mac_sch_pdu_nr: add to_string() helper to format MAC PDUs in logs

lib/include/srsran/mac/mac_sch_pdu_nr.h

@@ -102,6 +102,8 @@ public:
   // Used by BSR procedure to determine size of BSR types
   static uint32_t sizeof_ce(uint32_t lcid, bool is_ul);
 
+  void to_string(fmt::memory_buffer& buffer);
+
 private:
   srslog::basic_logger* logger;
 
@@ -141,6 +143,8 @@ public:
 
   uint32_t get_remaing_len();
 
+  void to_string(fmt::memory_buffer& buffer);
+
 private:
   uint32_t size_header_sdu(const uint32_t lcid_, const uint32_t nbytes);
   /// Private helper that adds a subPDU to the MAC PDU

lib/src/mac/mac_sch_pdu_nr.cc

@@ -278,6 +278,64 @@ inline bool mac_sch_subpdu_nr::is_ul_ccch()
   return (parent->is_ulsch() && (lcid == CCCH_SIZE_48 || lcid == CCCH_SIZE_64));
 }
 
+void mac_sch_subpdu_nr::to_string(fmt::memory_buffer& buffer)
+{
+  // Add space for new subPDU
+  fmt::format_to(buffer, " ");
+
+  // print subPDU
+  if (is_sdu()) {
+    fmt::format_to(buffer, "LCID={} len={}", get_lcid(), get_sdu_length());
+  } else {
+    if (parent->is_ulsch()) {
+      // UL-SCH case
+      switch (get_lcid()) {
+        case mac_sch_subpdu_nr::CRNTI:
+          fmt::format_to(buffer, "CRNTI: {:#04x}", get_c_rnti());
+          break;
+        case mac_sch_subpdu_nr::SHORT_TRUNC_BSR:
+          fmt::format_to(buffer, "SHORT_TRUNC_BSR: len={}", get_total_length());
+          break;
+        case mac_sch_subpdu_nr::LONG_TRUNC_BSR:
+          fmt::format_to(buffer, "LONG_TRUNC_BSR: len={}", get_total_length());
+          break;
+        case mac_sch_subpdu_nr::SHORT_BSR: {
+          lcg_bsr_t sbsr = get_sbsr();
+          fmt::format_to(buffer, "SBSR: lcg={} bs={}", sbsr.lcg_id, sbsr.buffer_size);
+        } break;
+        case mac_sch_subpdu_nr::LONG_BSR:
+          fmt::format_to(buffer, "LBSR: len={}", get_total_length());
+          break;
+        case mac_sch_subpdu_nr::SE_PHR:
+          fmt::format_to(buffer, "SE_PHR: ph={} pc={}", get_phr(), get_pcmax());
+          break;
+        case mac_sch_subpdu_nr::PADDING:
+          fmt::format_to(buffer, "PAD: len={}", get_sdu_length());
+          break;
+        default:
+          fmt::format_to(buffer, "CE={}", get_lcid());
+          break;
+      }
+    } else {
+      // DL-SCH PDU
+      switch (get_lcid()) {
+        case mac_sch_subpdu_nr::TA_CMD:
+          fmt::format_to(buffer, "TA: id={} command={}", get_ta().tag_id, get_ta().ta_command);
+          break;
+        case mac_sch_subpdu_nr::CON_RES_ID:
+          fmt::format_to(buffer, "CONRES: len={}", get_total_length());
+          break;
+        case mac_sch_subpdu_nr::PADDING:
+          fmt::format_to(buffer, "PAD: len={}", get_sdu_length());
+          break;
+        default:
+          fmt::format_to(buffer, "CE={}", get_lcid());
+          break;
+      }
+    }
+  }
+}
+
 void mac_sch_pdu_nr::pack()
 {
   // SDU and CEs are written in-place, only add padding if needed
@@ -436,4 +494,12 @@ uint32_t mac_sch_pdu_nr::add_sudpdu(mac_sch_subpdu_nr& subpdu)
   return SRSRAN_SUCCESS;
 }
 
+void mac_sch_pdu_nr::to_string(fmt::memory_buffer& buffer)
+{
+  fmt::format_to(buffer, "{}", is_ulsch() ? "UL" : "DL");
+  for (auto& subpdu : subpdus) {
+    subpdu.to_string(buffer);
+  }
+}
+
 } // namespace srsran

lib/src/mac/pdu.cc

@@ -1000,7 +1000,6 @@ uint8_t sch_subh::phr_report_table(float phr_value)
 
 void rar_pdu::to_string(fmt::memory_buffer& buffer)
 {
-  std::string msg("MAC PDU for RAR: ");
   fmt::format_to(buffer, "MAC PDU for RAR: ");
   pdu::to_string(buffer);
 }

lib/test/mac/mac_pdu_nr_test.cc

@@ -11,6 +11,7 @@
  */
 
 #include "srsran/common/mac_pcap.h"
+#include "srsran/common/string_helpers.h"
 #include "srsran/common/test_common.h"
 #include "srsran/config.h"
 #include "srsran/mac/mac_rar_pdu_nr.h"
@@ -217,8 +218,13 @@ int mac_dl_sch_pdu_pack_test5()
     pcap_handle->write_dl_crnti_nr(tx_buffer.msg, tx_buffer.N_bytes, PCAP_CRNTI, true, PCAP_TTI);
   }
 
+  // pretty print PDU
+  fmt::memory_buffer buff;
+  tx_pdu.to_string(buff);
+
   auto& mac_logger = srslog::fetch_basic_logger("MAC");
-  mac_logger.info(tx_buffer.msg, tx_buffer.N_bytes, "Generated MAC PDU (%d B)", tx_buffer.N_bytes);
+  mac_logger.info(
+      tx_buffer.msg, tx_buffer.N_bytes, "Generated MAC PDU (%d B): %s", tx_buffer.N_bytes, srsran::to_c_str(buff));
 
   return SRSRAN_SUCCESS;
 }
@@ -587,6 +593,13 @@ int mac_dl_sch_pdu_unpack_and_pack_test6()
     // 4th is padding
     subpdu = pdu_rx.get_subpdu(3);
     TESTASSERT(subpdu.get_lcid() == mac_sch_subpdu_nr::PADDING);
+
+    // pretty print PDU
+    fmt::memory_buffer buff;
+    pdu_rx.to_string(buff);
+
+    auto& mac_logger = srslog::fetch_basic_logger("MAC");
+    mac_logger.info("Received PDU: %s", srsran::to_c_str(buff));
   }
 
   // Let's pack the entire PDU again