initial commit

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

8 files changed, 3125 insertions, 0 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
new file mode 100644
index 0000000..be8a429
--- /dev/null
+++ b/src/CMakeLists.txt
@@ -0,0 +1,116 @@
+# Copyright 2018 Osmocom Project
+#
+# This file is part of osmo-fl2k
+#
+# 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/>.
+
+MACRO(LIBFL2K_APPEND_SRCS)
+    LIST(APPEND libosmo-fl2k_srcs ${ARGV})
+ENDMACRO(LIBFL2K_APPEND_SRCS)
+
+LIBFL2K_APPEND_SRCS(
+    libosmo-fl2k.c
+)
+
+########################################################################
+# Set up Windows DLL resource files
+########################################################################
+IF(MSVC)
+    include(${CMAKE_SOURCE_DIR}/cmake/Modules/Version.cmake)
+
+    configure_file(
+        ${CMAKE_CURRENT_SOURCE_DIR}/libosmo-fl2k.rc.in
+        ${CMAKE_CURRENT_BINARY_DIR}/libosmo-fl2k.rc
+    @ONLY)
+
+    LIBFL2K_APPEND_SRCS(${CMAKE_CURRENT_BINARY_DIR}/libosmo-fl2k.rc)
+ENDIF(MSVC)
+
+########################################################################
+# Setup shared library variant
+########################################################################
+add_library(libosmo-fl2k_shared SHARED ${libosmo-fl2k_srcs})
+target_link_libraries(libosmo-fl2k_shared ${LIBUSB_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT})
+set_target_properties(libosmo-fl2k_shared PROPERTIES DEFINE_SYMBOL "libosmofl2k_EXPORTS")
+set_target_properties(libosmo-fl2k_shared PROPERTIES OUTPUT_NAME osmo-fl2k)
+set_target_properties(libosmo-fl2k_shared PROPERTIES SOVERSION ${MAJOR_VERSION})
+set_target_properties(libosmo-fl2k_shared PROPERTIES VERSION ${LIBVER})
+
+########################################################################
+# Setup static library variant
+########################################################################
+add_library(libosmo-fl2k_static STATIC ${libosmo-fl2k_srcs})
+target_link_libraries(libosmo-fl2k_static ${LIBUSB_LIBRARIES})
+set_property(TARGET libosmo-fl2k_static APPEND PROPERTY COMPILE_DEFINITIONS "libosmofl2k_STATIC" )
+if(NOT WIN32)
+# Force same library filename for static and shared variants of the library
+set_target_properties(libosmo-fl2k_static PROPERTIES OUTPUT_NAME osmo-fl2k)
+endif()
+
+########################################################################
+# Setup libraries used in executables
+########################################################################
+if(WIN32)
+add_library(libgetopt_static STATIC
+    getopt/getopt.c
+)
+target_link_libraries(
+    libosmo-fl2k_shared
+)
+endif()
+
+########################################################################
+# Build utility
+########################################################################
+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)
+
+target_link_libraries(fl2k_file libosmo-fl2k_shared 
+    ${LIBUSB_LIBRARIES}
+    ${CMAKE_THREAD_LIBS_INIT}
+)
+
+target_link_libraries(fl2k_tcp libosmo-fl2k_shared 
+    ${LIBUSB_LIBRARIES}
+    ${CMAKE_THREAD_LIBS_INIT}
+)
+
+target_link_libraries(fl2k_test libosmo-fl2k_shared 
+    ${LIBUSB_LIBRARIES}
+    ${CMAKE_THREAD_LIBS_INIT}
+)
+
+
+if(UNIX)
+target_link_libraries(fl2k_test 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)
+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" )
+endif()
+########################################################################
+# Install built library files & utilities
+########################################################################
+install(TARGETS ${INSTALL_TARGETS}
+    LIBRARY DESTINATION ${LIB_INSTALL_DIR} # .so/.dylib file
+    ARCHIVE DESTINATION ${LIB_INSTALL_DIR} # .lib file
+    RUNTIME DESTINATION bin              # .dll file
+)
diff --git a/src/fl2k_file.c b/src/fl2k_file.c
new file mode 100644
index 0000000..363adc2
--- /dev/null
+++ b/src/fl2k_file.c
@@ -0,0 +1,207 @@
+/*
+ * 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>
+ *
+ * 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 <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#ifndef _WIN32
+#include <unistd.h>
+#else
+#include <windows.h>
+#include <io.h>
+#include <fcntl.h>
+#include "getopt/getopt.h"
+#endif
+
+#include "osmo-fl2k.h"
+
+static fl2k_dev_t *dev = NULL;
+
+static volatile int do_exit = 0;
+static volatile int repeat = 1;
+FILE *file;
+char *txbuf = NULL;
+
+void usage(void)
+{
+	fprintf(stderr,
+		"fl2k_file, a sample player for FL2K VGA dongles\n\n"
+		"Usage:\n"
+		"\t[-d device_index (default: 0)]\n"
+		"\t[-r repeat file (default: 1)]\n"
+		"\t[-s samplerate (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;
+		return TRUE;
+	}
+	return FALSE;
+}
+#else
+static void sighandler(int signum)
+{
+	fprintf(stderr, "Signal caught, exiting!\n");
+	fl2k_stop_tx(dev);
+	do_exit = 1;
+}
+#endif
+
+void fl2k_callback(fl2k_data_info_t *data_info)
+{
+	int r, left = FL2K_BUF_LEN;
+	static uint32_t repeat_cnt = 0;
+
+	data_info->sampletype_signed = 1;
+	data_info->r_buf = txbuf;
+	data_info->g_buf = txbuf;
+	data_info->b_buf = txbuf;
+
+	while (!do_exit && (left > 0)) {
+		r = fread(txbuf + (FL2K_BUF_LEN - left), 1, left, file);
+
+		if (ferror(file))
+			fprintf(stderr, "File Error\n");
+
+		if (feof(file)) {
+			if (repeat) {
+				repeat_cnt++;
+				fprintf(stderr, "repeat %d\n", repeat_cnt);
+				rewind(file);
+			} else {
+				fl2k_stop_tx(dev);
+				do_exit = 1;
+			}
+		}
+
+		if (r > 0)
+			left -= r;
+	}
+}
+
+int main(int argc, char **argv)
+{
+#ifndef _WIN32
+	struct sigaction sigact, sigign;
+#endif
+	int r, opt, i;
+	uint32_t samp_rate = 100000000;
+	uint32_t buf_num = 0;
+	int dev_index = 0;
+	void *status;
+	char *filename = NULL;
+
+	while ((opt = getopt(argc, argv, "d:r:s:")) != -1) {
+		switch (opt) {
+		case 'd':
+			dev_index = (uint32_t)atoi(optarg);
+			break;
+		case 'r':
+			repeat = (int)atoi(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);
+
+	file = fopen(filename, "rb");
+	if (!file) {
+		fprintf(stderr, "Failed to open %s\n", filename);
+		goto out;
+	}
+
+	txbuf = malloc(FL2K_BUF_LEN);
+	if (!txbuf) {
+		fprintf(stderr, "malloc error!\n");
+		goto out;
+	}
+
+	fl2k_open(&dev, (uint32_t)dev_index);
+	if (NULL == dev) {
+		fprintf(stderr, "Failed to open fl2k device #%d.\n", dev_index);
+		goto out;
+	}
+
+	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.\n");
+
+
+#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
+
+	while (!do_exit) {
+#ifndef _WIN32
+		usleep(500000);
+#else
+		Sleep(0.5);
+#endif
+	}
+
+	fl2k_close(dev);
+
+out:
+	if (txbuf)
+		free(txbuf);
+
+	if (file && (file != stdin))
+		fclose(file);
+
+	return 0;
+}
diff --git a/src/fl2k_tcp.c b/src/fl2k_tcp.c
new file mode 100644
index 0000000..ad0aa18
--- /dev/null
+++ b/src/fl2k_tcp.c
@@ -0,0 +1,250 @@
+/*
+ * 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>
+ *
+ * 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 <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#ifndef _WIN32
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h> /* for TCP_NODELAY */
+#include <fcntl.h>
+#else
+#include <winsock2.h>
+#include "getopt/getopt.h"
+#endif
+
+#include "osmo-fl2k.h"
+
+#ifdef _WIN32
+#pragma comment(lib, "ws2_32.lib")
+
+typedef int socklen_t;
+
+#else
+#define closesocket close
+#define SOCKADDR struct sockaddr
+#define SOCKET int
+#define SOCKET_ERROR -1
+#endif
+
+static SOCKET s;
+static fl2k_dev_t *dev = NULL;
+static volatile int do_exit = 0;
+static volatile int connected = 0;
+static char *txbuf = NULL;
+static fd_set readfds;
+static SOCKET sock;
+
+void usage(void)
+{
+	fprintf(stderr,
+		"fl2k_tcp, a spectrum client for FL2K VGA dongles\n\n"
+		"Usage:\t[-a server address]\n"
+		"\t[-d device index (default: 0)]\n"
+		"\t[-p port (default: 1234)]\n"
+		"\t[-s samplerate in Hz (default: 100 MS/s)]\n"
+		"\t[-b number of buffers (default: 4)]\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;
+		return TRUE;
+	}
+	return FALSE;
+}
+#else
+static void sighandler(int signum)
+{
+	fprintf(stderr, "Signal caught, exiting!\n");
+	do_exit = 1;
+	fl2k_stop_tx(dev);
+}
+#endif
+
+void fl2k_callback(fl2k_data_info_t *data_info)
+{
+	int left = FL2K_BUF_LEN;
+	int received;
+	int r;
+	struct timeval tv = { 1, 0 };
+
+	if (!connected)
+		return;
+
+	data_info->sampletype_signed = 1;
+	data_info->r_buf = txbuf;
+
+	while (!do_exit && (left > 0)) {
+		FD_ZERO(&readfds);
+		FD_SET(sock, &readfds);
+		tv.tv_sec = 1;
+		tv.tv_usec = 0;
+		r = select(sock + 1, &readfds, NULL, NULL, &tv);
+
+		if (r) {
+			received = recv(sock, txbuf + (FL2K_BUF_LEN - left), left, 0);
+			left -= received;
+		}
+	}
+}
+
+int main(int argc, char **argv)
+{
+	int r, opt, i;
+	char *addr = "127.0.0.1";
+	int port = 1234;
+	uint32_t samp_rate = 100000000;
+	struct sockaddr_in local, remote;
+	uint32_t buf_num = 0;
+	int dev_index = 0;
+	int dev_given = 0;
+	int flag = 1;
+
