_t> join(const Range& range,
     std::string answer = fmt::to_string(42);
   \endrst
  */
-template <typename T> inline std::string to_string(const T& value) {
-  return format("{}", value);
+template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
+inline std::string to_string(const T& value) {
+  std::string result;
+  detail::write<char>(std::back_inserter(result), value);
+  return result;
+}
+
+template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
+inline std::string to_string(T value) {
+  // The buffer should be large enough to store the number including the sign or
+  // "false" for bool.
+  constexpr int max_size = detail::digits10<T>() + 2;
+  char buffer[max_size > 5 ? max_size : 5];
+  char* begin = buffer;
+  return std::string(begin, detail::write<char>(begin, value));
 }
 
 /**
@@ -3346,36 +3449,65 @@ template <typename T> inline std::wstring to_wstring(const T& value) {
   return format(L"{}", value);
 }
 
-template <typename Char, std::size_t SIZE>
+template <typename Char, size_t SIZE>
 std::basic_string<Char> to_string(const basic_memory_buffer<Char, SIZE>& buf) {
-  return std::basic_string<Char>(buf.data(), buf.size());
+  auto size = buf.size();
+  detail::assume(size < std::basic_string<Char>().max_size());
+  return std::basic_string<Char>(buf.data(), size);
 }
 
 template <typename Char>
-typename buffer_context<Char>::iterator internal::vformat_to(
-    internal::buffer<Char>& buf, basic_string_view<Char> format_str,
+typename buffer_context<Char>::iterator detail::vformat_to(
+    detail::buffer<Char>& buf, basic_string_view<Char> format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  using range = buffer_range<Char>;
-  return vformat_to<arg_formatter<range>>(buf, to_string_view(format_str),
-                                          args);
-}
+  using af = arg_formatter<typename buffer_context<Char>::iterator, Char>;
+  return vformat_to<af>(std::back_inserter(buf), to_string_view(format_str),
+                        args);
+}
+
+#ifndef FMT_HEADER_ONLY
+extern template format_context::iterator detail::vformat_to(
+    detail::buffer<char>&, string_view, basic_format_args<format_context>);
+namespace detail {
+extern template FMT_API std::string grouping_impl<char>(locale_ref loc);
+extern template FMT_API std::string grouping_impl<wchar_t>(locale_ref loc);
+extern template FMT_API char thousands_sep_impl<char>(locale_ref loc);
+extern template FMT_API wchar_t thousands_sep_impl<wchar_t>(locale_ref loc);
+extern template FMT_API char decimal_point_impl(locale_ref loc);
+extern template FMT_API wchar_t decimal_point_impl(locale_ref loc);
+extern template int format_float<double>(double value, int precision,
+                                         float_specs specs, buffer<char>& buf);
+extern template int format_float<long double>(long double value, int precision,
+                                              float_specs specs,
+                                              buffer<char>& buf);
+int snprintf_float(float value, int precision, float_specs specs,
+                   buffer<char>& buf) = delete;
+extern template int snprintf_float<double>(double value, int precision,
+                                           float_specs specs,
+                                           buffer<char>& buf);
+extern template int snprintf_float<long double>(long double value,
+                                                int precision,
+                                                float_specs specs,
+                                                buffer<char>& buf);
+}  // namespace detail
+#endif
 
 template <typename S, typename Char = char_t<S>,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
-inline typename buffer_context<Char>::iterator vformat_to(
-    internal::buffer<Char>& buf, const S& format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  return internal::vformat_to(buf, to_string_view(format_str), args);
+          FMT_ENABLE_IF(detail::is_string<S>::value)>
+inline typename FMT_BUFFER_CONTEXT(Char)::iterator vformat_to(
+    detail::buffer<Char>& buf, const S& format_str,
+    basic_format_args<FMT_BUFFER_CONTEXT(type_identity_t<Char>)> args) {
+  return detail::vformat_to(buf, to_string_view(format_str), args);
 }
 
-template <typename S, typename... Args, std::size_t SIZE = inline_buffer_size,
-          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+template <typename S, typename... Args, size_t SIZE = inline_buffer_size,
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 inline typename buffer_context<Char>::iterator format_to(
     basic_memory_buffer<Char, SIZE>& buf, const S& format_str, Args&&... args) {
-  internal::check_format_string<Args...>(format_str);
+  detail::check_format_string<Args...>(format_str);
   using context = buffer_context<Char>;
-  return internal::vformat_to(buf, to_string_view(format_str),
-                              make_format_args<context>(args...));
+  return detail::vformat_to(buf, to_string_view(format_str),
+                            make_format_args<context>(args...));
 }
 
 template <typename OutputIt, typename Char = char>
@@ -3384,16 +3516,15 @@ using format_context_t = basic_format_context<OutputIt, Char>;
 template <typename OutputIt, typename Char = char>
 using format_args_t = basic_format_args<format_context_t<OutputIt, Char>>;
 
-template <typename S, typename OutputIt, typename... Args,
-          FMT_ENABLE_IF(
-              internal::is_output_iterator<OutputIt>::value &&
-              !internal::is_contiguous_back_insert_iterator<OutputIt>::value)>
+template <
+    typename S, typename OutputIt, typename... Args,
+    FMT_ENABLE_IF(detail::is_output_iterator<OutputIt>::value &&
+                  !detail::is_contiguous_back_insert_iterator<OutputIt>::value)>
 inline OutputIt vformat_to(
     OutputIt out, const S& format_str,
     format_args_t<type_identity_t<OutputIt>, char_t<S>> args) {
-  using range = internal::output_range<OutputIt, char_t<S>>;
-  return vformat_to<arg_formatter<range>>(range(out),
-                                          to_string_view(format_str), args);
+  using af = detail::arg_formatter<OutputIt, char_t<S>>;
+  return vformat_to<af>(out, to_string_view(format_str), args);
 }
 
 /**
@@ -3409,11 +3540,11 @@ inline OutputIt vformat_to(
  */
 template <typename OutputIt, typename S, typename... Args,
           FMT_ENABLE_IF(
-              internal::is_output_iterator<OutputIt>::value &&
-              !internal::is_contiguous_back_insert_iterator<OutputIt>::value &&
-              internal::is_string<S>::value)>
+              detail::is_output_iterator<OutputIt>::value &&
+              !detail::is_contiguous_back_insert_iterator<OutputIt>::value &&
+              detail::is_string<S>::value)>
 inline OutputIt format_to(OutputIt out, const S& format_str, Args&&... args) {
-  internal::check_format_string<Args...>(format_str);
+  detail::check_format_string<Args...>(format_str);
   using context = format_context_t<OutputIt, char_t<S>>;
   return vformat_to(out, to_string_view(format_str),
                     make_format_args<context>(args...));
@@ -3423,12 +3554,12 @@ template <typename OutputIt> struct format_to_n_result {
   /** Iterator past the end of the output range. */
   OutputIt out;
   /** Total (not truncated) output size. */
-  std::size_t size;
+  size_t size;
 };
 
 template <typename OutputIt, typename Char = typename OutputIt::value_type>
 using format_to_n_context =
-    format_context_t<internal::truncating_iterator<OutputIt>, Char>;
+    format_context_t<detail::truncating_iterator<OutputIt>, Char>;
 
 template <typename OutputIt, typename Char = typename OutputIt::value_type>
 using format_to_n_args = basic_format_args<format_to_n_context<OutputIt, Char>>;
@@ -3441,11 +3572,11 @@ make_format_to_n_args(const Args&... args) {
 }
 
 template <typename OutputIt, typename Char, typename... Args,
-          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value)>
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt>::value)>
 inline format_to_n_result<OutputIt> vformat_to_n(
-    OutputIt out, std::size_t n, basic_string_view<Char> format_str,
+    OutputIt out, size_t n, basic_string_view<Char> format_str,
     format_to_n_args<type_identity_t<OutputIt>, type_identity_t<Char>> args) {
-  auto it = vformat_to(internal::truncating_iterator<OutputIt>(out, n),
+  auto it = vformat_to(detail::truncating_iterator<OutputIt>(out, n),
                        format_str, args);
   return {it.base(), it.count()};
 }
@@ -3458,23 +3589,23 @@ inline format_to_n_result<OutputIt> vformat_to_n(
  \endrst
  */
 template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value&&
-                            internal::is_output_iterator<OutputIt>::value)>
-inline format_to_n_result<OutputIt> format_to_n(OutputIt out, std::size_t n,
+          FMT_ENABLE_IF(detail::is_string<S>::value&&
+                            detail::is_output_iterator<OutputIt>::value)>
+inline format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n,
                                                 const S& format_str,
                                                 const Args&... args) {
-  internal::check_format_string<Args...>(format_str);
+  detail::check_format_string<Args...>(format_str);
   using context = format_to_n_context<OutputIt, char_t<S>>;
   return vformat_to_n(out, n, to_string_view(format_str),
                       make_format_args<context>(args...));
 }
 
-template <typename Char>
-inline std::basic_string<Char> internal::vformat(
+template <typename Char, enable_if_t<(!std::is_same<Char, char>::value), int>>
+std::basic_string<Char> detail::vformat(
     basic_string_view<Char> format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buffer;
-  internal::vformat_to(buffer, format_str, args);
+  detail::vformat_to(buffer, format_str, args);
   return to_string(buffer);
 }
 
@@ -3483,15 +3614,15 @@ inline std::basic_string<Char> internal::vformat(
   ``format(format_str, args...)``.
  */
 template <typename... Args>
-inline std::size_t formatted_size(string_view format_str, const Args&... args) {
-  return format_to(internal::counting_iterator(), format_str, args...).count();
+inline size_t formatted_size(string_view format_str, const Args&... args) {
+  return format_to(detail::counting_iterator(), format_str, args...).count();
 }
 
 template <typename Char, FMT_ENABLE_IF(std::is_same<Char, wchar_t>::value)>
 void vprint(std::FILE* f, basic_string_view<Char> format_str,
             wformat_args args) {
   wmemory_buffer buffer;
-  internal::vformat_to(buffer, format_str, args);
+  detail::vformat_to(buffer, format_str, args);
   buffer.push_back(L'\0');
   if (std::fputws(buffer.data(), f) == -1)
     FMT_THROW(system_error(errno, "cannot write to file"));
@@ -3503,18 +3634,15 @@ void vprint(basic_string_view<Char> format_str, wformat_args args) {
 }
 
 #if FMT_USE_USER_DEFINED_LITERALS
-namespace internal {
+namespace detail {
 
 #  if FMT_USE_UDL_TEMPLATE
 template <typename Char, Char... CHARS> class udl_formatter {
  public:
   template <typename... Args>
   std::basic_string<Char> operator()(Args&&... args) const {
-    FMT_CONSTEXPR_DECL Char s[] = {CHARS..., '\0'};
-    FMT_CONSTEXPR_DECL bool invalid_format =
-        do_check_format_string<Char, error_handler, remove_cvref_t<Args>...>(
-            basic_string_view<Char>(s, sizeof...(CHARS)));
-    (void)invalid_format;
+    static FMT_CONSTEXPR_DECL Char s[] = {CHARS..., '\0'};
+    check_format_string<remove_cvref_t<Args>...>(FMT_STRING(s));
     return format(s, std::forward<Args>(args)...);
   }
 };
@@ -3530,39 +3658,23 @@ template <typename Char> struct udl_formatter {
 #  endif  // FMT_USE_UDL_TEMPLATE
 
 template <typename Char> struct udl_arg {
-  basic_string_view<Char> str;
+  const Char* str;
 
-  template <typename T> named_arg<T, Char> operator=(T&& value) const {
+  template <typename T> named_arg<Char, T> operator=(T&& value) const {
     return {str, std::forward<T>(value)};
   }
 };
-
-// Converts string literals to basic_string_view.
-template <typename Char, size_t N>
-FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
-    const Char (&s)[N]) {
-  // Remove trailing null character if needed. Won't be present if this is used
-  // with raw character array (i.e. not defined as a string).
-  return {s,
-          N - ((std::char_traits<Char>::to_int_type(s[N - 1]) == 0) ? 1 : 0)};
-}
-
-// Converts string_view to basic_string_view.
-template <typename Char>
-FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
-    const std_string_view<Char>& s) {
-  return {s.data(), s.size()};
-}
-}  // namespace internal
+}  // namespace detail
 
 inline namespace literals {
 #  if FMT_USE_UDL_TEMPLATE
 #    pragma GCC diagnostic push
+#    pragma GCC diagnostic ignored "-Wpedantic"
 #    if FMT_CLANG_VERSION
 #      pragma GCC diagnostic ignored "-Wgnu-string-literal-operator-template"
 #    endif
 template <typename Char, Char... CHARS>
-FMT_CONSTEXPR internal::udl_formatter<Char, CHARS...> operator""_format() {
+FMT_CONSTEXPR detail::udl_formatter<Char, CHARS...> operator""_format() {
   return {};
 }
 #    pragma GCC diagnostic pop
@@ -3577,12 +3689,12 @@ FMT_CONSTEXPR internal::udl_formatter<Char, CHARS...> operator""_format() {
     std::string message = "The answer is {}"_format(42);
   \endrst
  */
-FMT_CONSTEXPR internal::udl_formatter<char> operator"" _format(const char* s,
-                                                               std::size_t n) {
+FMT_CONSTEXPR detail::udl_formatter<char> operator"" _format(const char* s,
+                                                             size_t n) {
   return {{s, n}};
 }
-FMT_CONSTEXPR internal::udl_formatter<wchar_t> operator"" _format(
-    const wchar_t* s, std::size_t n) {
+FMT_CONSTEXPR detail::udl_formatter<wchar_t> operator"" _format(
+    const wchar_t* s, size_t n) {
   return {{s, n}};
 }
 #  endif  // FMT_USE_UDL_TEMPLATE
@@ -3597,47 +3709,16 @@ FMT_CONSTEXPR internal::udl_formatter<wchar_t> operator"" _format(
     fmt::print("Elapsed time: {s:.2f} seconds", "s"_a=1.23);
   \endrst
  */
-FMT_CONSTEXPR internal::udl_arg<char> operator"" _a(const char* s,
-                                                    std::size_t n) {
-  return {{s, n}};
+FMT_CONSTEXPR detail::udl_arg<char> operator"" _a(const char* s, size_t) {
+  return {s};
 }
-FMT_CONSTEXPR internal::udl_arg<wchar_t> operator"" _a(const wchar_t* s,
-                                                       std::size_t n) {
-  return {{s, n}};
+FMT_CONSTEXPR detail::udl_arg<wchar_t> operator"" _a(const wchar_t* s, size_t) {
+  return {s};
 }
 }  // namespace literals
 #endif  // FMT_USE_USER_DEFINED_LITERALS
 FMT_END_NAMESPACE
 
-#define FMT_STRING_IMPL(s, ...)                                     \
-  [] {                                                              \
-    /* Use a macro-like name to avoid shadowing warnings. */        \
-    struct FMT_COMPILE_STRING : fmt::compile_string {               \
-      using char_type = fmt::remove_cvref_t<decltype(s[0])>;        \
-      FMT_MAYBE_UNUSED __VA_ARGS__ FMT_CONSTEXPR                    \
-      operator fmt::basic_string_view<char_type>() const {          \
-        return fmt::internal::compile_string_to_view<char_type>(s); \
-      }                                                             \
-    };                                                              \
-    return FMT_COMPILE_STRING();                                    \
-  }()
-
-/**
-  \rst
-  Constructs a compile-time format string from a string literal *s*.
-
-  **Example**::
-
-    // A compile-time error because 'd' is an invalid specifier for strings.
-    std::string s = format(FMT_STRING("{:d}"), "foo");
-  \endrst
- */
-#define FMT_STRING(s) FMT_STRING_IMPL(s, )
-
-#if defined(FMT_STRING_ALIAS) && FMT_STRING_ALIAS
-#  define fmt(s) FMT_STRING_IMPL(s, [[deprecated]])
-#endif
-
 #ifdef FMT_HEADER_ONLY
 #  define FMT_FUNC inline
 #  include "format-inl.h"
diff --git a/lib/include/srslte/srslog/bundled/fmt/locale.h b/lib/include/srslte/srslog/bundled/fmt/locale.h
index 70bc1935e..988d15cdf 100644
--- a/lib/include/srslte/srslog/bundled/fmt/locale.h
+++ b/lib/include/srslte/srslog/bundled/fmt/locale.h
@@ -14,15 +14,15 @@
 
 FMT_BEGIN_NAMESPACE
 
-namespace internal {
+namespace detail {
 template <typename Char>
 typename buffer_context<Char>::iterator vformat_to(
     const std::locale& loc, buffer<Char>& buf,
     basic_string_view<Char> format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  using range = buffer_range<Char>;
-  return vformat_to<arg_formatter<range>>(buf, to_string_view(format_str), args,
-                                          internal::locale_ref(loc));
+  using af = arg_formatter<typename buffer_context<Char>::iterator, Char>;
+  return vformat_to<af>(std::back_inserter(buf), to_string_view(format_str),
+                        args, detail::locale_ref(loc));
 }
 
 template <typename Char>
@@ -30,43 +30,43 @@ std::basic_string<Char> vformat(
     const std::locale& loc, basic_string_view<Char> format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buffer;
-  internal::vformat_to(loc, buffer, format_str, args);
+  detail::vformat_to(loc, buffer, format_str, args);
   return fmt::to_string(buffer);
 }
-}  // namespace internal
+}  // namespace detail
 
 template <typename S, typename Char = char_t<S>>
 inline std::basic_string<Char> vformat(
     const std::locale& loc, const S& format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  return internal::vformat(loc, to_string_view(format_str), args);
+  return detail::vformat(loc, to_string_view(format_str), args);
 }
 
 template <typename S, typename... Args, typename Char = char_t<S>>
 inline std::basic_string<Char> format(const std::locale& loc,
                                       const S& format_str, Args&&... args) {
-  return internal::vformat(
+  return detail::vformat(
       loc, to_string_view(format_str),
-      internal::make_args_checked<Args...>(format_str, args...));
+      detail::make_args_checked<Args...>(format_str, args...));
 }
 
 template <typename S, typename OutputIt, typename... Args,
           typename Char = enable_if_t<
-              internal::is_output_iterator<OutputIt>::value, char_t<S>>>
+              detail::is_output_iterator<OutputIt>::value, char_t<S>>>
 inline OutputIt vformat_to(
     OutputIt out, const std::locale& loc, const S& format_str,
     format_args_t<type_identity_t<OutputIt>, Char> args) {
-  using range = internal::output_range<OutputIt, Char>;
-  return vformat_to<arg_formatter<range>>(
-      range(out), to_string_view(format_str), args, internal::locale_ref(loc));
+  using af = detail::arg_formatter<OutputIt, Char>;
+  return vformat_to<af>(out, to_string_view(format_str), args,
+                        detail::locale_ref(loc));
 }
 
 template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value&&
-                            internal::is_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt>::value&&
+                            detail::is_string<S>::value)>
 inline OutputIt format_to(OutputIt out, const std::locale& loc,
                           const S& format_str, Args&&... args) {
-  internal::check_format_string<Args...>(format_str);
+  detail::check_format_string<Args...>(format_str);
   using context = format_context_t<OutputIt, char_t<S>>;
   format_arg_store<context, Args...> as{args...};
   return vformat_to(out, loc, to_string_view(format_str),
diff --git a/lib/include/srslte/srslog/bundled/fmt/os.h b/lib/include/srslte/srslog/bundled/fmt/os.h
index a1a0d03b6..a9517ef80 100644
--- a/lib/include/srslte/srslog/bundled/fmt/os.h
+++ b/lib/include/srslte/srslog/bundled/fmt/os.h
@@ -50,7 +50,7 @@
 #ifdef FMT_SYSTEM
 #  define FMT_POSIX_CALL(call) FMT_SYSTEM(call)
 #else
-#  define FMT_SYSTEM(call) call
+#  define FMT_SYSTEM(call) ::call
 #  ifdef _WIN32
 // Fix warnings about deprecated symbols.
 #    define FMT_POSIX_CALL(call) ::_##call
@@ -133,7 +133,7 @@ class error_code {
 };
 
 #ifdef _WIN32
-namespace internal {
+namespace detail {
 // A converter from UTF-16 to UTF-8.
 // It is only provided for Windows since other systems support UTF-8 natively.
 class utf16_to_utf8 {
@@ -156,7 +156,7 @@ class utf16_to_utf8 {
 
