srsRAN_4G/lib/examples/pssch_ue.c

/**
 * Copyright 2013-2021 Software Radio Systems Limited
 *
 * This file is part of srsRAN.
 *
 * srsRAN 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.
 *
 * srsRAN 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 <semaphore.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>

#include "srsran/common/pcap.h"
#include "srsran/phy/ch_estimation/chest_sl.h"
#include "srsran/phy/common/phy_common_sl.h"
#include "srsran/phy/dft/ofdm.h"
#include "srsran/phy/phch/pscch.h"
#include "srsran/phy/phch/pssch.h"
#include "srsran/phy/phch/ra_sl.h"
#include "srsran/phy/phch/sci.h"
#include "srsran/phy/rf/rf.h"
#include "srsran/phy/ue/ue_sync.h"
#include "srsran/phy/utils/bit.h"
#include "srsran/phy/utils/debug.h"
#include "srsran/phy/utils/vector.h"

#define PCAP_FILENAME "/tmp/pssch.pcap"

static bool keep_running = true;

static srsran_cell_sl_t cell_sl = {.nof_prb = 50, .tm = SRSRAN_SIDELINK_TM4, .cp = SRSRAN_CP_NORM, .N_sl_id = 0};

typedef struct {
  bool     use_standard_lte_rates;
  bool     disable_plots;
  char*    input_file_name;
  uint32_t file_start_sf_idx;
  uint32_t nof_rx_antennas;
  char*    rf_dev;
  char*    rf_args;
  double   rf_freq;
  float    rf_gain;

  // Sidelink specific args
  uint32_t size_sub_channel;
  uint32_t num_sub_channel;
} prog_args_t;

void args_default(prog_args_t* args)
{
  args->disable_plots          = false;
  args->use_standard_lte_rates = false;
  args->input_file_name        = NULL;
  args->file_start_sf_idx      = 0;
  args->nof_rx_antennas        = 1;
  args->rf_dev                 = "";
  args->rf_dev                 = "";
  args->rf_args                = "";
  args->rf_freq                = 5.92e9;
  args->rf_gain                = 50;
  args->size_sub_channel       = 10;
  args->num_sub_channel        = 5;
}

static srsran_pscch_t pscch = {}; // Defined global for plotting thread
static srsran_pssch_t pssch = {};

#ifndef DISABLE_RF
static srsran_rf_t radio;
#endif // DISABLE_RF

static prog_args_t prog_args;

static srsran_filesource_t fsrc = {};

#ifdef ENABLE_GUI
#include "srsgui/srsgui.h"
void             init_plots();
static pthread_t plot_thread;
static sem_t     plot_sem;
#endif // ENABLE_GUI

void sig_int_handler(int signo)
{
  printf("SIGINT received. Exiting...\n");
  if (signo == SIGINT) {
    keep_running = false;
  } else if (signo == SIGSEGV) {
    exit(1);
  }
}

void pcap_pack_and_write(FILE*    pcap_file,
                         uint8_t* pdu,
                         uint32_t pdu_len_bytes,
                         uint8_t  reTX,
                         bool     crc_ok,
                         uint32_t tti,
                         uint16_t crnti,
                         uint8_t  direction,
                         uint8_t  rnti_type)
{
  MAC_Context_Info_t context = {.radioType      = FDD_RADIO,
                                .direction      = direction,
                                .rntiType       = rnti_type,
                                .rnti           = crnti,
                                .ueid           = 1,
                                .isRetx         = reTX,
                                .crcStatusOK    = crc_ok,
                                .sysFrameNumber = (uint16_t)(tti / SRSRAN_NOF_SF_X_FRAME),
                                .subFrameNumber = (uint16_t)(tti % SRSRAN_NOF_SF_X_FRAME),
                                .nbiotMode      = 0};
  if (pdu) {
    LTE_PCAP_MAC_WritePDU(pcap_file, &context, pdu, pdu_len_bytes);
  }
}