+#ifdef _WIN32
+	WSADATA wsd;
+	i = WSAStartup(MAKEWORD(2,2), &wsd);
+#else
+	struct sigaction sigact, sigign;
+#endif
+
+	while ((opt = getopt(argc, argv, "d:s:a:p:b:")) != -1) {
+		switch (opt) {
+		case 'd':
+			dev_index = (uint32_t)atoi(optarg);
+			dev_given = 1;
+			break;
+		case 's':
+			samp_rate = (uint32_t)atof(optarg);
+			break;
+		case 'a':
+			addr = optarg;
+			break;
+		case 'p':
+			port = atoi(optarg);
+			break;
+		case 'b':
+			buf_num = atoi(optarg);
+			break;
+		default:
+			usage();
+			break;
+		}
+	}
+
+	if (argc < optind)
+		usage();
+
+	if (dev_index < 0) {
+		exit(1);
+	}
+
+	txbuf = malloc(FL2K_BUF_LEN);
+
+	if (!txbuf) {
+		fprintf(stderr, "malloc error!\n");
+		exit(1);
+	}
+
+	fl2k_open(&dev, (uint32_t)dev_index);
+	if (NULL == dev) {
+		fprintf(stderr, "Failed to open fl2k device #%d.\n", dev_index);
+		exit(1);
+	}
+
+	r = fl2k_start_tx(dev, fl2k_callback, NULL, buf_num);
+
+	/* Set the sample rate */
+	r = fl2k_set_sample_rate(dev, samp_rate);
+	if (r < 0)
+		fprintf(stderr, "WARNING: Failed to set sample rate.\n");
+
+#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, &sigact, NULL);
+#else
+	SetConsoleCtrlHandler( (PHANDLER_ROUTINE) sighandler, TRUE );
+#endif
+
+	sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+
+	memset(&remote, 0, sizeof(remote));
+
+	remote.sin_family = AF_INET;
+	remote.sin_port = htons(port);
+	remote.sin_addr.s_addr = inet_addr(addr);
+
+	fprintf(stderr, "Connecting to %s:%d...\n", addr, port);
+	while (connect(sock, (struct sockaddr *)&remote, sizeof(remote)) != 0) {
+#ifndef _WIN32
+		usleep(500000);
+#else
+		Sleep(0.5);
+#endif
+		if (do_exit)
+			goto out;
+	}
+
+	setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char *)&flag,sizeof(flag));
+	fprintf(stderr, "Connected\n");
+	connected = 1;
+
+	while (!do_exit) {
+#ifndef _WIN32
+		usleep(500000);
+#else
+		Sleep(0.5);
+#endif
+	}
+
+out:
+	free(txbuf);
+	fl2k_close(dev);
+	closesocket(s);
+#ifdef _WIN32
+	WSACleanup();
+#endif
+
+	return 0;
+}
diff --git a/src/fl2k_test.c b/src/fl2k_test.c
new file mode 100644
index 0000000..ee2753d
--- /dev/null
+++ b/src/fl2k_test.c
@@ -0,0 +1,310 @@
+/*
+ * 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 rtl_test:
+ * 
+ * Copyright (C) 2012-2014 by Steve Markgraf <steve@steve-m.de>
+ * Copyright (C) 2012-2014 by Kyle Keen <keenerd@gmail.com>
+ * Copyright (C) 2014 by Michael Tatarinov <kukabu@gmail.com>
+ *
+ * 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 <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#ifdef __APPLE__
+#include <sys/time.h>
+#else
+#include <time.h>
+#endif
+
+#ifndef _WIN32
+#include <unistd.h>
+#else
+#include <windows.h>
+#include "getopt/getopt.h"
+#endif
+
+#include "osmo-fl2k.h"
+
+#define DEFAULT_SAMPLE_RATE		100000000
+#define PPM_DURATION			10
+#define PPM_DUMP_TIME			1
+
+struct time_generic
+	/* holds all the platform specific values */
+{
+#ifndef _WIN32
+	time_t tv_sec;
+	long tv_nsec;
+#else
+	long tv_sec;
+	long tv_nsec;
+	int init;
+	LARGE_INTEGER frequency;
+	LARGE_INTEGER ticks;
+#endif
+};
+
+static int do_exit = 0;
+static fl2k_dev_t *dev = NULL;
+
+static uint32_t samp_rate = DEFAULT_SAMPLE_RATE;
+static unsigned int ppm_duration = PPM_DURATION;
+
+static char *buffer;
+static int cb_cnt = 0;
+
+void usage(void)
+{
+	fprintf(stderr,
+		"fl2k_test, clock accuracy test for FL2K VGA dongles,\n"
+		"also outputs a square wave at fs/2\n\n"
+		"Usage:\n"
+		"\t[-d device_index (default: 0)]\n"
+		"\t[-s samplerate (default: 100 MS/s)]\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;
+		return TRUE;
+	}
+	return FALSE;
+}
+#else
+static void sighandler(int signum)
+{
+	fprintf(stderr, "Signal caught, exiting!\n");
+	fl2k_stop_tx(dev);
+	do_exit = 1;
+}
+#endif
+
+#ifndef _WIN32
+static int ppm_gettime(struct time_generic *tg)
+{
+	int rv = ENOSYS;
+	struct timespec ts;
+
+#ifdef __unix__
+	rv = clock_gettime(CLOCK_MONOTONIC, &ts);
+	tg->tv_sec = ts.tv_sec;
+	tg->tv_nsec = ts.tv_nsec;
+#elif __APPLE__
+	struct timeval tv;
+
+	rv = gettimeofday(&tv, NULL);
+	ts->tv_sec = tv.tv_sec;
+	ts->tv_nsec = tv.tv_usec * 1000;
+#endif
+	return rv;
+}
+#endif
+
+#ifdef _WIN32
+static int ppm_gettime(struct time_generic *tg)
+{
+	int rv;
+	int64_t frac;
+	if (!tg->init) {
+		QueryPerformanceFrequency(&tg->frequency);
+		tg->init = 1;
+	}
+	rv = QueryPerformanceCounter(&tg->ticks);
+	tg->tv_sec = tg->ticks.QuadPart / tg->frequency.QuadPart;
+	frac = (int64_t)(tg->ticks.QuadPart - (tg->tv_sec * tg->frequency.QuadPart));
+	tg->tv_nsec = (long)(frac * 1000000000L / (int64_t)tg->frequency.QuadPart);
+	return !rv;
+}
+#endif
+
+static int ppm_report(uint64_t nsamples, uint64_t interval)
+{
+	double real_rate, ppm;
+
+	real_rate = nsamples * 1e9 / interval;
+	ppm = 1e6 * (real_rate / (double)samp_rate - 1.);
+	return (int)round(ppm);
+}
+
+static void ppm_test(uint32_t len)
+{
+	static uint64_t nsamples = 0;
+	static uint64_t interval = 0;
+	static uint64_t nsamples_total = 0;
+	static uint64_t interval_total = 0;
+	static struct time_generic ppm_now;
+	static struct time_generic ppm_recent;
+
+	static enum {
+		PPM_INIT_NO,
+		PPM_INIT_DUMP,
+		PPM_INIT_RUN
+	} ppm_init = PPM_INIT_NO;
+
+	ppm_gettime(&ppm_now);
+
+	if (ppm_init != PPM_INIT_RUN) {
+		/*
+		* Kyle Keen wrote:
+		* PPM_DUMP_TIME throws out the first N seconds of data.
+		* The dongle's PPM is usually very bad when first starting up,
+		* typically incorrect by more than twice the final value.
+		* Discarding the first few seconds allows the value to stabilize much faster.
+		*/
+		if (ppm_init == PPM_INIT_NO) {
+			ppm_recent.tv_sec = ppm_now.tv_sec + PPM_DUMP_TIME;
+			ppm_init = PPM_INIT_DUMP;
+			return;
+		}
+		if (ppm_init == PPM_INIT_DUMP && ppm_recent.tv_sec < ppm_now.tv_sec)
+			return;
+		ppm_recent = ppm_now;
+		ppm_init = PPM_INIT_RUN;
+		return;
+	}
+	nsamples += (uint64_t)len;
+	interval = (uint64_t)(ppm_now.tv_sec - ppm_recent.tv_sec);
+	if (interval < ppm_duration)
+		return;
+	interval *= 1000000000UL;
+	interval += (int64_t)(ppm_now.tv_nsec - ppm_recent.tv_nsec);
+
+	nsamples_total += nsamples;
+	interval_total += interval;
+	printf("real sample rate: %i current PPM: %i cumulative PPM: %i\n",
+		(int)((1000000000UL * nsamples) / interval),
+		ppm_report(nsamples, interval),
+		ppm_report(nsamples_total, interval_total));
+	ppm_recent = ppm_now;
+	nsamples = 0;
+}
+
+void fl2k_callback(fl2k_data_info_t *data_info)
+{
+	/* drop first couple of callbacks until everything is settled */
+	if (cb_cnt > 20) {
+		ppm_test(FL2K_BUF_LEN);
+	} else {
+		/* as data is repetitive, it only needs to be handed
+		 * over until all transfer buffers contain the data */
+		data_info->r_buf = buffer;
+		cb_cnt++;
+	}
+
+}
+
+int main(int argc, char **argv)
+{
+#ifndef _WIN32
+	struct sigaction sigact;
+#endif
+	int r, opt, i;
+	uint32_t dev_index = 0;
+
+	while ((opt = getopt(argc, argv, "d:s:p::h")) != -1) {
+		switch (opt) {
+		case 'd':
+			dev_index = (uint32_t)atoi(optarg);
+			break;
+		case 's':
+			samp_rate = (uint32_t)atof(optarg);
+			break;
+		case 'p':
+			if (optarg)
+				ppm_duration = atoi(optarg);
+			break;
+		case 'h':
+		default:
+			usage();
+			break;
+		}
+	}
+
+	buffer = malloc(FL2K_BUF_LEN);
+	if (!buffer)
+		goto exit;
+
+	fl2k_open(&dev, (uint32_t)dev_index);
+	if (NULL == dev) {
+	fprintf(stderr, "Failed to open fl2k device #%d.\n", dev_index);
+		exit(1);
+	}
+
+#ifndef _WIN32
+	sigact.sa_handler = sighandler;
+	sigemptyset(&sigact.sa_mask);
+	sigact.sa_flags = 0;
+	sigaction(SIGINT, &sigact, NULL);
+	sigaction(SIGTERM, &sigact, NULL);
+	sigaction(SIGQUIT, &sigact, NULL);
+	sigaction(SIGPIPE, &sigact, NULL);
+#else
+	SetConsoleCtrlHandler( (PHANDLER_ROUTINE) sighandler, TRUE );
+#endif
+
+	/* initialize buffer with rect signal */
+	for (i = 0; i < FL2K_BUF_LEN; i += 2) {
+		buffer[i] = 0x00;
+		buffer[i+1] = 0xff;
+	}
+
+	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.\n");
+
+	samp_rate = fl2k_get_sample_rate(dev);
+
+	fprintf(stderr, "Reporting PPM error measurement every %u seconds...\n", ppm_duration);
+	fprintf(stderr, "Press ^C after a few minutes.\n");
+
+	while (!do_exit) {
+#ifndef _WIN32
+		usleep(500000);
+#else
+		Sleep(0.5);
+#endif
+	}
+
+	if (do_exit) {
+		fprintf(stderr, "\nUser cancel, exiting...\n");
+	}
+
+exit:
+	fl2k_close(dev);
+	free(buffer);
+
+	return 0;
+}
diff --git a/src/getopt/getopt.c b/src/getopt/getopt.c
new file mode 100644
index 0000000..f1d461a
--- /dev/null
+++ b/src/getopt/getopt.c
@@ -0,0 +1,1059 @@
+/* Getopt for GNU.
+   NOTE: getopt is now part of the C library, so if you don't know what
+   "Keep this file name-space clean" means, talk to drepper@gnu.org
+   before changing it!
+   Copyright (C) 1987,88,89,90,91,92,93,94,95,96,98,99,2000,2001
+   Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+/* This tells Alpha OSF/1 not to define a getopt prototype in <stdio.h>.