 FMT_API void format_windows_error(buffer<char>& out, int error_code,
                                   string_view message) FMT_NOEXCEPT;
-}  // namespace internal
+}  // namespace detail
 
 /** A Windows error. */
 class windows_error : public system_error {
@@ -277,7 +277,8 @@ class file {
   enum {
     RDONLY = FMT_POSIX(O_RDONLY),  // Open for reading only.
     WRONLY = FMT_POSIX(O_WRONLY),  // Open for writing only.
-    RDWR = FMT_POSIX(O_RDWR)       // Open for reading and writing.
+    RDWR = FMT_POSIX(O_RDWR),      // Open for reading and writing.
+    CREATE = FMT_POSIX(O_CREAT)    // Create if the file doesn't exist.
   };
 
   // Constructs a file object which doesn't represent any file.
@@ -313,10 +314,10 @@ class file {
   FMT_API long long size() const;
 
   // Attempts to read count bytes from the file into the specified buffer.
-  FMT_API std::size_t read(void* buffer, std::size_t count);
+  FMT_API size_t read(void* buffer, size_t count);
 
   // Attempts to write count bytes from the specified buffer to the file.
-  FMT_API std::size_t write(const void* buffer, std::size_t count);
+  FMT_API size_t write(const void* buffer, size_t count);
 
   // Duplicates a file descriptor with the dup function and returns
   // the duplicate as a file object.
@@ -341,6 +342,63 @@ class file {
 
 // Returns the memory page size.
 long getpagesize();
+
+class direct_buffered_file;
+
+template <typename S, typename... Args>
+void print(direct_buffered_file& f, const S& format_str,
+           const Args&... args);
+
+// A buffered file with a direct buffer access and no synchronization.
+class direct_buffered_file {
+ private:
+  file file_;
+
+  enum { buffer_size = 4096 };
+  char buffer_[buffer_size];
+  int pos_;
+
+  void flush() {
+    if (pos_ == 0) return;
+    file_.write(buffer_, pos_);
+    pos_ = 0;
+  }
+
+  int free_capacity() const { return buffer_size - pos_; }
+
+ public:
+  direct_buffered_file(cstring_view path, int oflag)
+    : file_(path, oflag), pos_(0) {}
+
+  ~direct_buffered_file() {
+    flush();
+  }
+
+  void close() {
+    flush();
+    file_.close();
+  }
+
+  template <typename S, typename... Args>
+  friend void print(direct_buffered_file& f, const S& format_str,
+                    const Args&... args) {
+    // We could avoid double buffering.
+    auto buf = fmt::memory_buffer();
+    fmt::format_to(std::back_inserter(buf), format_str, args...);
+    auto remaining_pos = 0;
+    auto remaining_size = buf.size();
+    while (remaining_size > detail::to_unsigned(f.free_capacity())) {
+      auto size = f.free_capacity();
+      memcpy(f.buffer_ + f.pos_, buf.data() + remaining_pos, size);
+      f.pos_ += size;
+      f.flush();
+      remaining_pos += size;
+      remaining_size -= size;
+    }
+    memcpy(f.buffer_ + f.pos_, buf.data() + remaining_pos, remaining_size);
+    f.pos_ += static_cast<int>(remaining_size);
+  }
+};
 #endif  // FMT_USE_FCNTL
 
 #ifdef FMT_LOCALE
diff --git a/lib/include/srslte/srslog/bundled/fmt/ostream.h b/lib/include/srslte/srslog/bundled/fmt/ostream.h
index 4526f5238..c16107f79 100644
--- a/lib/include/srslte/srslog/bundled/fmt/ostream.h
+++ b/lib/include/srslte/srslog/bundled/fmt/ostream.h
@@ -14,10 +14,10 @@
 
 FMT_BEGIN_NAMESPACE
 
-template <typename CHar> class basic_printf_parse_context;
+template <typename Char> class basic_printf_parse_context;
 template <typename OutputIt, typename Char> class basic_printf_context;
 
-namespace internal {
+namespace detail {
 
 template <class Char> class formatbuf : public std::basic_streambuf<Char> {
  private:
@@ -80,7 +80,7 @@ template <typename T, typename Char> class is_streamable {
 
 // Write the content of buf to os.
 template <typename Char>
-void write(std::basic_ostream<Char>& os, buffer<Char>& buf) {
+void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
   const Char* buf_data = buf.data();
   using unsigned_streamsize = std::make_unsigned<std::streamsize>::type;
   unsigned_streamsize size = buf.size();
@@ -101,8 +101,8 @@ void format_value(buffer<Char>& buf, const T& value,
 #if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
   if (loc) output.imbue(loc.get<std::locale>());
 #endif
-  output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
   output << value;
+  output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
   buf.resize(buf.size());
 }
 
@@ -110,7 +110,8 @@ void format_value(buffer<Char>& buf, const T& value,
 template <typename T, typename Char>
 struct fallback_formatter<T, Char, enable_if_t<is_streamable<T, Char>::value>>
     : private formatter<basic_string_view<Char>, Char> {
-  auto parse(basic_format_parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
     return formatter<basic_string_view<Char>, Char>::parse(ctx);
   }
   template <typename ParseCtx,
@@ -136,14 +137,14 @@ struct fallback_formatter<T, Char, enable_if_t<is_streamable<T, Char>::value>>
     return std::copy(buffer.begin(), buffer.end(), ctx.out());
   }
 };
-}  // namespace internal
+}  // namespace detail
 
 template <typename Char>
 void vprint(std::basic_ostream<Char>& os, basic_string_view<Char> format_str,
             basic_format_args<buffer_context<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buffer;
-  internal::vformat_to(buffer, format_str, args);
-  internal::write(os, buffer);
+  detail::vformat_to(buffer, format_str, args);
+  detail::write_buffer(os, buffer);
 }
 
 /**
@@ -156,10 +157,10 @@ void vprint(std::basic_ostream<Char>& os, basic_string_view<Char> format_str,
   \endrst
  */
 template <typename S, typename... Args,
-          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 void print(std::basic_ostream<Char>& os, const S& format_str, Args&&... args) {
   vprint(os, to_string_view(format_str),
-         internal::make_args_checked<Args...>(format_str, args...));
+         detail::make_args_checked<Args...>(format_str, args...));
 }
 FMT_END_NAMESPACE
 
diff --git a/lib/include/srslte/srslog/bundled/fmt/posix.h b/lib/include/srslte/srslog/bundled/fmt/posix.h
index 0e7bc646e..da19e9d53 100644
--- a/lib/include/srslte/srslog/bundled/fmt/posix.h
+++ b/lib/include/srslte/srslog/bundled/fmt/posix.h
@@ -1,2 +1,2 @@
 #include "os.h"
-#warning "fmt/posix.h is deprecated; use fmt/os.h instead"
\ No newline at end of file
+#warning "fmt/posix.h is deprecated; use fmt/os.h instead"
diff --git a/lib/include/srslte/srslog/bundled/fmt/printf.h b/lib/include/srslte/srslog/bundled/fmt/printf.h
index 5e0c4810a..d4440ed16 100644
--- a/lib/include/srslte/srslog/bundled/fmt/printf.h
+++ b/lib/include/srslte/srslog/bundled/fmt/printf.h
@@ -14,7 +14,7 @@
 #include "ostream.h"
 
 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {
 
 // Checks if a value fits in int - used to avoid warnings about comparing
 // signed and unsigned integers.
@@ -90,11 +90,11 @@ template <typename T, typename Context> class arg_converter {
     if (const_check(sizeof(target_type) <= sizeof(int))) {
       // Extra casts are used to silence warnings.
       if (is_signed) {
-        arg_ = internal::make_arg<Context>(
+        arg_ = detail::make_arg<Context>(
             static_cast<int>(static_cast<target_type>(value)));
       } else {
         using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
-        arg_ = internal::make_arg<Context>(
+        arg_ = detail::make_arg<Context>(
             static_cast<unsigned>(static_cast<unsigned_type>(value)));
       }
     } else {
@@ -102,9 +102,9 @@ template <typename T, typename Context> class arg_converter {
         // glibc's printf doesn't sign extend arguments of smaller types:
         //   std::printf("%lld", -42);  // prints "4294967254"
         // but we don't have to do the same because it's a UB.
-        arg_ = internal::make_arg<Context>(static_cast<long long>(value));
+        arg_ = detail::make_arg<Context>(static_cast<long long>(value));
       } else {
-        arg_ = internal::make_arg<Context>(
+        arg_ = detail::make_arg<Context>(
             static_cast<typename make_unsigned_or_bool<U>::type>(value));
       }
     }
@@ -133,7 +133,7 @@ template <typename Context> class char_converter {
 
   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
   void operator()(T value) {
-    arg_ = internal::make_arg<Context>(
+    arg_ = detail::make_arg<Context>(
         static_cast<typename Context::char_type>(value));
   }
 
@@ -141,6 +141,13 @@ template <typename Context> class char_converter {
   void operator()(T) {}  // No conversion needed for non-integral types.
 };
 
+// An argument visitor that return a pointer to a C string if argument is a
+// string or null otherwise.
+template <typename Char> struct get_cstring {
+  template <typename T> const Char* operator()(T) { return nullptr; }
+  const Char* operator()(const Char* s) { return s; }
+};
+
 // Checks if an argument is a valid printf width specifier and sets
 // left alignment if it is negative.
 template <typename Char> class printf_width_handler {
@@ -155,7 +162,7 @@ template <typename Char> class printf_width_handler {
   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
   unsigned operator()(T value) {
     auto width = static_cast<uint32_or_64_or_128_t<T>>(value);
-    if (internal::is_negative(value)) {
+    if (detail::is_negative(value)) {
       specs_.align = align::left;
       width = 0 - width;
     }
@@ -172,22 +179,20 @@ template <typename Char> class printf_width_handler {
 };
 
 template <typename Char, typename Context>
-void printf(buffer<Char>& buf, basic_string_view<Char> format,
-            basic_format_args<Context> args) {
+void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
+             basic_format_args<Context> args) {
   Context(std::back_inserter(buf), format, args).format();
 }
+}  // namespace detail
 
-template <typename OutputIt, typename Char, typename Context>
-internal::truncating_iterator<OutputIt> printf(
-    internal::truncating_iterator<OutputIt> it, basic_string_view<Char> format,
-    basic_format_args<Context> args) {
-  return Context(it, format, args).format();
+// For printing into memory_buffer.
+template <typename Char, typename Context>
+FMT_DEPRECATED void printf(detail::buffer<Char>& buf,
+                           basic_string_view<Char> format,
+                           basic_format_args<Context> args) {
+  return detail::vprintf(buf, format, args);
 }
-}  // namespace internal
-
-using internal::printf;  // For printing into memory_buffer.
-
-template <typename Range> class printf_arg_formatter;
+using detail::vprintf;
 
 template <typename Char>
 class basic_printf_parse_context : public basic_format_parse_context<Char> {
@@ -200,15 +205,15 @@ template <typename OutputIt, typename Char> class basic_printf_context;
   The ``printf`` argument formatter.
   \endrst
  */
-template <typename Range>
-class printf_arg_formatter : public internal::arg_formatter_base<Range> {
+template <typename OutputIt, typename Char>
+class printf_arg_formatter : public detail::arg_formatter_base<OutputIt, Char> {
  public:
-  using iterator = typename Range::iterator;
+  using iterator = OutputIt;
 
  private:
-  using char_type = typename Range::value_type;
-  using base = internal::arg_formatter_base<Range>;
-  using context_type = basic_printf_context<iterator, char_type>;
+  using char_type = Char;
+  using base = detail::arg_formatter_base<OutputIt, Char>;
+  using context_type = basic_printf_context<OutputIt, Char>;
 
   context_type& context_;
 
@@ -233,9 +238,9 @@ class printf_arg_formatter : public internal::arg_formatter_base<Range> {
     \endrst
    */
   printf_arg_formatter(iterator iter, format_specs& specs, context_type& ctx)
-      : base(Range(iter), &specs, internal::locale_ref()), context_(ctx) {}
+      : base(iter, &specs, detail::locale_ref()), context_(ctx) {}
 
-  template <typename T, FMT_ENABLE_IF(fmt::internal::is_integral<T>::value)>
+  template <typename T, FMT_ENABLE_IF(fmt::detail::is_integral<T>::value)>
   iterator operator()(T value) {
     // MSVC2013 fails to compile separate overloads for bool and char_type so
     // use std::is_same instead.
@@ -250,7 +255,11 @@ class printf_arg_formatter : public internal::arg_formatter_base<Range> {
         return (*this)(static_cast<int>(value));
       fmt_specs.sign = sign::none;
       fmt_specs.alt = false;
-      fmt_specs.align = align::right;
+      fmt_specs.fill[0] = ' ';  // Ignore '0' flag for char types.
+      // align::numeric needs to be overwritten here since the '0' flag is
+      // ignored for non-numeric types
+      if (fmt_specs.align == align::none || fmt_specs.align == align::numeric)
+        fmt_specs.align = align::right;
       return base::operator()(value);
     } else {
       return base::operator()(value);
@@ -316,12 +325,14 @@ template <typename T> struct printf_formatter {
 
   template <typename FormatContext>
   auto format(const T& value, FormatContext& ctx) -> decltype(ctx.out()) {
-    internal::format_value(internal::get_container(ctx.out()), value);
+    detail::format_value(detail::get_container(ctx.out()), value);
     return ctx.out();
   }
 };
 
-/** This template formats data and writes the output to a writer. */
+/**
+ This template formats data and writes the output through an output iterator.
+ */
 template <typename OutputIt, typename Char> class basic_printf_context {
  public:
   /** The character type for the output. */
@@ -351,9 +362,8 @@ template <typename OutputIt, typename Char> class basic_printf_context {
  public:
   /**
    \rst
-   Constructs a ``printf_context`` object. References to the arguments and
-   the writer are stored in the context object so make sure they have
-   appropriate lifetimes.
+   Constructs a ``printf_context`` object. References to the arguments are
+   stored in the context object so make sure they have appropriate lifetimes.
    \endrst
    */
   basic_printf_context(OutputIt out, basic_string_view<char_type> format_str,
@@ -363,7 +373,7 @@ template <typename OutputIt, typename Char> class basic_printf_context {
   OutputIt out() { return out_; }
   void advance_to(OutputIt it) { out_ = it; }
 
-  internal::locale_ref locale() { return {}; }
+  detail::locale_ref locale() { return {}; }
 
   format_arg arg(int id) const { return args_.get(id); }
 
@@ -374,7 +384,7 @@ template <typename OutputIt, typename Char> class basic_printf_context {
   }
 
   /** Formats stored arguments and writes the output to the range. */
-  template <typename ArgFormatter = printf_arg_formatter<buffer_range<Char>>>
+  template <typename ArgFormatter = printf_arg_formatter<OutputIt, Char>>
   OutputIt format();
 };
 
@@ -394,7 +404,9 @@ void basic_printf_context<OutputIt, Char>::parse_flags(format_specs& specs,
       specs.fill[0] = '0';
       break;
     case ' ':
-      specs.sign = sign::space;
+      if (specs.sign != sign::plus) {
+        specs.sign = sign::space;
+      }
       break;
     case '#':
       specs.alt = true;
@@ -412,7 +424,7 @@ basic_printf_context<OutputIt, Char>::get_arg(int arg_index) {
     arg_index = parse_ctx_.next_arg_id();
   else
     parse_ctx_.check_arg_id(--arg_index);
-  return internal::get_arg(*this, arg_index);
+  return detail::get_arg(*this, arg_index);
 }
 
 template <typename OutputIt, typename Char>
@@ -424,7 +436,7 @@ int basic_printf_context<OutputIt, Char>::parse_header(const Char*& it,
   if (c >= '0' && c <= '9') {
     // Parse an argument index (if followed by '$') or a width possibly
     // preceded with '0' flag(s).
-    internal::error_handler eh;
+    detail::error_handler eh;
     int value = parse_nonnegative_int(it, end, eh);
     if (it != end && *it == '$') {  // value is an argument index
       ++it;
@@ -443,12 +455,12 @@ int basic_printf_context<OutputIt, Char>::parse_header(const Char*& it,
   // Parse width.
   if (it != end) {
     if (*it >= '0' && *it <= '9') {
-      internal::error_handler eh;
+      detail::error_handler eh;
       specs.width = parse_nonnegative_int(it, end, eh);
     } else if (*it == '*') {
       ++it;
       specs.width = static_cast<int>(visit_format_arg(
-          internal::printf_width_handler<char_type>(specs), get_arg()));
+          detail::printf_width_handler<char_type>(specs), get_arg()));
     }
   }
   return arg_index;
@@ -476,38 +488,52 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
 
     // Parse argument index, flags and width.
     int arg_index = parse_header(it, end, specs);
-    if (arg_index == 0) on_error("argument index out of range");
+    if (arg_index == 0) on_error("argument not found");
 
     // Parse precision.
     if (it != end && *it == '.') {
       ++it;
       c = it != end ? *it : 0;
       if ('0' <= c && c <= '9') {
-        internal::error_handler eh;
+        detail::error_handler eh;
         specs.precision = parse_nonnegative_int(it, end, eh);
       } else if (c == '*') {
         ++it;
         specs.precision = static_cast<int>(
-            visit_format_arg(internal::printf_precision_handler(), get_arg()));
+            visit_format_arg(detail::printf_precision_handler(), get_arg()));
       } else {
         specs.precision = 0;
       }
     }
 
     format_arg arg = get_arg(arg_index);
-    if (specs.alt && visit_format_arg(internal::is_zero_int(), arg))
+    // For d, i, o, u, x, and X conversion specifiers, if a precision is
+    // specified, the '0' flag is ignored
+    if (specs.precision >= 0 && arg.is_integral())
+      specs.fill[0] =
+          ' ';  // Ignore '0' flag for non-numeric types or if '-' present.
+    if (specs.precision >= 0 && arg.type() == detail::type::cstring_type) {
+      auto str = visit_format_arg(detail::get_cstring<Char>(), arg);
+      auto str_end = str + specs.precision;
+      auto nul = std::find(str, str_end, Char());
+      arg = detail::make_arg<basic_printf_context>(basic_string_view<Char>(
+          str,
+          detail::to_unsigned(nul != str_end ? nul - str : specs.precision)));
+    }
+    if (specs.alt && visit_format_arg(detail::is_zero_int(), arg))
       specs.alt = false;
     if (specs.fill[0] == '0') {
-      if (arg.is_arithmetic())
+      if (arg.is_arithmetic() && specs.align != align::left)
         specs.align = align::numeric;
       else
-        specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types.
+        specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types or if '-'
+                              // flag is also present.
     }
 
     // Parse length and convert the argument to the required type.
     c = it != end ? *it++ : 0;
     char_type t = it != end ? *it : 0;
-    using internal::convert_arg;
+    using detail::convert_arg;
     switch (c) {
     case 'h':
       if (t == 'h') {
@@ -531,7 +557,7 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
       convert_arg<intmax_t>(arg, t);
       break;
     case 'z':
-      convert_arg<std::size_t>(arg, t);
+      convert_arg<size_t>(arg, t);
       break;
     case 't':
       convert_arg<std::ptrdiff_t>(arg, t);
@@ -556,7 +582,7 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
         specs.type = 'd';
         break;
       case 'c':
-        visit_format_arg(internal::char_converter<basic_printf_context>(arg),
+        visit_format_arg(detail::char_converter<basic_printf_context>(arg),
                          arg);
         break;
       }
@@ -565,15 +591,14 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
     start = it;
 
     // Format argument.
-    visit_format_arg(ArgFormatter(out, specs, *this), arg);
+    out = visit_format_arg(ArgFormatter(out, specs, *this), arg);
   }
   return std::copy(start, it, out);
 }
 
 template <typename Char>
 using basic_printf_context_t =
-    basic_printf_context<std::back_insert_iterator<internal::buffer<Char>>,
-                         Char>;
+    basic_printf_context<std::back_insert_iterator<detail::buffer<Char>>, Char>;
 
 using printf_context = basic_printf_context_t<char>;
 using wprintf_context = basic_printf_context_t<wchar_t>;
@@ -610,7 +635,7 @@ inline std::basic_string<Char> vsprintf(
     const S& format,
     basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buffer;
-  printf(buffer, to_string_view(format), args);
+  vprintf(buffer, to_string_view(format), args);
   return to_string(buffer);
 }
 