void usage(prog_args_t* args, char* prog)
{
  printf("Usage: %s [agrnmv] -f rx_frequency_hz\n", prog);
  printf("\t-a RF args [Default %s]\n", args->rf_args);
  printf("\t-d RF devicename [Default %s]\n", args->rf_dev);
  printf("\t-i input_file_name\n");
  printf("\t-m Start subframe_idx [Default %d]\n", args->file_start_sf_idx);
  printf("\t-g RF Gain [Default %.2f dB]\n", args->rf_gain);
  printf("\t-A nof_rx_antennas [Default %d]\n", args->nof_rx_antennas);
  printf("\t-c N_sl_id [Default %d]\n", cell_sl.N_sl_id);
  printf("\t-p nof_prb [Default %d]\n", cell_sl.nof_prb);
  printf("\t-s size_sub_channel [Default for 50 prbs %d]\n", args->size_sub_channel);
  printf("\t-n num_sub_channel [Default for 50 prbs %d]\n", args->num_sub_channel);
  printf("\t-t Sidelink transmission mode {1,2,3,4} [Default %d]\n", (cell_sl.tm + 1));
  printf("\t-r use_standard_lte_rates [Default %i]\n", args->use_standard_lte_rates);
#ifdef ENABLE_GUI
  printf("\t-w disable plots [Default enabled]\n");
#endif
  printf("\t-v srsran_verbose\n");
}

void parse_args(prog_args_t* args, int argc, char** argv)
{
  int opt;
  args_default(args);

  while ((opt = getopt(argc, argv, "acdimgpvwrxfA")) != -1) {
    switch (opt) {
      case 'a':
        args->rf_args = argv[optind];
        break;
      case 'c':
        cell_sl.N_sl_id = (int32_t)strtol(argv[optind], NULL, 10);
        break;
      case 'd':
        args->rf_dev = argv[optind];
        break;
      case 'i':
        args->input_file_name = argv[optind];
        break;
      case 'm':
        args->file_start_sf_idx = (uint32_t)strtol(argv[optind], NULL, 10);
        break;
      case 'g':
        args->rf_gain = strtof(argv[optind], NULL);
        break;
      case 'p':
        cell_sl.nof_prb = (int32_t)strtol(argv[optind], NULL, 10);
        break;
      case 'f':
        args->rf_freq = strtof(argv[optind], NULL);
        break;
      case 'A':
        args->nof_rx_antennas = (int32_t)strtol(argv[optind], NULL, 10);
        break;
      case 'v':
        srsran_verbose++;
        break;
      case 'w':
        args->disable_plots = true;
        break;
      case 'r':
        args->use_standard_lte_rates = true;
        break;
      default:
        usage(args, argv[0]);
        exit(-1);
    }
  }
  if (args->rf_freq < 0 && args->input_file_name == NULL) {
    usage(args, argv[0]);
    exit(-1);
  }
}

#ifndef DISABLE_RF
int srsran_rf_recv_wrapper(void* h, cf_t* data[SRSRAN_MAX_PORTS], uint32_t nsamples, srsran_timestamp_t* t)
{
  DEBUG(" ----  Receive %d samples  ----", nsamples);
  void* ptr[SRSRAN_MAX_PORTS];
  for (int i = 0; i < SRSRAN_MAX_PORTS; i++) {
    ptr[i] = data[i];
  }
  return srsran_rf_recv_with_time_multi(h, ptr, nsamples, true, &t->full_secs, &t->frac_secs);
}
#endif // DISABLE_RF

int main(int argc, char** argv)
{
  signal(SIGINT, sig_int_handler);
  sigset_t sigset;
  sigemptyset(&sigset);
  sigaddset(&sigset, SIGINT);
  sigprocmask(SIG_UNBLOCK, &sigset, NULL);

  uint32_t num_decoded_sci = 0;
  uint32_t num_decoded_tb  = 0;

  parse_args(&prog_args, argc, argv);

  FILE* pcap_file = DLT_PCAP_Open(MAC_LTE_DLT, PCAP_FILENAME);

  srsran_use_standard_symbol_size(prog_args.use_standard_lte_rates);

  srsran_sl_comm_resource_pool_t sl_comm_resource_pool;
  if (srsran_sl_comm_resource_pool_get_default_config(&sl_comm_resource_pool, cell_sl) != SRSRAN_SUCCESS) {
    ERROR("Error initializing sl_comm_resource_pool");
    return SRSRAN_ERROR;
  }

  if (prog_args.input_file_name) {
    if (srsran_filesource_init(&fsrc, prog_args.input_file_name, SRSRAN_COMPLEX_FLOAT_BIN)) {
      printf("Error opening file %s\n", prog_args.input_file_name);
      return SRSRAN_ERROR;
    }
  }

