compress.c - LeafOS-Project/android_external_tinycompress - Gitiles

 /*
  * BSD LICENSE
  *
  * tinycompress library for compress audio offload in alsa
  * Copyright (c) 2011-2012, Intel Corporation
  * All rights reserved.
  *
  * Author: Vinod Koul <vinod.koul@linux.intel.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * Redistributions of source code must retain the above copyright notice,
  * this list of conditions and the following disclaimer.
  * Redistributions in binary form must reproduce the above copyright notice,
  * this list of conditions and the following disclaimer in the documentation
  * and/or other materials provided with the distribution.
  * Neither the name of Intel Corporation nor the names of its contributors
  * may be used to endorse or promote products derived from this software
  * without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  *
  * LGPL LICENSE
  *
  * tinycompress library for compress audio offload in alsa
  * Copyright (c) 2011-2012, Intel Corporation.
  *
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU Lesser General Public License,
  * version 2.1, as published by the Free Software Foundation.
  *
  * This program is distributed in the hope 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 this program; if not, write to
  * the Free Software Foundation, Inc.,
  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  */

 #include <stdio.h>
 #include <stdlib.h>
 #include <fcntl.h>
 #include <stdarg.h>
 #include <string.h>
 #include <errno.h>
 #include <unistd.h>
 #include <poll.h>
 #include <stdbool.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <sys/time.h>
 #include <limits.h>

 #include <linux/types.h>
 #include <linux/ioctl.h>
 #define __force
 #define __bitwise
 #define __user
 #include <sound/asound.h>
 #include "sound/compress_params.h"
 #include "sound/compress_offload.h"
 #include "tinycompress/tinycompress.h"

 #define COMPR_ERR_MAX 128

 /* Default maximum time we will wait in a poll() - 20 seconds */
 #define DEFAULT_MAX_POLL_WAIT_MS    20000

 struct compress {
 	int fd;
 	unsigned int flags;
 	char error[COMPR_ERR_MAX];
 	struct compr_config *config;
 	int running;
 	int max_poll_wait_ms;
 	int nonblocking;
 	unsigned int gapless_metadata;
 	unsigned int next_track;
 };

 static int oops(struct compress *compress, int e, const char *fmt, ...)
 {
 	va_list ap;
 	int sz;

 	va_start(ap, fmt);
 	vsnprintf(compress->error, COMPR_ERR_MAX, fmt, ap);
 	va_end(ap);
 	sz = strlen(compress->error);

 	snprintf(compress->error + sz, COMPR_ERR_MAX - sz,
 		": %s", strerror(e));
 	errno = e;

 	return -1;
 }

 const char *compress_get_error(struct compress *compress)
 {
 	return compress->error;
 }
 static struct compress bad_compress = {
 	.fd = -1,
 };

 int is_compress_running(struct compress *compress)
 {
 	return ((compress->fd > 0) && compress->running) ? 1 : 0;
 }

 int is_compress_ready(struct compress *compress)
 {
 	return (compress->fd > 0) ? 1 : 0;
 }

 static int get_compress_version(struct compress *compress)
 {
 	int version = 0;

 	if (ioctl(compress->fd, SNDRV_COMPRESS_IOCTL_VERSION, &version)) {
 		oops(compress, errno, "cant read version");
 		return -1;
 	}
 	return version;
 }

 static bool _is_codec_supported(struct compress *compress, struct compr_config *config,
 				const struct snd_compr_caps *caps)
 {
 	bool codec = false;
 	unsigned int i;

 	for (i = 0; i < caps->num_codecs; i++) {
 		if (caps->codecs[i] == config->codec->id) {
 			/* found the codec */
 			codec = true;
 			break;
 		}
 	}
 	if (codec == false) {
 		oops(compress, ENXIO, "this codec is not supported");
 		return false;
 	}

