add fl2k_fm

Signed-off-by: Steve Markgraf <steve@steve-m.de>

2 files changed, 495 insertions, 1 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index be8a429..413348b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -76,7 +76,8 @@ endif()
 add_executable(fl2k_file fl2k_file.c)
 add_executable(fl2k_tcp fl2k_tcp.c)
 add_executable(fl2k_test fl2k_test.c)
-set(INSTALL_TARGETS libosmo-fl2k_shared libosmo-fl2k_static fl2k_file fl2k_tcp fl2k_test)
+add_executable(fl2k_fm fl2k_fm.c)
+set(INSTALL_TARGETS libosmo-fl2k_shared libosmo-fl2k_static fl2k_file fl2k_tcp fl2k_test fl2k_fm)
 
 target_link_libraries(fl2k_file libosmo-fl2k_shared 
     ${LIBUSB_LIBRARIES}
@@ -93,18 +94,26 @@ target_link_libraries(fl2k_test libosmo-fl2k_shared
     ${CMAKE_THREAD_LIBS_INIT}
 )
 
+target_link_libraries(fl2k_fm libosmo-fl2k_shared 
+    ${LIBUSB_LIBRARIES}
+    ${CMAKE_THREAD_LIBS_INIT}
+)
+
 
 if(UNIX)
 target_link_libraries(fl2k_test m)
+target_link_libraries(fl2k_fm m)
 endif()
 