+   Ditto for AIX 3.2 and <stdlib.h>.  */
+#ifndef _NO_PROTO
+# define _NO_PROTO
+#endif
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#if !defined __STDC__ || !__STDC__
+/* This is a separate conditional since some stdc systems
+   reject `defined (const)'.  */
+# ifndef const
+#  define const
+# endif
+#endif
+
+#include <stdio.h>
+
+/* Comment out all this code if we are using the GNU C Library, and are not
+   actually compiling the library itself.  This code is part of the GNU C
+   Library, but also included in many other GNU distributions.  Compiling
+   and linking in this code is a waste when using the GNU C library
+   (especially if it is a shared library).  Rather than having every GNU
+   program understand `configure --with-gnu-libc' and omit the object files,
+   it is simpler to just do this in the source for each such file.  */
+
+#define GETOPT_INTERFACE_VERSION 2
+#if !defined _LIBC && defined __GLIBC__ && __GLIBC__ >= 2
+# include <gnu-versions.h>
+# if _GNU_GETOPT_INTERFACE_VERSION == GETOPT_INTERFACE_VERSION
+#  define ELIDE_CODE
+# endif
+#endif
+
+#ifndef ELIDE_CODE
+
+
+/* This needs to come after some library #include
+   to get __GNU_LIBRARY__ defined.  */
+#ifdef	__GNU_LIBRARY__
+/* Don't include stdlib.h for non-GNU C libraries because some of them
+   contain conflicting prototypes for getopt.  */
+# include <stdlib.h>
+# include <unistd.h>
+#endif	/* GNU C library.  */
+
+#ifdef VMS
+# include <unixlib.h>
+# if HAVE_STRING_H - 0
+#  include <string.h>
+# endif
+#endif
+
+#ifndef _
+/* This is for other GNU distributions with internationalized messages.  */
+# if (HAVE_LIBINTL_H && ENABLE_NLS) || defined _LIBC
+#  include <libintl.h>
+#  ifndef _
+#   define _(msgid)	gettext (msgid)
+#  endif
+# else
+#  define _(msgid)	(msgid)
+# endif
+#endif
+
+/* This version of `getopt' appears to the caller like standard Unix `getopt'
+   but it behaves differently for the user, since it allows the user
+   to intersperse the options with the other arguments.
+
+   As `getopt' works, it permutes the elements of ARGV so that,
+   when it is done, all the options precede everything else.  Thus
+   all application programs are extended to handle flexible argument order.
+
+   Setting the environment variable POSIXLY_CORRECT disables permutation.
+   Then the behavior is completely standard.
+
+   GNU application programs can use a third alternative mode in which
+   they can distinguish the relative order of options and other arguments.  */
+
+#include "getopt.h"
+
+/* For communication from `getopt' to the caller.
+   When `getopt' finds an option that takes an argument,
+   the argument value is returned here.
+   Also, when `ordering' is RETURN_IN_ORDER,
+   each non-option ARGV-element is returned here.  */
+
+char *optarg;
+
+/* Index in ARGV of the next element to be scanned.
+   This is used for communication to and from the caller
+   and for communication between successive calls to `getopt'.
+
+   On entry to `getopt', zero means this is the first call; initialize.
+
+   When `getopt' returns -1, this is the index of the first of the
+   non-option elements that the caller should itself scan.
+
+   Otherwise, `optind' communicates from one call to the next
+   how much of ARGV has been scanned so far.  */
+
+/* 1003.2 says this must be 1 before any call.  */
+int optind = 1;
+
+/* Formerly, initialization of getopt depended on optind==0, which
+   causes problems with re-calling getopt as programs generally don't
+   know that. */
+
+int __getopt_initialized;
+
+/* The next char to be scanned in the option-element
+   in which the last option character we returned was found.
+   This allows us to pick up the scan where we left off.
+
+   If this is zero, or a null string, it means resume the scan
+   by advancing to the next ARGV-element.  */
+
+static char *nextchar;
+
+/* Callers store zero here to inhibit the error message
+   for unrecognized options.  */
+
+int opterr = 1;
+
+/* Set to an option character which was unrecognized.
+   This must be initialized on some systems to avoid linking in the
+   system's own getopt implementation.  */
+
+int optopt = '?';
+
+/* Describe how to deal with options that follow non-option ARGV-elements.
+
+   If the caller did not specify anything,
+   the default is REQUIRE_ORDER if the environment variable
+   POSIXLY_CORRECT is defined, PERMUTE otherwise.
+
+   REQUIRE_ORDER means don't recognize them as options;
+   stop option processing when the first non-option is seen.
+   This is what Unix does.
+   This mode of operation is selected by either setting the environment
+   variable POSIXLY_CORRECT, or using `+' as the first character
+   of the list of option characters.
+
+   PERMUTE is the default.  We permute the contents of ARGV as we scan,
+   so that eventually all the non-options are at the end.  This allows options
+   to be given in any order, even with programs that were not written to
+   expect this.
+
+   RETURN_IN_ORDER is an option available to programs that were written
+   to expect options and other ARGV-elements in any order and that care about
+   the ordering of the two.  We describe each non-option ARGV-element
+   as if it were the argument of an option with character code 1.
+   Using `-' as the first character of the list of option characters
+   selects this mode of operation.
+
+   The special argument `--' forces an end of option-scanning regardless
+   of the value of `ordering'.  In the case of RETURN_IN_ORDER, only
+   `--' can cause `getopt' to return -1 with `optind' != ARGC.  */
+
+static enum
+{
+  REQUIRE_ORDER, PERMUTE, RETURN_IN_ORDER
+} ordering;
+
+/* Value of POSIXLY_CORRECT environment variable.  */
+static char *posixly_correct;
+
+#ifdef	__GNU_LIBRARY__
+/* We want to avoid inclusion of string.h with non-GNU libraries
+   because there are many ways it can cause trouble.
+   On some systems, it contains special magic macros that don't work
+   in GCC.  */
+# include <string.h>
+# define my_index	strchr
+#else
+
+# if 1 //HAVE_STRING_H
+#  include <string.h>
+# else
+#  include <strings.h>
+# endif
+
+/* Avoid depending on library functions or files
+   whose names are inconsistent.  */
+
+#ifndef getenv
+#ifdef _MSC_VER
+// DDK will complain if you don't use the stdlib defined getenv
+#include <stdlib.h>
+#else
+extern char *getenv ();
+#endif
+#endif
+
+static char *
+my_index (str, chr)
+     const char *str;
+     int chr;
+{
+  while (*str)
+    {
+      if (*str == chr)
+	return (char *) str;
+      str++;
+    }
+  return 0;
+}
+
+/* If using GCC, we can safely declare strlen this way.
+   If not using GCC, it is ok not to declare it.  */
+#ifdef __GNUC__
+/* Note that Motorola Delta 68k R3V7 comes with GCC but not stddef.h.
+   That was relevant to code that was here before.  */
+# if (!defined __STDC__ || !__STDC__) && !defined strlen
+/* gcc with -traditional declares the built-in strlen to return int,
+   and has done so at least since version 2.4.5. -- rms.  */
+extern int strlen (const char *);
+# endif /* not __STDC__ */
+#endif /* __GNUC__ */
+
+#endif /* not __GNU_LIBRARY__ */
+
+/* Handle permutation of arguments.  */
+
+/* Describe the part of ARGV that contains non-options that have
+   been skipped.  `first_nonopt' is the index in ARGV of the first of them;
+   `last_nonopt' is the index after the last of them.  */
+
+static int first_nonopt;
+static int last_nonopt;
+
+#ifdef _LIBC
+/* Stored original parameters.
+   XXX This is no good solution.  We should rather copy the args so
+   that we can compare them later.  But we must not use malloc(3).  */
+extern int __libc_argc;
+extern char **__libc_argv;
+
+/* Bash 2.0 gives us an environment variable containing flags
+   indicating ARGV elements that should not be considered arguments.  */
+
+# ifdef USE_NONOPTION_FLAGS
+/* Defined in getopt_init.c  */
+extern char *__getopt_nonoption_flags;
+
+static int nonoption_flags_max_len;
+static int nonoption_flags_len;
+# endif
+
+# ifdef USE_NONOPTION_FLAGS
+#  define SWAP_FLAGS(ch1, ch2) \
+  if (nonoption_flags_len > 0)						      \
+    {									      \
+      char __tmp = __getopt_nonoption_flags[ch1];			      \
+      __getopt_nonoption_flags[ch1] = __getopt_nonoption_flags[ch2];	      \
+      __getopt_nonoption_flags[ch2] = __tmp;				      \
+    }
+# else
+#  define SWAP_FLAGS(ch1, ch2)
+# endif
+#else	/* !_LIBC */
+# define SWAP_FLAGS(ch1, ch2)
+#endif	/* _LIBC */
+
+/* Exchange two adjacent subsequences of ARGV.
+   One subsequence is elements [first_nonopt,last_nonopt)
+   which contains all the non-options that have been skipped so far.
+   The other is elements [last_nonopt,optind), which contains all
+   the options processed since those non-options were skipped.
+
+   `first_nonopt' and `last_nonopt' are relocated so that they describe
+   the new indices of the non-options in ARGV after they are moved.  */
+
+#if defined __STDC__ && __STDC__
+static void exchange (char **);
+#endif
+
+static void
+exchange (argv)
+     char **argv;
+{
+  int bottom = first_nonopt;
+  int middle = last_nonopt;
+  int top = optind;
+  char *tem;
+
+  /* Exchange the shorter segment with the far end of the longer segment.
+     That puts the shorter segment into the right place.
+     It leaves the longer segment in the right place overall,
+     but it consists of two parts that need to be swapped next.  */
+
+#if defined _LIBC && defined USE_NONOPTION_FLAGS
+  /* First make sure the handling of the `__getopt_nonoption_flags'
+     string can work normally.  Our top argument must be in the range
+     of the string.  */
+  if (nonoption_flags_len > 0 && top >= nonoption_flags_max_len)
+    {
+      /* We must extend the array.  The user plays games with us and
+	 presents new arguments.  */
+      char *new_str = malloc (top + 1);
+      if (new_str == NULL)
+	nonoption_flags_len = nonoption_flags_max_len = 0;
+      else
+	{
+	  memset (__mempcpy (new_str, __getopt_nonoption_flags,
+			     nonoption_flags_max_len),
+		  '\0', top + 1 - nonoption_flags_max_len);
+	  nonoption_flags_max_len = top + 1;
+	  __getopt_nonoption_flags = new_str;
+	}
+    }
+#endif
+
+  while (top > middle && middle > bottom)
+    {
+      if (top - middle > middle - bottom)
+	{
+	  /* Bottom segment is the short one.  */
+	  int len = middle - bottom;
+	  register int i;
+
+	  /* Swap it with the top part of the top segment.  */
+	  for (i = 0; i < len; i++)
+	    {
+	      tem = argv[bottom + i];
+	      argv[bottom + i] = argv[top - (middle - bottom) + i];
+	      argv[top - (middle - bottom) + i] = tem;
+	      SWAP_FLAGS (bottom + i, top - (middle - bottom) + i);
+	    }
+	  /* Exclude the moved bottom segment from further swapping.  */
+	  top -= len;
+	}
+      else
+	{
+	  /* Top segment is the short one.  */
+	  int len = top - middle;
+	  register int i;
+
+	  /* Swap it with the bottom part of the bottom segment.  */
+	  for (i = 0; i < len; i++)
+	    {
+	      tem = argv[bottom + i];
+	      argv[bottom + i] = argv[middle + i];
+	      argv[middle + i] = tem;
+	      SWAP_FLAGS (bottom + i, middle + i);
+	    }
+	  /* Exclude the moved top segment from further swapping.  */
+	  bottom += len;
+	}
+    }
+
+  /* Update records for the slots the non-options now occupy.  */
+
+  first_nonopt += (optind - last_nonopt);
+  last_nonopt = optind;
+}
+
+/* Initialize the internal data when the first call is made.  */
+
+#if defined __STDC__ && __STDC__
+static const char *_getopt_initialize (int, char *const *, const char *);
+#endif
+static const char *
+_getopt_initialize (argc, argv, optstring)
+     int argc;
+     char *const *argv;
+     const char *optstring;
+{
+  /* Start processing options with ARGV-element 1 (since ARGV-element 0
+     is the program name); the sequence of previously skipped
+     non-option ARGV-elements is empty.  */
+
+  first_nonopt = last_nonopt = optind;
+
+  nextchar = NULL;
+
+  posixly_correct = getenv ("POSIXLY_CORRECT");
+
+  /* Determine how to handle the ordering of options and nonoptions.  */
+
+  if (optstring[0] == '-')
+    {
+      ordering = RETURN_IN_ORDER;
+      ++optstring;
+    }
+  else if (optstring[0] == '+')
+    {
+      ordering = REQUIRE_ORDER;
+      ++optstring;
+    }
+  else if (posixly_correct != NULL)
+    ordering = REQUIRE_ORDER;
+  else
+    ordering = PERMUTE;
+
+#if defined _LIBC && defined USE_NONOPTION_FLAGS
+  if (posixly_correct == NULL
+      && argc == __libc_argc && argv == __libc_argv)
+    {
+      if (nonoption_flags_max_len == 0)
+	{
+	  if (__getopt_nonoption_flags == NULL
+	      || __getopt_nonoption_flags[0] == '\0')
+	    nonoption_flags_max_len = -1;
+	  else
+	    {
+	      const char *orig_str = __getopt_nonoption_flags;
+	      int len = nonoption_flags_max_len = strlen (orig_str);
+	      if (nonoption_flags_max_len < argc)
+		nonoption_flags_max_len = argc;
+	      __getopt_nonoption_flags =
+		(char *) malloc (nonoption_flags_max_len);
+	      if (__getopt_nonoption_flags == NULL)
+		nonoption_flags_max_len = -1;
+	      else
+		memset (__mempcpy (__getopt_nonoption_flags, orig_str, len),
+			'\0', nonoption_flags_max_len - len);
+	    }
+	}
+      nonoption_flags_len = nonoption_flags_max_len;
+    }
+  else
+    nonoption_flags_len = 0;
+#endif
+
+  return optstring;
+}
+
+/* Scan elements of ARGV (whose length is ARGC) for option characters
+   given in OPTSTRING.
