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Diffstat (limited to 'src/fl2k_iq.c')
| -rw-r--r-- | src/fl2k_iq.c | 525 |
1 files changed, 525 insertions, 0 deletions
diff --git a/src/fl2k_iq.c b/src/fl2k_iq.c new file mode 100644 index 0000000..2dce59b --- /dev/null +++ b/src/fl2k_iq.c @@ -0,0 +1,525 @@ +/* + * osmo-fl2k, turns FL2000-based USB 3.0 to VGA adapters into + * low cost DACs + * + * fl2k-iq + * Copyright (C) 2020 by Felix Erckenbrecht <eligs@eligs.de> + * + * based on fl2k-fm code: + * Copyright (C) 2016-2018 by Steve Markgraf <steve@steve-m.de> + * + * based on FM modulator code from VGASIG: + * Copyright (C) 2009 by Bartek Kania <mbk@gnarf.org> + * + * SPDX-License-Identifier: GPL-2.0+ + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <signal.h> +#include <string.h> +#include <errno.h> + +#ifndef _WIN32 +#include <unistd.h> +#include <fcntl.h> +#include <getopt.h> +#else +#include <windows.h> +#include <io.h> +#include <fcntl.h> +#include "getopt/getopt.h" +#endif + +#include <math.h> +#include <complex.h> +#include <pthread.h> + +#include "osmo-fl2k.h" +#include "rds_mod.h" + +#define BUFFER_SAMPLES_SHIFT 16 +#define BUFFER_SAMPLES (1 << BUFFER_SAMPLES_SHIFT) +#define BUFFER_SAMPLES_MASK ((1 << BUFFER_SAMPLES_SHIFT)-1) + +#define BASEBAND_BUF_SIZE 2048 + +fl2k_dev_t *dev = NULL; +volatile int do_exit = 0; + +pthread_t iq_thread; +pthread_mutex_t cb_mutex; +pthread_mutex_t iq_mutex; +pthread_cond_t cb_cond; +pthread_cond_t iq_cond; + +FILE *file; +int8_t *txbuf = NULL; +int8_t *ambuf = NULL; +int8_t *buf1 = NULL; +int8_t *buf2 = NULL; + +uint32_t samp_rate = 96000000; + +int base_freq = 1440000; +int rf_to_baseband_sample_ratio; +int input_freq = 48000; + +complex float *ampbuf; +complex float *slopebuf; +int writepos, readpos; +int swap_iq = 0; + +void usage(void) +{ + fprintf(stderr, + "fl2k_iq, an IQ modulator for FL2K VGA dongles\n\n" + "Usage:" + "\t[-d device index (default: 0)]\n" + "\t[-c center frequency (default: 1440 kHz)]\n" + "\t[-i input baseband sample rate (default: 48000 Hz)]\n" + "\t[-s samplerate in Hz (default: 96 MS/s)]\n" + "\t[-w swap I & Q (invert spectrum)\n" + "\tfilename (use '-' to read from stdin)\n\n" + ); + exit(1); +} + +#ifdef _WIN32 +BOOL WINAPI +sighandler(int signum) +{ + if (CTRL_C_EVENT == signum) { + fprintf(stderr, "Signal caught, exiting!\n"); + fl2k_stop_tx(dev); + do_exit = 1; + pthread_cond_signal(&iq_cond); + return TRUE; + } + return FALSE; +} +#else +static void sighandler(int signum) +{ + fprintf(stderr, "Signal caught, exiting!\n"); + fl2k_stop_tx(dev); + do_exit = 1; + pthread_cond_signal(&iq_cond); +} +#endif + +/* DDS Functions */ + +#ifndef M_PI +# define M_PI 3.14159265358979323846 /* pi */ +# define M_PI_2 1.57079632679489661923 /* pi/2 */ +# define M_PI_4 0.78539816339744830962 /* pi/4 */ +# define M_1_PI 0.31830988618379067154 /* 1/pi */ +# define M_2_PI 0.63661977236758134308 /* 2/pi */ +#endif +#define DDS_2PI (M_PI * 2) /* 2 * Pi */ +#define DDS_3PI2 (M_PI_2 * 3) /* 3/2 * pi */ + +#define TRIG_TABLE_ORDER 8 +#define TRIG_TABLE_SHIFT (32 - TRIG_TABLE_ORDER) +#define TRIG_TABLE_LEN (1 << TRIG_TABLE_ORDER) +#define ANG_INCR (0xffffffff / DDS_2PI) + +struct trigonometric_table_S { + int initialized; + int16_t sine[TRIG_TABLE_LEN]; + int16_t cosine[TRIG_TABLE_LEN]; +}; + +static struct trigonometric_table_S trig_table = { .initialized = 0 }; + +typedef struct { + float sample_freq; + float freq; + unsigned long int phase; + unsigned long int phase_step; + complex float amplitude; + complex float ampslope; +} dds_t; + +static inline void dds_set_freq(dds_t *dds, float freq) +{ + dds->freq = freq; + dds->phase_step = (freq / dds->sample_freq) * 2 * M_PI * ANG_INCR; +} + +static inline void dds_set_amp(dds_t *dds, complex float amplitude, complex float ampslope) +{ + dds->amplitude = amplitude; + dds->ampslope = ampslope; +} + +dds_t dds_init(float sample_freq, float freq, float phase, float amp) +{ + dds_t dds; + int i; + + dds.sample_freq = sample_freq; + dds.phase = phase * ANG_INCR; + dds_set_freq(&dds, freq); + dds_set_amp(&dds, amp, 0); + /* Initialize sine table, prescaled for 16 bit signed integer */ + if (!trig_table.initialized) { + float incr = 1.0 / (float)TRIG_TABLE_LEN; + for (i = 0; i < TRIG_TABLE_LEN; i++){ + trig_table.sine[i] = sin(incr * i * DDS_2PI) * 32767; + trig_table.cosine[i] = cos(incr * i * DDS_2PI) * 32767; + } + + trig_table.initialized = 1; + } + + return dds; +} + +static inline int8_t dds_real(dds_t *dds) +{ + int tmp; + int32_t amp_i, amp_q; + int8_t amp8; + + // advance dds generator + tmp = dds->phase >> TRIG_TABLE_SHIFT; + dds->phase += dds->phase_step; + dds->phase &= 0xffffffff; + + //amp = 255; + amp_i = creal(dds->amplitude) * 23170.0; // 0..15, * 1/SQRT(2) + amp_q = cimag(dds->amplitude) * 23170.0; + amp_i = amp_i * trig_table.sine[tmp]; // 0..31, * 1/SQRT(2) + amp_q = amp_q * trig_table.cosine[tmp]; // 0..31, * 1/SQRT(2) + amp8 = (int8_t) ((amp_i + amp_q) >> 24); // 0..31 >> 24 => 0..8 + dds->amplitude += dds->ampslope; + return amp8; +} + +static inline void dds_real_buf(dds_t *dds, int8_t *buf, int count) +{ + int i; + for (i = 0; i < count; i++) + buf[i] = dds_real(dds); +} + +/* Signal generation and some helpers */ + +/* Generate the radio signal using the pre-calculated amplitude information + * in the amp buffer */ +static void *iq_worker(void *arg) +{ + register float freq; + register float tmp; + dds_t base_signal; + int8_t *tmp_ptr; + uint32_t len = 0; + uint32_t readlen, remaining; + int buf_prefilled = 0; + + /* Prepare the oscillators */ + base_signal = dds_init(samp_rate, base_freq, 0, 1); + + while (!do_exit) { + dds_set_amp(&base_signal, ampbuf[readpos], slopebuf[readpos]); + readpos++; + readpos &= BUFFER_SAMPLES_MASK; + + /* check if we reach the end of the buffer */ + if ((len + rf_to_baseband_sample_ratio) > FL2K_BUF_LEN) { + readlen = FL2K_BUF_LEN - len; + remaining = rf_to_baseband_sample_ratio - readlen; + dds_real_buf(&base_signal, &ambuf[len], readlen); + + if (buf_prefilled) { + /* swap