 	if (config->fragment_size < caps->min_fragment_size) {
 		oops(compress, EINVAL, "requested fragment size %d is below min supported %d",
 			config->fragment_size, caps->min_fragment_size);
 		return false;
 	}
 	if (config->fragment_size > caps->max_fragment_size) {
 		oops(compress, EINVAL, "requested fragment size %d is above max supported %d",
 			config->fragment_size, caps->max_fragment_size);
 		return false;
 	}
 	if (config->fragments < caps->min_fragments) {
 		oops(compress, EINVAL, "requested fragments %d are below min supported %d",
 			config->fragments, caps->min_fragments);
 		return false;
 	}
 	if (config->fragments > caps->max_fragments) {
 		oops(compress, EINVAL, "requested fragments %d are above max supported %d",
 			config->fragments, caps->max_fragments);
 		return false;
 	}

 	/* TODO: match the codec properties */
 	return true;
 }

 static bool _is_codec_type_supported(int fd, struct snd_codec *codec)
 {
 	struct snd_compr_caps caps;
 	bool found = false;
 	unsigned int i;

 	if (ioctl(fd, SNDRV_COMPRESS_GET_CAPS, &caps)) {
 		oops(&bad_compress, errno, "cannot get device caps");
 		return false;
 	}

 	for (i = 0; i < caps.num_codecs; i++) {
 		if (caps.codecs[i] == codec->id) {
 			/* found the codec */
 			found = true;
 			break;
 		}
 	}
 	/* TODO: match the codec properties */
 	return found;
 }

 static inline void
 fill_compress_params(struct compr_config *config, struct snd_compr_params *params)
 {
 	params->buffer.fragment_size = config->fragment_size;
 	params->buffer.fragments = config->fragments;
 	memcpy(&params->codec, config->codec, sizeof(params->codec));
 }

 struct compress *compress_open(unsigned int card, unsigned int device,
 		unsigned int flags, struct compr_config *config)
 {
 	struct compress *compress;
 	struct snd_compr_params params;
 	struct snd_compr_caps caps;
 	char fn[256];

 	if (!config) {
 		oops(&bad_compress, EINVAL, "passed bad config");
 		return &bad_compress;
 	}

 	compress = calloc(1, sizeof(struct compress));
 	if (!compress) {
 		oops(&bad_compress, errno, "cannot allocate compress object");
 		return &bad_compress;
 	}

 	compress->next_track = 0;
 	compress->gapless_metadata = 0;
 	compress->config = calloc(1, sizeof(*config));
 	if (!compress->config)
 		goto input_fail;

 	snprintf(fn, sizeof(fn), "/dev/snd/comprC%uD%u", card, device);

 	compress->max_poll_wait_ms = DEFAULT_MAX_POLL_WAIT_MS;

 	compress->flags = flags;
 	if (!((flags & COMPRESS_OUT) || (flags & COMPRESS_IN))) {
 		oops(&bad_compress, EINVAL, "can't deduce device direction from given flags");
 		goto config_fail;
 	}

 	if (flags & COMPRESS_OUT) {
 		compress->fd = open(fn, O_RDONLY);
 	} else {
 		compress->fd = open(fn, O_WRONLY);
 	}
 	if (compress->fd < 0) {
 		oops(&bad_compress, errno, "cannot open device '%s'", fn);
 		goto config_fail;
 	}

 	if (ioctl(compress->fd, SNDRV_COMPRESS_GET_CAPS, &caps)) {
 		oops(compress, errno, "cannot get device caps");
 		goto codec_fail;
 	}

 	/* If caller passed "don't care" fill in default values */
 	if ((config->fragment_size == 0) || (config->fragments == 0)) {
 		config->fragment_size = caps.min_fragment_size;
 		config->fragments = caps.max_fragments;
 	}

