hackrfwfm.c

/* compile with gcc -lhackrf */
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <libhackrf/hackrf.h>
/* table of cos/sin pairs for x=0..1023:
 * cos(x*pi*2/1024) * 127, sin(x*pi*2/1024) * 127
 */
static const int8_t cos_sin_tbl[] = {
    127, 0, 126, 0, 126, 1, 126, 2, 126, 3, 126, 3, 126, 4, 126, 5, 126, 6,
    126, 7, 126, 7, 126, 8, 126, 9, 126, 10, 126, 10, 126, 11, 126, 12, 126,
    13, 126, 13, 126, 14, 126, 15, 125, 16, 125, 17, 125, 17, 125, 18, 125, 19,
    125, 20, 125, 20, 125, 21, 124, 22, 124, 23, 124, 24, 124, 24, 124, 25,
    124, 26, 124, 27, 123, 27, 123, 28, 123, 29, 123, 30, 123, 30, 123, 31,
    122, 32, 122, 33, 122, 33, 122, 34, 121, 35, 121, 36, 121, 36, 121, 37,
    121, 38, 120, 39, 120, 39, 120, 40, 120, 41, 119, 42, 119, 42, 119, 43,
    119, 44, 118, 44, 118, 45, 118, 46, 117, 47, 117, 47, 117, 48, 117, 49,
    116, 50, 116, 50, 116, 51, 115, 52, 115, 52, 115, 53, 114, 54, 114, 55,
    114, 55, 113, 56, 113, 57, 113, 57, 112, 58, 112, 59, 112, 59, 111, 60,
    111, 61, 110, 61, 110, 62, 110, 63, 109, 63, 109, 64, 108, 65, 108, 65,
    108, 66, 107, 67, 107, 67, 106, 68, 106, 69, 106, 69, 105, 70, 105, 71,
    104, 71, 104, 72, 103, 73, 103, 73, 102, 74, 102, 75, 102, 75, 101, 76,
    101, 76, 100, 77, 100, 78, 99, 78, 99, 79, 98, 79, 98, 80, 97, 81, 97, 81,
    96, 82, 96, 82, 95, 83, 95, 84, 94, 84, 94, 85, 93, 85, 93, 86, 92, 87, 91,
    87, 91, 88, 90, 88, 90, 89, 89, 89, 89, 90, 88, 90, 88, 91, 87, 91, 87, 92,
    86, 93, 85, 93, 85, 94, 84, 94, 84, 95, 83, 95, 82, 96, 82, 96, 81, 97, 81,
    97, 80, 98, 79, 98, 79, 99, 78, 99, 78, 100, 77, 100, 76, 101, 76, 101, 75,
    102, 75, 102, 74, 102, 73, 103, 73, 103, 72, 104, 71, 104, 71, 105, 70,
    105, 69, 106, 69, 106, 68, 106, 67, 107, 67, 107, 66, 108, 65, 108, 65,
    108, 64, 109, 63, 109, 63, 110, 62, 110, 61, 110, 61, 111, 60, 111, 59,
    112, 59, 112, 58, 112, 57, 113, 57, 113, 56, 113, 55, 114, 55, 114, 54,
    114, 53, 115, 52, 115, 52, 115, 51, 116, 50, 116, 50, 116, 49, 117, 48,
    117, 47, 117, 47, 117, 46, 118, 45, 118, 44, 118, 44, 119, 43, 119, 42,
    119, 42, 119, 41, 120, 40, 120, 39, 120, 39, 120, 38, 121, 37, 121, 36,
    121, 36, 121, 35, 121, 34, 122, 33, 122, 33, 122, 32, 122, 31, 123, 30,
    123, 30, 123, 29, 123, 28, 123, 27, 123, 27, 124, 26, 124, 25, 124, 24,
    124, 24, 124, 23, 124, 22, 124, 21, 125, 20, 125, 20, 125, 19, 125, 18,
    125, 17, 125, 17, 125, 16, 125, 15, 126, 14, 126, 13, 126, 13, 126, 12,
    126, 11, 126, 10, 126, 10, 126, 9, 126, 8, 126, 7, 126, 7, 126, 6, 126, 5,
    126, 4, 126, 3, 126, 3, 126, 2, 126, 1, 126, 0, 126, 0, 127, -1, 126, -2,
    126, -3, 126, -4, 126, -4, 126, -5, 126, -6, 126, -7, 126, -8, 126, -8,