+
+   If an element of ARGV starts with '-', and is not exactly "-" or "--",
+   then it is an option element.  The characters of this element
+   (aside from the initial '-') are option characters.  If `getopt'
+   is called repeatedly, it returns successively each of the option characters
+   from each of the option elements.
+
+   If `getopt' finds another option character, it returns that character,
+   updating `optind' and `nextchar' so that the next call to `getopt' can
+   resume the scan with the following option character or ARGV-element.
+
+   If there are no more option characters, `getopt' returns -1.
+   Then `optind' is the index in ARGV of the first ARGV-element
+   that is not an option.  (The ARGV-elements have been permuted
+   so that those that are not options now come last.)
+
+   OPTSTRING is a string containing the legitimate option characters.
+   If an option character is seen that is not listed in OPTSTRING,
+   return '?' after printing an error message.  If you set `opterr' to
+   zero, the error message is suppressed but we still return '?'.
+
+   If a char in OPTSTRING is followed by a colon, that means it wants an arg,
+   so the following text in the same ARGV-element, or the text of the following
+   ARGV-element, is returned in `optarg'.  Two colons mean an option that
+   wants an optional arg; if there is text in the current ARGV-element,
+   it is returned in `optarg', otherwise `optarg' is set to zero.
+
+   If OPTSTRING starts with `-' or `+', it requests different methods of
+   handling the non-option ARGV-elements.
+   See the comments about RETURN_IN_ORDER and REQUIRE_ORDER, above.
+
+   Long-named options begin with `--' instead of `-'.
+   Their names may be abbreviated as long as the abbreviation is unique
+   or is an exact match for some defined option.  If they have an
+   argument, it follows the option name in the same ARGV-element, separated
+   from the option name by a `=', or else the in next ARGV-element.
+   When `getopt' finds a long-named option, it returns 0 if that option's
+   `flag' field is nonzero, the value of the option's `val' field
+   if the `flag' field is zero.
+
+   The elements of ARGV aren't really const, because we permute them.
+   But we pretend they're const in the prototype to be compatible
+   with other systems.
+
+   LONGOPTS is a vector of `struct option' terminated by an
+   element containing a name which is zero.
+
+   LONGIND returns the index in LONGOPT of the long-named option found.
+   It is only valid when a long-named option has been found by the most
+   recent call.
+
+   If LONG_ONLY is nonzero, '-' as well as '--' can introduce
+   long-named options.  */
+
+int
+_getopt_internal (argc, argv, optstring, longopts, longind, long_only)
+     int argc;
+     char *const *argv;
+     const char *optstring;
+     const struct option *longopts;
+     int *longind;
+     int long_only;
+{
+  int print_errors = opterr;
+  if (optstring[0] == ':')
+    print_errors = 0;
+
+  if (argc < 1)
+    return -1;
+
+  optarg = NULL;
+
+  if (optind == 0 || !__getopt_initialized)
+    {
+      if (optind == 0)
+	optind = 1;	/* Don't scan ARGV[0], the program name.  */
+      optstring = _getopt_initialize (argc, argv, optstring);
+      __getopt_initialized = 1;
+    }
+
+  /* Test whether ARGV[optind] points to a non-option argument.
+     Either it does not have option syntax, or there is an environment flag
+     from the shell indicating it is not an option.  The later information
+     is only used when the used in the GNU libc.  */
+#if defined _LIBC && defined USE_NONOPTION_FLAGS
+# define NONOPTION_P (argv[optind][0] != '-' || argv[optind][1] == '\0'	      \
+		      || (optind < nonoption_flags_len			      \
+			  && __getopt_nonoption_flags[optind] == '1'))
+#else
+# define NONOPTION_P (argv[optind][0] != '-' || argv[optind][1] == '\0')
+#endif
+
+  if (nextchar == NULL || *nextchar == '\0')
+    {
+      /* Advance to the next ARGV-element.  */
+
+      /* Give FIRST_NONOPT & LAST_NONOPT rational values if OPTIND has been
+	 moved back by the user (who may also have changed the arguments).  */
+      if (last_nonopt > optind)
+	last_nonopt = optind;
+      if (first_nonopt > optind)
+	first_nonopt = optind;
+
+      if (ordering == PERMUTE)
+	{
+	  /* If we have just processed some options following some non-options,
+	     exchange them so that the options come first.  */
+
+	  if (first_nonopt != last_nonopt && last_nonopt != optind)
+	    exchange ((char **) argv);
+	  else if (last_nonopt != optind)
+	    first_nonopt = optind;
+
+	  /* Skip any additional non-options
+	     and extend the range of non-options previously skipped.  */
+
+	  while (optind < argc && NONOPTION_P)
+	    optind++;
+	  last_nonopt = optind;
+	}
+
+      /* The special ARGV-element `--' means premature end of options.
+	 Skip it like a null option,
+	 then exchange with previous non-options as if it were an option,
+	 then skip everything else like a non-option.  */
+
+      if (optind != argc && !strcmp (argv[optind], "--"))
+	{
+	  optind++;
+
+	  if (first_nonopt != last_nonopt && last_nonopt != optind)
+	    exchange ((char **) argv);
+	  else if (first_nonopt == last_nonopt)
+	    first_nonopt = optind;
+	  last_nonopt = argc;
+
+	  optind = argc;
+	}
+
+      /* If we have done all the ARGV-elements, stop the scan
+	 and back over any non-options that we skipped and permuted.  */
+
+      if (optind == argc)
+	{
+	  /* Set the next-arg-index to point at the non-options
+	     that we previously skipped, so the caller will digest them.  */
+	  if (first_nonopt != last_nonopt)
+	    optind = first_nonopt;
+	  return -1;
+	}
+
+      /* If we have come to a non-option and did not permute it,
+	 either stop the scan or describe it to the caller and pass it by.  */
+
+      if (NONOPTION_P)
+	{
+	  if (ordering == REQUIRE_ORDER)
+	    return -1;
+	  optarg = argv[optind++];
+	  return 1;
+	}
+
+      /* We have found another option-ARGV-element.
+	 Skip the initial punctuation.  */
+
+      nextchar = (argv[optind] + 1
+		  + (longopts != NULL && argv[optind][1] == '-'));
+    }
+
+  /* Decode the current option-ARGV-element.  */
+
+  /* Check whether the ARGV-element is a long option.
+
+     If long_only and the ARGV-element has the form "-f", where f is
+     a valid short option, don't consider it an abbreviated form of
+     a long option that starts with f.  Otherwise there would be no
+     way to give the -f short option.
+
+     On the other hand, if there's a long option "fubar" and
+     the ARGV-element is "-fu", do consider that an abbreviation of
+     the long option, just like "--fu", and not "-f" with arg "u".
+
+     This distinction seems to be the most useful approach.  */
+
+  if (longopts != NULL
+      && (argv[optind][1] == '-'
+	  || (long_only && (argv[optind][2] || !my_index (optstring, argv[optind][1])))))
+    {
+      char *nameend;
+      const struct option *p;
+      const struct option *pfound = NULL;
+      int exact = 0;
+      int ambig = 0;
+      int indfound = -1;
+      int option_index;
+
+      for (nameend = nextchar; *nameend && *nameend != '='; nameend++)
+	/* Do nothing.  */ ;
+
+      /* Test all long options for either exact match
+	 or abbreviated matches.  */
+      for (p = longopts, option_index = 0; p->name; p++, option_index++)
+	if (!strncmp (p->name, nextchar, nameend - nextchar))
+	  {
+	    if ((unsigned int) (nameend - nextchar)
+		== (unsigned int) strlen (p->name))
+	      {
+		/* Exact match found.  */
+		pfound = p;
+		indfound = option_index;
+		exact = 1;
+		break;
+	      }
+	    else if (pfound == NULL)
+	      {
+		/* First nonexact match found.  */
+		pfound = p;
+		indfound = option_index;
+	      }
+	    else if (long_only
+		     || pfound->has_arg != p->has_arg
+		     || pfound->flag != p->flag
+		     || pfound->val != p->val)
+	      /* Second or later nonexact match found.  */
+	      ambig = 1;
+	  }
+
+      if (ambig && !exact)
+	{
+	  if (print_errors)
+	    fprintf (stderr, _("%s: option `%s' is ambiguous\n"),
+		     argv[0], argv[optind]);
+	  nextchar += strlen (nextchar);
+	  optind++;
+	  optopt = 0;
+	  return '?';
+	}
+
+      if (pfound != NULL)
+	{
+	  option_index = indfound;
+	  optind++;
+	  if (*nameend)
+	    {
+	      /* Don't test has_arg with >, because some C compilers don't
+		 allow it to be used on enums.  */
+	      if (pfound->has_arg)
+		optarg = nameend + 1;
+	      else
+		{
+		  if (print_errors)
+		    {
+		      if (argv[optind - 1][1] == '-')
+			/* --option */
+			fprintf (stderr,
+				 _("%s: option `--%s' doesn't allow an argument\n"),
+				 argv[0], pfound->name);
+		      else
+			/* +option or -option */
+			fprintf (stderr,
+				 _("%s: option `%c%s' doesn't allow an argument\n"),
+				 argv[0], argv[optind - 1][0], pfound->name);
+		    }
+
+		  nextchar += strlen (nextchar);
+
+		  optopt = pfound->val;
+		  return '?';
+		}
+	    }
+	  else if (pfound->has_arg == 1)
+	    {
+	      if (optind < argc)
+		optarg = argv[optind++];
+	      else
+		{
+		  if (print_errors)
+		    fprintf (stderr,
+			   _("%s: option `%s' requires an argument\n"),
+			   argv[0], argv[optind - 1]);
+		  nextchar += strlen (nextchar);
+		  optopt = pfound->val;
+		  return optstring[0] == ':' ? ':' : '?';
+		}
+	    }
+	  nextchar += strlen (nextchar);
+	  if (longind != NULL)
+	    *longind = option_index;
+	  if (pfound->flag)
+	    {
+	      *(pfound->flag) = pfound->val;
+	      return 0;
+	    }
+	  return pfound->val;
+	}
+
+      /* Can't find it as a long option.  If this is not getopt_long_only,
+	 or the option starts with '--' or is not a valid short
+	 option, then it's an error.