 #if 0
 	/* FIXME need to turn this On when DSP supports
 	 * and treat in no support case
 	 */
 	if (_is_codec_supported(compress, config, &caps) == false) {
 		oops(compress, errno, "codec not supported\n");
 		goto codec_fail;
 	}
 #endif

 	memcpy(compress->config, config, sizeof(*compress->config));
 	fill_compress_params(config, &params);

 	if (ioctl(compress->fd, SNDRV_COMPRESS_SET_PARAMS, &params)) {
 		oops(&bad_compress, errno, "cannot set device");
 		goto codec_fail;
 	}

 	return compress;

 codec_fail:
 	close(compress->fd);
 	compress->fd = -1;
 config_fail:
 	free(compress->config);
 input_fail:
 	free(compress);
 	return &bad_compress;
 }

 void compress_close(struct compress *compress)
 {
 	if (compress == &bad_compress)
 		return;

 	if (compress->fd >= 0)
 		close(compress->fd);
 	compress->running = 0;
 	compress->fd = -1;
 	free(compress->config);
 	free(compress);
 }

 int compress_get_hpointer(struct compress *compress,
 		unsigned int *avail, struct timespec *tstamp)
 {
 	struct snd_compr_avail kavail;
 	__u64 time;

 	if (!is_compress_ready(compress))
 		return oops(compress, ENODEV, "device not ready");

 	if (ioctl(compress->fd, SNDRV_COMPRESS_AVAIL, &kavail))
 		return oops(compress, errno, "cannot get avail");
 	if (0 == kavail.tstamp.sampling_rate)
 		return oops(compress, ENODATA, "sample rate unknown");
 	*avail = (unsigned int)kavail.avail;
 	time = kavail.tstamp.pcm_io_frames / kavail.tstamp.sampling_rate;
 	tstamp->tv_sec = time;
 	time = kavail.tstamp.pcm_io_frames % kavail.tstamp.sampling_rate;
 	tstamp->tv_nsec = time * 1000000000 / kavail.tstamp.sampling_rate;
 	return 0;
 }

 int compress_get_tstamp(struct compress *compress,
 			unsigned long *samples, unsigned int *sampling_rate)
 {
 	struct snd_compr_tstamp ktstamp;

 	if (!is_compress_ready(compress))
 		return oops(compress, ENODEV, "device not ready");

 	if (ioctl(compress->fd, SNDRV_COMPRESS_TSTAMP, &ktstamp))
 		return oops(compress, errno, "cannot get tstamp");

 	*samples = ktstamp.pcm_io_frames;
 	*sampling_rate = ktstamp.sampling_rate;
 	return 0;
 }

 int compress_write(struct compress *compress, const void *buf, unsigned int size)
 {
 	struct snd_compr_avail avail;
 	struct pollfd fds;
 	int to_write = 0;	/* zero indicates we haven't written yet */
 	int written, total = 0, ret;
 	const char* cbuf = buf;
 	const unsigned int frag_size = compress->config->fragment_size;

 	if (!(compress->flags & COMPRESS_IN))
 		return oops(compress, EINVAL, "Invalid flag set");
 	if (!is_compress_ready(compress))
 		return oops(compress, ENODEV, "device not ready");
 	fds.fd = compress->fd;
 	fds.events = POLLOUT;

 	/*TODO: treat auto start here first */
 	while (size) {
 		if (ioctl(compress->fd, SNDRV_COMPRESS_AVAIL, &avail))
 			return oops(compress, errno, "cannot get avail");

 		/* We can write if we have at least one fragment available
 		 * or there is enough space for all remaining data
 		 */
 		if ((avail.avail < frag_size) && (avail.avail < size)) {

 			if (compress->nonblocking)
 				return total;

