srsRAN_4G/lib/src/phy/rf/rf_soapy_imp.c

/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2015 Software Radio Systems Limited
 *
 * \section LICENSE
 *
 * This file is part of the srsLTE library.
 *
 * 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 <sys/time.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>

#include "srslte/srslte.h"
#include "rf_soapy_imp.h"
#include "rf_helper.h"

#include <SoapySDR/Device.h>
#include <SoapySDR/Formats.h>
#include <SoapySDR/Time.h>
#include <SoapySDR/Logger.h>
#include <Types.h>

#define USE_TX_MTU 0
#define SET_RF_BW 1

#define PRINT_RX_STATS 0
#define PRINT_TX_STATS 0

#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))

typedef struct {
  char *devname;
  SoapySDRKwargs args;
  SoapySDRDevice *device;
  SoapySDRRange *ranges;
  SoapySDRStream *rxStream;
  SoapySDRStream *txStream;
  bool tx_stream_active;
  bool rx_stream_active;
  srslte_rf_info_t info;
  double tx_rate;
  size_t rx_mtu, tx_mtu;

  uint32_t num_time_errors;
  uint32_t num_lates;
  uint32_t num_overflows;
  uint32_t num_underflows;
  uint32_t num_other_errors;
  uint32_t num_stream_curruption;
} rf_soapy_handler_t;


cf_t zero_mem[64*1024];


int soapy_error(void *h)
{
  return 0;
}


void rf_soapy_get_freq_range(void *h)
{
  // not supported
}


void rf_soapy_suppress_handler(const char *x)
{
  // not supported
}


void rf_soapy_msg_handler(const char *msg)
{
  // not supported
}


void rf_soapy_suppress_stdout(void *h)
{
  // not supported
}


void rf_soapy_register_error_handler(void *notused, srslte_rf_error_handler_t new_handler)
{
  // not supported
}


char* rf_soapy_devname(void* h)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  return handler->devname; 
}


bool rf_soapy_rx_wait_lo_locked(void *h)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*)h;
  char *ret = SoapySDRDevice_readChannelSensor(handler->device, SOAPY_SDR_RX, 0, "lo_locked");
  if (ret != NULL) {
    return (strcmp(ret, "true") == 0 ? true : false);
  }
  return true;
}


void rf_soapy_set_tx_cal(void *h, srslte_rf_cal_t *cal)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  double actual_bw = SoapySDRDevice_getBandwidth(handler->device, SOAPY_SDR_TX, 0);
  char str_buf[25];
  snprintf(str_buf, sizeof(str_buf), "%f", actual_bw);
  if (SoapySDRDevice_writeSetting(handler->device, "CALIBRATE_TX", str_buf)) {
    printf("Error calibrating Rx\n");
  }
}


void rf_soapy_set_rx_cal(void *h, srslte_rf_cal_t *cal)
{
  // not supported
}


int rf_soapy_start_rx_stream(void *h, bool now)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if(handler->rx_stream_active == false){
    if(SoapySDRDevice_activateStream(handler->device, handler->rxStream, 0, 0, 0) != 0)
      return SRSLTE_ERROR;
    handler->rx_stream_active = true;
   }
  return SRSLTE_SUCCESS;
}


int rf_soapy_start_tx_stream(void *h)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if(handler->tx_stream_active == false){
    if(SoapySDRDevice_activateStream(handler->device, handler->txStream, 0, 0, 0) != 0)
      return SRSLTE_ERROR;
    handler->tx_stream_active = true;  
   }
  return SRSLTE_SUCCESS;
}


int rf_soapy_stop_rx_stream(void *h)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if (SoapySDRDevice_deactivateStream(handler->device, handler->rxStream, 0, 0) != 0)
    return SRSLTE_ERROR;
  
  handler->rx_stream_active = false;
  return SRSLTE_SUCCESS;
}


int rf_soapy_stop_tx_stream(void *h)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if(SoapySDRDevice_deactivateStream(handler->device, handler->txStream, 0, 0) != 0)
    return SRSLTE_ERROR;