+	 Otherwise interpret it as a short option.  */
+      if (!long_only || argv[optind][1] == '-'
+	  || my_index (optstring, *nextchar) == NULL)
+	{
+	  if (print_errors)
+	    {
+	      if (argv[optind][1] == '-')
+		/* --option */
+		fprintf (stderr, _("%s: unrecognized option `--%s'\n"),
+			 argv[0], nextchar);
+	      else
+		/* +option or -option */
+		fprintf (stderr, _("%s: unrecognized option `%c%s'\n"),
+			 argv[0], argv[optind][0], nextchar);
+	    }
+	  nextchar = (char *) "";
+	  optind++;
+	  optopt = 0;
+	  return '?';
+	}
+    }
+
+  /* Look at and handle the next short option-character.  */
+
+  {
+    char c = *nextchar++;
+    char *temp = my_index (optstring, c);
+
+    /* Increment `optind' when we start to process its last character.  */
+    if (*nextchar == '\0')
+      ++optind;
+
+    if (temp == NULL || c == ':')
+      {
+	if (print_errors)
+	  {
+	    if (posixly_correct)
+	      /* 1003.2 specifies the format of this message.  */
+	      fprintf (stderr, _("%s: illegal option -- %c\n"),
+		       argv[0], c);
+	    else
+	      fprintf (stderr, _("%s: invalid option -- %c\n"),
+		       argv[0], c);
+	  }
+	optopt = c;
+	return '?';
+      }
+    /* Convenience. Treat POSIX -W foo same as long option --foo */
+    if (temp[0] == 'W' && temp[1] == ';')
+      {
+	char *nameend;
+	const struct option *p;
+	const struct option *pfound = NULL;
+	int exact = 0;
+	int ambig = 0;
+	int indfound = 0;
+	int option_index;
+
+	/* This is an option that requires an argument.  */
+	if (*nextchar != '\0')
+	  {
+	    optarg = nextchar;
+	    /* If we end this ARGV-element by taking the rest as an arg,
+	       we must advance to the next element now.  */
+	    optind++;
+	  }
+	else if (optind == argc)
+	  {
+	    if (print_errors)
+	      {
+		/* 1003.2 specifies the format of this message.  */
+		fprintf (stderr, _("%s: option requires an argument -- %c\n"),
+			 argv[0], c);
+	      }
+	    optopt = c;
+	    if (optstring[0] == ':')
+	      c = ':';
+	    else
+	      c = '?';
+	    return c;
+	  }
+	else
+	  /* We already incremented `optind' once;
+	     increment it again when taking next ARGV-elt as argument.  */
+	  optarg = argv[optind++];
+
+	/* optarg is now the argument, see if it's in the
+	   table of longopts.  */
+
+	for (nextchar = nameend = optarg; *nameend && *nameend != '='; nameend++)
+	  /* Do nothing.  */ ;
+
+	/* Test all long options for either exact match
+	   or abbreviated matches.  */
+	for (p = longopts, option_index = 0; p->name; p++, option_index++)
+	  if (!strncmp (p->name, nextchar, nameend - nextchar))
+	    {
+	      if ((unsigned int) (nameend - nextchar) == strlen (p->name))
+		{
+		  /* Exact match found.  */
+		  pfound = p;
+		  indfound = option_index;
+		  exact = 1;
+		  break;
+		}
+	      else if (pfound == NULL)
+		{
+		  /* First nonexact match found.  */
+		  pfound = p;
+		  indfound = option_index;
+		}
+	      else
+		/* Second or later nonexact match found.  */
+		ambig = 1;
+	    }
+	if (ambig && !exact)
+	  {
+	    if (print_errors)
+	      fprintf (stderr, _("%s: option `-W %s' is ambiguous\n"),
+		       argv[0], argv[optind]);
+	    nextchar += strlen (nextchar);
+	    optind++;
+	    return '?';
+	  }
+	if (pfound != NULL)
+	  {
+	    option_index = indfound;
+	    if (*nameend)
+	      {
+		/* Don't test has_arg with >, because some C compilers don't
+		   allow it to be used on enums.  */
+		if (pfound->has_arg)
+		  optarg = nameend + 1;
+		else
+		  {
+		    if (print_errors)
+		      fprintf (stderr, _("\
+			%s: option `-W %s' doesn't allow an argument\n"),
+			       argv[0], pfound->name);
+
+		    nextchar += strlen (nextchar);
+		    return '?';
+		  }
+	      }
+	    else if (pfound->has_arg == 1)
+	      {
+		if (optind < argc)
+		  optarg = argv[optind++];
+		else
+		  {
+		    if (print_errors)
+		      fprintf (stderr,
+			       _("%s: option `%s' requires an argument\n"),
+			       argv[0], argv[optind - 1]);
+		    nextchar += strlen (nextchar);
+		    return optstring[0] == ':' ? ':' : '?';
+		  }
+	      }
+	    nextchar += strlen (nextchar);
+	    if (longind != NULL)
+	      *longind = option_index;
+	    if (pfound->flag)
+	      {
+		*(pfound->flag) = pfound->val;
+		return 0;
+	      }
+	    return pfound->val;
+	  }
+	  nextchar = NULL;
+	  return 'W';	/* Let the application handle it.   */
+      }
+    if (temp[1] == ':')
+      {
+	if (temp[2] == ':')
+	  {
+	    /* This is an option that accepts an argument optionally.  */
+	    if (*nextchar != '\0')
+	      {
+		optarg = nextchar;
+		optind++;
+	      }
+	    else
+	      optarg = NULL;
+	    nextchar = NULL;
+	  }
+	else
+	  {
+	    /* This is an option that requires an argument.  */
+	    if (*nextchar != '\0')
+	      {
+		optarg = nextchar;
+		/* If we end this ARGV-element by taking the rest as an arg,
+		   we must advance to the next element now.  */
+		optind++;
+	      }
+	    else if (optind == argc)
+	      {
+		if (print_errors)
+		  {
+		    /* 1003.2 specifies the format of this message.  */
+		    fprintf (stderr,
+			     _("%s: option requires an argument -- %c\n"),
+			     argv[0], c);
+		  }
+		optopt = c;
+		if (optstring[0] == ':')
+		  c = ':';
+		else
+		  c = '?';
+	      }
+	    else
+	      /* We already incremented `optind' once;
+		 increment it again when taking next ARGV-elt as argument.  */
+	      optarg = argv[optind++];
+	    nextchar = NULL;
+	  }
+      }
+    return c;
+  }
+}
+
+int
+getopt (argc, argv, optstring)
+     int argc;
+     char *const *argv;
+     const char *optstring;
+{
+  return _getopt_internal (argc, argv, optstring,
+			   (const struct option *) 0,
+			   (int *) 0,
+			   0);
+}
+
+#endif	/* Not ELIDE_CODE.  */
+
+#ifdef TEST
+
+/* Compile with -DTEST to make an executable for use in testing
+   the above definition of `getopt'.  */
+
+int
+main (argc, argv)
+     int argc;
+     char **argv;
+{
+  int c;
+  int digit_optind = 0;
+
+  while (1)
+    {
+      int this_option_optind = optind ? optind : 1;
+
+      c = getopt (argc, argv, "abc:d:0123456789");
+      if (c == -1)
+	break;
+
+      switch (c)
+	{
+	case '0':
+	case '1':
+	case '2':
+	case '3':
+	case '4':
+	case '5':
+	case '6':
+	case '7':
+	case '8':
+	case '9':
+	  if (digit_optind != 0 && digit_optind != this_option_optind)
+	    printf ("digits occur in two different argv-elements.\n");
+	  digit_optind = this_option_optind;
+	  printf ("option %c\n", c);
+	  break;
+
+	case 'a':
+	  printf ("option a\n");
+	  break;
+
+	case 'b':
+	  printf ("option b\n");
+	  break;
+
+	case 'c':
+	  printf ("option c with value `%s'\n", optarg);
+	  break;
+
+	case '?':
+	  break;
+
+	default:
+	  printf ("?? getopt returned character code 0%o ??\n", c);
+	}
+    }
+
+  if (optind < argc)
+    {
+      printf ("non-option ARGV-elements: ");
+      while (optind < argc)
+	printf ("%s ", argv[optind++]);
+      printf ("\n");
+    }
+
+  exit (0);
+}
+
+#endif /* TEST */
diff --git a/src/getopt/getopt.h b/src/getopt/getopt.h
new file mode 100644
index 0000000..a1b8dd6
--- /dev/null
+++ b/src/getopt/getopt.h
@@ -0,0 +1,180 @@
+/* Declarations for getopt.
+   Copyright (C) 1989-1994, 1996-1999, 2001 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef _GETOPT_H
+
+#ifndef __need_getopt
+# define _GETOPT_H 1
+#endif
+
+/* If __GNU_LIBRARY__ is not already defined, either we are being used
+   standalone, or this is the first header included in the source file.
+   If we are being used with glibc, we need to include <features.h>, but
+   that does not exist if we are standalone.  So: if __GNU_LIBRARY__ is
+   not defined, include <ctype.h>, which will pull in <features.h> for us
+   if it's from glibc.  (Why ctype.h?  It's guaranteed to exist and it
+   doesn't flood the namespace with stuff the way some other headers do.)  */
+#if !defined __GNU_LIBRARY__
+# include <ctype.h>
+#endif
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+/* For communication from `getopt' to the caller.
+   When `getopt' finds an option that takes an argument,
+   the argument value is returned here.
+   Also, when `ordering' is RETURN_IN_ORDER,
+   each non-option ARGV-element is returned here.  */
+
+extern char *optarg;
+
+/* Index in ARGV of the next element to be scanned.
+   This is used for communication to and from the caller
+   and for communication between successive calls to `getopt'.
+
+   On entry to `getopt', zero means this is the first call; initialize.
+
+   When `getopt' returns -1, this is the index of the first of the
+   non-option elements that the caller should itself scan.
+
+   Otherwise, `optind' communicates from one call to the next
+   how much of ARGV has been scanned so far.  */
+
+extern int optind;
+
+/* Callers store zero here to inhibit the error message `getopt' prints
+   for unrecognized options.  */
+
+extern int opterr;
+
+/* Set to an option character which was unrecognized.  */
+
+extern int optopt;
+
+#ifndef __need_getopt
+/* Describe the long-named options requested by the application.
+   The LONG_OPTIONS argument to getopt_long or getopt_long_only is a vector
+   of `struct option' terminated by an element containing a name which is
+   zero.
+
+   The field `has_arg' is:
+   no_argument		(or 0) if the option does not take an argument,
+   required_argument	(or 1) if the option requires an argument,
+   optional_argument 	(or 2) if the option takes an optional argument.
+
+   If the field `flag' is not NULL, it points to a variable that is set
+   to the value given in the field `val' when the option is found, but
+   left unchanged if the option is not found.