 			ret = poll(&fds, 1, compress->max_poll_wait_ms);
 			if (fds.revents & POLLERR) {
 				return oops(compress, EIO, "poll returned error!");
 			}
 			/* A pause will cause -EBADFD or zero.
 			 * This is not an error, just stop writing */
 			if ((ret == 0) || (ret == -EBADFD))
 				break;
 			if (ret < 0)
 				return oops(compress, errno, "poll error");
 			if (fds.revents & POLLOUT) {
 				continue;
 			}
 		}
 		/* write avail bytes */
 		if (size > avail.avail)
 			to_write =  avail.avail;
 		else
 			to_write = size;
 		written = write(compress->fd, cbuf, to_write);
 		/* If play was paused the write returns -EBADFD */
 		if (written == -EBADFD)
 			break;
 		if (written < 0)
 			return oops(compress, errno, "write failed!");

 		size -= written;
 		cbuf += written;
 		total += written;
 	}
 	return total;
 }

 int compress_read(struct compress *compress, void *buf, unsigned int size)
 {
 	struct snd_compr_avail avail;
 	struct pollfd fds;
 	int to_read = 0;
 	int num_read, total = 0, ret;
 	char* cbuf = buf;
 	const unsigned int frag_size = compress->config->fragment_size;

 	if (!(compress->flags & COMPRESS_OUT))
 		return oops(compress, EINVAL, "Invalid flag set");
 	if (!is_compress_ready(compress))
 		return oops(compress, ENODEV, "device not ready");
 	fds.fd = compress->fd;
 	fds.events = POLLIN;

 	while (size) {
 		if (ioctl(compress->fd, SNDRV_COMPRESS_AVAIL, &avail))
 			return oops(compress, errno, "cannot get avail");

 		if ( (avail.avail < frag_size) && (avail.avail < size) ) {
 			/* Less than one fragment available and not at the
 			 * end of the read, so poll
 			 */
 			if (compress->nonblocking)
 				return total;

 			ret = poll(&fds, 1, compress->max_poll_wait_ms);
 			if (fds.revents & POLLERR) {
 				return oops(compress, EIO, "poll returned error!");
 			}
 			/* A pause will cause -EBADFD or zero.
 			 * This is not an error, just stop reading */
 			if ((ret == 0) || (ret == -EBADFD))
 				break;
 			if (ret < 0)
 				return oops(compress, errno, "poll error");
 			if (fds.revents & POLLIN) {
 				continue;
 			}
 		}
 		/* read avail bytes */
 		if (size > avail.avail)
 			to_read = avail.avail;
 		else
 			to_read = size;
 		num_read = read(compress->fd, cbuf, to_read);
 		/* If play was paused the read returns -EBADFD */
 		if (num_read == -EBADFD)
 			break;
 		if (num_read < 0)
 			return oops(compress, errno, "read failed!");

 		size -= num_read;
 		cbuf += num_read;
 		total += num_read;
 	}

 	return total;
 }

 int compress_start(struct compress *compress)
 {
 	if (!is_compress_ready(compress))
 		return oops(compress, ENODEV, "device not ready");
 	if (ioctl(compress->fd, SNDRV_COMPRESS_START))
 		return oops(compress, errno, "cannot start the stream");
 	compress->running = 1;
 	return 0;

 }

 int compress_stop(struct compress *compress)
 {
 	if (!is_compress_running(compress))
 		return oops(compress, ENODEV, "device not ready");
 	if (ioctl(compress->fd, SNDRV_COMPRESS_STOP))
 		return oops(compress, errno, "cannot stop the stream");
 	return 0;
 }

 int compress_pause(struct compress *compress)
 {
 	if (!is_compress_running(compress))
 		return oops(compress, ENODEV, "device not ready");
 	if (ioctl(compress->fd, SNDRV_COMPRESS_PAUSE))
 		return oops(compress, errno, "cannot pause the stream");
 	return 0;
 }

 int compress_resume(struct compress *compress)
 {
 	if (ioctl(compress->fd, SNDRV_COMPRESS_RESUME))
 		return oops(compress, errno, "cannot resume the stream");
 	return 0;
 }

