622 lines
14 KiB
C
622 lines
14 KiB
C
/*
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* osmo-fl2k, turns FL2000-based USB 3.0 to VGA adapters into
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* low cost DACs
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*
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* Copyright (C) 2016-2018 by Steve Markgraf <steve@steve-m.de>
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*
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* based on FM modulator code from VGASIG:
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* Copyright (C) 2009 by Bartek Kania <mbk@gnarf.org>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <string.h>
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#include <errno.h>
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#ifndef _WIN32
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#include <unistd.h>
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#include <fcntl.h>
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#include <getopt.h>
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#else
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#include <windows.h>
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#include <io.h>
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#include <fcntl.h>
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#include "getopt/getopt.h"
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#endif
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#include <math.h>
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#include <pthread.h>
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#include "osmo-fl2k.h"
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#include "rds_mod.h"
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#define BUFFER_SAMPLES_SHIFT 16
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#define BUFFER_SAMPLES (1 << BUFFER_SAMPLES_SHIFT)
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#define BUFFER_SAMPLES_MASK ((1 << BUFFER_SAMPLES_SHIFT)-1)
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#define AUDIO_BUF_SIZE 1024
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fl2k_dev_t *dev = NULL;
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int do_exit = 0;
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pthread_t fm_thread;
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pthread_mutex_t cb_mutex;
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pthread_mutex_t fm_mutex;
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pthread_cond_t cb_cond;
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pthread_cond_t fm_cond;
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FILE *file;
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int8_t *txbuf = NULL;
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int8_t *fmbuf = NULL;
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int8_t *buf1 = NULL;
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int8_t *buf2 = NULL;
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uint32_t samp_rate = 100000000;
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/* default signal parameters */
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#define PILOT_FREQ 19000 /* In Hz */
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#define STEREO_CARRIER 38000 /* In Hz */
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int delta_freq = 75000;
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int carrier_freq = 97000000;
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int carrier_per_signal;
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int input_freq = 44100;
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int stereo_flag = 0;
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int rds_flag = 0;
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double *freqbuf;
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double *slopebuf;
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int writepos, readpos;
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void usage(void)
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{
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fprintf(stderr,
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"fl2k_fm, an FM modulator for FL2K VGA dongles\n\n"
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"Usage:"
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"\t[-d device index (default: 0)]\n"
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"\t[-c carrier frequency (default: 9.7 MHz)]\n"
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"\t[-f FM deviation (default: 75000 Hz, WBFM)]\n"
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"\t[-i input audio sample rate (default: 44100 Hz for mono FM)]\n"
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"\t[-s samplerate in Hz (default: 100 MS/s)]\n"
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"\t[--rds (enables RDS, forces audio sample rate to 228 kHz)]\n"
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"\t[--stereo (enables stereo, requires audio sample rate >= 114 kHz)]\n"
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"\tfilename (use '-' to read from stdin)\n\n"
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);
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exit(1);
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}
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#ifdef _WIN32
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BOOL WINAPI
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sighandler(int signum)
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{
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if (CTRL_C_EVENT == signum) {
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fprintf(stderr, "Signal caught, exiting!\n");
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fl2k_stop_tx(dev);
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do_exit = 1;
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pthread_cond_signal(&fm_cond);
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return TRUE;
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}
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return FALSE;
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}
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#else
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static void sighandler(int signum)
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{
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fprintf(stderr, "Signal caught, exiting!\n");
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fl2k_stop_tx(dev);
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do_exit = 1;
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pthread_cond_signal(&fm_cond);
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}
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#endif
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/* DDS Functions */
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#ifndef M_PI
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# define M_PI 3.14159265358979323846 /* pi */
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# define M_PI_2 1.57079632679489661923 /* pi/2 */
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# define M_PI_4 0.78539816339744830962 /* pi/4 */
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# define M_1_PI 0.31830988618379067154 /* 1/pi */
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# define M_2_PI 0.63661977236758134308 /* 2/pi */
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#endif
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#define DDS_2PI (M_PI * 2) /* 2 * Pi */
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#define DDS_3PI2 (M_PI_2 * 3) /* 3/2 * pi */
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#define SIN_TABLE_ORDER 8
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#define SIN_TABLE_SHIFT (32 - SIN_TABLE_ORDER)
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#define SIN_TABLE_LEN (1 << SIN_TABLE_ORDER)
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#define ANG_INCR (0xffffffff / DDS_2PI)
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int8_t sine_table[SIN_TABLE_LEN];
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int sine_table_init = 0;
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typedef struct {
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double sample_freq;
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double freq;
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double fslope;
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unsigned long int phase;
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unsigned long int phase_step;
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unsigned long int phase_slope;
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} dds_t;
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static inline void dds_setphase(dds_t *dds, double phase)
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{
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dds->phase = phase * ANG_INCR;
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}
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static inline double dds_getphase(dds_t *dds)
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{
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return dds->phase / ANG_INCR;
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}
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static inline void dds_set_freq(dds_t *dds, double freq, double fslope)
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{
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dds->fslope = fslope;
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dds->phase_step = (freq / dds->sample_freq) * 2 * M_PI * ANG_INCR;
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/* The slope parameter is used with the FM modulator to create
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* a simple but very fast and effective interpolation filter.