    126, -9, 126, -10, 126, -11, 126, -11, 126, -12, 126, -13, 126, -14, 126,
    -14, 126, -15, 126, -16, 126, -17, 125, -18, 125, -18, 125, -19, 125, -20,
    125, -21, 125, -21, 125, -22, 125, -23, 124, -24, 124, -25, 124, -25, 124,
    -26, 124, -27, 124, -28, 124, -28, 123, -29, 123, -30, 123, -31, 123, -31,
    123, -32, 123, -33, 122, -34, 122, -34, 122, -35, 122, -36, 121, -37, 121,
    -37, 121, -38, 121, -39, 121, -40, 120, -40, 120, -41, 120, -42, 120, -43,
    119, -43, 119, -44, 119, -45, 119, -45, 118, -46, 118, -47, 118, -48, 117,
    -48, 117, -49, 117, -50, 117, -51, 116, -51, 116, -52, 116, -53, 115, -53,
    115, -54, 115, -55, 114, -56, 114, -56, 114, -57, 113, -58, 113, -58, 113,
    -59, 112, -60, 112, -60, 112, -61, 111, -62, 111, -62, 110, -63, 110, -64,
    110, -64, 109, -65, 109, -66, 108, -66, 108, -67, 108, -68, 107, -68, 107,
    -69, 106, -70, 106, -70, 106, -71, 105, -72, 105, -72, 104, -73, 104, -74,
    103, -74, 103, -75, 102, -76, 102, -76, 102, -77, 101, -77, 101, -78, 100,
    -79, 100, -79, 99, -80, 99, -80, 98, -81, 98, -82, 97, -82, 97, -83, 96,
    -83, 96, -84, 95, -85, 95, -85, 94, -86, 94, -86, 93, -87, 93, -88, 92,
    -88, 91, -89, 91, -89, 90, -90, 90, -90, 89, -91, 89, -91, 88, -92, 88,
    -92, 87, -93, 87, -94, 86, -94, 85, -95, 85, -95, 84, -96, 84, -96, 83,
    -97, 82, -97, 82, -98, 81, -98, 81, -99, 80, -99, 79, -100, 79, -100, 78,
    -101, 78, -101, 77, -102, 76, -102, 76, -103, 75, -103, 75, -103, 74, -104,
    73, -104, 73, -105, 72, -105, 71, -106, 71, -106, 70, -107, 69, -107, 69,
    -107, 68, -108, 67, -108, 67, -109, 66, -109, 65, -109, 65, -110, 64, -110,
    63, -111, 63, -111, 62, -111, 61, -112, 61, -112, 60, -113, 59, -113, 59,
    -113, 58, -114, 57, -114, 57, -114, 56, -115, 55, -115, 55, -115, 54, -116,
    53, -116, 52, -116, 52, -117, 51, -117, 50, -117, 50, -118, 49, -118, 48,
    -118, 47, -118, 47, -119, 46, -119, 45, -119, 44, -120, 44, -120, 43, -120,
    42, -120, 42, -121, 41, -121, 40, -121, 39, -121, 39, -122, 38, -122, 37,
    -122, 36, -122, 36, -122, 35, -123, 34, -123, 33, -123, 33, -123, 32, -124,
    31, -124, 30, -124, 30, -124, 29, -124, 28, -124, 27, -125, 27, -125, 26,
    -125, 25, -125, 24, -125, 24, -125, 23, -125, 22, -126, 21, -126, 20, -126,
    20, -126, 19, -126, 18, -126, 17, -126, 17, -126, 16, -127, 15, -127, 14,
    -127, 13, -127, 13, -127, 12, -127, 11, -127, 10, -127, 10, -127, 9, -127,
    8, -127, 7, -127, 7, -127, 6, -127, 5, -127, 4, -127, 3, -127, 3, -127, 2,
    -127, 1, -127, 0, -127, 0, -127, -1, -127, -2, -127, -3, -127, -4, -127,
    -4, -127, -5, -127, -6, -127, -7, -127, -8, -127, -8, -127, -9, -127, -10,
    -127, -11, -127, -11, -127, -12, -127, -13, -127, -14, -127, -14, -127,