 int compress_drain(struct compress *compress)
 {
 	if (!is_compress_running(compress))
 		return oops(compress, ENODEV, "device not ready");
 	if (ioctl(compress->fd, SNDRV_COMPRESS_DRAIN))
 		return oops(compress, errno, "cannot drain the stream");
 	return 0;
 }

 int compress_partial_drain(struct compress *compress)
 {
 	if (!is_compress_running(compress))
 		return oops(compress, ENODEV, "device not ready");

 	if (!compress->next_track)
 		return oops(compress, EPERM, "next track not signalled");
 	if (ioctl(compress->fd, SNDRV_COMPRESS_PARTIAL_DRAIN))
 		return oops(compress, errno, "cannot drain the stream\n");
 	compress->next_track = 0;
 	return 0;
 }

 int compress_next_track(struct compress *compress)
 {
 	if (!is_compress_running(compress))
 		return oops(compress, ENODEV, "device not ready");

 	if (!compress->gapless_metadata)
 		return oops(compress, EPERM, "metadata not set");
 	if (ioctl(compress->fd, SNDRV_COMPRESS_NEXT_TRACK))
 		return oops(compress, errno, "cannot set next track\n");
 	compress->next_track = 1;
 	compress->gapless_metadata = 0;
 	return 0;
 }

 int compress_set_gapless_metadata(struct compress *compress,
 	struct compr_gapless_mdata *mdata)
 {
 	struct snd_compr_metadata metadata;
 	int version;

 	if (!is_compress_ready(compress))
 		return oops(compress, ENODEV, "device not ready");

 	version = get_compress_version(compress);
 	if (version <= 0)
 		return -1;

 	if (version < SNDRV_PROTOCOL_VERSION(0, 1, 1))
 		return oops(compress, ENXIO, "gapless apis not supported in kernel");

 	metadata.key = SNDRV_COMPRESS_ENCODER_PADDING;
 	metadata.value[0] = mdata->encoder_padding;
 	if (ioctl(compress->fd, SNDRV_COMPRESS_SET_METADATA, &metadata))
 		return oops(compress, errno, "can't set metadata for stream\n");

 	metadata.key = SNDRV_COMPRESS_ENCODER_DELAY;
 	metadata.value[0] = mdata->encoder_delay;
 	if (ioctl(compress->fd, SNDRV_COMPRESS_SET_METADATA, &metadata))
 		return oops(compress, errno, "can't set metadata for stream\n");
 	compress->gapless_metadata = 1;
 	return 0;
 }

 bool is_codec_supported(unsigned int card, unsigned int device,
 		unsigned int flags, struct snd_codec *codec)
 {
 	unsigned int dev_flag;
 	bool ret;
 	int fd;
 	char fn[256];

 	snprintf(fn, sizeof(fn), "/dev/snd/comprC%uD%u", card, device);

 	if (flags & COMPRESS_OUT)
 		dev_flag = O_RDONLY;
 	else
 		dev_flag = O_WRONLY;

 	fd = open(fn, dev_flag);
 	if (fd < 0)
 		return oops(&bad_compress, errno, "cannot open device '%s'", fn);

 	ret = _is_codec_type_supported(fd, codec);

 	close(fd);
 	return ret;
 }

 void compress_set_max_poll_wait(struct compress *compress, int milliseconds)
 {
 	compress->max_poll_wait_ms = milliseconds;
 }

 void compress_nonblock(struct compress *compress, int nonblock)
 {
 	compress->nonblocking = !!nonblock;
 }

 int compress_wait(struct compress *compress, int timeout_ms)
 {
 	struct pollfd fds;
 	int ret;

 	fds.fd = compress->fd;
 	fds.events = POLLOUT | POLLIN;

 	ret = poll(&fds, 1, timeout_ms);
 	if (ret > 0) {
 		if (fds.revents & POLLERR)
 			return oops(compress, EIO, "poll returned error!");
 		if (fds.revents & (POLLOUT | POLLIN))
 			return 0;
 	}
 	if (ret == 0)
 		return oops(compress, ETIME, "poll timed out");
 	if (ret < 0)
 		return oops(compress, errno, "poll error");