+
+   To have a long-named option do something other than set an `int' to
+   a compiled-in constant, such as set a value from `optarg', set the
+   option's `flag' field to zero and its `val' field to a nonzero
+   value (the equivalent single-letter option character, if there is
+   one).  For long options that have a zero `flag' field, `getopt'
+   returns the contents of the `val' field.  */
+
+struct option
+{
+# if (defined __STDC__ && __STDC__) || defined __cplusplus
+  const char *name;
+# else
+  char *name;
+# endif
+  /* has_arg can't be an enum because some compilers complain about
+     type mismatches in all the code that assumes it is an int.  */
+  int has_arg;
+  int *flag;
+  int val;
+};
+
+/* Names for the values of the `has_arg' field of `struct option'.  */
+
+# define no_argument		0
+# define required_argument	1
+# define optional_argument	2
+#endif	/* need getopt */
+
+
+/* Get definitions and prototypes for functions to process the
+   arguments in ARGV (ARGC of them, minus the program name) for
+   options given in OPTS.
+
+   Return the option character from OPTS just read.  Return -1 when
+   there are no more options.  For unrecognized options, or options
+   missing arguments, `optopt' is set to the option letter, and '?' is
+   returned.
+
+   The OPTS string is a list of characters which are recognized option
+   letters, optionally followed by colons, specifying that that letter
+   takes an argument, to be placed in `optarg'.
+
+   If a letter in OPTS is followed by two colons, its argument is
+   optional.  This behavior is specific to the GNU `getopt'.
+
+   The argument `--' causes premature termination of argument
+   scanning, explicitly telling `getopt' that there are no more
+   options.
+
+   If OPTS begins with `--', then non-option arguments are treated as
+   arguments to the option '\0'.  This behavior is specific to the GNU
+   `getopt'.  */
+
+#if (defined __STDC__ && __STDC__) || defined __cplusplus
+# ifdef __GNU_LIBRARY__
+/* Many other libraries have conflicting prototypes for getopt, with
+   differences in the consts, in stdlib.h.  To avoid compilation
+   errors, only prototype getopt for the GNU C library.  */
+extern int getopt (int __argc, char *const *__argv, const char *__shortopts);
+# else /* not __GNU_LIBRARY__ */
+extern int getopt ();
+# endif /* __GNU_LIBRARY__ */
+
+# ifndef __need_getopt
+extern int getopt_long (int __argc, char *const *__argv, const char *__shortopts,
+		        const struct option *__longopts, int *__longind);
+extern int getopt_long_only (int __argc, char *const *__argv,
+			     const char *__shortopts,
+		             const struct option *__longopts, int *__longind);
+
+/* Internal only.  Users should not call this directly.  */
+extern int _getopt_internal (int __argc, char *const *__argv,
+			     const char *__shortopts,
+		             const struct option *__longopts, int *__longind,
+			     int __long_only);
+# endif
+#else /* not __STDC__ */
+extern int getopt ();
+# ifndef __need_getopt
+extern int getopt_long ();
+extern int getopt_long_only ();
+
+extern int _getopt_internal ();
+# endif
+#endif /* __STDC__ */
+
+#ifdef	__cplusplus
+}
+#endif
+
+/* Make sure we later can get all the definitions and declarations.  */
+#undef __need_getopt
+
+#endif /* getopt.h */
diff --git a/src/libosmo-fl2k.c b/src/libosmo-fl2k.c
new file mode 100644
index 0000000..7786477
--- /dev/null
+++ b/src/libosmo-fl2k.c
@@ -0,0 +1,969 @@
+/*
+ * 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>
+ *
+ * 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 <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#ifndef _WIN32
+#include <unistd.h>
+#endif
+
+#include <math.h>
+#include <libusb.h>
+#include <pthread.h>
+
+/*
+ * All libusb callback functions should be marked with the LIBUSB_CALL macro
+ * to ensure that they are compiled with the same calling convention as libusb.
+ *
+ * If the macro isn't available in older libusb versions, we simply define it.
+ */
+#ifndef LIBUSB_CALL
+#define LIBUSB_CALL
+#endif
+
+/* libusb < 1.0.9 doesn't have libusb_handle_events_timeout_completed */
+#ifndef HAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED
+#define libusb_handle_events_timeout_completed(ctx, tv, c) \
+	libusb_handle_events_timeout(ctx, tv)
+#endif
+
+#include "osmo-fl2k.h"
+
+enum fl2k_async_status {
+	FL2K_INACTIVE = 0,
+	FL2K_CANCELING,
+	FL2K_RUNNING
+};
+
+typedef enum fl2k_buf_state {
+	BUF_EMPTY = 0,
+	BUF_SUBMITTED,
+	BUF_FILLED,
+} fl2k_buf_state_t;
+
+typedef struct fl2k_xfer_info {
+	fl2k_dev_t *dev;
+	uint64_t seq;
+	fl2k_buf_state_t state;
+} fl2k_xfer_info_t;
+
+struct fl2k_dev {
+	libusb_context *ctx;
+	struct libusb_device_handle *devh;
+	uint32_t xfer_num;
+	uint32_t xfer_buf_num;
+	uint32_t xfer_buf_len;
+	struct libusb_transfer **xfer;
+	unsigned char **xfer_buf;
+
+	fl2k_xfer_info_t *xfer_info;
+
+	fl2k_tx_cb_t cb;
+	void *cb_ctx;
+	enum fl2k_async_status async_status;
+	int async_cancel;
+
+	int use_zerocopy;
+	int terminate;
+
+	/* thread related */
+	pthread_t usb_worker_thread;
+	pthread_t sample_worker_thread;
+	pthread_mutex_t buf_mutex;
+	pthread_cond_t buf_cond;
+
+	double rate; /* Hz */
+
+	/* status */
+	int dev_lost;
+	int driver_active;
+	uint32_t underflow_cnt;
+};
+
+typedef struct fl2k_dongle {
+	uint16_t vid;
+	uint16_t pid;
+	const char *name;
+} fl2k_dongle_t;
+
+static fl2k_dongle_t known_devices[] = {
+	{ 0x1d5c, 0x2000, "FL2000DX OEM" },
+};
+
+#define DEFAULT_BUF_NUMBER	4
+
+#define CTRL_IN		(LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_ENDPOINT_IN)
+#define CTRL_OUT	(LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_ENDPOINT_OUT)
+#define CTRL_TIMEOUT	300
+#define BULK_TIMEOUT	0
+
+static int fl2k_read_reg(fl2k_dev_t *dev, uint16_t reg, uint32_t *val)
+{
+	int r;
+	uint8_t data[4];
+
+	if (!dev || !val)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	r = libusb_control_transfer(dev->devh, CTRL_IN, 0x40,
+				    0, reg, data, 4, CTRL_TIMEOUT);
+
+	if (r < 4)
+		fprintf(stderr, "Error, short read from register!\n");
+
+	*val = (data[3] << 24) | (data[2] << 16) | (data[1] << 8) | data[0];
+
+	return r;
+}
+
+static int fl2k_write_reg(fl2k_dev_t *dev, uint16_t reg, uint32_t val)
+{
+	uint8_t data[4];
+
+	if (!dev)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	data[0] = val & 0xff;
+	data[1] = (val >> 8) & 0xff;
+	data[2] = (val >> 16) & 0xff;
+	data[3] = (val >> 24) & 0xff;
+
+	return libusb_control_transfer(dev->devh, CTRL_OUT, 0x41,
+				       0, reg, data, 4, CTRL_TIMEOUT);
+}
+
+int fl2k_init_device(fl2k_dev_t *dev)
+{
+	if (!dev)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	/* initialization */
+	fl2k_write_reg(dev, 0x8020, 0xdf0000cc);
+
+	/* set DAC freq to lowest value possible to avoid
+	 * underrun during init */
+	fl2k_write_reg(dev, 0x802c, 0x00416f3f);
+
+	fl2k_write_reg(dev, 0x8048, 0x7ffb8004);
+	fl2k_write_reg(dev, 0x803c, 0xd701004d);
+	fl2k_write_reg(dev, 0x8004, 0x0000031c);
+	fl2k_write_reg(dev, 0x8004, 0x0010039d);
+	fl2k_write_reg(dev, 0x8008, 0x07800898);
+
+	fl2k_write_reg(dev, 0x801c, 0x00000000);
+	fl2k_write_reg(dev, 0x0070, 0x04186085);
+
+	/* blanking magic */
+	fl2k_write_reg(dev, 0x8008, 0xfeff0780);
+	fl2k_write_reg(dev, 0x800c, 0x0000f001);
+
+	/* VSYNC magic */
+	fl2k_write_reg(dev, 0x8010, 0x0400042a);
+	fl2k_write_reg(dev, 0x8014, 0x0010002d);
+
+	fl2k_write_reg(dev, 0x8004, 0x00000002);
+
+	return 0;
+}
+
+int fl2k_deinit_device(fl2k_dev_t *dev)
+{
+	int r = 0;
+
+	if (!dev)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	/* TODO, power down DACs, PLL, put device in reset */
+
+	return r;
+}
+
+static double fl2k_reg_to_freq(uint32_t reg)
+{
+	double sample_clock, offset, offs_div;
+	uint32_t pll_clock = 160000000;
+	uint8_t div = reg & 0x3f;
+	uint8_t out_div = (reg >> 8) & 0xf;
+	uint8_t frac = (reg >> 16) & 0xf;
+	uint8_t mult = (reg >> 20) & 0xf;
+
+	sample_clock = (pll_clock * mult) / (uint32_t)div;
+	offs_div = (pll_clock / 5.0f ) * mult;
+	offset = ((double)sample_clock/(offs_div/2)) * 1000000.0f;
+	sample_clock += (uint32_t)offset * frac;
+	sample_clock /= out_div;
+
+//	fprintf(stderr, "div: %d\tod: %d\tfrac: %d\tmult %d\tclock: %f\treg "
+//			"%08x\n", div, out_div, frac, mult, sample_clock, reg);
+
+	return sample_clock;
+}
+
+int fl2k_set_sample_rate(fl2k_dev_t *dev, uint32_t target_freq)
+{
+	double sample_clock, error, last_error = 1e20f;
+	uint32_t reg = 0, result_reg = 0;
+	uint8_t div, mult, frac, out_div;
+
+	if (!dev)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	/* Output divider (accepts value 1-15) 
+	 * works, but adds lots of phase noise, so do not use it */
+	out_div = 1;
+
+	/* Observation: PLL multiplier of 7 works, but has more phase
+	 * noise. Prefer multiplier 6 and 5 */
+	for (mult = 6; mult >= 3; mult--) {
+		for (div = 63; div > 1; div--) {