#ifndef DISABLE_RF
  if (!prog_args.input_file_name) {
    printf("Opening RF device...\n");

    if (srsran_rf_open_devname(&radio, prog_args.rf_dev, prog_args.rf_args, prog_args.nof_rx_antennas)) {
      ERROR("Error opening rf");
      exit(-1);
    }

    srsran_rf_set_rx_gain(&radio, prog_args.rf_gain);

    printf("Set RX freq: %.6f MHz\n",
           srsran_rf_set_rx_freq(&radio, prog_args.nof_rx_antennas, prog_args.rf_freq) / 1e6);
    printf("Set RX gain: %.1f dB\n", prog_args.rf_gain);
    int srate = srsran_sampling_freq_hz(cell_sl.nof_prb);

    if (srate != -1) {
      printf("Setting sampling rate %.2f MHz\n", (float)srate / 1000000);
      float srate_rf = srsran_rf_set_rx_srate(&radio, (double)srate);
      if (srate_rf != srate) {
        ERROR("Could not set sampling rate");
        exit(-1);
      }
    } else {
      ERROR("Invalid number of PRB %d", cell_sl.nof_prb);
      exit(-1);
    }
  }
#endif // DISABLE_RF

  // allocate Rx buffers for 1ms worth of samples
  uint32_t sf_len = SRSRAN_SF_LEN_PRB(cell_sl.nof_prb);
  printf("Using a SF len of %d samples\n", sf_len);

  cf_t* rx_buffer[SRSRAN_MAX_CHANNELS] = {};     //< For radio to receive samples
  cf_t* sf_buffer[SRSRAN_MAX_PORTS]    = {NULL}; ///< For OFDM object to store subframe after FFT

  for (int i = 0; i < prog_args.nof_rx_antennas; i++) {
    rx_buffer[i] = srsran_vec_cf_malloc(sf_len);
    if (!rx_buffer[i]) {
      perror("malloc");
      exit(-1);
    }
    sf_buffer[i] = srsran_vec_cf_malloc(sf_len);
    if (!sf_buffer[i]) {
      perror("malloc");
      exit(-1);
    }
  }

  uint32_t sf_n_re             = SRSRAN_CP_NSYMB(SRSRAN_CP_NORM) * SRSRAN_NRE * 2 * cell_sl.nof_prb;
  cf_t*    equalized_sf_buffer = srsran_vec_malloc(sizeof(cf_t) * sf_n_re);

  // RX
  srsran_ofdm_t     fft[SRSRAN_MAX_PORTS];
  srsran_ofdm_cfg_t ofdm_cfg = {};
  ofdm_cfg.nof_prb           = cell_sl.nof_prb;
  ofdm_cfg.cp                = SRSRAN_CP_NORM;
  ofdm_cfg.rx_window_offset  = 0.0f;
  ofdm_cfg.normalize         = true;
  ofdm_cfg.sf_type           = SRSRAN_SF_NORM;
  ofdm_cfg.freq_shift_f      = -0.5;
  for (int i = 0; i < prog_args.nof_rx_antennas; i++) {
    ofdm_cfg.in_buffer  = rx_buffer[0];
    ofdm_cfg.out_buffer = sf_buffer[0];

    if (srsran_ofdm_rx_init_cfg(&fft[i], &ofdm_cfg)) {
      ERROR("Error initiating FFT");
      goto clean_exit;
    }
  }

  // SCI
  srsran_sci_t sci;
  srsran_sci_init(&sci, &cell_sl, &sl_comm_resource_pool);
  uint8_t sci_rx[SRSRAN_SCI_MAX_LEN]      = {};
  char    sci_msg[SRSRAN_SCI_MSG_MAX_LEN] = {};

  // init PSCCH object
  if (srsran_pscch_init(&pscch, SRSRAN_MAX_PRB) != SRSRAN_SUCCESS) {
    ERROR("Error in PSCCH init");
    return SRSRAN_ERROR;
  }

  if (srsran_pscch_set_cell(&pscch, cell_sl) != SRSRAN_SUCCESS) {
    ERROR("Error in PSCCH set cell");
    return SRSRAN_ERROR;
  }