@@ -624,7 +649,7 @@ inline std::basic_string<Char> vsprintf(
   \endrst
 */
 template <typename S, typename... Args,
-          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 inline std::basic_string<Char> sprintf(const S& format, const Args&... args) {
   using context = basic_printf_context_t<Char>;
   return vsprintf(to_string_view(format), make_format_args<context>(args...));
@@ -635,8 +660,8 @@ inline int vfprintf(
     std::FILE* f, const S& format,
     basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buffer;
-  printf(buffer, to_string_view(format), args);
-  std::size_t size = buffer.size();
+  vprintf(buffer, to_string_view(format), args);
+  size_t size = buffer.size();
   return std::fwrite(buffer.data(), sizeof(Char), size, f) < size
              ? -1
              : static_cast<int>(size);
@@ -652,7 +677,7 @@ inline int vfprintf(
   \endrst
  */
 template <typename S, typename... Args,
-          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 inline int fprintf(std::FILE* f, const S& format, const Args&... args) {
   using context = basic_printf_context_t<Char>;
   return vfprintf(f, to_string_view(format),
@@ -676,7 +701,7 @@ inline int vprintf(
   \endrst
  */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
+          FMT_ENABLE_IF(detail::is_string<S>::value)>
 inline int printf(const S& format_str, const Args&... args) {
   using context = basic_printf_context_t<char_t<S>>;
   return vprintf(to_string_view(format_str),
@@ -688,8 +713,8 @@ inline int vfprintf(
     std::basic_ostream<Char>& os, const S& format,
     basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buffer;
-  printf(buffer, to_string_view(format), args);
-  internal::write(os, buffer);
+  vprintf(buffer, to_string_view(format), args);
+  detail::write_buffer(os, buffer);
   return static_cast<int>(buffer.size());
 }
 
@@ -698,7 +723,7 @@ template <typename ArgFormatter, typename Char,
           typename Context =
               basic_printf_context<typename ArgFormatter::iterator, Char>>
 typename ArgFormatter::iterator vprintf(
-    internal::buffer<Char>& out, basic_string_view<Char> format_str,
+    detail::buffer<Char>& out, basic_string_view<Char> format_str,
     basic_format_args<type_identity_t<Context>> args) {
   typename ArgFormatter::iterator iter(out);
   Context(iter, format_str, args).template format<ArgFormatter>();
diff --git a/lib/include/srslte/srslog/bundled/fmt/ranges.h b/lib/include/srslte/srslog/bundled/fmt/ranges.h
index f8f9adb71..c48f1727d 100644
--- a/lib/include/srslte/srslog/bundled/fmt/ranges.h
+++ b/lib/include/srslte/srslog/bundled/fmt/ranges.h
@@ -33,7 +33,7 @@ template <typename Char> struct formatting_base {
 
 template <typename Char, typename Enable = void>
 struct formatting_range : formatting_base<Char> {
-  static FMT_CONSTEXPR_DECL const std::size_t range_length_limit =
+  static FMT_CONSTEXPR_DECL const size_t range_length_limit =
       FMT_RANGE_OUTPUT_LENGTH_LIMIT;  // output only up to N items from the
                                       // range.
   Char prefix;
@@ -54,7 +54,7 @@ struct formatting_tuple : formatting_base<Char> {
   static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
 };
 
-namespace internal {
+namespace detail {
 
 template <typename RangeT, typename OutputIterator>
 OutputIterator copy(const RangeT& range, OutputIterator out) {
@@ -118,26 +118,24 @@ template <typename T> class is_tuple_like_ {
 #if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
 template <typename T, T... N>
 using integer_sequence = std::integer_sequence<T, N...>;
-template <std::size_t... N> using index_sequence = std::index_sequence<N...>;
-template <std::size_t N>
-using make_index_sequence = std::make_index_sequence<N>;
+template <size_t... N> using index_sequence = std::index_sequence<N...>;
+template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
 #else
 template <typename T, T... N> struct integer_sequence {
   using value_type = T;
 
-  static FMT_CONSTEXPR std::size_t size() { return sizeof...(N); }
+  static FMT_CONSTEXPR size_t size() { return sizeof...(N); }
 };
 
-template <std::size_t... N>
-using index_sequence = integer_sequence<std::size_t, N...>;
+template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;
 
-template <typename T, std::size_t N, T... Ns>
+template <typename T, size_t N, T... Ns>
 struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
 template <typename T, T... Ns>
 struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
 
-template <std::size_t N>
-using make_index_sequence = make_integer_sequence<std::size_t, N>;
+template <size_t N>
+using make_index_sequence = make_integer_sequence<size_t, N>;
 #endif
 
 template <class Tuple, class F, size_t... Is>
@@ -185,11 +183,11 @@ FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t) {
   return add_space ? L" '{}'" : L"'{}'";
 }
 
-}  // namespace internal
+}  // namespace detail
 
 template <typename T> struct is_tuple_like {
   static FMT_CONSTEXPR_DECL const bool value =
-      internal::is_tuple_like_<T>::value && !internal::is_range_<T>::value;
+      detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
 };
 
 template <typename TupleT, typename Char>
@@ -202,17 +200,17 @@ struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {
         if (formatting.add_prepostfix_space) {
           *out++ = ' ';
         }
-        out = internal::copy(formatting.delimiter, out);
+        out = detail::copy(formatting.delimiter, out);
       }
       out = format_to(out,
-                      internal::format_str_quoted(
+                      detail::format_str_quoted(
                           (formatting.add_delimiter_spaces && i > 0), v),
                       v);
       ++i;
     }
 
     formatting_tuple<Char>& formatting;
-    std::size_t& i;
+    size_t& i;
     typename std::add_lvalue_reference<decltype(
         std::declval<FormatContext>().out())>::type out;
   };
@@ -228,14 +226,14 @@ struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {
   template <typename FormatContext = format_context>
   auto format(const TupleT& values, FormatContext& ctx) -> decltype(ctx.out()) {
     auto out = ctx.out();
-    std::size_t i = 0;
-    internal::copy(formatting.prefix, out);
+    size_t i = 0;
+    detail::copy(formatting.prefix, out);
 
-    internal::for_each(values, format_each<FormatContext>{formatting, i, out});
+    detail::for_each(values, format_each<FormatContext>{formatting, i, out});
     if (formatting.add_prepostfix_space) {
       *out++ = ' ';
     }
-    internal::copy(formatting.postfix, out);
+    detail::copy(formatting.postfix, out);
 
     return ctx.out();
   }
@@ -243,10 +241,9 @@ struct formatter<TupleT, Char, enable_if_t<fmt::is_tuple_like<TupleT>::value>> {
 
 template <typename T, typename Char> struct is_range {
   static FMT_CONSTEXPR_DECL const bool value =
-      internal::is_range_<T>::value &&
-      !internal::is_like_std_string<T>::value &&
+      detail::is_range_<T>::value && !detail::is_like_std_string<T>::value &&
       !std::is_convertible<T, std::basic_string<Char>>::value &&
-      !std::is_constructible<internal::std_string_view<Char>, T>::value;
+      !std::is_constructible<detail::std_string_view<Char>, T>::value;
 };
 
 template <typename RangeT, typename Char>
@@ -262,15 +259,17 @@ struct formatter<RangeT, Char,
   template <typename FormatContext>
   typename FormatContext::iterator format(const RangeT& values,
                                           FormatContext& ctx) {
-    auto out = internal::copy(formatting.prefix, ctx.out());
-    std::size_t i = 0;
-    for (auto it = values.begin(), end = values.end(); it != end; ++it) {
+    auto out = detail::copy(formatting.prefix, ctx.out());
+    size_t i = 0;
+    auto it = values.begin();
+    auto end = values.end();
+    for (; it != end; ++it) {
       if (i > 0) {
         if (formatting.add_prepostfix_space) *out++ = ' ';
-        out = internal::copy(formatting.delimiter, out);
+        out = detail::copy(formatting.delimiter, out);
       }
       out = format_to(out,
-                      internal::format_str_quoted(
+                      detail::format_str_quoted(
                           (formatting.add_delimiter_spaces && i > 0), *it),
                       *it);
       if (++i > formatting.range_length_limit) {
@@ -279,11 +278,11 @@ struct formatter<RangeT, Char,
       }
     }
     if (formatting.add_prepostfix_space) *out++ = ' ';
-    return internal::copy(formatting.postfix, out);
+    return detail::copy(formatting.postfix, out);
   }
 };
 
-template <typename Char, typename... T> struct tuple_arg_join : internal::view {
+template <typename Char, typename... T> struct tuple_arg_join : detail::view {
   const std::tuple<T...>& tuple;
   basic_string_view<Char> sep;
 
@@ -301,14 +300,14 @@ struct formatter<tuple_arg_join<Char, T...>, Char> {
   template <typename FormatContext>
   typename FormatContext::iterator format(
       const tuple_arg_join<Char, T...>& value, FormatContext& ctx) {
-    return format(value, ctx, internal::make_index_sequence<sizeof...(T)>{});
+    return format(value, ctx, detail::make_index_sequence<sizeof...(T)>{});
   }
 
  private:
   template <typename FormatContext, size_t... N>
   typename FormatContext::iterator format(
       const tuple_arg_join<Char, T...>& value, FormatContext& ctx,
-      internal::index_sequence<N...>) {
+      detail::index_sequence<N...>) {
     return format_args(value, ctx, std::get<N>(value.tuple)...);
   }
 
@@ -371,14 +370,14 @@ FMT_CONSTEXPR tuple_arg_join<wchar_t, T...> join(const std::tuple<T...>& tuple,
   \endrst
  */
 template <typename T>
-arg_join<internal::iterator_t<const std::initializer_list<T>>, char> join(
-    std::initializer_list<T> list, string_view sep) {
+arg_join<const T*, const T*, char> join(std::initializer_list<T> list,
+                                        string_view sep) {
   return join(std::begin(list), std::end(list), sep);
 }
 
 template <typename T>
-arg_join<internal::iterator_t<const std::initializer_list<T>>, wchar_t> join(
-    std::initializer_list<T> list, wstring_view sep) {
+arg_join<const T*, const T*, wchar_t> join(std::initializer_list<T> list,
+                                           wstring_view sep) {
   return join(std::begin(list), std::end(list), sep);
 }
 
diff --git a/lib/include/srslte/srslog/detail/log_backend.h b/lib/include/srslte/srslog/detail/log_backend.h
index cc7712962..125177a62 100644
--- a/lib/include/srslte/srslog/detail/log_backend.h
+++ b/lib/include/srslte/srslog/detail/log_backend.h
@@ -42,6 +42,9 @@ public:
 
   /// Pushes a log entry into the backend.
   virtual void push(detail::log_entry&& entry) = 0;
+
+  /// Returns true when the backend has been started, otherwise false.
+  virtual bool is_running() const = 0;
 };
 
 } // namespace detail
diff --git a/lib/include/srslte/srslog/detail/log_entry.h b/lib/include/srslte/srslog/detail/log_entry.h
index 472e31849..7508ef3b4 100644
--- a/lib/include/srslte/srslog/detail/log_entry.h
+++ b/lib/include/srslte/srslog/detail/log_entry.h
@@ -23,6 +23,8 @@
 #define SRSLOG_DETAIL_LOG_ENTRY_H
 
 #include "srslte/srslog/bundled/fmt/printf.h"
+#include "srslte/srslog/detail/support/thread_utils.h"
+#include <chrono>
 
 namespace srslog {
 
@@ -30,12 +32,33 @@ class sink;
 
 namespace detail {
 
+/// This structure gives the user a way to log generic information as a context.
+struct log_context {
+  /// Generic contxt value.
+  uint32_t value;
+  /// When true, the context value will be printed in the log entry.
+  bool enabled;
+};
+
+/// This command flushes all the messages pending in the backend.
+struct flush_backend_cmd {
+  shared_variable<bool>& completion_flag;
+  std::vector<sink*> sinks;
+};
+
 /// This structure packs all the required data required to create a log entry in
 /// the backend.
+//:TODO: provide proper command objects when we have custom formatting.
 struct log_entry {
   sink* s;
+  std::chrono::high_resolution_clock::time_point tp;
+  log_context context;
   std::string fmtstring;
   fmt::dynamic_format_arg_store<fmt::printf_context> store;
+  std::string log_name;
+  char log_tag;
+  std::vector<uint8_t> hex_dump;
+  std::unique_ptr<flush_backend_cmd> flush_cmd;
 };
 
 } // namespace detail
diff --git a/lib/include/srslte/srslog/detail/support/any.h b/lib/include/srslte/srslog/detail/support/any.h
index 0fbbcb8e5..7b1b123ab 100644
--- a/lib/include/srslte/srslog/detail/support/any.h
+++ b/lib/include/srslte/srslog/detail/support/any.h
@@ -48,7 +48,7 @@ struct is_in_place_type_t<in_place_type_t<T>> : std::true_type {};
 class any
 {
 public:
-  //:FIXME: Clang 3.8 does not compile when default constructing a const object
+  //:TODO: Clang 3.8 does not compile when default constructing a const object
   // due to DR253. Declare the defaulted constructor out of the class.
   any();
 
@@ -149,7 +149,7 @@ private:
   std::unique_ptr<type_interface> storage;
 };
 
-//:FIXME: declared out of line, see FIXME above.
+//:TODO: declared out of line, see TODO above.
 inline any::any() = default;
 
 /// Constructs an any object containing an object of type T, passing the
diff --git a/lib/include/srslte/srslog/detail/support/work_queue.h b/lib/include/srslte/srslog/detail/support/work_queue.h
index 9f2b6c4af..065eda144 100644
--- a/lib/include/srslte/srslog/detail/support/work_queue.h
+++ b/lib/include/srslte/srslog/detail/support/work_queue.h
@@ -26,7 +26,7 @@
 #include <queue>
 
 #ifndef SRSLOG_QUEUE_CAPACITY
-#define SRSLOG_QUEUE_CAPACITY 2048
+#define SRSLOG_QUEUE_CAPACITY 8192
 #endif
 
 namespace srslog {
diff --git a/lib/include/srslte/srslog/event_trace.h b/lib/include/srslte/srslog/event_trace.h
new file mode 100644
index 000000000..d03bf595a
--- /dev/null
+++ b/lib/include/srslte/srslog/event_trace.h
@@ -0,0 +1,93 @@
+/*
+ * Copyright 2013-2020 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#ifndef SRSLOG_EVENT_TRACE_H
+#define SRSLOG_EVENT_TRACE_H
+
+#include <chrono>
+#include <string>
+
+namespace srslog {
+
+class log_channel;
+
+/// The event tracing framework allows to trace any kind of event inside an
+/// application.
+/// To enable event tracing the ENABLE_SRSLOG_EVENT_TRACE macro symbol should
+/// be defined, otherwise calls to the tracing framework will be ignored. This
+/// is important to avoid the overhead of tracing when it is not required.
+/// For details about each event trace type please refer to:
+/// https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/edit
+
+/// Initializes the event trace framework saving the trace events to a
+/// "event_trace.log" file.
+void event_trace_init();
+
+/// Initializes the event trace framework using the specified log channel to log
+/// all trace events.
+void event_trace_init(log_channel& c);
+
+#ifdef ENABLE_SRSLOG_EVENT_TRACE
+
+/// Generates the begin phase of a duration event.
+void trace_duration_begin(const std::string& category, const std::string& name);
+
+/// Generates the end phase of a duration event.
+void trace_duration_end(const std::string& category, const std::string& name);
+
+/// Generates a complete event.
+#define trace_complete_event(C, N)                                             \
+  auto scoped_complete_event_variable = detail::scoped_complete_event(C, N)
+
+#else
+
+/// No-ops.
+#define trace_duration_begin(C, N)
+#define trace_duration_end(C, N)
+#define trace_complete_event(C, N)
+
+#endif
+
+namespace detail {
+
+/// Scoped type object for implementing a complete event.
+class scoped_complete_event
+{
+public:
+  scoped_complete_event(std::string cat, std::string n) :
+    category(std::move(cat)),
+    name(std::move(n)),
+    start(std::chrono::steady_clock::now())
+  {}
+
+  ~scoped_complete_event();
+
+private:
+  const std::string category;
+  const std::string name;
+  std::chrono::time_point<std::chrono::steady_clock> start;
+};
+
+} // namespace detail
+
+} // namespace srslog
+
+#endif // SRSLOG_EVENT_TRACE_H
diff --git a/lib/include/srslte/srslog/log_channel.h b/lib/include/srslte/srslog/log_channel.h
index 9cbf2745c..400fa7d90 100644
--- a/lib/include/srslte/srslog/log_channel.h
+++ b/lib/include/srslte/srslog/log_channel.h
@@ -23,10 +23,30 @@
 #define SRSLOG_LOG_CHANNEL_H
 
 #include "srslte/srslog/detail/log_backend.h"
-#include "srslte/srslog/detail/support/thread_utils.h"
+#include <cassert>
 
 namespace srslog {
 
+/// Log channel configuration settings.
+struct log_channel_config {
+  log_channel_config() = default;
+  log_channel_config(std::string n, char tag, bool should_print_context) :
+    name(std::move(n)),
+    tag(tag),
+    should_print_context(should_print_context)
+  {}
+
+  /// Optional log channel name. If set, will get printed for each log entry.
+  /// Disabled by default.
+  std::string name;
+  /// Optional log channel tag. If set, will get printed for each log entry.
+  /// Disabled by default.
+  char tag = '\0';
+  /// When set to true, each log entry will get printed with the context value.
+  /// Disabled by default.
+  bool should_print_context = false;
+};
+
 /// A log channel is the entity used for logging messages.
 ///
 /// It can deliver a log entry to one or more different sinks, for example a
@@ -38,9 +58,21 @@ class log_channel
 {
 public:
   log_channel(std::string id, sink& s, detail::log_backend& backend) :
+    log_channel(std::move(id), s, backend, {})
+  {}
+
+  log_channel(std::string id,
+              sink& s,
+              detail::log_backend& backend,
+              log_channel_config config) :
     log_id(std::move(id)),
     log_sink(s),
     backend(backend),
+    log_name(std::move(config.name)),
+    log_tag(config.tag),
+    should_print_context(config.should_print_context),
+    ctx_value(0),
+    hex_max_size(0),
     is_enabled(true)
   {}
 
@@ -57,21 +89,67 @@ public:
   /// Returns the id string of the channel.
   const std::string& id() const { return log_id; }
 
+  /// Set the log channel context to the specified value.
+  void set_context(uint32_t x) { ctx_value = x; }
+
+  /// Set the maximum number of bytes to can be printed in a hex dump.
+  /// Set to -1 to indicate no hex dump limit.
+  void set_hex_dump_max_size(int size) { hex_max_size = size; }
+
   /// Builds the provided log entry and passes it to the backend. When the
   /// channel is disabled the log entry will be discarded.
   template <typename... Args>
   void operator()(const std::string& fmtstr, Args&&... args)
+  {
+    if (!enabled()) {
+      return;
+    }
+    assert(&log_sink);
+    // Populate the store with all incoming arguments.
+    fmt::dynamic_format_arg_store<fmt::printf_context> store;
+    (void)std::initializer_list<int>{(store.push_back(args), 0)...};
+
+    // Send the log entry to the backend.
+    detail::log_entry entry = {&log_sink,
+                               std::chrono::high_resolution_clock::now(),
+                               {ctx_value, should_print_context},
+                               fmtstr,
+                               std::move(store),
+                               log_name,
+                               log_tag};
+    backend.push(std::move(entry));
+  }
+
+  /// Builds the provided log entry and passes it to the backend. When the
+  /// channel is disabled the log entry will be discarded.
+  template <typename... Args>
+  void operator()(const uint8_t* buffer,
+                  size_t len,
+                  const std::string& fmtstr,
+                  Args&&... args)
   {
     if (!enabled()) {
       return;
     }
 
+    assert(&log_sink);
     // Populate the store with all incoming arguments.
     fmt::dynamic_format_arg_store<fmt::printf_context> store;
     (void)std::initializer_list<int>{(store.push_back(args), 0)...};
 
+    // Calculate the length to capture in the buffer.
+    if (hex_max_size >= 0)
+      len = std::min<size_t>(len, hex_max_size);
+
     // Send the log entry to the backend.
-    detail::log_entry entry = {&log_sink, fmtstr, std::move(store)};
+    detail::log_entry entry = {&log_sink,
+                               std::chrono::high_resolution_clock::now(),
+                               {ctx_value, should_print_context},
+                               fmtstr,
+                               std::move(store),
+                               log_name,
+                               log_tag,
+                               std::vector<uint8_t>(buffer, buffer + len)};
     backend.push(std::move(entry));
   }
 