+			for (frac = 1; frac <= 15; frac++) {
+				reg =  (mult << 20) | (frac << 16) |
+				       (0x60 << 8) | (out_div << 8) | div;
+
+				sample_clock = fl2k_reg_to_freq(reg);
+				error = sample_clock - (double)target_freq;
+
+				/* Keep closest match */
+				if (fabsf(error) < last_error) {
+					result_reg = reg;
+					last_error = fabsf(error);
+				}
+			}
+		}
+	}
+
+	sample_clock = fl2k_reg_to_freq(result_reg);
+	error = sample_clock - (double)target_freq;
+	dev->rate = sample_clock;
+
+	if (fabsf(error) > 1)
+		fprintf(stderr, "Requested sample rate %d not possible, using"
+		                " %f, error is %f\n", target_freq, sample_clock, error); 
+
+	return fl2k_write_reg(dev, 0x802c, result_reg);
+}
+
+uint32_t fl2k_get_sample_rate(fl2k_dev_t *dev)
+{
+	if (!dev)
+		return 0;
+
+	return (uint32_t)dev->rate;
+}
+
+static fl2k_dongle_t *find_known_device(uint16_t vid, uint16_t pid)
+{
+	unsigned int i;
+	fl2k_dongle_t *device = NULL;
+
+	for (i = 0; i < sizeof(known_devices)/sizeof(fl2k_dongle_t); i++ ) {
+		if (known_devices[i].vid == vid && known_devices[i].pid == pid) {
+			device = &known_devices[i];
+			break;
+		}
+	}
+
+	return device;
+}
+
+uint32_t fl2k_get_device_count(void)
+{
+	int i,r;
+	libusb_context *ctx;
+	libusb_device **list;
+	uint32_t device_count = 0;
+	struct libusb_device_descriptor dd;
+	ssize_t cnt;
+
+	r = libusb_init(&ctx);
+	if (r < 0)
+		return 0;
+
+	cnt = libusb_get_device_list(ctx, &list);
+
+	for (i = 0; i < cnt; i++) {
+		libusb_get_device_descriptor(list[i], &dd);
+
+		if (find_known_device(dd.idVendor, dd.idProduct))
+			device_count++;
+	}
+
+	libusb_free_device_list(list, 1);
+
+	libusb_exit(ctx);
+
+	return device_count;
+}
+
+const char *fl2k_get_device_name(uint32_t index)
+{
+	int i,r;
+	libusb_context *ctx;
+	libusb_device **list;
+	struct libusb_device_descriptor dd;
+	fl2k_dongle_t *device = NULL;
+	uint32_t device_count = 0;
+	ssize_t cnt;
+
+	r = libusb_init(&ctx);
+	if (r < 0)
+		return "";
+
+	cnt = libusb_get_device_list(ctx, &list);
+
+	for (i = 0; i < cnt; i++) {
+		libusb_get_device_descriptor(list[i], &dd);
+
+		device = find_known_device(dd.idVendor, dd.idProduct);
+
+		if (device) {
+			device_count++;
+
+			if (index == device_count - 1)
+				break;
+		}
+	}
+
+	libusb_free_device_list(list, 1);
+
+	libusb_exit(ctx);
+
+	if (device)
+		return device->name;
+	else
+		return "";
+}
+
+int fl2k_open(fl2k_dev_t **out_dev, uint32_t index)
+{
+	int r;
+	int i;
+	libusb_device **list;
+	fl2k_dev_t *dev = NULL;
+	libusb_device *device = NULL;
+	uint32_t device_count = 0;
+	struct libusb_device_descriptor dd;
+	uint8_t reg;
+	ssize_t cnt;
+
+	dev = malloc(sizeof(fl2k_dev_t));
+	if (NULL == dev)
+		return -ENOMEM;
+
+	memset(dev, 0, sizeof(fl2k_dev_t));
+
+	r = libusb_init(&dev->ctx);
+	if(r < 0){
+		free(dev);
+		return -1;
+	}
+
+	libusb_set_debug(dev->ctx, 3);
+
+	dev->dev_lost = 1;
+
+	cnt = libusb_get_device_list(dev->ctx, &list);
+
+	for (i = 0; i < cnt; i++) {
+		device = list[i];
+
+		libusb_get_device_descriptor(list[i], &dd);
+
+		if (find_known_device(dd.idVendor, dd.idProduct)) {
+			device_count++;
+		}
+
+		if (index == device_count - 1)
+			break;
+
+		device = NULL;
+	}
+
+	if (!device) {
+		r = -1;
+		goto err;
+	}
+
+	r = libusb_open(device, &dev->devh);
+	libusb_free_device_list(list, 1);
+	if (r < 0) {
+		fprintf(stderr, "usb_open error %d\n", r);
+		if(r == LIBUSB_ERROR_ACCESS)
+			fprintf(stderr, "Please fix the device permissions, e.g. "
+			"by installing the udev rules file\n");
+		goto err;
+	}
+
+	/* If the adapter has an SPI flash for the Windows driver, we
+	 * need to detach the USB mass storage driver first in order to
+	 * open the device */
+	if (libusb_kernel_driver_active(dev->devh, 3) == 1) {
+		fprintf(stderr, "Kernel mass storage driver is attached, "
+				"detaching driver. This may take more than"
+				" 10 seconds!\n");
+		r = libusb_detach_kernel_driver(dev->devh, 3);
+		if (r < 0) {
+			fprintf(stderr, "Failed to detach mass storage "
+					"driver: %d\n", r);
+			goto err;
+		}
+	}
+
+	r = libusb_claim_interface(dev->devh, 0);
+	if (r < 0) {
+		fprintf(stderr, "usb_claim_interface 0 error %d\n", r);
+		goto err;
+	}
+	r = libusb_claim_interface(dev->devh, 1);
+
+	if (r < 0) {
+		fprintf(stderr, "usb_claim_interface 1 error %d\n", r);
+		goto err;
+	}
+
+	r = fl2k_init_device(dev);
+	if (r < 0)
+		goto err;
+
+	dev->dev_lost = 0;
+
+found:
+	*out_dev = dev;
+
+	return 0;
+err:
+	if (dev) {
+		if (dev->ctx)
+			libusb_exit(dev->ctx);
+
+		free(dev);
+	}
+
+	return r;
+}
+
+int fl2k_close(fl2k_dev_t *dev)
+{
+	if (!dev)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	if(!dev->dev_lost) {
+		/* block until all async operations have been completed (if any) */
+		while (FL2K_INACTIVE != dev->async_status) {
+#ifdef _WIN32
+			Sleep(1);
+#else
+			usleep(1000);
+#endif
+		}
+
+		fl2k_deinit_device(dev);
+	}
+
+	libusb_release_interface(dev->devh, 0);
+	libusb_close(dev->devh);
+	libusb_exit(dev->ctx);
+
+	free(dev);
+
+	return 0;
+}
+
+static struct libusb_transfer *fl2k_get_next_xfer(fl2k_dev_t *dev,
+					          fl2k_buf_state_t state)
+{
+	unsigned int i;
+	int next_buf = -1;
+	uint64_t next_seq = 0;
+	fl2k_xfer_info_t *xfer_info;
+
+	for (i = 0; i < dev->xfer_buf_num; i++) {
+		xfer_info = (fl2k_xfer_info_t *)dev->xfer[i]->user_data;
+		if (!xfer_info)
+			continue;
+
+		if (xfer_info->state == state) {
+			if (state == BUF_EMPTY) {
+				return dev->xfer[i];
+			} else if ((xfer_info->seq < next_seq) || next_buf < 0) {
+				next_seq = xfer_info->seq;
+				next_buf = i;
+			}
+		}
+	}
+
+	if ((state == BUF_FILLED) && (next_buf >= 0))
+		return dev->xfer[next_buf];
+	else
+		return NULL;
+}
+
+static void LIBUSB_CALL _libusb_callback(struct libusb_transfer *xfer)
+{
+	fl2k_xfer_info_t *xfer_info = (fl2k_xfer_info_t *)xfer->user_data;
+	fl2k_xfer_info_t *next_xfer_info;
+	fl2k_dev_t *dev = (fl2k_dev_t *)xfer_info->dev;
+	struct libusb_transfer *next_xfer = NULL;
+
+	if (LIBUSB_TRANSFER_COMPLETED == xfer->status) {
+		/* resubmit transfer */
+		if (FL2K_RUNNING == dev->async_status) {
+			/* get next transfer */
+			next_xfer = fl2k_get_next_xfer(dev, BUF_FILLED);
+
+			if (next_xfer) {
+				next_xfer_info = (fl2k_xfer_info_t *) next_xfer->user_data;
+
+				/* Submit next filled transfer */
+				next_xfer_info->state = BUF_SUBMITTED;
+				libusb_submit_transfer(next_xfer);
+
+				xfer_info->state = BUF_EMPTY;
+				pthread_cond_signal(&dev->buf_cond);
+			} else {
+				/* We need to re-submit the transfer
+				 * in any case, as otherwise the device
+				 * stops to output data and hangs
+				 * (happens only in the hacked 'gapless'
+				 * mode without HSYNC and VSYNC)  */
+				libusb_submit_transfer(xfer);
+				pthread_cond_signal(&dev->buf_cond);
+				dev->underflow_cnt++;
+			}
+		}
+	} else if (LIBUSB_TRANSFER_CANCELLED != xfer->status) {
+			dev->dev_lost = 1;
+			fl2k_stop_tx(dev);
+			pthread_cond_signal(&dev->buf_cond);
+			fprintf(stderr, "cb transfer status: %d, "
+				"canceling...\n", xfer->status);
+	}
+}
+
+static int fl2k_alloc_submit_transfers(fl2k_dev_t *dev)
+{
+	unsigned int i;
+	int r = 0;
+
+	if (!dev)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	dev->xfer = malloc(dev->xfer_buf_num * sizeof(struct libusb_transfer *));
+
+	for (i = 0; i < dev->xfer_buf_num; ++i)
+		dev->xfer[i] = libusb_alloc_transfer(0);
+
+	dev->xfer_buf = malloc(dev->xfer_buf_num * sizeof(unsigned char *));
+	dev->xfer_info = malloc(dev->xfer_buf_num * sizeof(fl2k_xfer_info_t));
+
+#if defined (__linux__) && LIBUSB_API_VERSION >= 0x01000105
+	fprintf(stderr, "Using %d zero-copy buffers\n", dev->xfer_buf_num);
+
+	dev->use_zerocopy = 1;
+	for (i = 0; i < dev->xfer_buf_num; ++i) {
+		dev->xfer_buf[i] = libusb_dev_mem_alloc(dev->devh, dev->xfer_buf_len);
+
+		if (!dev->xfer_buf[i]) {
+			fprintf(stderr, "Failed to allocate zerocopy"
+					" buffer for transfer %d\n",
+					 i);
+
+			// TODO: free dev_mem buffers again
+			dev->use_zerocopy = 0;
+			break;
+		}
+	}
+#endif
+
+	if (!dev->use_zerocopy) {
+		for (i = 0; i < dev->xfer_buf_num; ++i) {
+			dev->xfer_buf[i] = malloc(dev->xfer_buf_len);
+
+			if (!dev->xfer_buf[i])
+				return FL2K_ERROR_NO_MEM;
+		}
+	}
+
+	/* fill transfers */
+	for (i = 0; i < dev->xfer_buf_num; ++i) {
+		libusb_fill_bulk_transfer(dev->xfer[i],
+					  dev->devh,
+					  0x01,
+					  dev->xfer_buf[i],
+					  dev->xfer_buf_len,
+					  _libusb_callback,
+					  &dev->xfer_info[i],
+					  0);
+
+		dev->xfer_info[i].dev = dev;
+		dev->xfer_info[i].state = BUF_EMPTY;
+
+		/* if we allocate the memory through the Kernel, it is
+		 * already cleared */
+		if (!dev->use_zerocopy)
+			memset(dev->xfer_buf[i], 0, dev->xfer_buf_len);
+	}
+
+	/* submit transfers */
+	for (i = 0; i < dev->xfer_num; ++i) {
+		r = libusb_submit_transfer(dev->xfer[i]);
+		dev->xfer_info[i].state = BUF_SUBMITTED;
+