 	return oops(compress, EIO, "poll signalled unhandled event");
 }
	/*
	* BSD LICENSE
	*
	* tinycompress library for compress audio offload in alsa
	* Copyright (c) 2011-2012, Intel Corporation
	* All rights reserved.
	*
	* Author: Vinod Koul <vinod.koul@linux.intel.com>
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are met:
	*
	* Redistributions of source code must retain the above copyright notice,
	* this list of conditions and the following disclaimer.
	* Redistributions in binary form must reproduce the above copyright notice,
	* this list of conditions and the following disclaimer in the documentation
	* and/or other materials provided with the distribution.
	* Neither the name of Intel Corporation nor the names of its contributors
	* may be used to endorse or promote products derived from this software
	* without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	* THE POSSIBILITY OF SUCH DAMAGE.
	*
	* LGPL LICENSE
	*
	* tinycompress library for compress audio offload in alsa
	* Copyright (c) 2011-2012, Intel Corporation.
	*
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms and conditions of the GNU Lesser General Public License,
	* version 2.1, as published by the Free Software Foundation.
	*
	* This program is distributed in the hope 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 this program; if not, write to
	* the Free Software Foundation, Inc.,
	* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
	*/

	#include <stdio.h>
	#include <stdlib.h>
	#include <fcntl.h>
	#include <stdarg.h>
	#include <string.h>
	#include <errno.h>
	#include <unistd.h>
	#include <poll.h>
	#include <stdbool.h>
	#include <sys/ioctl.h>
	#include <sys/mman.h>
	#include <sys/time.h>
	#include <limits.h>

	#include <linux/types.h>
	#include <linux/ioctl.h>
	#define __force
	#define __bitwise
	#define __user
	#include <sound/asound.h>
	#include "sound/compress_params.h"
	#include "sound/compress_offload.h"
	#include "tinycompress/tinycompress.h"

	#define COMPR_ERR_MAX 128

	/* Default maximum time we will wait in a poll() - 20 seconds */
	#define DEFAULT_MAX_POLL_WAIT_MS 20000

	struct compress {
	int fd;
	unsigned int flags;
	char error[COMPR_ERR_MAX];
	struct compr_config *config;
	int running;
	int max_poll_wait_ms;
	int nonblocking;
	unsigned int gapless_metadata;
	unsigned int next_track;
	};

	static int oops(struct compress compress, int e, const char fmt, ...)
	{
	va_list ap;
	int sz;

	va_start(ap, fmt);
	vsnprintf(compress->error, COMPR_ERR_MAX, fmt, ap);
	va_end(ap);
	sz = strlen(compress->error);

	snprintf(compress->error + sz, COMPR_ERR_MAX - sz,
	": %s", strerror(e));
	errno = e;

	return -1;
	}

	const char compress_get_error(struct compress compress)
	{
	return compress->error;
	}
	static struct compress bad_compress = {
	.fd = -1,
	};

	int is_compress_running(struct compress *compress)
	{
	return ((compress->fd > 0) && compress->running) ? 1 : 0;
	}

	int is_compress_ready(struct compress *compress)
	{
	return (compress->fd > 0) ? 1 : 0;
	}

	static int get_compress_version(struct compress *compress)
	{
	int version = 0;

	if (ioctl(compress->fd, SNDRV_COMPRESS_IOCTL_VERSION, &version)) {
	oops(compress, errno, "cant read version");
	return -1;
	}
	return version;
	}

	static bool _is_codec_supported(struct compress compress, struct compr_config config,
	const struct snd_compr_caps *caps)
	{
	bool codec = false;
	unsigned int i;

	for (i = 0; i < caps->num_codecs; i++) {
	if (caps->codecs[i] == config->codec->id) {
	/* found the codec */
	codec = true;
	break;
	}
	}
	if (codec == false) {
	oops(compress, ENXIO, "this codec is not supported");
	return false;
	}