  handler->tx_stream_active = false;
  return SRSLTE_SUCCESS;
}


void rf_soapy_flush_buffer(void *h)
{
  int n;
  cf_t tmp1[1024];
  cf_t tmp2[1024];
  void *data[2] = {tmp1, tmp2};
  do {
    n = rf_soapy_recv_with_time_multi(h, data, 1024, 0, NULL, NULL);
  } while (n > 0);
}


bool rf_soapy_has_rssi(void *h)
{
  // TODO: implement rf_soapy_has_rssi()
  return false;
}


float rf_soapy_get_rssi(void *h)
{
  printf("TODO: implement rf_soapy_get_rssi()\n");
  return 0.0;
}


//TODO: add multi-channel support
int rf_soapy_open_multi(char *args, void **h, uint32_t nof_rx_antennas)
{
  size_t length;
  const SoapySDRKwargs *soapy_args = SoapySDRDevice_enumerate(NULL, &length);
  
  if (length == 0) {
    printf("No Soapy devices found.\n");
    return SRSLTE_ERROR;
  }
  char* devname = DEVNAME_NONE;
  for (size_t i = 0; i < length; i++) {
    printf("Soapy has found device #%d: ", (int)i);
    for (size_t j = 0; j < soapy_args[i].size; j++) {
      printf("%s=%s, ", soapy_args[i].keys[j], soapy_args[i].vals[j]);
      if(!strcmp(soapy_args[i].keys[j],"name") && !strcmp(soapy_args[i].vals[j], "LimeSDR-USB")){
        devname = DEVNAME_LIME;
      } else if (!strcmp(soapy_args[i].keys[j],"name") && !strcmp(soapy_args[i].vals[j], "LimeSDR Mini")){
        devname = DEVNAME_LIME_MINI;
      }
    }
    printf("\n");
  }
  
  SoapySDRDevice *sdr = SoapySDRDevice_make(&(soapy_args[0]));
  if (sdr == NULL) {
    printf("Failed to create Soapy object\n");
    return SRSLTE_ERROR;
  }
  
  // create handler
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) malloc(sizeof(rf_soapy_handler_t));
  bzero(handler, sizeof(rf_soapy_handler_t));
  *h = handler;
  handler->device = sdr;
  handler->tx_stream_active = false;
  handler->rx_stream_active = false;
  handler->devname = devname;

  // init rx/tx rate to lowest LTE rate to avoid decimation warnings
  rf_soapy_set_rx_srate(handler, 1.92e6);
  rf_soapy_set_tx_srate(handler, 1.92e6);

  if(SoapySDRDevice_getNumChannels(handler->device, SOAPY_SDR_RX) > 0){
    printf("Setting up RX stream\n");
    if(SoapySDRDevice_setupStream(handler->device, &(handler->rxStream), SOAPY_SDR_RX, SOAPY_SDR_CF32, NULL, 0, NULL) != 0) {
      printf("Rx setupStream fail: %s\n", SoapySDRDevice_lastError());
      return SRSLTE_ERROR;
    }
    handler->rx_mtu = SoapySDRDevice_getStreamMTU(handler->device, handler->rxStream);
  }

  if(SoapySDRDevice_getNumChannels(handler->device, SOAPY_SDR_TX) > 0){
    printf("Setting up TX stream\n");
    if (SoapySDRDevice_setupStream(handler->device, &(handler->txStream), SOAPY_SDR_TX, SOAPY_SDR_CF32, NULL, 0, NULL) != 0) {
      printf("Tx setupStream fail: %s\n", SoapySDRDevice_lastError());
      return SRSLTE_ERROR;
    }
    handler->tx_mtu = SoapySDRDevice_getStreamMTU(handler->device, handler->txStream);
  }

  // list device sensors
  size_t list_length;
  char** list;
  list = SoapySDRDevice_listSensors(handler->device, &list_length);
  printf("Available device sensors: \n");
  for(int i = 0; i < list_length; i++) {
    printf(" - %s\n", list[i]);
  }