 if(WIN32)
 target_link_libraries(fl2k_file libgetopt_static)
 target_link_libraries(fl2k_tcp ws2_32 libgetopt_static)
 target_link_libraries(fl2k_test libgetopt_static)
+target_link_libraries(fl2k_fm libgetopt_static)
 set_property(TARGET fl2k_file APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
 set_property(TARGET fl2k_tcp APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
 set_property(TARGET fl2k_test APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
+set_property(TARGET fl2k_fm APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
 endif()
 ########################################################################
 # Install built library files & utilities
diff --git a/src/fl2k_fm.c b/src/fl2k_fm.c
new file mode 100644
index 0000000..6d619dc
--- /dev/null
+++ b/src/fl2k_fm.c
@@ -0,0 +1,485 @@
+/*
+ * osmo-fl2k, turns FL2000-based USB 3.0 to VGA adapters into
+ * low cost DACs
+ *
+ * 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>
+ *
+ * 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>
+#else
+#include <windows.h>
+#include <io.h>
+#include <fcntl.h>
+#include "getopt/getopt.h"
+#endif
+
+#include <math.h>
+#include <pthread.h>
+
+#include "osmo-fl2k.h"
+
+#define BUFFER_SAMPLES_SHIFT	16
+#define BUFFER_SAMPLES		(1 << BUFFER_SAMPLES_SHIFT)
+#define BUFFER_SAMPLES_MASK	((1 << BUFFER_SAMPLES_SHIFT)-1)
+
+#define AUDIO_BUF_SIZE		1024
+
+fl2k_dev_t *dev = NULL;
+int do_exit = 0;
+
+pthread_t fm_thread;
+pthread_mutex_t cb_mutex;
+pthread_mutex_t fm_mutex;
+pthread_cond_t cb_cond;
+pthread_cond_t fm_cond;
+
+FILE *file;
+int8_t *txbuf = NULL;
+int8_t *fmbuf = NULL;
+int8_t *buf1 = NULL;
+int8_t *buf2 = NULL;
+
+uint32_t samp_rate = 100000000;
+
+/* default signal parameters */
+int delta_freq = 75000;
+int carrier_freq = 97000000;
+int carrier_per_signal;
+int input_freq = 44100;
+
+double *freqbuf; 
+double *slopebuf; 
+int writepos, readpos;
+
+void usage(void)
+{
+	fprintf(stderr,
+		"fl2k_fm, an FM modulator for FL2K VGA dongles\n\n"
+		"Usage:"
+		"\t[-d device index (default: 0)]\n"
+		"\t[-c carrier frequency (default: 9.7 MHz)]\n"
+		"\t[-f FM deviation (default: 75000 Hz, WBFM)]\n"
+		"\t[-i input audio sample rate (default: 44100 Hz)]\n"
+		"\t[-s samplerate in Hz (default: 100 MS/s)]\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(&fm_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(&fm_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 SIN_TABLE_ORDER	8
+#define SIN_TABLE_SHIFT	(32 - SIN_TABLE_ORDER)
+#define SIN_TABLE_LEN	(1 << SIN_TABLE_ORDER)
+#define ANG_INCR	(0xffffffff / DDS_2PI)
+
+int8_t sine_table[SIN_TABLE_LEN];
+int sine_table_init = 0;
+
+typedef struct {
+	double sample_freq;
+	double freq;
+	double fslope;
+	unsigned long int phase;
+	unsigned long int phase_step;
+	unsigned long int phase_slope;
+} dds_t;
+
+inline void dds_setphase(dds_t *dds, double phase)
+{
+	dds->phase = phase * ANG_INCR;
+}
+
+inline double dds_getphase(dds_t *dds)
+{
+	return dds->phase / ANG_INCR;
+}
+
+inline void dds_set_freq(dds_t *dds, double freq, double fslope)
+{
+	dds->fslope = fslope;
+	dds->phase_step = (freq / dds->sample_freq) * 2 * M_PI * ANG_INCR;
+
+	/* The slope parameter is used with the FM modulator to create
+	 * a simple but very fast and effective interpolation filter.
+	 * See the fm modulator for details */
+	dds->freq = freq;
+	dds->phase_slope = (fslope / dds->sample_freq) * 2 * M_PI * ANG_INCR;
+}
+
+dds_t dds_init(double sample_freq, double freq, double phase)
+{
+	dds_t dds;
+	int i;
+
+	dds.sample_freq = sample_freq;
+	dds.phase = phase * ANG_INCR;
+	dds_set_freq(&dds, freq, 0);
+
+	/* Initialize sine table, prescaled for 8 bit signed integer */
+	if (!sine_table_init) {
+		double incr = 1.0 / (double)SIN_TABLE_LEN;
+		for (i = 0; i < SIN_TABLE_LEN; i++)
+			sine_table[i] = sin(incr * i * DDS_2PI) * 127;
+
+		sine_table_init = 1;
+	}
+
+	return dds;
+}
+
+inline int8_t dds_real(dds_t *dds)
+{
+	int tmp;
+
+	tmp = dds->phase >> SIN_TABLE_SHIFT;
+	dds->phase += dds->phase_step;
+	dds->phase &= 0xffffffff;
+
+	dds->phase_step += dds->phase_slope;
+
+	return sine_table[tmp];
+}
+
+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 frequency information
+ * in the freq buffer */
+static void *fm_worker(void *arg)
+{
+	register double freq;
+	register double tmp;
+	dds_t carrier;
+	int8_t *tmp_ptr;
+	uint32_t len = 0;
+	uint32_t readlen, remaining;
+	int buf_prefilled = 0;
+
+	/* Prepare the oscillators */
+	carrier = dds_init(samp_rate, carrier_freq, 0);
+
+	while (!do_exit) {
+		dds_set_freq(&carrier, freqbuf[readpos], slopebuf[readpos]);
+		readpos++;
+		readpos &= BUFFER_SAMPLES_MASK;
+
+		/* check if we reach the end of the buffer */
+		if ((len + carrier_per_signal) > FL2K_BUF_LEN) {
+			readlen = FL2K_BUF_LEN - len;
+			remaining = carrier_per_signal - readlen;
+			dds_real_buf(&carrier, &fmbuf[len], readlen);
+
+			if (buf_prefilled) {
+				/* swap buffers */
+				tmp_ptr = fmbuf;
+				fmbuf = txbuf;
+				txbuf = tmp_ptr;
+				pthread_cond_wait(&cb_cond, &cb_mutex);
+			}
+
+			dds_real_buf(&carrier, fmbuf, remaining);
+			len = remaining;
+
+			buf_prefilled = 1;
+		} else {
+			dds_real_buf(&carrier, &fmbuf[len], carrier_per_signal);
+			len += carrier_per_signal;
+		}
+
+		pthread_cond_signal(&fm_cond);
+	}
+
+	pthread_exit(NULL);
+}
+
+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;
+}
+
+inline double modulate_sample(int lastwritepos, double lastfreq, double sample)
+{
+	double freq, slope;
+
+	/* Calculate modulator frequency at this point to lessen
+	 * the calculations needed in the signal generator */
+	freq = sample * delta_freq;
+	freq += carrier_freq;
+
+	/* 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 frequency
+	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 = freq - lastfreq;
+	slope /= carrier_per_signal;
+	slopebuf[lastwritepos] = slope;
+	freqbuf[writepos] = freq;
+
+	return freq;
+}
+
+void modulator(void)
+{
+	unsigned int i;
+	size_t len;
+	double freq;
+	double lastfreq = carrier_freq;
+	double slope;
+	int16_t audio_buf[AUDIO_BUF_SIZE];
+	uint32_t lastwritepos = writepos;
+
+	while (!do_exit) {
+		len = writelen(AUDIO_BUF_SIZE);
+		if (len > 1) {
+			len = fread(audio_buf, 2, len, file);
+
+			if (len == 0)
+				do_exit = 1;
+
+			for (i = 0; i < len; i++) {
+				/* Modulate and buffer the sample */
+				lastfreq = modulate_sample(lastwritepos, lastfreq,
+							   audio_buf[i]/32767.0);
+				lastwritepos = writepos++;
+				writepos %= BUFFER_SAMPLES;
+			}
+		} else {
+			pthread_cond_wait(&fm_cond, &fm_mutex);
+		}
+	}
+}
+
+void fl2k_callback(fl2k_data_info_t *data_info)
+{
+	if (data_info->device_error) {
+		do_exit = 1;
+		pthread_cond_signal(&fm_cond);
+	}
+
+	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;
+
+#ifndef _WIN32
+	struct sigaction sigact, sigign;
+#endif
+
+	while ((opt = getopt(argc, argv, "d:c:f:i:s:")) != -1) {
+		switch (opt) {
+		case 'd':
+			dev_index = (uint32_t)atoi(optarg);
+			break;
+		case 'c':
+			carrier_freq = (uint32_t)atof(optarg);
+			break;
+		case 'f':
+			delta_freq = (uint32_t)atof(optarg);
+			break;
+		case 'i':
+			input_freq = (uint32_t)atof(optarg);
+			break;
+		case 's':
+			samp_rate = (uint32_t)atof(optarg);
+			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);
+	}
+
+	fmbuf = buf1;
+	txbuf = buf2;
+
+	/* Decoded audio */
+	freqbuf = malloc(BUFFER_SAMPLES * sizeof(double));
+	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;
+
+	carrier_freq = samp_rate - carrier_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
+
+	modulator();
+
+out:
+	fl2k_close(dev);
+
+	if (file != stdin)
+		fclose(file);
+
+	free(freqbuf);
+	free(slopebuf);
+	free(buf1);
+	free(buf2);
+
+	return 0;
+}