uhd/host/examples/tx_samples_c.c

/*
 * Copyright 2015 Ettus Research LLC
 * Copyright 2018 Ettus Research, a National Instruments Company
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 */

#include <uhd.h>

#include "getopt.h"

#include <math.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define EXECUTE_OR_GOTO(label, ...) \
    if(__VA_ARGS__){ \
        return_code = EXIT_FAILURE; \
        goto label; \
    }

void print_help(void){
    fprintf(stderr, "tx_samples_c - A simple TX example using UHD's C API\n\n"

                    "Options:\n"
                    "    -a (device args)\n"
                    "    -f (frequency in Hz)\n"
                    "    -r (sample rate in Hz)\n"
                    "    -g (gain)\n"
                    "    -n (number of samples to transmit)\n"
                    "    -v (enable verbose prints)\n"
                    "    -h (print this help message)\n");
}

bool stop_signal_called = false;

void sigint_handler(int code){
    (void)code;
    stop_signal_called = true;
}

int main(int argc, char* argv[]){
    int option = 0;
    double freq = 2e9;
    double rate = 1e6;
    double gain = 0;
    char* device_args = NULL;
    size_t channel = 0;
    uint64_t total_num_samps = 0;
    bool verbose = false;
    int return_code = EXIT_SUCCESS;
    char error_string[512];

    // Process options
    while((option = getopt(argc, argv, "a:f:r:g:n:vh")) != -1){
        switch(option){
            case 'a':
                device_args = strdup(optarg);
                break;

            case 'f':
                freq = atof(optarg);
                break;

            case 'r':
                rate = atof(optarg);
                break;

            case 'g':
                gain = atof(optarg);
                break;

            case 'n':
                total_num_samps = atoll(optarg);
                break;

            case 'v':
                verbose = true;
                break;

            case 'h':
                print_help();
                goto free_option_strings;

            default:
                print_help();
                return_code = EXIT_FAILURE;
                goto free_option_strings;
        }
    }

    if (!device_args)
        device_args = strdup("");

    // Create USRP
    uhd_usrp_handle usrp;
    fprintf(stderr, "Creating USRP with args \"%s\"...\n", device_args);
    EXECUTE_OR_GOTO(free_option_strings,
        uhd_usrp_make(&usrp, device_args)
    )

    // Create TX streamer
    uhd_tx_streamer_handle tx_streamer;
    EXECUTE_OR_GOTO(free_usrp,
        uhd_tx_streamer_make(&tx_streamer)
    )

    // Create TX metadata
    uhd_tx_metadata_handle md;
    EXECUTE_OR_GOTO(free_tx_streamer,
        uhd_tx_metadata_make(&md, false, 0, 0.1, true, false)
    )

    // Create other necessary structs
    uhd_tune_request_t tune_request = {
        .target_freq = freq,
        .rf_freq_policy = UHD_TUNE_REQUEST_POLICY_AUTO,
        .dsp_freq_policy = UHD_TUNE_REQUEST_POLICY_AUTO
    };
    uhd_tune_result_t tune_result;

    uhd_stream_args_t stream_args = {
        .cpu_format = "fc32",
        .otw_format = "sc16",
        .args = "",
        .channel_list = &channel,
        .n_channels = 1
    };

    size_t samps_per_buff;
    float* buff = NULL;
    const void** buffs_ptr = NULL;

    // Set rate
    fprintf(stderr, "Setting TX Rate: %f...\n", rate);
    EXECUTE_OR_GOTO(free_tx_metadata,
        uhd_usrp_set_tx_rate(usrp, rate, channel)
    )

    // See what rate actually is
    EXECUTE_OR_GOTO(free_tx_metadata,
        uhd_usrp_get_tx_rate(usrp, channel, &rate)
    )
    fprintf(stderr, "Actual TX Rate: %f...\n\n", rate);

    // Set gain
    fprintf(stderr, "Setting TX Gain: %f db...\n", gain);
    EXECUTE_OR_GOTO(free_tx_metadata,
        uhd_usrp_set_tx_gain(usrp, gain, 0, "")
    )

    // See what gain actually is
    EXECUTE_OR_GOTO(free_tx_metadata,
        uhd_usrp_get_tx_gain(usrp, channel, "", &gain)
    )
    fprintf(stderr, "Actual TX Gain: %f...\n", gain);

    // Set frequency
    fprintf(stderr, "Setting TX frequency: %f MHz...\n", freq / 1e6);
    EXECUTE_OR_GOTO(free_tx_metadata,
        uhd_usrp_set_tx_freq(usrp, &tune_request, channel, &tune_result)
    )

    // See what frequency actually is
    EXECUTE_OR_GOTO(free_tx_metadata,
        uhd_usrp_get_tx_freq(usrp, channel, &freq)
    )
    fprintf(stderr, "Actual TX frequency: %f MHz...\n", freq / 1e6);

    // Set up streamer
    stream_args.channel_list = &channel;
    EXECUTE_OR_GOTO(free_tx_streamer,
        uhd_usrp_get_tx_stream(usrp, &stream_args, tx_streamer)
    )

    // Set up buffer
    EXECUTE_OR_GOTO(free_tx_streamer,
        uhd_tx_streamer_max_num_samps(tx_streamer, &samps_per_buff)
    )
    fprintf(stderr, "Buffer size in samples: %zu\n", samps_per_buff);
    buff = calloc(sizeof(float), samps_per_buff * 2);
    buffs_ptr = (const void**)&buff;
    size_t i = 0;
    for(i = 0; i < (samps_per_buff*2); i+=2){
        buff[i]   = 0.1f;
        buff[i+1] = 0;
    }

    // Ctrl+C will exit loop
    signal(SIGINT, &sigint_handler);
    fprintf(stderr, "Press Ctrl+C to stop streaming...\n");

    // Actual streaming
    uint64_t num_acc_samps = 0;
    size_t num_samps_sent = 0;

    while(1) {
        if (stop_signal_called) break;
        if (total_num_samps > 0 && num_acc_samps >= total_num_samps) break;

        EXECUTE_OR_GOTO(free_buff,
            uhd_tx_streamer_send(tx_streamer, buffs_ptr, samps_per_buff, &md, 0.1, &num_samps_sent)
        )

        num_acc_samps += num_samps_sent;

        if(verbose){
            fprintf(stderr, "Sent %zu samples\n", num_samps_sent);
        }
    }

    free_buff:
        free(buff);

    free_tx_streamer:
        if(verbose){
            fprintf(stderr, "Cleaning up TX streamer.\n");
        }
        uhd_tx_streamer_free(&tx_streamer);

    free_tx_metadata:
        if(verbose){
            fprintf(stderr, "Cleaning up TX metadata.\n");
        }
        uhd_tx_metadata_free(&md);

    free_usrp:
        if(verbose){
            fprintf(stderr, "Cleaning up USRP.\n");
        }
        if(return_code != EXIT_SUCCESS && usrp != NULL){
            uhd_usrp_last_error(usrp, error_string, 512);
            fprintf(stderr, "USRP reported the following error: %s\n", error_string);
        }
        uhd_usrp_free(&usrp);

    free_option_strings:
        if(device_args)
            free(device_args);

    fprintf(stderr, (return_code ? "Failure\n" : "Success\n"));

    return return_code;
}