@@ -79,6 +157,11 @@ private:
   const std::string log_id;
   sink& log_sink;
   detail::log_backend& backend;
+  const std::string log_name;
+  const char log_tag;
+  const bool should_print_context;
+  detail::shared_variable<uint32_t> ctx_value;
+  detail::shared_variable<int> hex_max_size;
   detail::shared_variable<bool> is_enabled;
 };
 
diff --git a/lib/include/srslte/srslog/logger.h b/lib/include/srslte/srslog/logger.h
index b69803acc..c8a4e01e3 100644
--- a/lib/include/srslte/srslog/logger.h
+++ b/lib/include/srslte/srslog/logger.h
@@ -31,6 +31,7 @@ namespace detail {
 /// The logger_impl template class contains the common functionality to loggers.
 /// Its main responsibility is to control the logging level by individually
 /// enabling or disabling the logging channels that form the logger.
+/// NOTE: Thread safe class.
 template <typename T, typename Enum>
 class logger_impl : public T
 {
@@ -60,11 +61,31 @@ public:
   /// Change the logging level.
   void set_level(Enum lvl)
   {
+    detail::scoped_lock lock(m);
     for (unsigned i = 0, e = channels.size(); i != e; ++i) {
       channels[i]->set_enabled(static_cast<Enum>(i) <= lvl);
     }
   }
 
+  /// Set the specified context value to all the channels of the logger.
+  void set_context(uint32_t x)
+  {
+    detail::scoped_lock lock(m);
+    for (auto channel : channels) {
+      channel->set_context(x);
+    }
+  }
+
+  /// Set the maximum number of bytes to can be printed in a hex dump to all the
+  /// channels of the logger.
+  void set_hex_dump_max_size(int x)
+  {
+    detail::scoped_lock lock(m);
+    for (auto channel : channels) {
+      channel->set_hex_dump_max_size(x);
+    }
+  }
+
 private:
   /// Comparison operator for enum types, used by the set_level method.
   friend bool operator<=(Enum lhs, Enum rhs)
@@ -75,6 +96,7 @@ private:
 private:
   const std::string logger_id;
   const std::array<log_channel*, size> channels;
+  mutable detail::mutex m;
 };
 
 /// Type trait to detect if T is a logger.
@@ -117,12 +139,13 @@ using build_logger_type = detail::logger_impl<T, Enum>;
 /// Common logger types.
 ///
 
-/// Basic logger with three levels.
-enum class basic_levels { error, warning, info, LAST };
+/// Basic logger with four levels.
+enum class basic_levels { error, warning, info, debug, LAST };
 struct basic_logger_channels {
   log_channel& error;
   log_channel& warning;
   log_channel& info;
+  log_channel& debug;
 };
 using basic_logger = build_logger_type<basic_logger_channels, basic_levels>;
 
diff --git a/lib/include/srslte/srslog/srslog.h b/lib/include/srslte/srslog/srslog.h
index d79815460..922bf27dc 100644
--- a/lib/include/srslte/srslog/srslog.h
+++ b/lib/include/srslte/srslog/srslog.h
@@ -28,32 +28,102 @@
 
 namespace srslog {
 
+///
+/// NOTE: All functions are thread safe unless otherwise specified.
+///
+
 ///
 /// Log channel management functions.
 ///
 
+/// Finds a log channel with the specified id string in the repository. On
+/// success returns a pointer to the requested log channel, otherwise nullptr.
+log_channel* find_log_channel(const std::string& id);
+
+/// Returns an instance of a log_channel with the specified id that writes to
+/// the default sink using the default log channel configuration.
+/// NOTE: Any '#' characters in the id will get removed.
+log_channel& fetch_log_channel(const std::string& id);
+
+/// Returns an instance of a log_channel with the specified id that writes to
+/// the specified sink.
+/// NOTE: Any '#' characters in the id will get removed.
+log_channel&
+fetch_log_channel(const std::string& id, sink& s, log_channel_config config);
+
 /// Creates a new log channel instance with the specified id string and sink,
 /// then registers it in the log channel repository so that it can be later
 /// retrieved in other parts of the application. Returns a pointer to the
 /// newly created channel, otherwise when a channel is already registered with
 /// the same id it returns nullptr.
+/// NOTE: The input id string should not contain any '#' characters otherwise
+/// nullptr is returned.
+/// NOTE: Deprecated, use fetch_log_channel instead.
 log_channel* create_log_channel(const std::string& id, sink& s);
 
-/// Finds a log channel with the specified id string in the repository. On
-/// success returns a pointer to the requested log channel, otherwise nullptr.
-log_channel* find_log_channel(const std::string& id);
+namespace detail {
+
+/// Internal helper functions.
+detail::any* fetch_logger(const std::string& id, detail::any&& logger);
+detail::any* find_logger(const std::string& id);
+
+} // namespace detail
 
 ///
 /// Logger management functions.
 ///
 
-namespace detail {
+/// Finds a logger with the specified id string and type in the repository. On
+/// success returns a pointer to the requested logger, otherwise nullptr.
+/// NOTE: T should be a type that is a logger.
+template <typename T>
+inline T* find_logger(const std::string& id)
+{
+  static_assert(detail::is_logger<T>::value, "T should be a logger type");
+  detail::any* p = detail::find_logger(id);
 
-/// Internal helper functions.
-detail::any* create_logger(const std::string& id, detail::any&& logger);
-detail::any* find_logger(const std::string& id);
+  return detail::any_cast<T>(p);
+}
 
-} // namespace detail
+/// Returns an instance of a basic logger (see basic_logger type) with the
+/// specified id string. All logger channels will write into the default sink.
+/// The context value of the logger can be printed on each log entry by setting
+/// to true the should_print_context argument.
+basic_logger& fetch_basic_logger(const std::string& id,
+                                 bool should_print_context = true);
+
+/// Returns an instance of a basic logger (see basic_logger type) with the
+/// specified id string. All logger channels will write into the specified sink.
+/// The context value of the logger can be printed on each log entry by setting
+/// to true the should_print_context argument.
+basic_logger& fetch_basic_logger(const std::string& id,
+                                 sink& s,
+                                 bool should_print_context = true);
+
+/// Returns a logger instance with the specified id string, type and channel
+/// references.
+/// NOTE: T should be a type that is a logger.
+template <typename T, typename... Args>
+inline T& fetch_logger(const std::string& id, Args&&... args)
+{
+  static_assert(detail::is_logger<T>::value, "T should be a logger type");
+  auto logger = detail::make_any<T>(id, std::forward<Args>(args)...);
+  detail::any* p = detail::fetch_logger(id, std::move(logger));
+
+  return *detail::any_cast<T>(p);
+}
+
+/// Creates a new basic logger instance (see basic_logger type) with the
+/// specified id string and sink, registering it into the logger repository so
+/// that it can be later retrieved in other parts of the application. The
+/// context value of the logger can be printed on each log entry by setting to
+/// true the should_print_context argument. All logger channels will write into
+/// the specified sink. Returns a pointer to the newly created logger, otherwise
+/// when a logger is already registered with the same id it returns nullptr.
+/// NOTE: Deprecated, use fetch_basic_logger instead.
+basic_logger* create_basic_logger(const std::string& id,
+                                  sink& s,
+                                  bool should_print_context = true);
 
 /// Creates a new logger instance with the specified id string, type and channel
 /// references, registering it into the logger repository so that it can be
@@ -61,24 +131,13 @@ detail::any* find_logger(const std::string& id);
 /// newly created logger, otherwise when a logger is already registered with the
 /// same id it returns nullptr.
 /// NOTE: T should be a type that is a logger.
+/// NOTE: Deprecated, use fetch_logger instead.
 template <typename T, typename... Args>
 inline T* create_logger(const std::string& id, Args&&... args)
 {
   static_assert(detail::is_logger<T>::value, "T should be a logger type");
   auto logger = detail::make_any<T>(id, std::forward<Args>(args)...);
-  detail::any* p = detail::create_logger(id, std::move(logger));
-
-  return detail::any_cast<T>(p);
-}
-
-/// Finds a logger with the specified id string and type in the repository. On
-/// success returns a pointer to the requested logger, otherwise nullptr.
-/// NOTE: T should be a type that is a logger.
-template <typename T>
-inline T* find_logger(const std::string& id)
-{
-  static_assert(detail::is_logger<T>::value, "T should be a logger type");
-  detail::any* p = detail::find_logger(id);
+  detail::any* p = detail::fetch_logger(id, std::move(logger));
 
   return detail::any_cast<T>(p);
 }
@@ -87,15 +146,47 @@ inline T* find_logger(const std::string& id)
 /// Sink management functions.
 ///
 
+/// Installs the specified sink to be used as the default one by new log
+/// channels and loggers.
+/// The initial default sink writes to stdout.
+void set_default_sink(sink& s);
+
+/// Returns the instance of the default sink being used.
+sink& get_default_sink();
+
 /// Finds a sink with the specified id string in the repository. On
 /// success returns a pointer to the requested sink, otherwise nullptr.
 sink* find_sink(const std::string& id);
 
+/// Returns an instance of a sink that writes to the stdout stream.
+sink& fetch_stdout_sink();
+
+/// Returns an instance of a sink that writes to the stderr stream.
+sink& fetch_stderr_sink();
+
+/// Returns an instance of a sink that writes into a file in the specified path.
+/// Specifying a max_size value different to zero will make the sink create a
+/// new file each time the current file exceeds this value. The units of
+/// max_size are bytes.
+/// NOTE: Any '#' characters in the id will get removed.
+sink& fetch_file_sink(const std::string& path, size_t max_size = 0);
+
+/// Creates a new sink that writes into the a file in the specified path and
+/// registers it into a sink repository so that it can be later retrieved in
+/// other parts of the application. Returns a pointer to the newly created sink
+/// or nullptr if a sink with the same path was already registered.
+/// Specifying a max_size value different to zero will make the sink create a
+/// new file each time the current file exceeds this value. The units of
+/// max_size are bytes.
+/// NOTE: Deprecated, use fetch_file_sink instead.
+sink* create_file_sink(const std::string& path, size_t max_size = 0);
+
 /// Creates a new sink that writes into the stdout stream and registers it into
 /// a sink repository so that it can be later retrieved in other parts of the
 /// application. Different stdout sinks can be created by providing different
 /// names. Returns a pointer to the newly created sink or nullptr if a sink with
 /// the same name was already registered.
+/// NOTE: Deprecated, use get_stdout_sink instead.
 sink* create_stdout_sink(const std::string& name = "stdout");
 
 /// Creates a new sink that writes into the stderr stream and registers it into
@@ -103,17 +194,9 @@ sink* create_stdout_sink(const std::string& name = "stdout");
 /// application. Different stderr sinks can be created by providing different
 /// names. Returns a pointer to the newly created sink or nullptr if a sink with
 /// the same name was already registered.
+/// NOTE: Deprecated, use get_stderr_sink instead.
 sink* create_stderr_sink(const std::string& name = "stderr");
 
-/// Creates a new sink that writes into the a file in the specified path and
-/// registers it into a sink repository so that it can be later retrieved in
-/// other parts of the application. Returns a pointer to the newly created sink
-/// or nullptr if a sink with the same path was already registered.
-/// Specifying a max_size value different to zero will make the sink create a
-/// new file each time the current file exceeds this value. The units of
-/// max_size are bytes.
-sink* create_file_sink(const std::string& path, size_t max_size = 0);
-
 ///
 /// Framework configuration and control functions.
 ///
@@ -123,9 +206,14 @@ sink* create_file_sink(const std::string& path, size_t max_size = 0);
 /// NOTE: Calling this function more than once has no side effects.
 void init();
 
+/// Flushes the contents of all the registered sinks. The caller thread will
+/// block until the operation is completed.
+/// NOTE: This function does nothing if init() has not been called.
+void flush();
+
 /// Installs the specified error handler to receive any error messages generated
 /// by the framework.
-/// NOTE: This function should be called before init().
+/// NOTE: This function should be called before init() and is NOT thread safe.
 void set_error_handler(error_handler handler);
 
 } // namespace srslog
diff --git a/lib/include/srslte/srslog/srslog_c.h b/lib/include/srslte/srslog/srslog_c.h
new file mode 100644
index 000000000..5b10e724c
--- /dev/null
+++ b/lib/include/srslte/srslog/srslog_c.h
@@ -0,0 +1,168 @@
+/*
+ * Copyright 2013-2020 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#ifndef SRSLOG_SRSLOG_C_H
+#define SRSLOG_SRSLOG_C_H
+
+#ifdef __cplusplus
+#include <cstddef>
+#else
+#include <stddef.h>
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Common types.
+ */
+typedef int srslog_bool;
+typedef struct srslog_opaque_sink srslog_sink;
+typedef struct srslog_opaque_log_channel srslog_log_channel;
+typedef struct srslog_opaque_basic_logger srslog_logger;
+
+/**
+ * This function initializes the logging framework. It must be called before
+ * any log entry is generated.
+ * NOTE: Calling this function more than once has no side effects.
+ */
+void srslog_init(void);
+
+/**
+ * Installs the specified sink to be used as the default one by new log
+ * channels and loggers.
+ * The initial default sink writes to stdout.
+ */
+void srslog_set_default_sink(srslog_sink* s);
+
+/**
+ * Returns the instance of the default sink being used.
+ */
+srslog_sink* srslog_get_default_sink(void);
+
+/**
+ * Returns an instance of a log_channel with the specified id that writes to
+ * the default sink using the default log channel configuration.
+ * NOTE: Any '#' characters in the id will get removed.
+ */
+srslog_log_channel* srslog_fetch_log_channel(const char* id);
+
+/**
+ * Finds a log channel with the specified id string in the repository. On
+ * success returns a pointer to the requested log channel, otherwise NULL.
+ */
+srslog_log_channel* srslog_find_log_channel(const char* id);
+
+/**
+ * Controls whether the specified channel accepts incoming log entries.
+ */
+void srslog_set_log_channel_enabled(srslog_log_channel* channel,
+                                    srslog_bool enabled);
+
+/**
+ * Returns 1 if the specified channel is accepting incoming log entries,
+ * otherwise 0.
+ */
+srslog_bool srslog_is_log_channel_enabled(srslog_log_channel* channel);
+
+/**
+ * Returns the id string of the specified channel.
+ */
+const char* srslog_get_log_channel_id(srslog_log_channel* channel);
+
+/**
+ * Logs the provided log entry using the specified log channel. When the channel
+ * is disabled the log entry wil be discarded.
+ * NOTE: Only printf style formatting is supported when using the C API.
+ */
+void srslog_log(srslog_log_channel* channel, const char* fmt, ...);
+
+/**
+ * Returns an instance of a basic logger (see basic_logger type) with the
+ * specified id string. All logger channels will write into the default sink.
+ */
+srslog_logger* srslog_fetch_default_logger(const char* id);
+
+/**
+ * Finds a logger with the specified id string in the repository. On success
+ * returns a pointer to the requested log channel, otherwise NULL.
+ */
+srslog_logger* srslog_find_default_logger(const char* id);
+
+/**
+ * These functions log the provided log entry using the specified logger.
+ * Entries are automatically discarded depending on the configured level of the
+ * logger.
+ * NOTE: Only printf style formatting is supported when using the C API.
+ */
+void srslog_debug(srslog_logger* log, const char* fmt, ...);
+void srslog_info(srslog_logger* log, const char* fmt, ...);
+void srslog_warning(srslog_logger* log, const char* fmt, ...);
+void srslog_error(srslog_logger* log, const char* fmt, ...);
+
+/**
+ * Returns the id string of the specified logger.
+ */
+const char* srslog_get_logger_id(srslog_logger* log);
+
+typedef enum {
+  srslog_lvl_error,   /**< error logging level */
+  srslog_lvl_warning, /**< warning logging level */
+  srslog_lvl_info,    /**< info logging level */
+  srslog_lvl_debug    /**< debug logging level */
+} srslog_log_levels;
+
+/**
+ * Sets the logging level into the specified logger.
+ */
+void srslog_set_logger_level(srslog_logger* log, srslog_log_levels lvl);
+
+/**
+ * Finds a sink with the specified id string in the repository. On
+ * success returns a pointer to the requested sink, otherwise NULL.
+ */
+srslog_sink* srslog_find_sink(const char* id);
+
+/**
+ * Returns an instance of a sink that writes to the stdout stream.
+ */
+srslog_sink* srslog_fetch_stdout_sink(void);
+
+/**
+ * Returns an instance of a sink that writes to the stderr stream.
+ */
+srslog_sink* srslog_fetch_stderr_sink(void);
+
+/**
+ * Returns an instance of a sink that writes into a file in the specified path.
+ * Specifying a max_size value different to zero will make the sink create a
+ * new file each time the current file exceeds this value. The units of
+ * max_size are bytes.
+ * NOTE: Any '#' characters in the id will get removed.
+ */
+srslog_sink* srslog_fetch_file_sink(const char* path, size_t max_size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/lib/src/common/log_filter.cc b/lib/src/common/log_filter.cc
index 84fc1119f..0af43d66e 100644
--- a/lib/src/common/log_filter.cc
+++ b/lib/src/common/log_filter.cc
@@ -103,29 +103,26 @@ void log_filter::all_log(srslte::LOG_LEVEL_ENUM level,
                          bool                   long_msg)
 {
   char buffer_tti[16]  = {};
-  char buffer_time[64] = {};
 
   if (logger_h) {
     logger::unique_log_str_t log_str = nullptr;
 
     if (long_msg || hex) {
       // For long messages, dynamically allocate a new log_str with enough size outside the pool.
-      uint32_t log_str_msg_len = sizeof(buffer_tti) + sizeof(buffer_time) + 20 + strlen(msg) + CHARS_FOR_HEX_DUMP(size);
+      uint32_t log_str_msg_len = sizeof(buffer_tti) + 20 + strlen(msg) + CHARS_FOR_HEX_DUMP(size);
       log_str = logger::unique_log_str_t(new logger::log_str(nullptr, log_str_msg_len), logger::log_str_deleter());
     } else {
       log_str = logger_h->allocate_unique_log_str();
     }
 
     if (log_str) {
-      now_time(buffer_time, sizeof(buffer_time));
       if (do_tti) {
         get_tti_str(tti, buffer_tti, sizeof(buffer_tti));
       }
 
       snprintf(log_str->str(),
                log_str->get_buffer_size(),
-               "%s [%-4s] %s %s%s%s%s%s",
-               buffer_time,
+               "[%-4s] %s %s%s%s%s%s",
                get_service_name().c_str(),
                log_level_text_short[level],
                do_tti ? buffer_tti : "",
diff --git a/lib/src/srslog/CMakeLists.txt b/lib/src/srslog/CMakeLists.txt
index 48b9656ab..ffaafeca5 100644
--- a/lib/src/srslog/CMakeLists.txt
+++ b/lib/src/srslog/CMakeLists.txt
@@ -19,8 +19,10 @@
 #
 
 set(SOURCES
+    backend_worker.cpp
     srslog.cpp
-    backend_worker.cpp)
+    srslog_c.cpp
+    event_trace.cpp)
 
 add_subdirectory(bundled/fmt)
 
diff --git a/lib/src/srslog/backend_worker.cpp b/lib/src/srslog/backend_worker.cpp
index c1d2396dc..5b0d6ba4f 100644
--- a/lib/src/srslog/backend_worker.cpp
+++ b/lib/src/srslog/backend_worker.cpp
@@ -20,6 +20,7 @@
  */
 
 #include "backend_worker.h"
+#include "formatter.h"
 #include "srslte/srslog/sink.h"
 #include <cassert>
 
@@ -69,7 +70,7 @@ void backend_worker::do_work()
       continue;
     }
 
-    report_queue_on_full();
+    report_queue_on_full_once();
 
     process_log_entry(std::move(item.second));
   }
@@ -79,12 +80,32 @@ void backend_worker::do_work()
   process_outstanding_entries();
 }
 
+/// Executes the flush command over all registered sinks.
+static void process_flush_command(const detail::flush_backend_cmd& cmd)
+{
+  for (const auto sink : cmd.sinks) {
+    sink->flush();
+  }
+
+  // Notify caller thread we are done.
+  cmd.completion_flag = true;
+}
+
 void backend_worker::process_log_entry(detail::log_entry&& entry)
 {
-  std::string result = fmt::vsprintf(entry.fmtstring, std::move(entry.store));
+  // Check first for flush commands.
+  if (entry.flush_cmd) {
+    process_flush_command(*entry.flush_cmd);
+    return;
+  }
+
+  // Save sink pointer before moving the entry.
+  sink* s = entry.s;
+
+  std::string result = format_log_entry_to_text(std::move(entry));
   detail::memory_buffer buffer(result);
 