buffers */ + tmp_ptr = ambuf; + ambuf = txbuf; + txbuf = tmp_ptr; + pthread_mutex_lock(&cb_mutex); + pthread_cond_wait(&cb_cond, &cb_mutex); + pthread_mutex_unlock(&cb_mutex); + } + + dds_real_buf(&base_signal, ambuf, remaining); + len = remaining; + + buf_prefilled = 1; + } else { + dds_real_buf(&base_signal, &ambuf[len], rf_to_baseband_sample_ratio); + len += rf_to_baseband_sample_ratio; + } + pthread_mutex_lock(&iq_mutex); + pthread_cond_signal(&iq_cond); + pthread_mutex_unlock(&iq_mutex); + } + + pthread_exit(NULL); +} + +static inline int writelen(int maxlen) +{ + int rp = readpos; + int len; + int r; + + if (rp < writepos) + rp += BUFFER_SAMPLES; + + len = rp - writepos; + + r = len > maxlen ? maxlen : len; + + return r; +} + +static inline float complex modulate_sample_iq(const int lastwritepos, const float complex lastamp, const float complex sample) +{ + float complex amp; + float complex slope; + + /* Calculate modulator amplitudes at this point to lessen + * the calculations needed in the signal generator */ + amp = sample; + + /* What we do here is calculate a linear "slope" from + the previous sample to this one. This is then used by + the modulator to gently increase/decrease the amplitude + with each sample without the need to recalculate + the dds parameters. In fact this gives us a very + efficient and pretty good interpolation filter. */ + slope = amp - lastamp; + slope = slope * 1.0/ (float) rf_to_baseband_sample_ratio; + slopebuf[writepos] = slope; + ampbuf[writepos] = lastamp; + + return amp; +} + + +void iq_modulator() +{ + unsigned int i; + size_t len; + float freq; + float complex lastamp = 0; + int16_t baseband_buf[BASEBAND_BUF_SIZE][2]; + uint32_t lastwritepos = writepos; + float complex sample; + + while (!do_exit) { + int swap = swap_iq; + len = writelen(BASEBAND_BUF_SIZE); + if (len > 1) { + len = fread(baseband_buf, 4, len, file); + + if (len == 0){ + if(ferror(file)){ + do_exit = 1; + } + } + + for (i = 0; i < len; i++) { + sample = (float) baseband_buf[i][0+swap] / 32768.0 + I * (float) baseband_buf[i][1-swap] / 32768.0; + + /* Modulate and buffer the sample */ + lastamp = modulate_sample_iq(lastwritepos, lastamp, sample); + lastwritepos = writepos++; + writepos %= BUFFER_SAMPLES; + } + } else { + pthread_mutex_lock(&iq_mutex); + pthread_cond_wait(&iq_cond, &iq_mutex); + pthread_mutex_unlock(&iq_mutex); + } + } +} + + +void fl2k_callback(fl2k_data_info_t *data_info) +{ + if (data_info->device_error) { + fprintf(stderr, "Device error, exiting.\n"); + do_exit = 1; + pthread_mutex_lock(&iq_mutex); + pthread_cond_signal(&iq_cond); + pthread_mutex_unlock(&iq_mutex); + } + + pthread_cond_signal(&cb_cond); + + data_info->sampletype_signed = 1; + data_info->r_buf = (char *)txbuf; +} + +int main(int argc, char **argv) +{ + int r, opt; + uint32_t buf_num = 0; + int dev_index = 0; + pthread_attr_t attr; + char *filename = NULL; + int option_index = 0; + int input_freq_specified = 0; + +#ifndef _WIN32 + struct sigaction