  // PSCCH Channel estimation
  srsran_chest_sl_cfg_t pscch_chest_sl_cfg = {};
  srsran_chest_sl_t     pscch_chest        = {};
  if (srsran_chest_sl_init(&pscch_chest, SRSRAN_SIDELINK_PSCCH, cell_sl, sl_comm_resource_pool) != SRSRAN_SUCCESS) {
    ERROR("Error in chest PSCCH init");
    return SRSRAN_ERROR;
  }

  if (srsran_pssch_init(&pssch, &cell_sl, &sl_comm_resource_pool) != SRSRAN_SUCCESS) {
    ERROR("Error initializing PSSCH");
    return SRSRAN_ERROR;
  }

  srsran_chest_sl_cfg_t pssch_chest_sl_cfg = {};
  srsran_chest_sl_t     pssch_chest        = {};
  if (srsran_chest_sl_init(&pssch_chest, SRSRAN_SIDELINK_PSSCH, cell_sl, sl_comm_resource_pool) != SRSRAN_SUCCESS) {
    ERROR("Error in chest PSSCH init");
    return SRSRAN_ERROR;
  }

  uint8_t tb[SRSRAN_SL_SCH_MAX_TB_LEN]            = {};
  uint8_t packed_tb[SRSRAN_SL_SCH_MAX_TB_LEN / 8] = {};

#ifndef DISABLE_RF
  srsran_ue_sync_t ue_sync = {};
  if (!prog_args.input_file_name) {
    srsran_cell_t cell = {};
    cell.nof_prb       = cell_sl.nof_prb;
    cell.cp            = SRSRAN_CP_NORM;
    cell.nof_ports     = 1;

    if (srsran_ue_sync_init_multi_decim_mode(&ue_sync,
                                             cell.nof_prb,
                                             false,
                                             srsran_rf_recv_wrapper,
                                             prog_args.nof_rx_antennas,
                                             (void*)&radio,
                                             1,
                                             SYNC_MODE_GNSS)) {
      fprintf(stderr, "Error initiating sync_gnss\n");
      exit(-1);
    }

    if (srsran_ue_sync_set_cell(&ue_sync, cell)) {
      ERROR("Error initiating ue_sync");
      exit(-1);
    }

    srsran_rf_start_rx_stream(&radio, false);
  }
#endif

#ifdef ENABLE_GUI
  if (!prog_args.disable_plots) {
    init_plots(&pscch);
    sleep(1);
  }
#endif

  uint32_t subframe_count      = 0;
  uint32_t pscch_prb_start_idx = 0;

  uint32_t current_sf_idx = 0;
  if (prog_args.input_file_name) {
    current_sf_idx = prog_args.file_start_sf_idx;
  }

  while (keep_running) {
    if (prog_args.input_file_name) {
      // read subframe from file
      int nread = srsran_filesource_read(&fsrc, rx_buffer[0], sf_len);
      if (nread < 0) {
        fprintf(stderr, "Error reading from file\n");
        goto clean_exit;
      } else if (nread == 0) {
        goto clean_exit;
      } else if (nread < sf_len) {
        fprintf(stderr, "Couldn't read entire subframe. Still processing ..\n");
        nread = -1;
      }
    } else {
#ifndef DISABLE_RF
      // receive subframe from radio
      int ret = srsran_ue_sync_zerocopy(&ue_sync, rx_buffer, sf_len);
      if (ret < 0) {
        ERROR("Error calling srsran_ue_sync_work()");
      }

      // update SF index
      current_sf_idx = srsran_ue_sync_get_sfidx(&ue_sync);
#endif // DISABLE_RF
    }