    -15, -127, -16, -126, -17, -126, -18, -126, -18, -126, -19, -126, -20,
    -126, -21, -126, -21, -126, -22, -125, -23, -125, -24, -125, -25, -125,
    -25, -125, -26, -125, -27, -125, -28, -124, -28, -124, -29, -124, -30,
    -124, -31, -124, -31, -124, -32, -123, -33, -123, -34, -123, -34, -123,
    -35, -122, -36, -122, -37, -122, -37, -122, -38, -122, -39, -121, -40,
    -121, -40, -121, -41, -121, -42, -120, -43, -120, -43, -120, -44, -120,
    -45, -119, -45, -119, -46, -119, -47, -118, -48, -118, -48, -118, -49,
    -118, -50, -117, -51, -117, -51, -117, -52, -116, -53, -116, -53, -116,
    -54, -115, -55, -115, -56, -115, -56, -114, -57, -114, -58, -114, -58,
    -113, -59, -113, -60, -113, -60, -112, -61, -112, -62, -111, -62, -111,
    -63, -111, -64, -110, -64, -110, -65, -109, -66, -109, -66, -109, -67,
    -108, -68, -108, -68, -107, -69, -107, -70, -107, -70, -106, -71, -106,
    -72, -105, -72, -105, -73, -104, -74, -104, -74, -103, -75, -103, -76,
    -103, -76, -102, -77, -102, -77, -101, -78, -101, -79, -100, -79, -100,
    -80, -99, -80, -99, -81, -98, -82, -98, -82, -97, -83, -97, -83, -96, -84,
    -96, -85, -95, -85, -95, -86, -94, -86, -94, -87, -93, -88, -92, -88, -92,
    -89, -91, -89, -91, -90, -90, -90, -90, -91, -89, -91, -89, -92, -88, -92,
    -88, -93, -87, -94, -86, -94, -86, -95, -85, -95, -85, -96, -84, -96, -83,
    -97, -83, -97, -82, -98, -82, -98, -81, -99, -80, -99, -80, -100, -79,
    -100, -79, -101, -78, -101, -77, -102, -77, -102, -76, -103, -76, -103,
    -75, -103, -74, -104, -74, -104, -73, -105, -72, -105, -72, -106, -71,
    -106, -70, -107, -70, -107, -69, -107, -68, -108, -68, -108, -67, -109,
    -66, -109, -66, -109, -65, -110, -64, -110, -64, -111, -63, -111, -62,
    -111, -62, -112, -61, -112, -60, -113, -60, -113, -59, -113, -58, -114,
    -58, -114, -57, -114, -56, -115, -56, -115, -55, -115, -54, -116, -53,
    -116, -53, -116, -52, -117, -51, -117, -51, -117, -50, -118, -49, -118,
    -48, -118, -48, -118, -47, -119, -46, -119, -45, -119, -45, -120, -44,
    -120, -43, -120, -43, -120, -42, -121, -41, -121, -40, -121, -40, -121,
    -39, -122, -38, -122, -37, -122, -37, -122, -36, -122, -35, -123, -34,
    -123, -34, -123, -33, -123, -32, -124, -31, -124, -31, -124, -30, -124,
    -29, -124, -28, -124, -28, -125, -27, -125, -26, -125, -25, -125, -25,
    -125, -24, -125, -23, -125, -22, -126, -21, -126, -21, -126, -20, -126,
    -19, -126, -18, -126, -18, -126, -17, -126, -16, -127, -15, -127, -14,
    -127, -14, -127, -13, -127, -12, -127, -11, -127, -11, -127, -10, -127, -9,
    -127, -8, -127, -8, -127, -7, -127, -6, -127, -5, -127, -4, -127, -4, -127,