	if (config->fragment_size < caps->min_fragment_size) {
	oops(compress, EINVAL, "requested fragment size %d is below min supported %d",
	config->fragment_size, caps->min_fragment_size);
	return false;
	}
	if (config->fragment_size > caps->max_fragment_size) {
	oops(compress, EINVAL, "requested fragment size %d is above max supported %d",
	config->fragment_size, caps->max_fragment_size);
	return false;
	}
	if (config->fragments < caps->min_fragments) {
	oops(compress, EINVAL, "requested fragments %d are below min supported %d",
	config->fragments, caps->min_fragments);
	return false;
	}
	if (config->fragments > caps->max_fragments) {
	oops(compress, EINVAL, "requested fragments %d are above max supported %d",
	config->fragments, caps->max_fragments);
	return false;
	}

	/* TODO: match the codec properties */
	return true;
	}

	static bool _is_codec_type_supported(int fd, struct snd_codec *codec)
	{
	struct snd_compr_caps caps;
	bool found = false;
	unsigned int i;

	if (ioctl(fd, SNDRV_COMPRESS_GET_CAPS, &caps)) {
	oops(&bad_compress, errno, "cannot get device caps");
	return false;
	}

	for (i = 0; i < caps.num_codecs; i++) {
	if (caps.codecs[i] == codec->id) {
	/* found the codec */
	found = true;
	break;
	}
	}
	/* TODO: match the codec properties */
	return found;
	}

	static inline void
	fill_compress_params(struct compr_config config, struct snd_compr_params params)
	{
	params->buffer.fragment_size = config->fragment_size;
	params->buffer.fragments = config->fragments;
	memcpy(&params->codec, config->codec, sizeof(params->codec));
	}

	struct compress *compress_open(unsigned int card, unsigned int device,
	unsigned int flags, struct compr_config *config)
	{
	struct compress *compress;
	struct snd_compr_params params;
	struct snd_compr_caps caps;
	char fn[256];

	if (!config) {
	oops(&bad_compress, EINVAL, "passed bad config");
	return &bad_compress;
	}

	compress = calloc(1, sizeof(struct compress));
	if (!compress) {
	oops(&bad_compress, errno, "cannot allocate compress object");
	return &bad_compress;
	}

	compress->next_track = 0;
	compress->gapless_metadata = 0;
	compress->config = calloc(1, sizeof(*config));
	if (!compress->config)
	goto input_fail;

	snprintf(fn, sizeof(fn), "/dev/snd/comprC%uD%u", card, device);

	compress->max_poll_wait_ms = DEFAULT_MAX_POLL_WAIT_MS;

	compress->flags = flags;
	if (!((flags & COMPRESS_OUT) \|\| (flags & COMPRESS_IN))) {
	oops(&bad_compress, EINVAL, "can't deduce device direction from given flags");
	goto config_fail;
	}

	if (flags & COMPRESS_OUT) {
	compress->fd = open(fn, O_RDONLY);
	} else {
	compress->fd = open(fn, O_WRONLY);
	}
	if (compress->fd < 0) {
	oops(&bad_compress, errno, "cannot open device '%s'", fn);
	goto config_fail;
	}

	if (ioctl(compress->fd, SNDRV_COMPRESS_GET_CAPS, &caps)) {
	oops(compress, errno, "cannot get device caps");
	goto codec_fail;
	}

	/* If caller passed "don't care" fill in default values */
	if ((config->fragment_size == 0) \|\| (config->fragments == 0)) {
	config->fragment_size = caps.min_fragment_size;
	config->fragments = caps.max_fragments;
	}