    // do FFT (on first port)
    srsran_ofdm_rx_sf(&fft[0]);

    for (int sub_channel_idx = 0; sub_channel_idx < sl_comm_resource_pool.num_sub_channel; sub_channel_idx++) {
      pscch_prb_start_idx = sub_channel_idx * sl_comm_resource_pool.size_sub_channel;

      for (uint32_t cyclic_shift = 0; cyclic_shift <= 9; cyclic_shift += 3) {
        // PSCCH Channel estimation
        pscch_chest_sl_cfg.cyclic_shift  = cyclic_shift;
        pscch_chest_sl_cfg.prb_start_idx = pscch_prb_start_idx;
        srsran_chest_sl_set_cfg(&pscch_chest, pscch_chest_sl_cfg);
        srsran_chest_sl_ls_estimate_equalize(&pscch_chest, sf_buffer[0], equalized_sf_buffer);

        if (srsran_pscch_decode(&pscch, equalized_sf_buffer, sci_rx, pscch_prb_start_idx) == SRSRAN_SUCCESS) {
          if (srsran_sci_format1_unpack(&sci, sci_rx) == SRSRAN_SUCCESS) {
            srsran_sci_info(&sci, sci_msg, sizeof(sci_msg));
            fprintf(stdout, "%s", sci_msg);

            num_decoded_sci++;

            // plot PSCCH
#ifdef ENABLE_GUI
            if (!prog_args.disable_plots) {
              sem_post(&plot_sem);
            }
#endif

            // Decode PSSCH
            uint32_t sub_channel_start_idx = 0;
            uint32_t L_subCH               = 0;
            srsran_ra_sl_type0_from_riv(
                sci.riv, sl_comm_resource_pool.num_sub_channel, &L_subCH, &sub_channel_start_idx);

            // 3GPP TS 36.213 Section 14.1.1.4C
            uint32_t pssch_prb_start_idx = (sub_channel_idx * sl_comm_resource_pool.size_sub_channel) +
                                           pscch.pscch_nof_prb + sl_comm_resource_pool.start_prb_sub_channel;
            uint32_t nof_prb_pssch = ((L_subCH + sub_channel_idx) * sl_comm_resource_pool.size_sub_channel) -
                                     pssch_prb_start_idx + sl_comm_resource_pool.start_prb_sub_channel;

            // make sure PRBs are valid for DFT precoding
            nof_prb_pssch = srsran_dft_precoding_get_valid_prb(nof_prb_pssch);

            uint32_t N_x_id = 0;
            for (int j = 0; j < SRSRAN_SCI_CRC_LEN; j++) {
              N_x_id += pscch.sci_crc[j] * exp2(SRSRAN_SCI_CRC_LEN - 1 - j);
            }

            uint32_t rv_idx = 0;
            if (sci.retransmission == true) {
              rv_idx = 1;
            }

            // PSSCH Channel estimation
            pssch_chest_sl_cfg.N_x_id        = N_x_id;
            pssch_chest_sl_cfg.sf_idx        = current_sf_idx;
            pssch_chest_sl_cfg.prb_start_idx = pssch_prb_start_idx;
            pssch_chest_sl_cfg.nof_prb       = nof_prb_pssch;
            srsran_chest_sl_set_cfg(&pssch_chest, pssch_chest_sl_cfg);
            srsran_chest_sl_ls_estimate_equalize(&pssch_chest, sf_buffer[0], equalized_sf_buffer);

            srsran_pssch_cfg_t pssch_cfg = {
                pssch_prb_start_idx, nof_prb_pssch, N_x_id, sci.mcs_idx, rv_idx, current_sf_idx};
            if (srsran_pssch_set_cfg(&pssch, pssch_cfg) == SRSRAN_SUCCESS) {
              if (srsran_pssch_decode(&pssch, equalized_sf_buffer, tb, SRSRAN_SL_SCH_MAX_TB_LEN) == SRSRAN_SUCCESS) {
                num_decoded_tb++;

                // pack bit sand write to PCAP
                srsran_bit_pack_vector(tb, packed_tb, pssch.sl_sch_tb_len);
                pcap_pack_and_write(pcap_file,
                                    packed_tb,
                                    pssch.sl_sch_tb_len / 8,
                                    0,
                                    true,
                                    current_sf_idx,
                                    0x1001,
                                    DIRECTION_UPLINK,
                                    SL_RNTI);