+		if (r < 0) {
+			fprintf(stderr, "Failed to submit transfer %i\n"
+					"Please increase your allowed " 
+					"usbfs buffer size with the "
+					"following command:\n"
+					"echo 0 > /sys/module/usbcore"
+					"/parameters/usbfs_memory_mb\n", i);
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int _fl2k_free_async_buffers(fl2k_dev_t *dev)
+{
+	unsigned int i;
+
+	if (!dev)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	if (dev->xfer) {
+		for (i = 0; i < dev->xfer_buf_num; ++i) {
+			if (dev->xfer[i]) {
+				libusb_free_transfer(dev->xfer[i]);
+			}
+		}
+
+		free(dev->xfer);
+		dev->xfer = NULL;
+	}
+
+	if (dev->xfer_buf) {
+		for (i = 0; i < dev->xfer_buf_num; ++i) {
+			if (dev->xfer_buf[i]) {
+				if (dev->use_zerocopy) {
+					libusb_dev_mem_free(dev->devh,
+							    dev->xfer_buf[i],
+							    dev->xfer_buf_len);
+				} else {
+					free(dev->xfer_buf[i]);
+				}
+			}
+		}
+
+		free(dev->xfer_buf);
+		dev->xfer_buf = NULL;
+	}
+
+	return 0;
+}
+
+static void *fl2k_usb_worker(void *arg)
+{
+	fl2k_dev_t *dev = (fl2k_dev_t *)arg;
+	struct timeval tv = { 1, 0 };
+	struct timeval zerotv = { 0, 0 };
+	enum fl2k_async_status next_status = FL2K_INACTIVE;
+	int r = 0;
+	unsigned int i;
+
+	while (FL2K_RUNNING == dev->async_status) {
+		r = libusb_handle_events_timeout_completed(dev->ctx, &tv,
+							   &dev->async_cancel);
+	}
+
+	while (FL2K_INACTIVE != dev->async_status) {
+		r = libusb_handle_events_timeout_completed(dev->ctx, &tv,
+							   &dev->async_cancel);
+		if (r < 0) {
+			/*fprintf(stderr, "handle_events returned: %d\n", r);*/
+			if (r == LIBUSB_ERROR_INTERRUPTED) /* stray signal */
+				continue;
+			break;
+		}
+
+		if (FL2K_CANCELING == dev->async_status) {
+			next_status = FL2K_INACTIVE;
+
+			if (!dev->xfer)
+				break;
+
+			for (i = 0; i < dev->xfer_buf_num; ++i) {
+				if (!dev->xfer[i])
+					continue;
+
+				if (LIBUSB_TRANSFER_CANCELLED !=
+						dev->xfer[i]->status) {
+					r = libusb_cancel_transfer(dev->xfer[i]);
+					/* handle events after canceling
+					 * to allow transfer status to
+					 * propagate */
+					libusb_handle_events_timeout_completed(dev->ctx,
+									       &zerotv, NULL);
+					if (r < 0)
+						continue;
+
+					next_status = FL2K_CANCELING;
+				}
+			}
+
+			if (dev->dev_lost || FL2K_INACTIVE == next_status) {
+				/* handle any events that still need to
+				 * be handled before exiting after we
+				 * just cancelled all transfers */
+				libusb_handle_events_timeout_completed(dev->ctx,
+								       &zerotv, NULL);
+				break;
+			}
+		}
+	}
+
+	_fl2k_free_async_buffers(dev);
+	dev->async_status = next_status;
+
+	pthread_exit(NULL);
+}
+
+/* Buffer format conversion functions for R, G, B DACs */
+static inline void fl2k_convert_r(char *out,
+				  char *in,
+				  uint32_t len,
+				  uint8_t offset)
+{
+	unsigned int i, j = 0;
+
+	if (!in || !out)
+		return;
+
+	for (i = 0; i < len; i += 24) {
+		out[i+ 6] = in[j++] + offset;
+		out[i+ 1] = in[j++] + offset;
+		out[i+12] = in[j++] + offset;
+		out[i+15] = in[j++] + offset;
+		out[i+10] = in[j++] + offset;
+		out[i+21] = in[j++] + offset;
+		out[i+16] = in[j++] + offset;
+		out[i+19] = in[j++] + offset;
+	}
+}
+
+static inline void fl2k_convert_g(char *out,
+				  char *in,
+				  uint32_t len,
+				  uint8_t offset)
+{
+	unsigned int i, j = 0;
+
+	if (!in || !out)
+		return;
+
+	for (i = 0; i < len; i += 24) {
+		out[i+ 5] = in[j++] + offset;
+		out[i+ 0] = in[j++] + offset;
+		out[i+ 3] = in[j++] + offset;
+		out[i+14] = in[j++] + offset;
+		out[i+ 9] = in[j++] + offset;
+		out[i+20] = in[j++] + offset;
+		out[i+23] = in[j++] + offset;
+		out[i+18] = in[j++] + offset;
+	}
+}
+
+static inline void fl2k_convert_b(char *out,
+				  char *in,
+				  uint32_t len,
+				  uint8_t offset)
+{
+	unsigned int i, j = 0;
+
+	if (!in || !out)
+		return;
+
+	for (i = 0; i < len; i += 24) {
+		out[i+ 4] = in[j++] + offset;
+		out[i+ 7] = in[j++] + offset;
+		out[i+ 2] = in[j++] + offset;
+		out[i+13] = in[j++] + offset;
+		out[i+ 8] = in[j++] + offset;
+		out[i+11] = in[j++] + offset;
+		out[i+22] = in[j++] + offset;
+		out[i+17] = in[j++] + offset;
+	}
+}
+
+static void *fl2k_sample_worker(void *arg)
+{
+	int r = 0;
+	unsigned int i, j;
+	fl2k_dev_t *dev = (fl2k_dev_t *)arg;
+	fl2k_xfer_info_t *xfer_info = NULL;
+	struct libusb_transfer *xfer = NULL;
+	char *out_buf = NULL;
+	fl2k_data_info_t data_info;
+	uint32_t underflows = 0;
+	uint64_t buf_cnt = 0;
+
+	while (FL2K_RUNNING == dev->async_status) {
+		memset(&data_info, 0, sizeof(fl2k_data_info_t));
+
+		data_info.len = FL2K_BUF_LEN;
+		data_info.underflow_cnt = dev->underflow_cnt;
+		data_info.ctx = dev->cb_ctx;
+
+		if (dev->underflow_cnt > underflows) {
+			fprintf(stderr, "Underflow! Skipped %d buffers\n",
+					dev->underflow_cnt - underflows);
+			underflows = dev->underflow_cnt;
+		}
+
+		/* call application callback to get samples */
+		if (dev->cb)
+			dev->cb(&data_info);
+
+		xfer = fl2k_get_next_xfer(dev, BUF_EMPTY);
+
+		if (!xfer) {
+			pthread_cond_wait(&dev->buf_cond, &dev->buf_mutex);
+			/* in the meantime, the device might be gone */
+			if (FL2K_RUNNING != dev->async_status)
+				break;
+
+			xfer = fl2k_get_next_xfer(dev, BUF_EMPTY);
+			if (!xfer) {
+				fprintf(stderr, "no free transfer, skipping"
+						" input buffer\n");
+				continue;
+			}
+		}
+
+		/* We have an empty USB transfer buffer */
+		xfer_info = (fl2k_xfer_info_t *)xfer->user_data;
+		out_buf = (char *)xfer->buffer;
+
+		/* Re-arrange and copy bytes in buffer for DACs */
+		fl2k_convert_r(out_buf, data_info.r_buf, dev->xfer_buf_len,
+			       data_info.sampletype_signed ? 128 : 0);
+
+		fl2k_convert_g(out_buf, data_info.g_buf, dev->xfer_buf_len,
+			       data_info.sampletype_signed ? 128 : 0);
+
+		fl2k_convert_b(out_buf, data_info.b_buf, dev->xfer_buf_len,
+			       data_info.sampletype_signed ? 128 : 0);
+
+		xfer_info->seq = buf_cnt++;
+		xfer_info->state = BUF_FILLED;
+	}
+
+	/* notify application if we've lost the device */
+	if (dev->dev_lost && dev->cb) {
+		data_info.device_error = 1;
+		dev->cb(&data_info);
+		fl2k_stop_tx(dev);
+	}
+
+	pthread_exit(NULL);
+}
+
+
+int fl2k_start_tx(fl2k_dev_t *dev, fl2k_tx_cb_t cb, void *ctx,
+		  uint32_t buf_num)
+{
+	int r = 0;
+	int i;
+	pthread_attr_t attr;
+
+	if (!dev || !cb)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	dev->async_status = FL2K_RUNNING;
+	dev->async_cancel = 0;
+
+	dev->cb = cb;
+	dev->cb_ctx = ctx;
+
+	if (buf_num > 0)
+		dev->xfer_num = buf_num;
+	else
+		dev->xfer_num = DEFAULT_BUF_NUMBER;
+
+	/* have two spare buffers that can be filled while the
+	 * others are submitted */
+	dev->xfer_buf_num = dev->xfer_num + 2;
+	dev->xfer_buf_len = FL2K_XFER_LEN;
+
+	r = fl2k_alloc_submit_transfers(dev);
+	if (r < 0)
+		goto cleanup;
+
+	pthread_mutex_init(&dev->buf_mutex, NULL);
+	pthread_cond_init(&dev->buf_cond, NULL);
+	pthread_attr_init(&attr);
+
+	r = pthread_create(&dev->usb_worker_thread, &attr,
+			   fl2k_usb_worker, (void *)dev);
+	if (r < 0) {
+		fprintf(stderr, "Error spawning USB worker thread!\n");
+		goto cleanup;
+	}
+
+	r = pthread_create(&dev->sample_worker_thread, &attr,
+			   fl2k_sample_worker, (void *)dev);
+	if (r < 0) {
+		fprintf(stderr, "Error spawning sample worker thread!\n");
+		goto cleanup;
+	}
+
+	pthread_attr_destroy(&attr);
+
+	return 0;
+
+cleanup:
+	_fl2k_free_async_buffers(dev);
+	return FL2K_ERROR_BUSY;
+
+}
+
+int fl2k_stop_tx(fl2k_dev_t *dev)
+{
+	if (!dev)
+		return FL2K_ERROR_INVALID_PARAM;
+
+	/* if streaming, try to cancel gracefully */
+	if (FL2K_RUNNING == dev->async_status) {
+		dev->async_status = FL2K_CANCELING;
+		dev->async_cancel = 1;
+		return 0;
+	/* if called while in pending state, change the state forcefully */
+	} else if (FL2K_INACTIVE != dev->async_status) {
+		dev->async_status = FL2K_INACTIVE;
+		return 0;
+	}
+
+	return FL2K_ERROR_BUSY;
+}
diff --git a/src/libosmo-fl2k.rc.in b/src/libosmo-fl2k.rc.in
new file mode 100644
index 0000000..48747e4
--- /dev/null
+++ b/src/libosmo-fl2k.rc.in
@@ -0,0 +1,34 @@
+
+#include <afxres.h>
+
+VS_VERSION_INFO VERSIONINFO
+  FILEVERSION 0,0,0,0
+  PRODUCTVERSION 0,0,0,0
+  FILEFLAGSMASK 0x3fL
+#ifndef NDEBUG
+  FILEFLAGS 0x0L
+#else
+  FILEFLAGS 0x1L
+#endif
+  FILEOS VOS__WINDOWS32
+  FILETYPE VFT_DLL
+  FILESUBTYPE VFT2_DRV_INSTALLABLE
+  BEGIN
+    BLOCK "StringFileInfo"
+    BEGIN
+      BLOCK "040904b0"
+      BEGIN
+        VALUE "FileDescription", "osmocom libosmo-fl2k"
+        VALUE "FileVersion", "@VERSION@"
+        VALUE "InternalName", "libosmo-fl2k.dll"
+        VALUE "LegalCopyright", "Licensed under GPLv2+"
+        VALUE "OriginalFilename", "libosmo-fl2k.dll"
+        VALUE "ProductName", "osmocom libosmo-fl2k"
+        VALUE "ProductVersion", "@VERSION@"
+      END
+    END
+    BLOCK "VarFileInfo"
+    BEGIN
+      VALUE "Translation", 0x409, 1200
+    END
+  END