  // list channel sensors
  list = SoapySDRDevice_listChannelSensors(handler->device, SOAPY_SDR_RX, 0, &list_length);
  printf("Available sensors for RX channel 0: \n");
  for(int i = 0; i < list_length; i++) {
    printf(" - %s\n", list[i]);
  }

  // Set static radio info
  SoapySDRRange tx_range = SoapySDRDevice_getGainRange(handler->device, SOAPY_SDR_TX, 0);
  SoapySDRRange rx_range = SoapySDRDevice_getGainRange(handler->device, SOAPY_SDR_RX, 0);
  handler->info.min_tx_gain = tx_range.minimum;
  handler->info.max_tx_gain = tx_range.maximum;
  handler->info.min_rx_gain = rx_range.minimum;
  handler->info.max_rx_gain = rx_range.maximum;

  // Check device arguments
  if (args) {
    // config file
    const char config_arg[] = "config=";
    char config_str[64] = {0};
    char *config_ptr = strstr(args, config_arg);
    if (config_ptr) {
      copy_subdev_string(config_str, config_ptr + strlen(config_arg));
      printf("Loading config file %s\n", config_str);
      SoapySDRDevice_writeSetting(handler->device, "LOAD_CONFIG", config_str);
      remove_substring(args, config_arg);
      remove_substring(args, config_str);
    }

    // rx antenna
    const char rx_ant_arg[] = "rxant=";
    char rx_ant_str[64] = {0};
    char *rx_ant_ptr = strstr(args, rx_ant_arg);
    if (rx_ant_ptr) {
      copy_subdev_string(rx_ant_str, rx_ant_ptr + strlen(rx_ant_arg));
      printf("Setting Rx antenna to %s\n", rx_ant_str);
      if (SoapySDRDevice_setAntenna(handler->device, SOAPY_SDR_RX, 0, rx_ant_str) != 0) {
        fprintf(stderr, "Failed to set Rx antenna.\n");
      }
      remove_substring(args, rx_ant_arg);
      remove_substring(args, rx_ant_str);
    }

    // tx antenna
    const char tx_ant_arg[] = "txant=";
    char tx_ant_str[64] = {0};
    char *tx_ant_ptr = strstr(args, tx_ant_arg);
    if (tx_ant_ptr) {
      copy_subdev_string(tx_ant_str, tx_ant_ptr + strlen(tx_ant_arg));
      printf("Setting Tx antenna to %s\n", tx_ant_str);
      if (SoapySDRDevice_setAntenna(handler->device, SOAPY_SDR_TX, 0, tx_ant_str) != 0) {
        fprintf(stderr, "Failed to set Tx antenna.\n");
      }
      remove_substring(args, tx_ant_arg);
      remove_substring(args, tx_ant_str);
    }

    // log level
    const char loglevel_arg[] = "loglevel=";
    char loglevel_str[64] = {0};
    char *loglevel_ptr = strstr(args, loglevel_arg);
    if (loglevel_ptr) {
      copy_subdev_string(loglevel_str, loglevel_ptr + strlen(loglevel_arg));
      if (strcmp(loglevel_str, "error") == 0) {
        SoapySDR_setLogLevel(SOAPY_SDR_ERROR);
      }
      remove_substring(args, loglevel_arg);
      remove_substring(args, loglevel_str);
    }
  }

  // receive one subframe to allow for transceiver calibration
  if (strstr(devname, "lime")) {
    // set default tx gain and leave some time to calibrate tx
    rf_soapy_set_tx_gain(handler, 45);
    rf_soapy_set_rx_gain(handler, 35);

    cf_t dummy_buffer[1920];
    cf_t *dummy_buffer_array[SRSLTE_MAX_PORTS];
    dummy_buffer_array[0] = dummy_buffer;
    rf_soapy_start_rx_stream(handler, true);
    rf_soapy_recv_with_time_multi(handler, (void**)dummy_buffer_array, 1920, false, NULL, NULL);
    rf_soapy_stop_rx_stream(handler);