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* See the fm modulator for details */
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dds->freq = freq;
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dds->phase_slope = (fslope / dds->sample_freq) * 2 * M_PI * ANG_INCR;
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}
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dds_t dds_init(double sample_freq, double freq, double phase)
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{
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dds_t dds;
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int i;
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dds.sample_freq = sample_freq;
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dds.phase = phase * ANG_INCR;
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dds_set_freq(&dds, freq, 0);
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/* Initialize sine table, prescaled for 8 bit signed integer */
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if (!sine_table_init) {
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double incr = 1.0 / (double)SIN_TABLE_LEN;
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for (i = 0; i < SIN_TABLE_LEN; i++)
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sine_table[i] = sin(incr * i * DDS_2PI) * 127;
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sine_table_init = 1;
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}
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return dds;
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}
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static inline int8_t dds_real(dds_t *dds)
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{
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int tmp;
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tmp = dds->phase >> SIN_TABLE_SHIFT;
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dds->phase += dds->phase_step;
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dds->phase &= 0xffffffff;
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dds->phase_step += dds->phase_slope;
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return sine_table[tmp];
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}
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static inline void dds_real_buf(dds_t *dds, int8_t *buf, int count)
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{
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int i;
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for (i = 0; i < count; i++)
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buf[i] = dds_real(dds);
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}
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/* Signal generation and some helpers */
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/* Generate the radio signal using the pre-calculated frequency information
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* in the freq buffer */
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static void *fm_worker(void *arg)
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{
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register double freq;
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register double tmp;
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dds_t carrier;
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int8_t *tmp_ptr;
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uint32_t len = 0;
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uint32_t readlen, remaining;
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int buf_prefilled = 0;
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/* Prepare the oscillators */
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carrier = dds_init(samp_rate, carrier_freq, 0);
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while (!do_exit) {
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dds_set_freq(&carrier, freqbuf[readpos], slopebuf[readpos]);
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readpos++;
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readpos &= BUFFER_SAMPLES_MASK;
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/* check if we reach the end of the buffer */
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if ((len + carrier_per_signal) > FL2K_BUF_LEN) {
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readlen = FL2K_BUF_LEN - len;
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remaining = carrier_per_signal - readlen;
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dds_real_buf(&carrier, &fmbuf[len], readlen);
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if (buf_prefilled) {
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/* swap buffers */
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tmp_ptr = fmbuf;
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fmbuf = txbuf;
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txbuf = tmp_ptr;
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pthread_cond_wait(&cb_cond, &cb_mutex);
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}
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dds_real_buf(&carrier, fmbuf, remaining);
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len = remaining;
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buf_prefilled = 1;
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} else {
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dds_real_buf(&carrier, &fmbuf[len], carrier_per_signal);
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len += carrier_per_signal;
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}
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pthread_cond_signal(&fm_cond);
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}
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pthread_exit(NULL);
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}
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static inline int writelen(int maxlen)
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{
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int rp = readpos;
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int len;
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int r;
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if (rp < writepos)
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rp += BUFFER_SAMPLES;
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len = rp - writepos;
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r = len > maxlen ? maxlen : len;
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return r;
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}
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static inline double modulate_sample(int lastwritepos, double lastfreq, double sample)
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{
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double freq, slope;
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/* Calculate modulator frequency at this point to lessen
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* the calculations needed in the signal generator */
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freq = sample * delta_freq;
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freq += carrier_freq;
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/* What we do here is calculate a linear "slope" from
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the previous sample to this one. This is then used by
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the modulator to gently increase/decrease the frequency
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with each sample without the need to recalculate
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the dds parameters. In fact this gives us a very
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efficient and pretty good interpolation filter. */
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slope = freq - lastfreq;
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slope /= carrier_per_signal;