-  if (auto err_str = entry.s->write(buffer)) {
+  if (auto err_str = s->write(buffer)) {
     err_handler(err_str.get_error());
   }
 }
diff --git a/lib/src/srslog/backend_worker.h b/lib/src/srslog/backend_worker.h
index 2ae0d29bb..0d2c9f7ca 100644
--- a/lib/src/srslog/backend_worker.h
+++ b/lib/src/srslog/backend_worker.h
@@ -41,8 +41,7 @@ class backend_worker
 
 public:
   explicit backend_worker(detail::work_queue<detail::log_entry>& queue) :
-    queue(queue),
-    running_flag(false)
+    queue(queue), running_flag(false)
   {}
 
   backend_worker(const backend_worker&) = delete;
@@ -100,7 +99,8 @@ private:
 
   /// Checks the current size of the queue reporting an error message if it is
   /// about to reach its maximum capacity.
-  void report_queue_on_full() const
+  /// Error message is only reported once to avoid spamming.
+  void report_queue_on_full_once()
   {
     if (queue.is_almost_full()) {
       err_handler(
@@ -108,6 +108,7 @@ private:
                       "capacity of {} elements, new log entries will get "
                       "discarded.\nConsider increasing the queue capacity.",
                       queue.get_capacity()));
+      err_handler = [](const std::string&) {};
     }
   }
 
diff --git a/lib/src/srslog/bundled/fmt/format.cc b/lib/src/srslog/bundled/fmt/format.cc
index 9a9abf8d0..a64a1f389 100644
--- a/lib/src/srslog/bundled/fmt/format.cc
+++ b/lib/src/srslog/bundled/fmt/format.cc
@@ -8,12 +8,12 @@
 #include "fmt/format-inl.h"
 
 FMT_BEGIN_NAMESPACE
-namespace internal {
+namespace detail {
 
 template <typename T>
 int format_float(char* buf, std::size_t size, const char* format, int precision,
                  T value) {
-#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+#ifdef FMT_FUZZ
   if (precision > 100000)
     throw std::runtime_error(
         "fuzz mode - avoid large allocation inside snprintf");
@@ -23,154 +23,47 @@ int format_float(char* buf, std::size_t size, const char* format, int precision,
   return precision < 0 ? snprintf_ptr(buf, size, format, value)
                        : snprintf_ptr(buf, size, format, precision, value);
 }
-struct sprintf_specs {
-  int precision;
-  char type;
-  bool alt : 1;
+}  // namespace detail
 
-  template <typename Char>
-  constexpr sprintf_specs(basic_format_specs<Char> specs)
-      : precision(specs.precision), type(specs.type), alt(specs.alt) {}
-
-  constexpr bool has_precision() const { return precision >= 0; }
-};
-
-// This is deprecated and is kept only to preserve ABI compatibility.
-template <typename Double>
-char* sprintf_format(Double value, internal::buffer<char>& buf,
-                     sprintf_specs specs) {
-  // Buffer capacity must be non-zero, otherwise MSVC's vsnprintf_s will fail.
-  FMT_ASSERT(buf.capacity() != 0, "empty buffer");
-
-  // Build format string.
-  enum { max_format_size = 10 };  // longest format: %#-*.*Lg
-  char format[max_format_size];
-  char* format_ptr = format;
-  *format_ptr++ = '%';
-  if (specs.alt || !specs.type) *format_ptr++ = '#';
-  if (specs.precision >= 0) {
-    *format_ptr++ = '.';
-    *format_ptr++ = '*';
-  }
-  if (std::is_same<Double, long double>::value) *format_ptr++ = 'L';
-
-  char type = specs.type;
-
-  if (type == '%')
-    type = 'f';
-  else if (type == 0 || type == 'n')
-    type = 'g';
-#if FMT_MSC_VER
-  if (type == 'F') {
-    // MSVC's printf doesn't support 'F'.
-    type = 'f';
-  }
-#endif
-  *format_ptr++ = type;
-  *format_ptr = '\0';
-
-  // Format using snprintf.
-  char* start = nullptr;
-  char* decimal_point_pos = nullptr;
-  for (;;) {
-    std::size_t buffer_size = buf.capacity();
-    start = &buf[0];
-    int result =
-        format_float(start, buffer_size, format, specs.precision, value);
-    if (result >= 0) {
-      unsigned n = internal::to_unsigned(result);
-      if (n < buf.capacity()) {
-        // Find the decimal point.
-        auto p = buf.data(), end = p + n;
-        if (*p == '+' || *p == '-') ++p;
-        if (specs.type != 'a' && specs.type != 'A') {
-          while (p < end && *p >= '0' && *p <= '9') ++p;
-          if (p < end && *p != 'e' && *p != 'E') {
-            decimal_point_pos = p;
-            if (!specs.type) {
-              // Keep only one trailing zero after the decimal point.
-              ++p;
-              if (*p == '0') ++p;
-              while (p != end && *p >= '1' && *p <= '9') ++p;
-              char* where = p;
-              while (p != end && *p == '0') ++p;
-              if (p == end || *p < '0' || *p > '9') {
-                if (p != end) std::memmove(where, p, to_unsigned(end - p));
-                n -= static_cast<unsigned>(p - where);
-              }
-            }
-          }
-        }
-        buf.resize(n);
-        break;  // The buffer is large enough - continue with formatting.
-      }
-      buf.reserve(n + 1);
-    } else {
-      // If result is negative we ask to increase the capacity by at least 1,
-      // but as std::vector, the buffer grows exponentially.
-      buf.reserve(buf.capacity() + 1);
-    }
-  }
-  return decimal_point_pos;
-}
-}  // namespace internal
-
-template FMT_API char* internal::sprintf_format(double, internal::buffer<char>&,
-                                                sprintf_specs);
-template FMT_API char* internal::sprintf_format(long double,
-                                                internal::buffer<char>&,
-                                                sprintf_specs);
-
-template struct FMT_INSTANTIATION_DEF_API internal::basic_data<void>;
+template struct FMT_INSTANTIATION_DEF_API detail::basic_data<void>;
 
 // Workaround a bug in MSVC2013 that prevents instantiation of format_float.
-int (*instantiate_format_float)(double, int, internal::float_specs,
-                                internal::buffer<char>&) =
-    internal::format_float;
+int (*instantiate_format_float)(double, int, detail::float_specs,
+                                detail::buffer<char>&) = detail::format_float;
 
 #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-template FMT_API internal::locale_ref::locale_ref(const std::locale& loc);
-template FMT_API std::locale internal::locale_ref::get<std::locale>() const;
+template FMT_API detail::locale_ref::locale_ref(const std::locale& loc);
+template FMT_API std::locale detail::locale_ref::get<std::locale>() const;
 #endif
 
 // Explicit instantiations for char.
 
-template FMT_API std::string internal::grouping_impl<char>(locale_ref);
-template FMT_API char internal::thousands_sep_impl(locale_ref);
-template FMT_API char internal::decimal_point_impl(locale_ref);
+template FMT_API std::string detail::grouping_impl<char>(locale_ref);
+template FMT_API char detail::thousands_sep_impl(locale_ref);
+template FMT_API char detail::decimal_point_impl(locale_ref);
 
-template FMT_API void internal::buffer<char>::append(const char*, const char*);
+template FMT_API void detail::buffer<char>::append(const char*, const char*);
 
-template FMT_API void internal::arg_map<format_context>::init(
-    const basic_format_args<format_context>& args);
+template FMT_API FMT_BUFFER_CONTEXT(char)::iterator detail::vformat_to(
+    detail::buffer<char>&, string_view,
+    basic_format_args<FMT_BUFFER_CONTEXT(char)>);
 
-template FMT_API std::string internal::vformat<char>(
-    string_view, basic_format_args<format_context>);
-
-template FMT_API format_context::iterator internal::vformat_to(
-    internal::buffer<char>&, string_view, basic_format_args<format_context>);
-
-template FMT_API int internal::snprintf_float(double, int,
-                                              internal::float_specs,
-                                              internal::buffer<char>&);
-template FMT_API int internal::snprintf_float(long double, int,
-                                              internal::float_specs,
-                                              internal::buffer<char>&);
-template FMT_API int internal::format_float(double, int, internal::float_specs,
-                                            internal::buffer<char>&);
-template FMT_API int internal::format_float(long double, int,
-                                            internal::float_specs,
-                                            internal::buffer<char>&);
+template FMT_API int detail::snprintf_float(double, int, detail::float_specs,
+                                            detail::buffer<char>&);
+template FMT_API int detail::snprintf_float(long double, int,
+                                            detail::float_specs,
+                                            detail::buffer<char>&);
+template FMT_API int detail::format_float(double, int, detail::float_specs,
+                                          detail::buffer<char>&);
+template FMT_API int detail::format_float(long double, int, detail::float_specs,
+                                          detail::buffer<char>&);
 
 // Explicit instantiations for wchar_t.
 
-template FMT_API std::string internal::grouping_impl<wchar_t>(locale_ref);
-template FMT_API wchar_t internal::thousands_sep_impl(locale_ref);
-template FMT_API wchar_t internal::decimal_point_impl(locale_ref);
-
-template FMT_API void internal::buffer<wchar_t>::append(const wchar_t*,
-                                                        const wchar_t*);
+template FMT_API std::string detail::grouping_impl<wchar_t>(locale_ref);
+template FMT_API wchar_t detail::thousands_sep_impl(locale_ref);
+template FMT_API wchar_t detail::decimal_point_impl(locale_ref);
 
-template FMT_API std::wstring internal::vformat<wchar_t>(
-    wstring_view, basic_format_args<wformat_context>);
+template FMT_API void detail::buffer<wchar_t>::append(const wchar_t*,
+                                                      const wchar_t*);
 FMT_END_NAMESPACE
diff --git a/lib/src/srslog/bundled/fmt/os.cc b/lib/src/srslog/bundled/fmt/os.cc
index 10a372a46..386119db1 100644
--- a/lib/src/srslog/bundled/fmt/os.cc
+++ b/lib/src/srslog/bundled/fmt/os.cc
@@ -73,14 +73,14 @@ inline std::size_t convert_rwcount(std::size_t count) { return count; }
 FMT_BEGIN_NAMESPACE
 
 #ifdef _WIN32
-internal::utf16_to_utf8::utf16_to_utf8(wstring_view s) {
+detail::utf16_to_utf8::utf16_to_utf8(wstring_view s) {
   if (int error_code = convert(s)) {
     FMT_THROW(windows_error(error_code,
                             "cannot convert string from UTF-16 to UTF-8"));
   }
 }
 
-int internal::utf16_to_utf8::convert(wstring_view s) {
+int detail::utf16_to_utf8::convert(wstring_view s) {
   if (s.size() > INT_MAX) return ERROR_INVALID_PARAMETER;
   int s_size = static_cast<int>(s.size());
   if (s_size == 0) {
@@ -105,13 +105,13 @@ void windows_error::init(int err_code, string_view format_str,
                          format_args args) {
   error_code_ = err_code;
   memory_buffer buffer;
-  internal::format_windows_error(buffer, err_code, vformat(format_str, args));
+  detail::format_windows_error(buffer, err_code, vformat(format_str, args));
   std::runtime_error& base = *this;
   base = std::runtime_error(to_string(buffer));
 }
 
-void internal::format_windows_error(internal::buffer<char>& out, int error_code,
-                                    string_view message) FMT_NOEXCEPT {
+void detail::format_windows_error(detail::buffer<char>& out, int error_code,
+                                  string_view message) FMT_NOEXCEPT {
   FMT_TRY {
     wmemory_buffer buf;
     buf.resize(inline_buffer_size);
@@ -124,10 +124,7 @@ void internal::format_windows_error(internal::buffer<char>& out, int error_code,
       if (result != 0) {
         utf16_to_utf8 utf8_message;
         if (utf8_message.convert(system_message) == ERROR_SUCCESS) {
-          internal::writer w(out);
-          w.write(message);
-          w.write(": ");
-          w.write(utf8_message);
+          format_to(std::back_inserter(out), "{}: {}", message, utf8_message);
           return;
         }
         break;
@@ -143,7 +140,7 @@ void internal::format_windows_error(internal::buffer<char>& out, int error_code,
 
 void report_windows_error(int error_code,
                           fmt::string_view message) FMT_NOEXCEPT {
-  report_error(internal::format_windows_error, error_code, message);
+  report_error(detail::format_windows_error, error_code, message);
 }
 #endif  // _WIN32
 
@@ -234,14 +231,14 @@ std::size_t file::read(void* buffer, std::size_t count) {
   RWResult result = 0;
   FMT_RETRY(result, FMT_POSIX_CALL(read(fd_, buffer, convert_rwcount(count))));
   if (result < 0) FMT_THROW(system_error(errno, "cannot read from file"));
-  return internal::to_unsigned(result);
+  return detail::to_unsigned(result);
 }
 
 std::size_t file::write(const void* buffer, std::size_t count) {
   RWResult result = 0;
   FMT_RETRY(result, FMT_POSIX_CALL(write(fd_, buffer, convert_rwcount(count))));
   if (result < 0) FMT_THROW(system_error(errno, "cannot write to file"));
-  return internal::to_unsigned(result);
+  return detail::to_unsigned(result);
 }
 
 file file::dup(int fd) {
@@ -292,7 +289,11 @@ void file::pipe(file& read_end, file& write_end) {
 
 buffered_file file::fdopen(const char* mode) {
   // Don't retry as fdopen doesn't return EINTR.
+  #if defined(__MINGW32__) && defined(_POSIX_)
+  FILE* f = ::fdopen(fd_, mode);
+  #else
   FILE* f = FMT_POSIX_CALL(fdopen(fd_, mode));
+  #endif
   if (!f)
     FMT_THROW(
         system_error(errno, "cannot associate stream with file descriptor"));
diff --git a/lib/src/srslog/event_trace.cpp b/lib/src/srslog/event_trace.cpp
new file mode 100644
index 000000000..f3754bbb2
--- /dev/null
+++ b/lib/src/srslog/event_trace.cpp
@@ -0,0 +1,123 @@
+/*
+ * Copyright 2013-2020 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#include "srslte/srslog/event_trace.h"
+#include "srslte/srslog/srslog.h"
+#include <cassert>
+#include <ctime>
+
+#undef trace_duration_begin
+#undef trace_duration_end
+#undef trace_complete_event
+
+using namespace srslog;
+
+/// Log channel where event traces will get sent.
+static log_channel* tracer = nullptr;
+
+void srslog::event_trace_init()
+{
+  // Nothing to do if the user previously set a custom channel or this is not
+  // the first time this function is called.
+  if (tracer) {
+    return;
+  }
+
+  // Default file name where event traces will get stored.
+  static constexpr char default_file_name[] = "event_trace.log";
+
+  // Create the default event trace channel.
+  //:TODO: handle name reservation.
+  sink* s = create_file_sink(default_file_name);
+  assert(s && "Default event file sink is reserved");
+  tracer = create_log_channel("event_trace_channel", *s);
+  assert(tracer && "Default event trace channel is reserved");
+}
+
+void srslog::event_trace_init(log_channel& c)
+{
+  // Nothing to set when a channel has already been installed.
+  if (!tracer) {
+    tracer = &c;
+  }
+}
+
+/// Fills in the input buffer with the current time.
+static void format_time(char* buffer, size_t len)
+{
+  std::time_t t = std::time(nullptr);
+  std::strftime(buffer, len, "%FT%T", std::localtime(&t));
+}
+
+namespace srslog {
+
+void trace_duration_begin(const std::string& category, const std::string& name)
+{
+  if (!tracer) {
+    return;
+  }
+
+  char fmt_time[24];
+  format_time(fmt_time, sizeof(fmt_time));
+  (*tracer)("[%s] [TID:%0u] Entering \"%s\": %s",
+            fmt_time,
+            (unsigned)::pthread_self(),
+            category,
+            name);
+}
+
+void trace_duration_end(const std::string& category, const std::string& name)
+{
+  if (!tracer) {
+    return;
+  }
+
+  char fmt_time[24];
+  format_time(fmt_time, sizeof(fmt_time));
+  (*tracer)("[%s] [TID:%0u] Leaving \"%s\": %s",
+            fmt_time,
+            (unsigned)::pthread_self(),
+            category,
+            name);
+}
+
+} // namespace srslog
+
+/// Private implementation of the complete event destructor.
+srslog::detail::scoped_complete_event::~scoped_complete_event()
+{
+  if (!tracer)
+    return;
+
+  auto end = std::chrono::steady_clock::now();
+  unsigned long long diff =
+      std::chrono::duration_cast<std::chrono::microseconds>(end - start)
+          .count();
+
+  char fmt_time[24];
+  format_time(fmt_time, sizeof(fmt_time));
+  (*tracer)("[%s] [TID:%0u] Complete event \"%s\" (duration %lld us): %s",
+            fmt_time,
+            (unsigned)::pthread_self(),
+            category,
+            diff,
+            name);
+}
diff --git a/lib/src/srslog/formatter.h b/lib/src/srslog/formatter.h
new file mode 100644
index 000000000..4c3e53916
--- /dev/null
+++ b/lib/src/srslog/formatter.h
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2013-2020 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#ifndef SRSLOG_FORMATTER_H
+#define SRSLOG_FORMATTER_H
+
+#include "srslte/srslog/bundled/fmt/chrono.h"
+#include "srslte/srslog/bundled/fmt/ranges.h"
+#include "srslte/srslog/detail/log_entry.h"
+
+namespace srslog {
+
+namespace detail {
+
+/// Formats into a hex dump a range of elements, storing the result in the input
+/// buffer.
+inline void format_hex_dump(const std::vector<uint8_t>& v,
+                            fmt::memory_buffer& buffer)
+{
+  if (v.empty()) {
+    return;
+  }
+
+  const size_t elements_per_line = 16;
+
+  for (auto i = v.cbegin(), e = v.cend(); i != e;) {
+    auto num_elements =
+        std::min<size_t>(elements_per_line, std::distance(i, e));
+
+    fmt::format_to(buffer,
+                   "    {:04x}: {:02x}\n",
+                   std::distance(v.cbegin(), i),
+                   fmt::join(i, i + num_elements, " "));
+
+    std::advance(i, num_elements);
+  }
+}
+
+} // namespace detail
+
+/// Formats to text all the fields of a log entry,
+inline std::string format_log_entry_to_text(detail::log_entry&& entry)
+{
+  fmt::memory_buffer buffer;
+
+  // Time stamp data preparation.
+  std::tm current_time =
+      fmt::gmtime(std::chrono::high_resolution_clock::to_time_t(entry.tp));
+  auto us_fraction = std::chrono::duration_cast<std::chrono::microseconds>(
+                         entry.tp.time_since_epoch())
+                         .count() %
+                     1000000u;
+  fmt::format_to(buffer, "{:%H:%M:%S}.{:06} ", current_time, us_fraction);
+
+  // Format optional fields if present.
+  if (!entry.log_name.empty()) {
+    fmt::format_to(buffer, "[{: <4.4}] ", entry.log_name);
+  }
+  if (entry.log_tag != '\0') {
+    fmt::format_to(buffer, "[{}] ", entry.log_tag);
+  }
+  if (entry.context.enabled) {
+    fmt::format_to(buffer, "[{:5}] ", entry.context.value);
+  }
+
+  // Message formatting.
+  fmt::format_to(
+      buffer, "{}\n", fmt::vsprintf(entry.fmtstring, std::move(entry.store)));
+
+  // Optional hex dump formatting.
+  detail::format_hex_dump(entry.hex_dump, buffer);
+
+  return fmt::to_string(buffer);
+}
+
+} // namespace srslog
+
+#endif // SRSLOG_FORMATTER_H
diff --git a/lib/src/srslog/log_backend_impl.h b/lib/src/srslog/log_backend_impl.h
index 1c5eba61e..41dc1bd78 100644
--- a/lib/src/srslog/log_backend_impl.h
+++ b/lib/src/srslog/log_backend_impl.h
@@ -45,15 +45,14 @@ public:
     queue.push(std::move(entry));
   }
 