    usleep(10000);
  }

  // list gains and AGC mode
  bool has_agc = SoapySDRDevice_hasGainMode(handler->device, SOAPY_SDR_RX, 0);
  list = SoapySDRDevice_listGains(handler->device, SOAPY_SDR_RX, 0, &list_length);
  printf("State of gain elements for Rx channel 0 (AGC %s):\n", has_agc ? "supported":"not supported");
  for(int i = 0; i < list_length; i++) {
    printf(" - %s: %.2f dB\n", list[i], SoapySDRDevice_getGainElement(handler->device, SOAPY_SDR_RX, 0, list[i]));
  }

  has_agc = SoapySDRDevice_hasGainMode(handler->device, SOAPY_SDR_TX, 0);
  printf("State of gain elements for Tx channel 0 (AGC %s):\n", has_agc ? "supported":"not supported");
  for(int i = 0; i < list_length; i++) {
    printf(" - %s: %.2f dB\n", list[i], SoapySDRDevice_getGainElement(handler->device, SOAPY_SDR_TX, 0, list[i]));
  }

  // print actual antenna configuration
  char *ant = SoapySDRDevice_getAntenna(handler->device, SOAPY_SDR_RX, 0);
  printf("Rx antenna set to %s\n", ant);

  ant = SoapySDRDevice_getAntenna(handler->device, SOAPY_SDR_TX, 0);
  printf("Tx antenna set to %s\n", ant);

  return SRSLTE_SUCCESS;
}


int rf_soapy_open(char *args, void **h)
{
  return rf_soapy_open_multi(args, h, 1);
}


int rf_soapy_close(void *h)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if (handler->tx_stream_active) {
    rf_soapy_stop_tx_stream(handler);
    SoapySDRDevice_closeStream(handler->device, handler->txStream);
  }
  
  if (handler->rx_stream_active) {
    rf_soapy_stop_rx_stream(handler);
    SoapySDRDevice_closeStream(handler->device, handler->rxStream);
  }
  
  SoapySDRDevice_unmake(handler->device);
  free(handler);

  // print statistics
  if (handler->num_lates) printf("#lates=%d\n", handler->num_lates);
  if (handler->num_overflows) printf("#overflows=%d\n", handler->num_overflows);
  if (handler->num_underflows) printf("#underflows=%d\n", handler->num_underflows);
  if (handler->num_time_errors) printf("#time_errors=%d\n", handler->num_time_errors);
  if (handler->num_other_errors) printf("#other_errors=%d\n", handler->num_other_errors);

  return SRSLTE_SUCCESS;
}

void rf_soapy_set_master_clock_rate(void *h, double rate)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if (SoapySDRDevice_setMasterClockRate(handler->device, rate) != 0) {
    printf("rf_soapy_set_master_clock_rate Rx fail: %s\n", SoapySDRDevice_lastError());
  }

  printf("Set master clock rate to %.2f MHz\n", SoapySDRDevice_getMasterClockRate(handler->device)/1e6);
}


bool rf_soapy_is_master_clock_dynamic(void *h)
{
  printf("TODO: implement rf_soapy_is_master_clock_dynamic()\n");
  return false;
}


double rf_soapy_set_rx_srate(void *h, double rate)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;

  // Restart streaming, as the Lime seems to have problems reconfiguring the sample rate during streaming
  bool rx_stream_active = handler->rx_stream_active;
  if (rx_stream_active) {
    rf_soapy_stop_rx_stream(handler);
  }

  if (SoapySDRDevice_setSampleRate(handler->device, SOAPY_SDR_RX, 0, rate) != 0) {
    printf("setSampleRate Rx fail: %s\n", SoapySDRDevice_lastError());
    return SRSLTE_ERROR;
  }