sigact, sigign; +#endif + + static struct option long_options[] = + { + {0, 0, 0, 0} + }; + + while (1) { + opt = getopt_long(argc, argv, "wd:c:i:s:", long_options, &option_index); + + /* end of options reached */ + if (opt == -1) + break; + + switch (opt) { + case 0: + break; + case 'd': + dev_index = (uint32_t)atoi(optarg); + break; + case 'c': + base_freq = (uint32_t)atof(optarg); + break; + case 'i': + input_freq = (uint32_t)atof(optarg); + input_freq_specified = 1; + break; + case 's': + samp_rate = (uint32_t)atof(optarg); + break; + case 'w': + swap_iq = 1; + break; + default: + usage(); + break; + } + } + + if (argc <= optind) { + usage(); + } else { + filename = argv[optind]; + } + + if (dev_index < 0) { + exit(1); + } + + if (strcmp(filename, "-") == 0) { /* Read samples from stdin */ + file = stdin; +#ifdef _WIN32 + _setmode(_fileno(stdin), _O_BINARY); +#endif + } else { + file = fopen(filename, "rb"); + if (!file) { + fprintf(stderr, "Failed to open %s\n", filename); + return -ENOENT; + } + } + + /* allocate buffer */ + buf1 = malloc(FL2K_BUF_LEN); + buf2 = malloc(FL2K_BUF_LEN); + if (!buf1 || !buf2) { + fprintf(stderr, "malloc error!\n"); + exit(1); + } + + ambuf = buf1; + txbuf = buf2; + + /* Decoded audio */ + slopebuf = malloc(BUFFER_SAMPLES * sizeof(float complex)); + ampbuf = malloc(BUFFER_SAMPLES * sizeof(float complex)); + readpos = 0; + writepos = 1; + + fprintf(stderr, "Samplerate: %3.2f MHz\n", (float)samp_rate/1000000); + fprintf(stderr, "Center frequency: %5.0f kHz\n", (float)base_freq/1000); + if(swap_iq) + fprintf(stderr, "Spectral inversion active.\n"); + + pthread_mutex_init(&cb_mutex, NULL); + pthread_mutex_init(&iq_mutex, NULL); + pthread_cond_init(&cb_cond, NULL); + pthread_cond_init(&iq_cond, NULL); + pthread_attr_init(&attr); + + fl2k_open(&dev, (uint32_t)dev_index); + if (NULL == dev) { + fprintf(stderr, "Failed to open fl2k device #%d.\n", dev_index); + goto out; + } + + r = pthread_create(&iq_thread, &attr, iq_worker, NULL); + if (r < 0) { + fprintf(stderr, "Error spawning IQ worker thread!\n"); + goto out; + } + + pthread_attr_destroy(&attr); + r = fl2k_start_tx(dev, fl2k_callback, NULL, 0); + + /* Set the sample rate */ + r = fl2k_set_sample_rate(dev, samp_rate); + if (r < 0) + fprintf(stderr, "WARNING: Failed to set sample rate. %d\n", r); + + /* read back actual frequency */ + samp_rate = fl2k_get_sample_rate(dev); + + /* Calculate needed constants */ + rf_to_baseband_sample_ratio = samp_rate / input_freq; + +#ifndef _WIN32 + sigact.sa_handler = sighandler; + sigemptyset(&sigact.sa_mask); + sigact.sa_flags = 0; + sigign.sa_handler = SIG_IGN; + sigaction(SIGINT, &sigact, NULL); + sigaction(SIGTERM, &sigact, NULL); + sigaction(SIGQUIT, &sigact, NULL); + sigaction(SIGPIPE, &sigign, NULL); +#else + SetConsoleCtrlHandler( (PHANDLER_ROUTINE) sighandler, TRUE ); +#endif + + iq_modulator(); + +out: + fl2k_close(dev); + + if (file != stdin) + fclose(file); + + free(ampbuf); + free(slopebuf); + free(buf1); + free(buf2); + + return 0; +} |