    -3, -127, -2, -127, -1, -127, -1, -127, 0, -127, 1, -127, 2, -127, 3, -127,
    3, -127, 4, -127, 5, -127, 6, -127, 7, -127, 7, -127, 8, -127, 9, -127, 10,
    -127, 10, -127, 11, -127, 12, -127, 13, -127, 13, -127, 14, -127, 15, -127,
    16, -126, 17, -126, 17, -126, 18, -126, 19, -126, 20, -126, 20, -126, 21,
    -126, 22, -125, 23, -125, 24, -125, 24, -125, 25, -125, 26, -125, 27, -125,
    27, -124, 28, -124, 29, -124, 30, -124, 30, -124, 31, -124, 32, -123, 33,
    -123, 33, -123, 34, -123, 35, -122, 36, -122, 36, -122, 37, -122, 38, -122,
    39, -121, 39, -121, 40, -121, 41, -121, 42, -120, 42, -120, 43, -120, 44,
    -120, 44, -119, 45, -119, 46, -119, 47, -118, 47, -118, 48, -118, 49, -118,
    50, -117, 50, -117, 51, -117, 52, -116, 52, -116, 53, -116, 54, -115, 55,
    -115, 55, -115, 56, -114, 57, -114, 57, -114, 58, -113, 59, -113, 59, -113,
    60, -112, 61, -112, 61, -111, 62, -111, 63, -111, 63, -110, 64, -110, 65,
    -109, 65, -109, 66, -109, 67, -108, 67, -108, 68, -107, 69, -107, 69, -107,
    70, -106, 71, -106, 71, -105, 72, -105, 73, -104, 73, -104, 74, -103, 75,
    -103, 75, -103, 76, -102, 76, -102, 77, -101, 78, -101, 78, -100, 79, -100,
    79, -99, 80, -99, 81, -98, 81, -98, 82, -97, 82, -97, 83, -96, 84, -96, 84,
    -95, 85, -95, 85, -94, 86, -94, 87, -93, 87, -92, 88, -92, 88, -91, 89,
    -91, 89, -90, 90, -90, 90, -89, 91, -89, 91, -88, 92, -88, 93, -87, 93,
    -86, 94, -86, 94, -85, 95, -85, 95, -84, 96, -83, 96, -83, 97, -82, 97,
    -82, 98, -81, 98, -80, 99, -80, 99, -79, 100, -79, 100, -78, 101, -77, 101,
    -77, 102, -76, 102, -76, 102, -75, 103, -74, 103, -74, 104, -73, 104, -72,
    105, -72, 105, -71, 106, -70, 106, -70, 106, -69, 107, -68, 107, -68, 108,
    -67, 108, -66, 108, -66, 109, -65, 109, -64, 110, -64, 110, -63, 110, -62,
    111, -62, 111, -61, 112, -60, 112, -60, 112, -59, 113, -58, 113, -58, 113,
    -57, 114, -56, 114, -56, 114, -55, 115, -54, 115, -53, 115, -53, 116, -52,
    116, -51, 116, -51, 117, -50, 117, -49, 117, -48, 117, -48, 118, -47, 118,
    -46, 118, -45, 119, -45, 119, -44, 119, -43, 119, -43, 120, -42, 120, -41,
    120, -40, 120, -40, 121, -39, 121, -38, 121, -37, 121, -37, 121, -36, 122,
    -35, 122, -34, 122, -34, 122, -33, 123, -32, 123, -31, 123, -31, 123, -30,
    123, -29, 123, -28, 124, -28, 124, -27, 124, -26, 124, -25, 124, -25, 124,
    -24, 124, -23, 125, -22, 125, -21, 125, -21, 125, -20, 125, -19, 125, -18,
    125, -18, 125, -17, 126, -16, 126, -15, 126, -14, 126, -14, 126, -13, 126,
    -12, 126, -11, 126, -11, 126, -10, 126, -9, 126, -8, 126, -8, 126, -7, 126,
    -6, 126, -5, 126, -4, 126, -4, 126, -3, 126, -2, 126, -1, 127, -1
};
/* easier handling: */
static const uint16_t *cos_sin = (uint16_t*) cos_sin_tbl;