#if SET_RF_BW
  // Set bandwidth close to current rate
  size_t bw_length;
  SoapySDRRange *bw_range = SoapySDRDevice_getBandwidthRange(handler->device, SOAPY_SDR_RX, 0, &bw_length);
  double bw = rate * 0.75;
  bw = MIN(bw, bw_range->maximum);
  bw = MAX(bw, bw_range->minimum);
  bw = MAX(bw, 2.5e6); // For the Lime to avoid warnings
  if (SoapySDRDevice_setBandwidth(handler->device, SOAPY_SDR_RX, 0, bw) != 0) {
    printf("setBandwidth fail: %s\n", SoapySDRDevice_lastError());
    return SRSLTE_ERROR;
  }
  printf("Set Rx bandwidth to %.2f MHz\n", SoapySDRDevice_getBandwidth(handler->device, SOAPY_SDR_RX, 0)/1e6);
#endif

  if (rx_stream_active) {
    rf_soapy_start_rx_stream(handler, true);
  }

  return SoapySDRDevice_getSampleRate(handler->device, SOAPY_SDR_RX,0);
}

double rf_soapy_set_tx_srate(void *h, double rate)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;

  // stop/start streaming during rate reconfiguration
  bool rx_stream_active = handler->rx_stream_active;
  if (handler->rx_stream_active) {
    rf_soapy_stop_rx_stream(handler);
  }

  if (SoapySDRDevice_setSampleRate(handler->device, SOAPY_SDR_TX, 0, rate) != 0) {
    printf("setSampleRate Tx fail: %s\n", SoapySDRDevice_lastError());
    return SRSLTE_ERROR;
  }

#if SET_RF_BW
  size_t bw_length;
  SoapySDRRange *bw_range = SoapySDRDevice_getBandwidthRange(handler->device, SOAPY_SDR_TX, 0, &bw_length);
  // try to set the BW a bit narrower than sampling rate to prevent aliasing but make sure to stay within device boundaries
  double bw = rate * 0.75;
  bw = MAX(bw, bw_range->minimum);
  bw = MIN(bw, bw_range->maximum);
  if (SoapySDRDevice_setBandwidth(handler->device, SOAPY_SDR_TX, 0, bw) != 0) {
    printf("setBandwidth fail: %s\n", SoapySDRDevice_lastError());
    return SRSLTE_ERROR;
  }
  printf("Set Tx bandwidth to %.2f MHz\n", SoapySDRDevice_getBandwidth(handler->device, SOAPY_SDR_TX, 0)/1e6);
#endif

  if (rx_stream_active) {
    rf_soapy_start_rx_stream(handler, true);
  }

  handler->tx_rate = SoapySDRDevice_getSampleRate(handler->device, SOAPY_SDR_TX, 0);
  return handler->tx_rate;
}


double rf_soapy_set_rx_gain(void *h, double gain)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if (SoapySDRDevice_setGain(handler->device, SOAPY_SDR_RX, 0, gain) != 0)
  {
    printf("setGain fail: %s\n", SoapySDRDevice_lastError());
    return SRSLTE_ERROR;
  }
  return rf_soapy_get_rx_gain(h);
}


double rf_soapy_set_tx_gain(void *h, double gain)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if (SoapySDRDevice_setGain(handler->device, SOAPY_SDR_TX, 0, gain) != 0)
  {
    printf("setGain fail: %s\n", SoapySDRDevice_lastError());
    return SRSLTE_ERROR;
  }
  return rf_soapy_get_tx_gain(h);
}


double rf_soapy_get_rx_gain(void *h)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  return SoapySDRDevice_getGain(handler->device, SOAPY_SDR_RX, 0);
}


double rf_soapy_get_tx_gain(void *h)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  return SoapySDRDevice_getGain(handler->device, SOAPY_SDR_TX, 0);
}


srslte_rf_info_t * rf_soapy_get_info(void *h)
{
  srslte_rf_info_t *info = NULL;
  if (h) {
    rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
    info = &handler->info;
  }
  return info;
}


double rf_soapy_set_rx_freq(void *h, double freq)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if (SoapySDRDevice_setFrequency(handler->device, SOAPY_SDR_RX, 0, freq, NULL) != 0)
  {
    printf("setFrequency fail: %s\n", SoapySDRDevice_lastError());
    return SRSLTE_ERROR;
  }
  printf("Tuned Rx to %.2f MHz\n", SoapySDRDevice_getFrequency(handler->device, SOAPY_SDR_RX, 0)/1e6);