+  bool is_running() const override { return worker.is_running(); }
+
   /// Installs the specified error handler into the backend worker.
   void set_error_handler(error_handler err_handler)
   {
     worker.set_error_handler(std::move(err_handler));
   }
 
-  /// Returns true if the backend has been started, otherwise returns false.
-  bool is_started() const { return worker.is_running(); }
-
   /// Stops the backend worker thread.
   void stop() { worker.stop(); }
 
diff --git a/lib/src/srslog/object_repository.h b/lib/src/srslog/object_repository.h
index bc5ec4cb5..4f3db863a 100644
--- a/lib/src/srslog/object_repository.h
+++ b/lib/src/srslog/object_repository.h
@@ -24,6 +24,7 @@
 
 #include "srslte/srslog/detail/support/thread_utils.h"
 #include <unordered_map>
+#include <vector>
 
 namespace srslog {
 
@@ -49,8 +50,19 @@ public:
     return &insertion.first->second;
   }
 
-  /// Finds a value with the specified key in the repository. Returns a
-  /// pointer to the value, otherwise nullptr if not found.
+  /// Inserts a new entry in-place into the repository if there is no element
+  /// with the specified key. Returns a reference to the inserted element or to
+  /// the already existing element if no insertion happened.
+  template <typename... Args>
+  V& emplace(Args&&... args)
+  {
+    detail::scoped_lock lock(m);
+    auto insertion = repo.emplace(std::forward<Args>(args)...);
+    return insertion.first->second;
+  }
+
+  /// Finds a value with the specified key in the repository. Returns a pointer
+  /// to the value, otherwise nullptr if not found.
   V* find(const K& key)
   {
     detail::scoped_lock lock(m);
@@ -63,6 +75,32 @@ public:
     const auto it = repo.find(key);
     return (it != repo.cend()) ? &it->second : nullptr;
   }
+
+  /// Returns a copy of the contents of the repository.
+  std::vector<V*> contents()
+  {
+    detail::scoped_lock lock(m);
+
+    std::vector<V*> data;
+    data.reserve(repo.size());
+    for (auto& elem : repo) {
+      data.push_back(&elem.second);
+    }
+
+    return data;
+  }
+  std::vector<const V*> contents() const
+  {
+    detail::scoped_lock lock(m);
+
+    std::vector<const V*> data;
+    data.reserve(repo.size());
+    for (const auto& elem : repo) {
+      data.push_back(&elem.second);
+    }
+
+    return data;
+  }
 };
 
 } // namespace srslog
diff --git a/lib/src/srslog/sink_repository.h b/lib/src/srslog/sink_repository.h
new file mode 100644
index 000000000..ff2e0f4c3
--- /dev/null
+++ b/lib/src/srslog/sink_repository.h
@@ -0,0 +1,123 @@
+/*
+ * Copyright 2013-2020 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#ifndef SRSLOG_SINK_REPOSITORY_H
+#define SRSLOG_SINK_REPOSITORY_H
+
+#include "object_repository.h"
+#include "sinks/stream_sink.h"
+
+namespace srslog {
+
+/// The sink repository stores sink instances associated to an id. Both stdout
+/// and stderr stream sinks are created on construction so they accessible
+/// without the need of creating them previously.
+/// NOTE: Thread safe class.
+class sink_repository
+{
+  /// Identifiers for stdout and stderr sinks.
+  static constexpr char stdout_id[] = "stdout#";
+  static constexpr char stderr_id[] = "stderr#";
+
+  object_repository<std::string, std::unique_ptr<sink> > repo;
+
+public:
+  sink_repository()
+  {
+    //:TODO: GCC5 or lower versions emits an error if we use the new() expression directly, use redundant
+    //piecewise_construct instead.
+    repo.emplace(std::piecewise_construct,
+                 std::forward_as_tuple(stdout_id),
+                 std::forward_as_tuple(new stream_sink(sink_stream_type::stdout)));
+    repo.emplace(std::piecewise_construct,
+                 std::forward_as_tuple(stderr_id),
+                 std::forward_as_tuple(new stream_sink(sink_stream_type::stderr)));
+  }
+
+  /// Returns the instance of the sink that writes to stdout.
+  sink& get_stdout_sink()
+  {
+    auto s = repo.find(stdout_id);
+    assert(s && "stdout sink should always exist");
+    return *(s->get());
+  }
+  const sink& get_stdout_sink() const
+  {
+    const auto s = repo.find(stdout_id);
+    assert(s && "stdout sink should always exist");
+    return *(s->get());
+  }
+
+  /// Returns the instance of the sink that writes to stderr.
+  sink& get_stderr_sink()
+  {
+    auto s = repo.find(stderr_id);
+    assert(s && "stderr sink should always exist");
+    return *(s->get());
+  }
+  const sink& get_stderr_sink() const
+  {
+    const auto s = repo.find(stderr_id);
+    assert(s && "stderr sink should always exist");
+    return *(s->get());
+  }
+
+  /// Finds a sink with the specified id in the repository. Returns a pointer to
+  /// the sink, otherwise nullptr if not found.
+  sink* find(const std::string& id)
+  {
+    auto p = repo.find(id);
+    return (p) ? p->get() : nullptr;
+  }
+  const sink* find(const std::string& id) const
+  {
+    const auto p = repo.find(id);
+    return (p) ? p->get() : nullptr;
+  }
+
+  /// Returns an instance of a sink specified by the input arguments.
+  template <typename... Args>
+  sink& fetch_sink(Args&&... args)
+  {
+    return *repo.emplace(std::forward<Args>(args)...);
+  }
+
+  /// Returns a copy of the list of registered sinks.
+  std::vector<sink*> contents() const
+  {
+    auto repo_contents = repo.contents();
+
+    std::vector<sink*> data;
+    data.reserve(repo_contents.size());
+    for (const auto& s : repo_contents) {
+      data.push_back(s->get());
+    }
+
+    return data;
+  }
+};
+
+constexpr char sink_repository::stdout_id[];
+constexpr char sink_repository::stderr_id[];
+
+} // namespace srslog
+
+#endif // SRSLOG_SINK_REPOSITORY_H
diff --git a/lib/src/srslog/sinks/file_sink.h b/lib/src/srslog/sinks/file_sink.h
index 400a8fe92..ecd438191 100644
--- a/lib/src/srslog/sinks/file_sink.h
+++ b/lib/src/srslog/sinks/file_sink.h
@@ -69,6 +69,10 @@ public:
 
   detail::error_string flush() override { return handler.flush(); }
 
+protected:
+  /// Returns the current file index.
+  uint32_t get_file_index() const { return file_index; }
+
 private:
   /// Returns true when the sink has never written data to a file, otherwise
   /// returns false.
diff --git a/lib/src/srslog/sinks/stream_sink.h b/lib/src/srslog/sinks/stream_sink.h
index d8369d99e..8db10a8ce 100644
--- a/lib/src/srslog/sinks/stream_sink.h
+++ b/lib/src/srslog/sinks/stream_sink.h
@@ -46,6 +46,8 @@ public:
   {
     assert(handle && "Invalid stream handle");
     std::fwrite(buffer.data(), sizeof(char), buffer.size(), handle);
+    // We want to see the output instantly.
+    std::fflush(handle);
     return {};
   }
 
diff --git a/lib/src/srslog/srslog.cpp b/lib/src/srslog/srslog.cpp
index f5f0ed8a6..510f962e9 100644
--- a/lib/src/srslog/srslog.cpp
+++ b/lib/src/srslog/srslog.cpp
@@ -21,77 +21,294 @@
 
 #include "srslte/srslog/srslog.h"
 #include "sinks/file_sink.h"
-#include "sinks/stream_sink.h"
 #include "srslog_instance.h"
 
 using namespace srslog;
 
-log_channel* srslog::create_log_channel(const std::string& id, sink& s)
+/// Returns a copy of the input string with any occurrences of the '#' character
+/// removed.
+static std::string remove_sharp_chars(const std::string& s)
 {
-  srslog_instance& instance = srslog_instance::get();
-
-  auto channel = std::unique_ptr<log_channel>(
-      new log_channel(id, s, instance.get_backend()));
-  auto p = instance.get_channel_repo().insert(id, std::move(channel));
+  std::string result(s);
+  result.erase(std::remove(result.begin(), result.end(), '#'), result.end());
+  return result;
+}
 
-  return (p) ? p->get() : nullptr;
+/// Generic argument function that fetches a log channel from the repository.
+template <typename... Args>
+static log_channel& fetch_log_channel_helper(const std::string& id, Args&&... args)
+{
+  return srslog_instance::get().get_channel_repo().emplace(
+      std::piecewise_construct, std::forward_as_tuple(id), std::forward_as_tuple(id, std::forward<Args>(args)...));
 }
 
+///
+/// Log channel management function implementations.
+///
+
 log_channel* srslog::find_log_channel(const std::string& id)
 {
-  auto p = srslog_instance::get().get_channel_repo().find(id);
-  return (p) ? p->get() : nullptr;
+  return srslog_instance::get().get_channel_repo().find(id);
 }
 
-sink* srslog::find_sink(const std::string& id)
+log_channel& srslog::fetch_log_channel(const std::string& id)
 {
-  auto p = srslog_instance::get().get_sink_repo().find(id);
-  return (p) ? p->get() : nullptr;
+  assert(!id.empty() && "Empty id string");
+
+  std::string      clean_id = remove_sharp_chars(id);
+  srslog_instance& instance = srslog_instance::get();
+  return fetch_log_channel_helper(clean_id, instance.get_default_sink(), instance.get_backend());
 }
 
-/// Helper for creating and registering sinks.
-template <typename T, typename... Args>
-static sink* create_sink(const std::string& id, Args&&... args)
+log_channel& srslog::fetch_log_channel(const std::string& id, sink& s, log_channel_config config)
 {
-  auto new_sink = std::unique_ptr<sink>(new T(std::forward<Args>(args)...));
-  auto p =
-      srslog_instance::get().get_sink_repo().insert(id, std::move(new_sink));
+  assert(!id.empty() && "Empty id string");
 
-  return (p) ? p->get() : nullptr;
+  std::string      clean_id = remove_sharp_chars(id);
+  srslog_instance& instance = srslog_instance::get();
+  return fetch_log_channel_helper(clean_id, s, instance.get_backend(), std::move(config));
 }
 
-sink* srslog::create_stdout_sink(const std::string& name)
+///
+/// Sink management function implementations.
+///
+
+void srslog::set_default_sink(sink& s)
 {
-  return create_sink<stream_sink>(name, sink_stream_type::stdout);
+  srslog_instance::get().set_default_sink(s);
 }
 
-sink* srslog::create_stderr_sink(const std::string& name)
+sink& srslog::get_default_sink()
 {
-  return create_sink<stream_sink>(name, sink_stream_type::stderr);
+  return srslog_instance::get().get_default_sink();
 }
 
-sink* srslog::create_file_sink(const std::string& path, size_t max_size)
+sink* srslog::find_sink(const std::string& id)
 {
-  return create_sink<file_sink>(path, path, max_size);
+  return srslog_instance::get().get_sink_repo().find(id);
 }
 
+sink& srslog::fetch_stdout_sink()
+{
+  return srslog_instance::get().get_sink_repo().get_stdout_sink();
+}
+
+sink& srslog::fetch_stderr_sink()
+{
+  return srslog_instance::get().get_sink_repo().get_stderr_sink();
+}
+
+sink& srslog::fetch_file_sink(const std::string& path, size_t max_size)
+{
+  assert(!path.empty() && "Empty path string");
+
+  std::string clean_path = remove_sharp_chars(path);
+  //:TODO: GCC5 or lower versions emits an error if we use the new() expression directly, use redundant
+  // piecewise_construct instead.
+  return srslog_instance::get().get_sink_repo().fetch_sink(std::piecewise_construct,
+                                                           std::forward_as_tuple(clean_path),
+                                                           std::forward_as_tuple(new file_sink(clean_path, max_size)));
+}
+
+///
+/// Framework configuration and control function implementations.
+///
+
 void srslog::init()
 {
   srslog_instance::get().get_backend().start();
 }
 
-detail::any* srslog::detail::create_logger(const std::string& id,
-                                           detail::any&& logger)
+void srslog::flush()
 {
-  return srslog_instance::get().get_logger_repo().insert(id, std::move(logger));
+  srslog_instance& instance = srslog_instance::get();
+
+  // Nothing to do when the backend is not running yet.
+  if (!instance.get_backend().is_running()) {
+    return;
+  }
+
+  // The backend will set this shared variable when done.
+  detail::shared_variable<bool> completion_flag(false);
+
+  detail::log_entry cmd;
+  cmd.flush_cmd = std::unique_ptr<detail::flush_backend_cmd>(
+      new detail::flush_backend_cmd{completion_flag, instance.get_sink_repo().contents()});
+
+  instance.get_backend().push(std::move(cmd));
+
+  // Block the caller thread until we are signaled that the flush is completed.
+  while (!completion_flag) {
+    std::this_thread::sleep_for(std::chrono::microseconds(100));
+  }
 }
 
+void srslog::set_error_handler(error_handler handler)
+{
+  srslog_instance::get().set_error_handler(std::move(handler));
+}
+
+///
+/// Logger management function implementations.
+///
+
 detail::any* srslog::detail::find_logger(const std::string& id)
 {
   return srslog_instance::get().get_logger_repo().find(id);
 }
 
-void srslog::set_error_handler(error_handler handler)
+detail::any* srslog::detail::fetch_logger(const std::string& id, detail::any&& logger)
 {
-  srslog_instance::get().set_error_handler(std::move(handler));
+  assert(!id.empty() && "Empty id string");
+  return &srslog_instance::get().get_logger_repo().emplace(id, std::move(logger));
+}
+
+/// Builds a logger name out of the id and tag.
+static std::string build_logger_name(const std::string& id, char tag)
+{
+  return fmt::format("{}#{}", id, tag);
+}
+
+/// Fetches a logger with all its log channels.
+static basic_logger& fetch_basic_logger_helper(const std::string& id, sink& s, bool should_print_context)
+{
+  static constexpr char basic_logger_chan_tags[] = {'E', 'W', 'I', 'D'};
+
+  srslog_instance& instance = srslog_instance::get();
+
+  // User created log channels cannot have ids with a # character, encode the
+  // ids here with a # to ensure all channels are unique.
+
+  log_channel& error =
+      fetch_log_channel_helper(build_logger_name(id, basic_logger_chan_tags[0]),
+                               s,
+                               instance.get_backend(),
+                               log_channel_config{id, basic_logger_chan_tags[0], should_print_context});
+  log_channel& warning =
+      fetch_log_channel_helper(build_logger_name(id, basic_logger_chan_tags[1]),
+                               s,
+                               instance.get_backend(),
+                               log_channel_config{id, basic_logger_chan_tags[1], should_print_context});
+  log_channel& info = fetch_log_channel_helper(build_logger_name(id, basic_logger_chan_tags[2]),
+                                               s,
+                                               instance.get_backend(),
+                                               log_channel_config{id, basic_logger_chan_tags[2], should_print_context});
+  log_channel& debug =
+      fetch_log_channel_helper(build_logger_name(id, basic_logger_chan_tags[3]),
+                               s,
+                               instance.get_backend(),
+                               log_channel_config{id, basic_logger_chan_tags[3], should_print_context});
+
+  return fetch_logger<basic_logger>(id, error, warning, info, debug);
+}
+
+basic_logger& srslog::fetch_basic_logger(const std::string& id, bool should_print_context)
+{
+  assert(!id.empty() && "Empty id string");
+  return fetch_basic_logger_helper(id, srslog_instance::get().get_default_sink(), should_print_context);
+}
+
+basic_logger& srslog::fetch_basic_logger(const std::string& id, sink& s, bool should_print_context)
+{
+  assert(!id.empty() && "Empty id string");
+  return fetch_basic_logger_helper(id, s, should_print_context);
+}
+
+///
+/// Deprecated functions to be removed.
+///
+
+/// Creates and registers a log channel. Returns a pointer to the newly created
+/// channel on success, otherwise nullptr.
+static log_channel* create_and_register_log_channel(const std::string& id, sink& s)
+{
+  assert(!id.empty() && "Empty id string");
+
+  srslog_instance& instance = srslog_instance::get();
+
+  auto& p = instance.get_channel_repo().emplace(
+      std::piecewise_construct, std::forward_as_tuple(id), std::forward_as_tuple(id, s, instance.get_backend()));
+
+  return &p;
+}
+
+static log_channel* create_and_register_log_channel(const std::string& id, log_channel_config config, sink& s)
+{
+  assert(!id.empty() && "Empty id string");
+
+  srslog_instance& instance = srslog_instance::get();
+
+  auto& p =
+      instance.get_channel_repo().emplace(std::piecewise_construct,
+                                          std::forward_as_tuple(id),
+                                          std::forward_as_tuple(id, s, instance.get_backend(), std::move(config)));
+
+  return &p;
+}
+
+/// Returns true if the input string contains a sharp character, otherwise
+/// returns false.
+static bool contains_sharp_char(const std::string& s)
+{
+  return s.find('#') != std::string::npos;
+}
+
+log_channel* srslog::create_log_channel(const std::string& id, sink& s)
+{
+  if (contains_sharp_char(id)) {
+    return nullptr;
+  }
+
+  return create_and_register_log_channel(id, s);
+}
+
+sink* srslog::create_stdout_sink(const std::string& name)
+{
+  return &srslog_instance::get().get_sink_repo().get_stdout_sink();
+}
+
+sink* srslog::create_stderr_sink(const std::string& name)
+{
+  return &srslog_instance::get().get_sink_repo().get_stderr_sink();
+}
+
+sink* srslog::create_file_sink(const std::string& path, size_t max_size)
+{
+  //:TODO: GCC5 or lower versions emits an error if we use the new() expression directly, use redundant
+  // piecewise_construct instead.
+  return &srslog_instance::get().get_sink_repo().fetch_sink(
+      std::piecewise_construct, std::forward_as_tuple(path), std::forward_as_tuple(new file_sink(path, max_size)));
+}
+
+basic_logger* srslog::create_basic_logger(const std::string& id, sink& s, bool should_print_context)
+{
+  assert(!id.empty() && "Empty id string");
+
+  static constexpr char basic_logger_chan_tags[] = {'E', 'W', 'I', 'D'};
+
+  auto& logger_repo = srslog_instance::get().get_logger_repo();
+
+  // Nothing to do when the logger already exists.
+  if (logger_repo.find(id)) {
+    return nullptr;
+  }
+
+  // User created log channels cannot have ids with a # character, encode the
+  // ids here with a # to ensure all channel creations will be successful
+  // without any id clashes.
+
+  log_channel* error = create_and_register_log_channel(
+      build_logger_name(id, basic_logger_chan_tags[0]), {id, basic_logger_chan_tags[0], should_print_context}, s);
+  assert(error && "Could not create channel");
+  log_channel* warning = create_and_register_log_channel(
+      build_logger_name(id, basic_logger_chan_tags[1]), {id, basic_logger_chan_tags[1], should_print_context}, s);
+  assert(warning && "Could not create channel");
+  log_channel* info = create_and_register_log_channel(
+      build_logger_name(id, basic_logger_chan_tags[2]), {id, basic_logger_chan_tags[2], should_print_context}, s);
+  assert(info && "Could not create channel");
+  log_channel* debug = create_and_register_log_channel(
+      build_logger_name(id, basic_logger_chan_tags[3]), {id, basic_logger_chan_tags[3], should_print_context}, s);
+  assert(debug && "Could not create channel");
+
+  return create_logger<basic_logger>(id, *error, *warning, *info, *debug);
 }
diff --git a/lib/src/srslog/srslog_c.cpp b/lib/src/srslog/srslog_c.cpp
new file mode 100644
index 000000000..4ec3a84e1
--- /dev/null
+++ b/lib/src/srslog/srslog_c.cpp
@@ -0,0 +1,196 @@
+/*
+ * Copyright 2013-2020 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#include "srslte/srslog/srslog_c.h"
+#include "srslte/srslog/srslog.h"
+#include <cassert>
+#include <cstdarg>
+
+using namespace srslog;
+
+template <typename To, typename From>
+static inline To* c_cast(From* x)
+{
+  return reinterpret_cast<To*>(x);
+}
+
+/// Helper to format the input argument list writing it into a channel.
+static void log_to(log_channel& c, const char* fmt, std::va_list args)
+{
+  char buffer[1024];
+  std::vsnprintf(buffer, sizeof(buffer) - 1, fmt, args);
+  c(buffer);
+}
+
+void srslog_init(void)
+{
+  init();
+}
+
+void srslog_set_default_sink(srslog_sink* s)
+{
+  assert(s && "Expected a valid sink");
+  set_default_sink(*c_cast<sink>(s));
+}
+
+srslog_sink* srslog_get_default_sink(void)
+{
+  return c_cast<srslog_sink>(&get_default_sink());
+}
+
+srslog_log_channel* srslog_fetch_log_channel(const char* id)
+{
+  return c_cast<srslog_log_channel>(&fetch_log_channel(id));
+}
+
+srslog_log_channel* srslog_find_log_channel(const char* id)
+{
+  return c_cast<srslog_log_channel>(find_log_channel(id));
+}
+
+void srslog_set_log_channel_enabled(srslog_log_channel* channel,
+                                    srslog_bool enabled)
+{
+  assert(channel && "Expected a valid channel");
+  c_cast<log_channel>(channel)->set_enabled(enabled);
+}
+
+srslog_bool srslog_is_log_channel_enabled(srslog_log_channel* channel)
+{
+  assert(channel && "Expected a valid channel");
+  return c_cast<log_channel>(channel)->enabled();
+}
+
+const char* srslog_get_log_channel_id(srslog_log_channel* channel)
+{
+  assert(channel && "Expected a valid channel");
+  return c_cast<log_channel>(channel)->id().c_str();
+}
+
+void srslog_log(srslog_log_channel* channel, const char* fmt, ...)
+{
+  assert(channel && "Expected a valid channel");
+
+  std::va_list args;
+  va_start(args, fmt);
+  log_to(*c_cast<log_channel>(channel), fmt, args);
+  va_end(args);
+}
+
+srslog_logger* srslog_fetch_default_logger(const char* id)
+{
+  return c_cast<srslog_logger>(&fetch_basic_logger(id));
+}
+
+srslog_logger* srslog_find_default_logger(const char* id)
+{
+  return c_cast<srslog_logger>(find_logger<basic_logger>(id));
+}
+
+void srslog_debug(srslog_logger* log, const char* fmt, ...)
+{
+  assert(log && "Expected a valid logger");
+
+  std::va_list args;
+  va_start(args, fmt);
+  log_to(c_cast<basic_logger>(log)->debug, fmt, args);
+  va_end(args);
+}
+
+void srslog_info(srslog_logger* log, const char* fmt, ...)
+{
+  assert(log && "Expected a valid logger");
+
+  std::va_list args;
+  va_start(args, fmt);
+  log_to(c_cast<basic_logger>(log)->info, fmt, args);
+  va_end(args);
+}
+
+void srslog_warning(srslog_logger* log, const char* fmt, ...)
+{
+  assert(log && "Expected a valid logger");
+
+  std::va_list args;
+  va_start(args, fmt);
+  log_to(c_cast<basic_logger>(log)->warning, fmt, args);
+  va_end(args);
+}
+
+void srslog_error(srslog_logger* log, const char* fmt, ...)
+{
+  assert(log && "Expected a valid logger");
+
+  std::va_list args;
+  va_start(args, fmt);
+  log_to(c_cast<basic_logger>(log)->error, fmt, args);
+  va_end(args);
+}
+
+const char* srslog_get_logger_id(srslog_logger* log)
+{
+  assert(log && "Expected a valid logger");
+  return c_cast<basic_logger>(log)->id().c_str();
+}
+
+/// Translate the C API level enum to basic_levels.
+static basic_levels convert_c_enum_to_basic_levels(srslog_log_levels lvl)
+{
+  switch (lvl) {
+    case srslog_lvl_debug:
+      return basic_levels::debug;
+    case srslog_lvl_info:
+      return basic_levels::info;
+    case srslog_lvl_warning:
+      return basic_levels ::warning;
+    case srslog_lvl_error:
+      return basic_levels::error;
+  }
+
+  assert(false && "Invalid enum value");
+  return basic_levels::error;
+}
+
+void srslog_set_logger_level(srslog_logger* log, srslog_log_levels lvl)
+{
+  assert(log && "Expected a valid logger");
+  c_cast<basic_logger>(log)->set_level(convert_c_enum_to_basic_levels(lvl));
+}
+
+srslog_sink* srslog_find_sink(const char* id)
+{
+  return c_cast<srslog_sink>(find_sink(id));
+}
+
+srslog_sink* srslog_fetch_stdout_sink(void)
+{
+  return c_cast<srslog_sink>(&fetch_stdout_sink());
+}
+
+srslog_sink* srslog_fetch_stderr_sink(void)
+{
+  return c_cast<srslog_sink>(&fetch_stderr_sink());
+}
+
+srslog_sink* srslog_fetch_file_sink(const char* path, size_t max_size)
+{
+  return c_cast<srslog_sink>(&fetch_file_sink(path, max_size));
+}
diff --git a/lib/src/srslog/srslog_instance.h b/lib/src/srslog/srslog_instance.h
index f4e18799a..a61ca5065 100644
--- a/lib/src/srslog/srslog_instance.h
+++ b/lib/src/srslog/srslog_instance.h
@@ -23,17 +23,16 @@
 #define SRSLOG_SRSLOG_INSTANCE_H
 