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slopebuf[lastwritepos] = slope;
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freqbuf[writepos] = freq;
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return freq;
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}
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void fm_modulator_mono(int use_rds)
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{
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unsigned int i;
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size_t len;
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double freq;
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double lastfreq = carrier_freq;
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int16_t audio_buf[AUDIO_BUF_SIZE];
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uint32_t lastwritepos = writepos;
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double sample;
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double rds_samples[AUDIO_BUF_SIZE];
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while (!do_exit) {
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len = writelen(AUDIO_BUF_SIZE);
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if (len > 1) {
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len = fread(audio_buf, 2, len, file);
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if (len == 0)
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do_exit = 1;
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if (use_rds)
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get_rds_samples(rds_samples, len);
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for (i = 0; i < len; i++) {
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sample = audio_buf[i] / 32767.0;
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if (use_rds) {
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sample *= 4;
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sample += rds_samples[i];
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sample /= 5;
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}
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/* Modulate and buffer the sample */
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lastfreq = modulate_sample(lastwritepos, lastfreq, sample);
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lastwritepos = writepos++;
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writepos %= BUFFER_SAMPLES;
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}
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} else {
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pthread_cond_wait(&fm_cond, &fm_mutex);
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}
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}
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}
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void fm_modulator_stereo(int use_rds)
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{
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unsigned int i;
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size_t len, sample_cnt;
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double freq;
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double lastfreq = carrier_freq;
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int16_t audio_buf[AUDIO_BUF_SIZE];
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uint32_t lastwritepos = writepos;
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dds_t pilot, stereo;
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double L, R, LpR, LmR, sample;
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double rds_samples[AUDIO_BUF_SIZE];
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/* Prepare stereo carriers */
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pilot = dds_init(input_freq, PILOT_FREQ, 0);
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stereo = dds_init(input_freq, STEREO_CARRIER, 0);
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while (!do_exit) {
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len = writelen(AUDIO_BUF_SIZE);
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if (len > 1 && !(len % 2)) {
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len = fread(audio_buf, 2, len, file);
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if (len == 0)
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do_exit = 1;
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/* stereo => two audio samples per baseband sample */
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sample_cnt = len/2;
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if (use_rds)
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get_rds_samples(rds_samples, sample_cnt);
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for (i = 0; i < sample_cnt; i++) {
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/* Get samples for both channels, and calculate the
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* mono (L+R) and the difference signal used to recreate
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* the stereo data (L-R). */
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L = audio_buf[i*2] / 32767.0;
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R = audio_buf[i*2+1] / 32767.0;
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LpR = (L + R) / 2;
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LmR = (L - R) / 2;
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/* Create a composite sample consisting of the mono
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* signal at baseband, a 19kHz pilot and a the difference
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* signal DSB-SC modulated on a 38kHz carrier */
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sample = 4.05 * LpR; /* Mono signal */
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sample += 0.9 * (dds_real(&pilot)/127.0); /* Pilot */
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sample += 4.05 * LmR * (dds_real(&stereo)/127.0); /* DSB-SC stereo */
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if (use_rds) {
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/* add RDS signal */
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sample += rds_samples[i];
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/* Normalize so we get the signal within [-1, 1] */
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sample /= 10;
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} else {
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sample /= 9;
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}
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lastfreq = modulate_sample(lastwritepos, lastfreq, sample);
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lastwritepos = writepos++;
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writepos %= BUFFER_SAMPLES;
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}
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} else {
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pthread_cond_wait(&fm_cond, &fm_mutex);
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}
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}
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}
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void fl2k_callback(fl2k_data_info_t *data_info)
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{
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if (data_info->device_error) {
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fprintf(stderr, "Device error, exiting.\n");
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do_exit = 1;
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pthread_cond_signal(&fm_cond);
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}
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pthread_cond_signal(&cb_cond);
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data_info->sampletype_signed = 1;
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data_info->r_buf = (char *)txbuf;
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}