  // wait until LO is locked
  rf_soapy_rx_wait_lo_locked(handler);

  return SoapySDRDevice_getFrequency(handler->device, SOAPY_SDR_RX, 0);
}

double rf_soapy_set_tx_freq(void *h, double freq)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  if (SoapySDRDevice_setFrequency(handler->device, SOAPY_SDR_TX, 0, freq, NULL) != 0)
  {
    printf("setFrequency fail: %s\n", SoapySDRDevice_lastError());
    return SRSLTE_ERROR;
  }

  printf("Tuned Tx to %.2f MHz\n", SoapySDRDevice_getFrequency(handler->device, SOAPY_SDR_TX, 0)/1e6);

  return SoapySDRDevice_getFrequency(handler->device, SOAPY_SDR_TX, 0);
}


void rf_soapy_get_time(void *h, time_t *secs, double *frac_secs)
{
  printf("Todo: implement rf_soapy_get_time()\n");
}


//TODO: add multi-channel support
int  rf_soapy_recv_with_time_multi(void *h,
                                   void *data[SRSLTE_MAX_PORTS],
                                   uint32_t nsamples,
                                   bool blocking,
                                   time_t *secs,
                                   double *frac_secs)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
  int flags; //flags set by receive operation
  int num_channels = 1; // temp
  const long timeoutUs = 400000; // arbitrarily chosen
  
  int trials = 0;
  int ret = 0;
  long long timeNs; //timestamp for receive buffer
  int n = 0;

#if PRINT_RX_STATS
  printf("rx: nsamples=%d rx_mtu=%zd\n", nsamples, handler->rx_mtu);
#endif

  do {
    size_t rx_samples = MIN(nsamples - n, handler->rx_mtu);
#if PRINT_RX_STATS
    printf(" - rx_samples=%zd\n", rx_samples);
#endif

    void *buffs_ptr[4];
    for (int i=0; i<num_channels; i++){
      cf_t *data_c = (cf_t*) data[i];
      buffs_ptr[i] = &data_c[n];
    }

    ret = SoapySDRDevice_readStream(handler->device, handler->rxStream, buffs_ptr, rx_samples, &flags, &timeNs, timeoutUs);
    if (ret == SOAPY_SDR_OVERFLOW || (ret > 0 && (flags & SOAPY_SDR_END_ABRUPT) != 0)) {
      handler->num_overflows++;
      fprintf(stderr, "O");
      fflush(stderr);
      continue;
    } else
    if (ret == SOAPY_SDR_TIMEOUT) {
      handler->num_time_errors++;
      fprintf(stderr, "T");
      fflush(stderr);
      continue;
    } else
    if (ret < 0) {
      // unspecific error
      printf("SoapySDRDevice_readStream returned %d: %s\n", ret, SoapySDR_errToStr(ret));
      handler->num_other_errors++;
    }

    // update rx time only for first segment
    if (secs != NULL && frac_secs != NULL && n == 0) {
      *secs = timeNs / 1e9;
      *frac_secs = (timeNs % 1000000000)/1e9;
      //printf("rx_time: secs=%lld, frac_secs=%lf timeNs=%llu\n", *secs, *frac_secs, timeNs);
    }

#if PRINT_RX_STATS
    printf(" - rx: %d/%zd\n", ret, rx_samples);
#endif

    n += ret;
    trials++;
  } while (n < nsamples && trials < 100);

  return n;
}


int rf_soapy_recv_with_time(void *h,
                            void *data,
                            uint32_t nsamples,
                            bool blocking,
                            time_t *secs,
                            double *frac_secs)
{
  return rf_soapy_recv_with_time_multi(h, &data, nsamples, blocking, secs, frac_secs);
}


int rf_soapy_send_timed(void *h,
                      void *data,
                      int nsamples,
                      time_t secs,
                      double frac_secs,
                      bool has_time_spec,
                      bool blocking,
                      bool is_start_of_burst,
                      bool is_end_of_burst)
{
  void *_data[SRSLTE_MAX_PORTS]= {data, zero_mem, zero_mem, zero_mem};
  return rf_soapy_send_timed_multi(h, _data, nsamples, secs, frac_secs, has_time_spec, blocking, is_start_of_burst, is_end_of_burst);
}