 #include "log_backend_impl.h"
-#include "object_repository.h"
+#include "sink_repository.h"
 #include "srslte/srslog/detail/support/any.h"
 #include "srslte/srslog/log_channel.h"
-#include "srslte/srslog/sink.h"
 
 namespace srslog {
 
 /// Singleton of the framework containing all the required classes.
 class srslog_instance
 {
-  srslog_instance() = default;
+  srslog_instance() { default_sink = &sink_repo.get_stdout_sink(); }
 
 public:
   srslog_instance(const srslog_instance& other) = delete;
@@ -52,15 +51,13 @@ public:
   const logger_repo_type& get_logger_repo() const { return logger_repo; }
 
   /// Log channel repository accessor.
-  using channel_repo_type =
-      object_repository<std::string, std::unique_ptr<log_channel>>;
+  using channel_repo_type = object_repository<std::string, log_channel>;
   channel_repo_type& get_channel_repo() { return channel_repo; }
   const channel_repo_type& get_channel_repo() const { return channel_repo; }
 
   /// Sink repository accessor.
-  using sink_repo_type = object_repository<std::string, std::unique_ptr<sink>>;
-  sink_repo_type& get_sink_repo() { return sink_repo; }
-  const sink_repo_type& get_sink_repo() const { return sink_repo; }
+  sink_repository& get_sink_repo() { return sink_repo; }
+  const sink_repository& get_sink_repo() const { return sink_repo; }
 
   /// Backend accessor.
   detail::log_backend& get_backend() { return backend; }
@@ -72,13 +69,20 @@ public:
     backend.set_error_handler(std::move(callback));
   }
 
+  /// Set the specified sink as the default one.
+  void set_default_sink(sink& s) { default_sink = &s; }
+
+  /// Returns the default sink.
+  sink& get_default_sink() { return *default_sink; }
+
 private:
   /// NOTE: The order of declaration of each member is important here for proper
   /// destruction.
-  sink_repo_type sink_repo;
+  sink_repository sink_repo;
   log_backend_impl backend;
   channel_repo_type channel_repo;
   logger_repo_type logger_repo;
+  detail::shared_variable<sink*> default_sink{nullptr};
 };
 
 } // namespace srslog
diff --git a/lib/test/srslog/CMakeLists.txt b/lib/test/srslog/CMakeLists.txt
index 0d98d3e17..372bd14f5 100644
--- a/lib/test/srslog/CMakeLists.txt
+++ b/lib/test/srslog/CMakeLists.txt
@@ -48,3 +48,13 @@ add_executable(file_utils_test file_utils_test.cpp)
 target_include_directories(file_utils_test PUBLIC ../../)
 target_link_libraries(file_utils_test srslog)
 add_test(file_utils_test file_utils_test)
+
+add_executable(tracer_test event_trace_test.cpp)
+add_definitions(-DENABLE_SRSLOG_EVENT_TRACE)
+target_link_libraries(tracer_test srslog)
+add_test(tracer_test tracer_test)
+
+add_executable(formatter_test formatter_test.cpp)
+target_include_directories(formatter_test PUBLIC ../../)
+target_link_libraries(formatter_test srslog)
+add_test(formatter_test formatter_test)
diff --git a/lib/test/srslog/event_trace_test.cpp b/lib/test/srslog/event_trace_test.cpp
new file mode 100644
index 000000000..1f931221d
--- /dev/null
+++ b/lib/test/srslog/event_trace_test.cpp
@@ -0,0 +1,107 @@
+/*
+ * Copyright 2013-2020 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#include "srslte/srslog/event_trace.h"
+#include "srslte/srslog/log_channel.h"
+#include "srslte/srslog/sink.h"
+#include "testing_helpers.h"
+
+using namespace srslog;
+
+namespace {
+
+/// A Dummy implementation of a sink.
+class sink_dummy : public sink
+{
+public:
+  detail::error_string write(detail::memory_buffer buffer) override
+  {
+    return {};
+  }
+
+  detail::error_string flush() override { return {}; }
+};
+
+/// A Spy implementation of a log backend. Tests can query if the push method
+/// has been invoked.
+class backend_spy : public detail::log_backend
+{
+public:
+  void start() override {}
+
+  void push(detail::log_entry&& entry) override
+  {
+    std::string result = fmt::vsprintf(entry.fmtstring, std::move(entry.store));
+    ++count;
+  }
+
+  bool is_running() const override { return true; }
+
+  void reset() { count = 0; }
+
+  unsigned push_invocation_count() const { return count; }
+
+private:
+  unsigned count = 0;
+};
+
+} // namespace
+
+static bool
+when_tracing_with_duration_event_then_two_events_are_generated(backend_spy& spy)
+{
+  trace_duration_begin("a", "b");
+  ASSERT_EQ(spy.push_invocation_count(), 1);
+
+  trace_duration_end("a", "b");
+  ASSERT_EQ(spy.push_invocation_count(), 2);
+
+  return true;
+}
+
+static bool
+when_tracing_with_complete_event_then_one_event_is_generated(backend_spy& spy)
+{
+  {
+    trace_complete_event("a", "b");
+  }
+  ASSERT_EQ(spy.push_invocation_count(), 1);
+
+  return true;
+}
+
+int main()
+{
+  sink_dummy s;
+  backend_spy backend;
+  log_channel c("test", s, backend);
+
+  // Inject our spy into the framework.
+  event_trace_init(c);
+
+  TEST_FUNCTION(when_tracing_with_duration_event_then_two_events_are_generated,
+                backend);
+  backend.reset();
+  TEST_FUNCTION(when_tracing_with_complete_event_then_one_event_is_generated,
+                backend);
+
+  return 0;
+}
diff --git a/lib/test/srslog/file_sink_test.cpp b/lib/test/srslog/file_sink_test.cpp
index 052ad4cb4..203685eb5 100644
--- a/lib/test/srslog/file_sink_test.cpp
+++ b/lib/test/srslog/file_sink_test.cpp
@@ -19,13 +19,13 @@
  *
  */
 
-#include "src/srslog/sinks/file_sink.h"
 #include "file_test_utils.h"
+#include "src/srslog/sinks/file_sink.h"
 #include "testing_helpers.h"
 
 using namespace srslog;
 
-static const char* const log_filename = "testfile.log";
+static constexpr char log_filename[] = "file_sink_test.log";
 
 static bool when_data_is_written_to_file_then_contents_are_valid()
 {
@@ -48,6 +48,18 @@ static bool when_data_is_written_to_file_then_contents_are_valid()
   return true;
 }
 
+/// A Test-Specific Subclass of file_sink. This subclass provides public access
+/// to the data members of the parent class.
+class file_sink_subclass : public file_sink
+{
+public:
+  file_sink_subclass(std::string name, size_t max_size) :
+    file_sink(std::move(name), max_size)
+  {}
+
+  uint32_t get_num_of_files() const { return get_file_index(); }
+};
+
 static bool when_data_written_exceeds_size_threshold_then_new_file_is_created()
 {
   std::string filename0 =
@@ -59,7 +71,7 @@ static bool when_data_written_exceeds_size_threshold_then_new_file_is_created()
   file_test_utils::scoped_file_deleter deleter = {
       filename0, filename1, filename2};
 
-  file_sink file(log_filename, 5001);
+  file_sink_subclass file(log_filename, 5001);
 
   // Build a 1000 byte entry.
   std::string entry(1000, 'a');
@@ -71,16 +83,14 @@ static bool when_data_written_exceeds_size_threshold_then_new_file_is_created()
   file.flush();
 
   // Only one file should exist.
-  ASSERT_EQ(file_test_utils::file_exists(filename0), true);
-  ASSERT_EQ(file_test_utils::file_exists(filename1), false);
+  ASSERT_EQ(file.get_num_of_files(), 1);
 
   // Trigger a file rotation.
   file.write(detail::memory_buffer(entry));
   file.flush();
 
   // A second file should be created.
-  ASSERT_EQ(file_test_utils::file_exists(filename0), true);
-  ASSERT_EQ(file_test_utils::file_exists(filename1), true);
+  ASSERT_EQ(file.get_num_of_files(), 2);
 
   // Fill in the second file with 4000 bytes, one byte less than the threshold.
   for (unsigned i = 0; i != 4; ++i) {
@@ -88,19 +98,15 @@ static bool when_data_written_exceeds_size_threshold_then_new_file_is_created()
   }
   file.flush();
 
-  // Two file should exist, third should not be created yet.
-  ASSERT_EQ(file_test_utils::file_exists(filename0), true);
-  ASSERT_EQ(file_test_utils::file_exists(filename1), true);
-  ASSERT_EQ(file_test_utils::file_exists(filename2), false);
+  // Two files should exist, third should not be created yet.
+  ASSERT_EQ(file.get_num_of_files(), 2);
 
   // Trigger a file rotation.
   file.write(detail::memory_buffer(entry));
   file.flush();
 
   // Three files should exist.
-  ASSERT_EQ(file_test_utils::file_exists(filename0), true);
-  ASSERT_EQ(file_test_utils::file_exists(filename1), true);
-  ASSERT_EQ(file_test_utils::file_exists(filename2), true);
+  ASSERT_EQ(file.get_num_of_files(), 3);
 
   return true;
 }
diff --git a/lib/test/srslog/file_utils_test.cpp b/lib/test/srslog/file_utils_test.cpp
index f4ae83043..da27ca3cd 100644
--- a/lib/test/srslog/file_utils_test.cpp
+++ b/lib/test/srslog/file_utils_test.cpp
@@ -19,14 +19,14 @@
  *
  */
 
-#include "src/srslog/sinks/file_utils.h"
 #include "file_test_utils.h"
+#include "src/srslog/sinks/file_utils.h"
 #include "testing_helpers.h"
 
 using namespace srslog;
 
-static const char* const log_filename = "testfile.log";
-static const char* const log_filename2 = "testfile2.log";
+static constexpr char log_filename[] = "file_utils_test.log";
+static constexpr char log_filename2[] = "file_utils_test2.log";
 
 static bool filename_extension_split_test()
 {
diff --git a/lib/test/srslog/formatter_test.cpp b/lib/test/srslog/formatter_test.cpp
new file mode 100644
index 000000000..7b772519a
--- /dev/null
+++ b/lib/test/srslog/formatter_test.cpp
@@ -0,0 +1,121 @@
+/*
+ * Copyright 2013-2020 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#include "src/srslog/formatter.h"
+#include "testing_helpers.h"
+#include <numeric>
+
+using namespace srslog;
+
+/// Helper to build a log entry.
+static detail::log_entry build_log_entry()
+{
+  // Create a time point 50000us from epoch.
+  using tp_ty = std::chrono::time_point<std::chrono::high_resolution_clock>;
+  tp_ty tp(std::chrono::microseconds(50000));
+
+  fmt::dynamic_format_arg_store<fmt::printf_context> store;
+  store.push_back(88);
+
+  return {nullptr, tp, {10, true}, "Text %d", std::move(store), "ABC", 'Z'};
+}
+
+static bool when_fully_filled_log_entry_then_result_everything_is_formatted()
+{
+  std::string result = format_log_entry_to_text(build_log_entry());
+  std::string expected = "00:00:00.050000 [ABC ] [Z] [   10] Text 88\n";
+
+  ASSERT_EQ(result, expected);
+
+  return true;
+}
+
+static bool when_log_entry_without_name_is_passed_then_name_is_not_formatted()
+{
+  auto entry = build_log_entry();
+  entry.log_name = "";
+
+  std::string result = format_log_entry_to_text(std::move(entry));
+  std::string expected = "00:00:00.050000 [Z] [   10] Text 88\n";
+
+  ASSERT_EQ(result, expected);
+
+  return true;
+}
+
+static bool when_log_entry_without_tag_is_passed_then_tag_is_not_formatted()
+{
+  auto entry = build_log_entry();
+  entry.log_tag = '\0';
+
+  std::string result = format_log_entry_to_text(std::move(entry));
+  std::string expected = "00:00:00.050000 [ABC ] [   10] Text 88\n";
+
+  ASSERT_EQ(result, expected);
+
+  return true;
+}
+
+static bool
+when_log_entry_without_context_is_passed_then_context_is_not_formatted()
+{
+  auto entry = build_log_entry();
+  entry.context.enabled = false;
+
+  std::string result = format_log_entry_to_text(std::move(entry));
+  std::string expected = "00:00:00.050000 [ABC ] [Z] Text 88\n";
+
+  ASSERT_EQ(result, expected);
+
+  return true;
+}
+
+static bool when_log_entry_with_hex_dump_is_passed_then_hex_dump_is_formatted()
+{
+  auto entry = build_log_entry();
+  entry.hex_dump.resize(20);
+  std::iota(entry.hex_dump.begin(), entry.hex_dump.end(), 0);
+
+  std::string result = format_log_entry_to_text(std::move(entry));
+  std::string expected =
+      "00:00:00.050000 [ABC ] [Z] [   10] Text 88\n"
+      "    0000: 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f\n"
+      "    0010: 10 11 12 13\n";
+
+  ASSERT_EQ(result, expected);
+
+  return true;
+}
+
+int main()
+{
+  TEST_FUNCTION(
+      when_fully_filled_log_entry_then_result_everything_is_formatted);
+  TEST_FUNCTION(
+      when_log_entry_without_name_is_passed_then_name_is_not_formatted);
+  TEST_FUNCTION(when_log_entry_without_tag_is_passed_then_tag_is_not_formatted);
+  TEST_FUNCTION(
+      when_log_entry_without_context_is_passed_then_context_is_not_formatted);
+  TEST_FUNCTION(
+      when_log_entry_with_hex_dump_is_passed_then_hex_dump_is_formatted);
+
+  return 0;
+}
diff --git a/lib/test/srslog/log_backend_test.cpp b/lib/test/srslog/log_backend_test.cpp
index 795cae178..cf85c60ce 100644
--- a/lib/test/srslog/log_backend_test.cpp
+++ b/lib/test/srslog/log_backend_test.cpp
@@ -29,9 +29,9 @@ static bool when_backend_is_started_then_is_started_returns_true()
 {
   log_backend_impl backend;
 
-  ASSERT_EQ(backend.is_started(), false);
+  ASSERT_EQ(backend.is_running(), false);
   backend.start();
-  ASSERT_EQ(backend.is_started(), true);
+  ASSERT_EQ(backend.is_running(), true);
 
   return true;
 }
@@ -43,7 +43,7 @@ static bool when_backend_is_started_and_stopped_then_is_started_returns_false()
   backend.start();
   backend.stop();
 
-  ASSERT_EQ(backend.is_started(), false);
+  ASSERT_EQ(backend.is_running(), false);
 
   return true;
 }
@@ -80,7 +80,7 @@ static bool when_backend_is_not_started_then_pushed_log_entries_are_ignored()
   sink_spy spy;
   log_backend_impl backend;
 
-  detail::log_entry entry = {&spy, "Test"};
+  detail::log_entry entry = {&spy};
   backend.push(std::move(entry));
 
   ASSERT_EQ(spy.write_invocation_count(), 0);
@@ -88,19 +88,16 @@ static bool when_backend_is_not_started_then_pushed_log_entries_are_ignored()
   return true;
 }
 
-/// Helper to build a log entry.
+/// Builds a basic log entry.
 static detail::log_entry build_log_entry(sink* s)
 {
-  // Populate store with some arguments.
-  fmt::dynamic_format_arg_store<fmt::printf_context> store;
-  store.push_back(3);
-  store.push_back("Hello");
-  store.push_back(3.14);
+  using tp_ty = std::chrono::time_point<std::chrono::high_resolution_clock>;
+  tp_ty tp;
 