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int main(int argc, char **argv)
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{
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int r, opt;
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uint32_t buf_num = 0;
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int dev_index = 0;
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pthread_attr_t attr;
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char *filename = NULL;
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int option_index = 0;
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int input_freq_specified = 0;
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#ifndef _WIN32
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struct sigaction sigact, sigign;
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#endif
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static struct option long_options[] =
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{
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{"stereo", no_argument, &stereo_flag, 1},
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{"rds", no_argument, &rds_flag, 1},
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{0, 0, 0, 0}
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};
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while (1) {
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opt = getopt_long(argc, argv, "d:c:f:i:s:", long_options, &option_index);
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/* end of options reached */
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if (opt == -1)
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break;
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switch (opt) {
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case 0:
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break;
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case 'd':
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dev_index = (uint32_t)atoi(optarg);
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break;
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case 'c':
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carrier_freq = (uint32_t)atof(optarg);
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break;
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case 'f':
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delta_freq = (uint32_t)atof(optarg);
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break;
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case 'i':
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input_freq = (uint32_t)atof(optarg);
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input_freq_specified = 1;
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break;
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case 's':
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samp_rate = (uint32_t)atof(optarg);
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break;
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default:
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usage();
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break;
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}
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}
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if (argc <= optind) {
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usage();
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} else {
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filename = argv[optind];
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}
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if (dev_index < 0) {
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exit(1);
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}
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if (rds_flag && input_freq_specified) {
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if (input_freq != RDS_MODULATOR_RATE) {
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fprintf(stderr, "RDS modulator only works with "
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"228 kHz audio sample rate!\n");
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exit(1);
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}
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} else if (rds_flag && !input_freq_specified) {
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input_freq = RDS_MODULATOR_RATE;
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}
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if (stereo_flag && input_freq < (RDS_MODULATOR_RATE/2)) {
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fprintf(stderr, "Audio sample rate needs to be at least "
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"114 kHz for stereo FM!\n");
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exit(1);
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}
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if (strcmp(filename, "-") == 0) { /* Read samples from stdin */
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file = stdin;
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#ifdef _WIN32
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_setmode(_fileno(stdin), _O_BINARY);
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#endif
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} else {
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file = fopen(filename, "rb");
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if (!file) {
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fprintf(stderr, "Failed to open %s\n", filename);
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return -ENOENT;
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}
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}
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/* allocate buffer */
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buf1 = malloc(FL2K_BUF_LEN);
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buf2 = malloc(FL2K_BUF_LEN);
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if (!buf1 || !buf2) {
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fprintf(stderr, "malloc error!\n");
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exit(1);
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}
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fmbuf = buf1;
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txbuf = buf2;
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/* Decoded audio */
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freqbuf = malloc(BUFFER_SAMPLES * sizeof(double));
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slopebuf = malloc(BUFFER_SAMPLES * sizeof(double));
|
|
readpos = 0;
|
|
writepos = 1;
|
|
|
|
fprintf(stderr, "Samplerate:\t%3.2f MHz\n", (double)samp_rate/1000000);
|
|
fprintf(stderr, "Carrier:\t%3.2f MHz\n", (double)carrier_freq/1000000);
|
|
fprintf(stderr, "Frequencies:\t%3.2f MHz, %3.2f MHz\n",
|
|
(double)((samp_rate - carrier_freq) / 1000000.0),
|
|
(double)((samp_rate + carrier_freq) / 1000000.0));
|
|
|
|
pthread_mutex_init(&cb_mutex, NULL);
|
|
pthread_mutex_init(&fm_mutex, NULL);
|
|
pthread_cond_init(&cb_cond, NULL);
|
|
pthread_cond_init(&fm_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(&fm_thread, &attr, fm_worker, NULL);
|
|
if (r < 0) {
|
|
fprintf(stderr, "Error spawning FM 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 */
|
|
carrier_per_signal = samp_rate / input_freq;
|
|
|
|
/* Set RDS parameters */
|
|
set_rds_pi(0x0dac);
|
|
set_rds_ps("fl2k_fm");
|
|
set_rds_rt("VGA FM transmitter");
|
|
|
|
#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
|
|
|
|
if (stereo_flag) {
|
|
fm_modulator_stereo(rds_flag);
|
|
} else {
|
|
if (rds_flag)
|
|
fprintf(stderr, "Warning: RDS with mono (without 19 kHz pilot"
|
|
" tone) doesn't work with all receivers!\n");
|
|
|
|
fm_modulator_mono(rds_flag);
|
|
}
|
|
|
|
out:
|
|
fl2k_close(dev);
|
|
|
|
if (file != stdin)
|
|
fclose(file);
|
|
|
|
free(freqbuf);
|
|
free(slopebuf);
|
|
free(buf1);
|
|
free(buf2);
|
|
|
|
return 0;
|
|
}
|