// Todo: Check correct handling of flags, use RF metrics API, fix timed transmissions
int rf_soapy_send_timed_multi(void *h,
                            void *data[SRSLTE_MAX_PORTS],
                            int nsamples,
                            time_t secs,
                            double frac_secs,
                            bool has_time_spec,
                            bool blocking,
                            bool is_start_of_burst,
                            bool is_end_of_burst)
{
  rf_soapy_handler_t *handler = (rf_soapy_handler_t *) h;
  int flags = 0;
  const long timeoutUs = 100000; // arbitrarily chosen
  long long timeNs = 0;
  int trials = 0;
  int ret = 0;
  int n = 0;

#if PRINT_TX_STATS
  printf("tx: namples=%d, mtu=%zd\n", nsamples, handler->tx_mtu);
#endif

  if (!handler->tx_stream_active) {
    rf_soapy_start_tx_stream(h);
  }

  // Convert initial tx time
  if (has_time_spec) {
    timeNs = secs * 1000000000;
    timeNs = timeNs + (frac_secs * 1000000000);
  }

  do {
#if USE_TX_MTU
    size_t tx_samples = MIN(nsamples - n, handler->tx_mtu);
#else
    size_t tx_samples = nsamples;
    if (tx_samples > nsamples - n) {
      tx_samples = nsamples - n;
    }
#endif

    // (re-)set stream flags
    flags = 0;
    if (is_start_of_burst && is_end_of_burst) {
      flags |= SOAPY_SDR_ONE_PACKET;
    }

    if (is_end_of_burst) {
      flags |= SOAPY_SDR_END_BURST;
    }

    // only set time flag for first tx
    if(has_time_spec && n == 0) {
      flags |= SOAPY_SDR_HAS_TIME;
    }

#if PRINT_TX_STATS
    printf(" - tx_samples=%zd at timeNs=%llu flags=%d\n", tx_samples, timeNs, flags);
#endif

    ret = SoapySDRDevice_writeStream(handler->device, handler->txStream, (const void *)data, tx_samples, &flags, timeNs, timeoutUs);
    if (ret >= 0) {
      // Tx was ok
#if PRINT_TX_STATS
      printf(" - tx: %d/%zd\n", ret, tx_samples);
#endif
      // Advance tx time
      if (has_time_spec && ret < nsamples) {
        long long adv = SoapySDR_ticksToTimeNs(ret, handler->tx_rate);
#if PRINT_TX_STATS
        printf(" - tx: timeNs_old=%llu, adv=%llu, timeNs_new=%llu, tx_rate=%f\n", timeNs, adv, timeNs+adv, handler->tx_rate);
#endif
        timeNs += adv;
      }
      n += ret;
    }
    else
    if (ret < 0) {
      // An error has occured
      switch (ret) {
        case SOAPY_SDR_TIMEOUT:
          handler->num_lates++;
          printf("L");
          break;
        case SOAPY_SDR_STREAM_ERROR:
          handler->num_stream_curruption++;
          printf("E");
          break;
        case SOAPY_SDR_TIME_ERROR:
          handler->num_time_errors++;
          printf("T");
          break;
        case SOAPY_SDR_UNDERFLOW:
          handler->num_underflows++;
          printf("U");
          break;
        default:
          fprintf(stderr, "Error during writeStream\n");
          exit(-1);
          return SRSLTE_ERROR;
      }
    }
    trials++;
  } while (n < nsamples && trials < 100);

  if (n != nsamples) {
    fprintf(stderr, "Couldn't write all samples after %d trials.\n", trials);
  }

  return n;
}