-  // Send the log entry to the backend.
-  detail::log_entry entry = {s, "Arg1:%u Arg2:%s Arg3:%.2f", std::move(store)};
+  fmt::dynamic_format_arg_store<fmt::printf_context> store;
+  store.push_back(88);
 
-  return entry;
+  return {s, tp, {0, false}, "Text %d", std::move(store), "", '\0'};
 }
 
 static bool when_backend_is_started_then_pushed_log_entries_are_sent_to_sink()
@@ -116,7 +113,7 @@ static bool when_backend_is_started_then_pushed_log_entries_are_sent_to_sink()
   backend.stop();
 
   ASSERT_EQ(spy.write_invocation_count(), 1);
-  ASSERT_EQ(spy.received_buffer(), "Arg1:3 Arg2:Hello Arg3:3.14");
+  ASSERT_NE(spy.received_buffer().find("Text 88"), std::string::npos);
 
   return true;
 }
diff --git a/lib/test/srslog/log_channel_test.cpp b/lib/test/srslog/log_channel_test.cpp
index 1de6121ff..ef2791cb8 100644
--- a/lib/test/srslog/log_channel_test.cpp
+++ b/lib/test/srslog/log_channel_test.cpp
@@ -46,6 +46,8 @@ public:
   void start() override {}
 
   void push(detail::log_entry&& entry) override {}
+
+  bool is_running() const override { return true; }
 };
 
 } // namespace
@@ -102,6 +104,8 @@ public:
     ++count;
   }
 
+  bool is_running() const override { return true; }
+
   unsigned push_invocation_count() const { return count; }
 
   const detail::log_entry& last_entry() const { return e; }
@@ -120,12 +124,10 @@ when_logging_in_log_channel_then_log_entry_is_pushed_into_the_backend()
   sink_dummy s;
   log_channel log("id", s, backend);
 
-  std::string fmtstring = "Arg1: %u Arg2: %s";
+  std::string fmtstring = "test";
   log(fmtstring, 42, "Hello");
 
   ASSERT_EQ(backend.push_invocation_count(), 1);
-  ASSERT_NE(backend.last_entry().s, nullptr);
-  ASSERT_EQ(backend.last_entry().fmtstring, fmtstring);
 
   return true;
 }
@@ -137,7 +139,7 @@ static bool when_logging_in_disabled_log_channel_then_log_entry_is_ignored()
   log_channel log("id", s, backend);
 
   log.set_enabled(false);
-  std::string fmtstring = "Arg1: %u Arg2: %s";
+  std::string fmtstring = "test";
   log(fmtstring, 42, "Hello");
 
   ASSERT_EQ(backend.push_invocation_count(), 0);
@@ -145,6 +147,99 @@ static bool when_logging_in_disabled_log_channel_then_log_entry_is_ignored()
   return true;
 }
 
+static bool when_logging_then_filled_in_log_entry_is_pushed_into_the_backend()
+{
+  backend_spy backend;
+  sink_dummy s;
+
+  std::string name = "name";
+  char tag = 'A';
+
+  log_channel log("id", s, backend, {name, tag, true});
+
+  std::string fmtstring = "test";
+  uint32_t ctx = 10;
+
+  log.set_context(ctx);
+  log(fmtstring, 42, "Hello");
+
+  ASSERT_EQ(backend.push_invocation_count(), 1);
+
+  const detail::log_entry& entry = backend.last_entry();
+  ASSERT_NE(entry.tp.time_since_epoch().count(), 0);
+  ASSERT_EQ(entry.context.value, ctx);
+  ASSERT_EQ(entry.context.enabled, true);
+  ASSERT_EQ(entry.fmtstring, fmtstring);
+  ASSERT_EQ(entry.log_name, name);
+  ASSERT_EQ(entry.log_tag, tag);
+
+  return true;
+}
+
+static bool
+when_logging_with_hex_dump_then_filled_in_log_entry_is_pushed_into_the_backend()
+{
+  backend_spy backend;
+  sink_dummy s;
+
+  std::string name = "name";
+  char tag = 'A';
+
+  log_channel log("id", s, backend, {name, tag, true});
+
+  std::string fmtstring = "test";
+  uint32_t ctx = 4;
+
+  log.set_context(ctx);
+  log.set_hex_dump_max_size(4);
+  uint8_t hex[] = {0, 1, 2, 3, 4, 5, 6, 7, 8};
+  log(hex, sizeof(hex), fmtstring, 42, "Hello");
+
+  ASSERT_EQ(backend.push_invocation_count(), 1);
+
+  const detail::log_entry& entry = backend.last_entry();
+  ASSERT_NE(entry.tp.time_since_epoch().count(), 0);
+  ASSERT_EQ(entry.context.value, ctx);
+  ASSERT_EQ(entry.context.enabled, true);
+  ASSERT_EQ(entry.fmtstring, fmtstring);
+  ASSERT_EQ(entry.log_name, name);
+  ASSERT_EQ(entry.log_tag, tag);
+  ASSERT_EQ(entry.hex_dump.size(), 4);
+  ASSERT_EQ(
+      std::equal(entry.hex_dump.begin(), entry.hex_dump.end(), std::begin(hex)),
+      true);
+
+  return true;
+}
+
+static bool
+when_hex_array_length_is_less_than_hex_log_max_size_then_array_length_is_used()
+{
+  backend_spy backend;
+  sink_dummy s;
+
+  std::string name = "name";
+  char tag = 'A';
+
+  log_channel log("id", s, backend);
+
+  std::string fmtstring = "test";
+
+  log.set_hex_dump_max_size(10);
+  uint8_t hex[] = {0, 1, 2};
+  log(hex, sizeof(hex), fmtstring, 42, "Hello");
+
+  ASSERT_EQ(backend.push_invocation_count(), 1);
+
+  const detail::log_entry& entry = backend.last_entry();
+  ASSERT_EQ(entry.hex_dump.size(), 3);
+  ASSERT_EQ(
+      std::equal(entry.hex_dump.begin(), entry.hex_dump.end(), std::begin(hex)),
+      true);
+
+  return true;
+}
+
 int main()
 {
   TEST_FUNCTION(when_log_channel_is_created_then_id_matches_expected_value);
@@ -153,6 +248,12 @@ int main()
   TEST_FUNCTION(
       when_logging_in_log_channel_then_log_entry_is_pushed_into_the_backend);
   TEST_FUNCTION(when_logging_in_disabled_log_channel_then_log_entry_is_ignored);
+  TEST_FUNCTION(
+      when_logging_then_filled_in_log_entry_is_pushed_into_the_backend);
+  TEST_FUNCTION(
+      when_logging_with_hex_dump_then_filled_in_log_entry_is_pushed_into_the_backend);
+  TEST_FUNCTION(
+      when_hex_array_length_is_less_than_hex_log_max_size_then_array_length_is_used);
 
   return 0;
 }
diff --git a/lib/test/srslog/logger_test.cpp b/lib/test/srslog/logger_test.cpp
index 54d996a54..ef2d8f62d 100644
--- a/lib/test/srslog/logger_test.cpp
+++ b/lib/test/srslog/logger_test.cpp
@@ -25,7 +25,7 @@
 
 using namespace srslog;
 
-static const char* const logger_id = "TestLogger";
+static constexpr char logger_id[] = "TestLogger";
 
 namespace {
 
@@ -48,6 +48,8 @@ public:
   void start() override {}
 
   void push(detail::log_entry&& entry) override {}
+
+  bool is_running() const override { return true; }
 };
 
 /// Definition of a three level logger
diff --git a/lib/test/srslog/srslog_test.cpp b/lib/test/srslog/srslog_test.cpp
index 7ab130bef..60dd2d7f2 100644
--- a/lib/test/srslog/srslog_test.cpp
+++ b/lib/test/srslog/srslog_test.cpp
@@ -25,102 +25,93 @@
 
 using namespace srslog;
 
-static const char* const test_id = "Test";
+static constexpr char test_id1[] = "Test1";
+static constexpr char test_id2[] = "Test2";
 
-//:FIXME: older compilers may not have defined this C++11 trait.
+//:TODO: older compilers may not have defined this C++11 trait.
 #if (defined(__clang__) && (__clang_major__ >= 5)) ||                          \
     (defined(__GNUG__) && (__GNUC__ >= 5))
 static_assert(std::is_trivially_copyable<detail::memory_buffer>::value,
               "Expected to be trivially copyable");
 #endif
 
-namespace {
-
-/// A Dummy implementation of a sink.
-class sink_dummy : public sink
-{
-public:
-  detail::error_string write(detail::memory_buffer buffer) override
-  {
-    return {};
-  }
-
-  detail::error_string flush() override { return {}; }
-};
-
-} // namespace
-
-static bool when_no_channel_exists_then_channel_is_created()
+static bool when_fetching_channel_then_channel_instance_is_returned()
 {
-  sink_dummy s;
-  log_channel* channel = create_log_channel(test_id, s);
+  log_channel& channel1 = fetch_log_channel(test_id1);
+  log_channel& channel2 = fetch_log_channel(test_id2, fetch_stdout_sink(), {});
 
-  ASSERT_NE(channel, nullptr);
-  ASSERT_EQ(channel->id(), test_id);
+  ASSERT_EQ(channel1.id(), test_id1);
+  ASSERT_EQ(channel2.id(), test_id2);
 
   return true;
 }
 
-static bool when_channel_already_exists_then_nullptr_is_returned()
+static bool when_valid_id_is_passed_then_channel_is_found()
 {
-  sink_dummy s;
-  log_channel* channel = create_log_channel(test_id, s);
+  log_channel* channel1 = find_log_channel(test_id1);
+  log_channel* channel2 = find_log_channel(test_id2);
+
+  ASSERT_NE(channel1, nullptr);
+  ASSERT_EQ(channel1->id(), test_id1);
 
-  ASSERT_EQ(channel, nullptr);
+  ASSERT_NE(channel2, nullptr);
+  ASSERT_EQ(channel2->id(), test_id2);
 
   return true;
 }
 
-static bool when_valid_id_is_passed_then_channel_is_found()
+static bool when_non_existent_id_is_passed_then_nothing_is_found()
 {
-  log_channel* c = find_log_channel(test_id);
-
-  ASSERT_NE(c, nullptr);
-  ASSERT_EQ(c->id(), test_id);
+  ASSERT_EQ(find_log_channel("non_existent_channel"), nullptr);
 
   return true;
 }
 
-static bool when_invalid_id_is_passed_then_nothing_is_found()
+static bool
+when_id_with_sharps_is_passed_then_channel_is_fetched_with_clean_id()
 {
-  ASSERT_EQ(find_log_channel("invalid"), nullptr);
+  log_channel& channel1 = fetch_log_channel("a1#a");
+  log_channel& channel2 = fetch_log_channel("a2#a", fetch_stdout_sink(), {});
+
+  ASSERT_EQ(channel1.id(), "a1a");
+  ASSERT_EQ(channel2.id(), "a2a");
 
   return true;
 }
 
-static const char* const logger_id = "TestLogger";
+static constexpr char logger_id[] = "TestLogger";
+static constexpr char basic_logger_id1[] = "BasicTestLogger";
+static constexpr char basic_logger_id2[] = "BasicTestLogger2";
 
-static bool when_no_logger_exists_then_logger_is_created()
+static bool when_fetching_logger_then_logger_instance_is_returned()
 {
-  sink_dummy s;
-  log_channel& error = *create_log_channel("logger#error", s);
-  log_channel& warning = *create_log_channel("logger#warning", s);
-  log_channel& info = *create_log_channel("logger#info", s);
-  basic_logger* logger =
-      create_logger<basic_logger>(logger_id, error, warning, info);
+  log_channel& error = fetch_log_channel("logger.error");
+  log_channel& warning = fetch_log_channel("logger.warning");
+  log_channel& info = fetch_log_channel("logger.info");
+  log_channel& debug = fetch_log_channel("logger.debug");
+
+  auto& logger =
+      fetch_logger<basic_logger>(logger_id, error, warning, info, debug);
 
-  ASSERT_NE(logger, nullptr);
-  ASSERT_EQ(logger->id(), logger_id);
+  ASSERT_EQ(logger.id(), logger_id);
 
   return true;
 }
 
-static bool when_logger_already_exists_then_nullptr_is_returned()
+static bool when_fetching_basic_logger_then_basic_logger_instance_is_returned()
 {
-  log_channel& error = *find_log_channel("logger#error");
-  log_channel& warning = *find_log_channel("logger#warning");
-  log_channel& info = *find_log_channel("logger#info");
-  basic_logger* logger =
-      create_logger<basic_logger>(logger_id, error, warning, info);
+  basic_logger& logger1 = fetch_basic_logger(basic_logger_id1);
+  basic_logger& logger2 = fetch_basic_logger(basic_logger_id2, fetch_stdout_sink());
 
-  ASSERT_EQ(logger, nullptr);
+  ASSERT_EQ(logger1.id(), basic_logger_id1);
+  ASSERT_EQ(logger2.id(), basic_logger_id2);
 
   return true;
 }
 
 static bool when_valid_id_and_type_is_passed_then_logger_is_found()
 {
-  basic_logger* l = find_logger<basic_logger>(logger_id);
+  auto* l = find_logger<basic_logger>(logger_id);
 
   ASSERT_NE(l, nullptr);
   ASSERT_EQ(l->id(), logger_id);
@@ -156,58 +147,66 @@ static bool when_valid_id_with_invalid_type_is_passed_then_no_logger_is_found()
   return true;
 }
 
-static bool when_no_sink_exists_then_sink_is_created()
+static constexpr char file_name[] = "file_fetch_test.txt";
+
+static bool when_file_sink_is_fetched_then_sink_instance_is_returned()
 {
-  sink* s = create_stdout_sink();
+  fetch_file_sink(file_name);
+  sink* s = find_sink(file_name);
 
   ASSERT_NE(s, nullptr);
 
   return true;
 }
 
-static bool when_sink_already_exists_then_nullptr_is_returned()
+static bool when_invalid_id_is_passed_then_no_sink_is_found()
 {
-  sink* s = create_stdout_sink();
-
-  ASSERT_EQ(s, nullptr);
+  ASSERT_EQ(find_sink("invalid"), nullptr);
 
   return true;
 }
 
-static bool when_valid_id_is_passed_then_sink_is_found()
+static bool when_no_installed_default_sink_then_stdout_sink_is_used()
 {
-  sink* s = find_sink("stdout");
+  sink& default_sink = get_default_sink();
 
-  ASSERT_NE(s, nullptr);
+  ASSERT_EQ(&default_sink, &fetch_stdout_sink());
 
   return true;
 }
 
-static bool when_invalid_id_is_passed_then_no_sink_is_found()
+static bool
+when_setting_stderr_as_default_then_get_default_returns_stderr_sink()
 {
-  ASSERT_EQ(find_sink("invalid"), nullptr);
+  set_default_sink(fetch_stderr_sink());
+  sink& default_sink = get_default_sink();
+
+  ASSERT_EQ(&default_sink, &fetch_stderr_sink());
 
   return true;
 }
 
 int main()
 {
-  TEST_FUNCTION(when_no_channel_exists_then_channel_is_created);
-  TEST_FUNCTION(when_channel_already_exists_then_nullptr_is_returned);
+  TEST_FUNCTION(when_fetching_channel_then_channel_instance_is_returned);
   TEST_FUNCTION(when_valid_id_is_passed_then_channel_is_found);
-  TEST_FUNCTION(when_invalid_id_is_passed_then_nothing_is_found);
-  TEST_FUNCTION(when_no_logger_exists_then_logger_is_created);
-  TEST_FUNCTION(when_logger_already_exists_then_nullptr_is_returned);
+  TEST_FUNCTION(when_non_existent_id_is_passed_then_nothing_is_found);
+  TEST_FUNCTION(
+      when_id_with_sharps_is_passed_then_channel_is_fetched_with_clean_id);
+  TEST_FUNCTION(when_fetching_logger_then_logger_instance_is_returned);
+  TEST_FUNCTION(
+      when_fetching_basic_logger_then_basic_logger_instance_is_returned);
   TEST_FUNCTION(when_valid_id_and_type_is_passed_then_logger_is_found);
   TEST_FUNCTION(
       when_invalid_id_with_valid_type_is_passed_then_no_logger_is_found);
   TEST_FUNCTION(when_invalid_id_and_type_is_passed_then_no_logger_is_found);
   TEST_FUNCTION(
       when_valid_id_with_invalid_type_is_passed_then_no_logger_is_found);
-  TEST_FUNCTION(when_no_sink_exists_then_sink_is_created);
-  TEST_FUNCTION(when_sink_already_exists_then_nullptr_is_returned);
-  TEST_FUNCTION(when_valid_id_is_passed_then_sink_is_found);
+  TEST_FUNCTION(when_file_sink_is_fetched_then_sink_instance_is_returned);
   TEST_FUNCTION(when_invalid_id_is_passed_then_no_sink_is_found);
+  TEST_FUNCTION(when_no_installed_default_sink_then_stdout_sink_is_used);
+  TEST_FUNCTION(
+      when_setting_stderr_as_default_then_get_default_returns_stderr_sink);
 
   return 0;
 }
diff --git a/lib/test/srslog/testing_helpers.h b/lib/test/srslog/testing_helpers.h
index 9d33fffbd..12771ba3a 100644
--- a/lib/test/srslog/testing_helpers.h
+++ b/lib/test/srslog/testing_helpers.h
@@ -25,9 +25,9 @@
 #include <cstdio>
 
 /// Invokes the given test function and printing test results to stdout.
-#define TEST_FUNCTION(func)                                                    \
+#define TEST_FUNCTION(func, ...)                                               \
   do {                                                                         \
-    if (!func()) {                                                             \
+    if (!func(__VA_ARGS__)) {                                                  \
       std::printf("Test \"%s\" FAILED! - %s:%u\n", #func, __FILE__, __LINE__); \
       return -1;                                                               \
     } else {                                                                   \
diff --git a/srsue/test/upper/nas_test.cc b/srsue/test/upper/nas_test.cc
index ab0dfc6bf..8f7be9745 100644
--- a/srsue/test/upper/nas_test.cc
+++ b/srsue/test/upper/nas_test.cc
@@ -75,6 +75,8 @@ uint8_t deactivate_eps_bearer_pdu[] = {0x27, 0x00, 0x00, 0x00, 0x00, 0x00, 0x62,
 uint16 mcc = 61441;
 uint16 mnc = 65281;
 
+static srslte::logger* g_logger = nullptr;
+
 using namespace srslte;
 
 namespace srslte {
@@ -271,14 +273,6 @@ int mme_attach_request_test()
   srslte::log_filter usim_log("USIM");
   srslte::log_filter gw_log("GW");
 
-  // Setup logging.
-  srslog::sink *log_sink = srslog::find_sink("stdout");
-  srslog::log_channel* chan = srslog::create_log_channel("mme_attach_request_test", *log_sink);
-  srslte::srslog_wrapper log_wrapper(*chan);
-
-  // Start the log backend.
-  srslog::init();
-
   rrc_log.set_level(srslte::LOG_LEVEL_DEBUG);
   usim_log.set_level(srslte::LOG_LEVEL_DEBUG);
   gw_log.set_level(srslte::LOG_LEVEL_DEBUG);
@@ -316,8 +310,7 @@ int mme_attach_request_test()
     gw_args.log.gw_level     = "debug";
     gw_args.log.gw_hex_limit = 100000;
 
-    srslte::logger*       logger = &log_wrapper;
-    gw.init(gw_args, logger, &stack);
+    gw.init(gw_args, g_logger, &stack);
     stack.init(&nas);
 
     usleep(5000); // Wait for stack to initialize before stoping it.
@@ -489,6 +482,15 @@ int dedicated_eps_bearer_test()
 
 int main(int argc, char** argv)
 {
+  // Setup logging.
+  srslog::sink&          log_sink = srslog::fetch_stdout_sink();
+  srslog::log_channel*   chan     = srslog::create_log_channel("mme_attach_request_test", log_sink);
+  srslte::srslog_wrapper log_wrapper(*chan);
+  g_logger = &log_wrapper;
+
+  // Start the log backend.
+  srslog::init();
+
   srslte::logmap::set_default_log_level(LOG_LEVEL_DEBUG);
   srslte::logmap::set_default_hex_limit(100000);