uint16_t my_adc_get_single() {
    uint8_t sample[1];
    if(feof(stdin)) exit(0);
    fread(sample, 1, 1, stdin);
    uint16_t v = sample[0] << 2;
    return v;
}

/*
 * the following follows the example of hackrf's sgpio_isr
 * which triggers write to SGPIO on 8 planes
 * will be triggered with FREQ/16
 **/
void tx(uint8_t *samples) {
    uint16_t *samplebuf = (uint16_t*) samples;
    static uint32_t audiosamplebuf = 0; // we use this to rotate 3x 10bit
    static uint32_t audiosample = 0;
    static int16_t audiosample_diff = 0;
    static uint8_t audioctr = 0;

    /* ADC 10 bit conversion time is 2.45 us minimum (see UM10503, ch. 47)
     * so we fetch a new audio sample only every 4th run.
     * This means we get 1 new audio sample per 64 generated I/Q samples.
     **/
    if(0 == (audioctr++ & 3)) {
        // f = 125kHz, -> 8us

        // moving average over 4 samples:
        uint16_t sample = my_adc_get_single();

        uint32_t audiosample_new =
            sample +
            (audiosamplebuf & 0x3FF) +
            ((audiosamplebuf & (0x3FF<<11)) >> 11) +
            (audiosamplebuf >> 22);

        audiosamplebuf = (audiosamplebuf << 11) + sample;

        /* we will linearly go from previous sample to this over 4x 16 steps.
         * we start with 64x the previous sample (already accumulated in the
         * variable), 0x the current one, and will on each step add the
         * difference, which we need to calculate here:
         **/
        audiosample_diff = audiosample_new - (audiosample >> 6);
    }
    /* prepare 16 I/Q samples.
     * "audiosample" contains the sum of 64 audio samples and thus
     * needs to be shifted/divided.
     **/
    static uint32_t j = 0;
    for(int i=0; i<16; i++) {
        audiosample += audiosample_diff;
        j = j + audiosample + ((2048 - 128) << 11);
        samplebuf[i] = cos_sin[(j >> 16) % 1024];
    }
}

static hackrf_device* dev = NULL;
int transmit(hackrf_transfer* transfer) {
    //fprintf(stderr, "run %d\n", count);
    //fwrite(transfer->buffer, transfer->buffer_length, 1, stdout);
    for(int i=0; i <= (transfer->buffer_length - 32); i = i+32) {
        tx(transfer->buffer + i);
    }
    return HACKRF_SUCCESS;
}

int main() {
    hackrf_init();
    hackrf_device_list_t* list = hackrf_device_list();
    
    if(list->devicecount != 1) {
        fprintf(stderr, "hackrf device count must be 1\n");
        exit(-1);
    }
    hackrf_device_list_free(list);

    if(hackrf_open(&dev) != HACKRF_SUCCESS) {
        fprintf(stderr, "cannot open device\n");
        exit(-1);
    }

    if(hackrf_set_freq(dev, 100500000 - 500000) != HACKRF_SUCCESS) {
        fprintf(stderr, "error setting freq\n");
        hackrf_close(dev);
        exit(-1);
    }
    if(hackrf_set_sample_rate(dev, 8000000) != HACKRF_SUCCESS) {
        fprintf(stderr, "error setting sample rate\n");
        hackrf_close(dev);
        exit(-1);
    }
    if(hackrf_set_baseband_filter_bandwidth(dev, 1750000) != HACKRF_SUCCESS) {
        fprintf(stderr, "error setting bb filter bw\n");
        hackrf_close(dev);
        exit(-1);
    }
    if(hackrf_set_txvga_gain(dev, 35) != HACKRF_SUCCESS) {
        fprintf(stderr, "error setting txvga gain\n");
        hackrf_close(dev);
        exit(-1);
    }
    if(hackrf_start_tx(dev, transmit, NULL) != HACKRF_SUCCESS) {
        fprintf(stderr, "error starting transmit thread\n");
        hackrf_close(dev);
        exit(-1);
    }

    while(1) {};

    hackrf_stop_rx(dev);

    hackrf_close(dev);
    return 0;
}