#ifdef ENABLE_GUI
                // plot PSSCH
                if (!prog_args.disable_plots) {
                  sem_post(&plot_sem);
                }
                if (prog_args.input_file_name) {
                  printf("Press Enter to continue ...\n");
                  getchar();
                }
#endif
              }
            }
          }
        }
        if (SRSRAN_VERBOSE_ISDEBUG()) {
          char filename[64];
          snprintf(filename,
                   64,
                   "pscch_rx_syms_sf%d_shift%d_prbidx%d.bin",
                   subframe_count,
                   cyclic_shift,
                   pscch_prb_start_idx);
          printf("Saving PSCCH symbols (%d) to %s\n", pscch.E / SRSRAN_PSCCH_QM, filename);
          srsran_vec_save_file(filename, pscch.mod_symbols, pscch.E / SRSRAN_PSCCH_QM * sizeof(cf_t));
        }
      }
    }

    current_sf_idx = (current_sf_idx + 1) % 10;
    subframe_count++;
  }

clean_exit:
  printf("num_decoded_sci=%d num_decoded_tb=%d\n", num_decoded_sci, num_decoded_tb);

  if (pcap_file != NULL) {
    printf("Saving PCAP file to %s\n", PCAP_FILENAME);
    DLT_PCAP_Close(pcap_file);
  }

#ifdef ENABLE_GUI
  if (!prog_args.disable_plots) {
    sem_post(&plot_sem);
    usleep(1000);
    if (!pthread_kill(plot_thread, 0)) {
      pthread_kill(plot_thread, SIGHUP);
      pthread_join(plot_thread, NULL);
    }
  }
  sdrgui_exit();
#endif

#ifndef DISABLE_RF
  srsran_rf_stop_rx_stream(&radio);
  srsran_rf_close(&radio);
  srsran_ue_sync_free(&ue_sync);
#endif // DISABLE_RF

  srsran_sci_free(&sci);
  srsran_pscch_free(&pscch);
  srsran_chest_sl_free(&pscch_chest);
  srsran_chest_sl_free(&pssch_chest);

  for (int i = 0; i < prog_args.nof_rx_antennas; i++) {
    if (rx_buffer[i]) {
      free(rx_buffer[i]);
    }
    if (sf_buffer[i]) {
      free(sf_buffer[i]);
    }
    srsran_ofdm_rx_free(&fft[i]);
  }

  if (equalized_sf_buffer) {
    free(equalized_sf_buffer);
  }

  return SRSRAN_SUCCESS;
}

///< Plotting Functions
#ifdef ENABLE_GUI

plot_scatter_t pscatequal_pscch;
plot_scatter_t pscatequal_pssch;

void* plot_thread_run(void* arg)
{
  sdrgui_init();

  plot_scatter_init(&pscatequal_pscch);
  plot_scatter_setTitle(&pscatequal_pscch, "PSCCH - Equalized Symbols");
  plot_scatter_setXAxisScale(&pscatequal_pscch, -4, 4);
  plot_scatter_setYAxisScale(&pscatequal_pscch, -4, 4);

  plot_scatter_init(&pscatequal_pssch);
  plot_scatter_setTitle(&pscatequal_pssch, "PSSCH - Equalized Symbols");
  plot_scatter_setXAxisScale(&pscatequal_pssch, -4, 4);
  plot_scatter_setYAxisScale(&pscatequal_pssch, -4, 4);

  plot_scatter_addToWindowGrid(&pscatequal_pscch, (char*)"pssch_ue", 0, 0);
  plot_scatter_addToWindowGrid(&pscatequal_pssch, (char*)"pssch_ue", 0, 1);

  while (keep_running) {
    sem_wait(&plot_sem);
    plot_scatter_setNewData(&pscatequal_pscch, pscch.mod_symbols, pscch.E / SRSRAN_PSCCH_QM);
    if (pssch.G > 0 && pssch.Qm > 0) {
      plot_scatter_setNewData(&pscatequal_pssch, pssch.symbols, pssch.G / pssch.Qm);
    }
  }

  return NULL;
}

void init_plots()
{
  if (sem_init(&plot_sem, 0, 0)) {
    perror("sem_init");
    exit(-1);
  }

  pthread_attr_t     attr;
  struct sched_param param;
  param.sched_priority = 0;
  pthread_attr_init(&attr);
  pthread_attr_setschedpolicy(&attr, SCHED_OTHER);
  pthread_attr_setschedparam(&attr, &param);
  if (pthread_create(&plot_thread, NULL, plot_thread_run, NULL)) {
    perror("pthread_create");
    exit(-1);
  }
}

#endif // ENABLE_GUI