	#if 0
	/* FIXME need to turn this On when DSP supports
	* and treat in no support case
	*/
	if (_is_codec_supported(compress, config, &caps) == false) {
	oops(compress, errno, "codec not supported\n");
	goto codec_fail;
	}
	#endif

	memcpy(compress->config, config, sizeof(*compress->config));
	fill_compress_params(config, &params);

	if (ioctl(compress->fd, SNDRV_COMPRESS_SET_PARAMS, &params)) {
	oops(&bad_compress, errno, "cannot set device");
	goto codec_fail;
	}

	return compress;

	codec_fail:
	close(compress->fd);
	compress->fd = -1;
	config_fail:
	free(compress->config);
	input_fail:
	free(compress);
	return &bad_compress;
	}

	void compress_close(struct compress *compress)
	{
	if (compress == &bad_compress)
	return;

	if (compress->fd >= 0)
	close(compress->fd);
	compress->running = 0;
	compress->fd = -1;
	free(compress->config);
	free(compress);
	}

	int compress_get_hpointer(struct compress *compress,
	unsigned int avail, struct timespec tstamp)
	{
	struct snd_compr_avail kavail;
	__u64 time;

	if (!is_compress_ready(compress))
	return oops(compress, ENODEV, "device not ready");

	if (ioctl(compress->fd, SNDRV_COMPRESS_AVAIL, &kavail))
	return oops(compress, errno, "cannot get avail");
	if (0 == kavail.tstamp.sampling_rate)
	return oops(compress, ENODATA, "sample rate unknown");
	*avail = (unsigned int)kavail.avail;
	time = kavail.tstamp.pcm_io_frames / kavail.tstamp.sampling_rate;
	tstamp->tv_sec = time;
	time = kavail.tstamp.pcm_io_frames % kavail.tstamp.sampling_rate;
	tstamp->tv_nsec = time * 1000000000 / kavail.tstamp.sampling_rate;
	return 0;
	}

	int compress_get_tstamp(struct compress *compress,
	unsigned long samples, unsigned int sampling_rate)
	{
	struct snd_compr_tstamp ktstamp;

	if (!is_compress_ready(compress))
	return oops(compress, ENODEV, "device not ready");

	if (ioctl(compress->fd, SNDRV_COMPRESS_TSTAMP, &ktstamp))
	return oops(compress, errno, "cannot get tstamp");

	*samples = ktstamp.pcm_io_frames;
	*sampling_rate = ktstamp.sampling_rate;
	return 0;
	}

	int compress_write(struct compress compress, const void buf, unsigned int size)
	{
	struct snd_compr_avail avail;
	struct pollfd fds;
	int to_write = 0; /* zero indicates we haven't written yet */
	int written, total = 0, ret;
	const char* cbuf = buf;
	const unsigned int frag_size = compress->config->fragment_size;

	if (!(compress->flags & COMPRESS_IN))
	return oops(compress, EINVAL, "Invalid flag set");
	if (!is_compress_ready(compress))
	return oops(compress, ENODEV, "device not ready");
	fds.fd = compress->fd;
	fds.events = POLLOUT;

	/TODO: treat auto start here first /
	while (size) {
	if (ioctl(compress->fd, SNDRV_COMPRESS_AVAIL, &avail))
	return oops(compress, errno, "cannot get avail");

	/* We can write if we have at least one fragment available
	* or there is enough space for all remaining data
	*/
	if ((avail.avail < frag_size) && (avail.avail < size)) {

	if (compress->nonblocking)
	return total;

	ret = poll(&fds, 1, compress->max_poll_wait_ms);
	if (fds.revents & POLLERR) {
	return oops(compress, EIO, "poll returned error!");
	}
	/* A pause will cause -EBADFD or zero.
	* This is not an error, just stop writing */
	if ((ret == 0) \|\| (ret == -EBADFD))
	break;
	if (ret < 0)
	return oops(compress, errno, "poll error");
	if (fds.revents & POLLOUT) {
	continue;
	}
	}
	/* write avail bytes */
	if (size > avail.avail)
	to_write = avail.avail;
	else
	to_write = size;
	written = write(compress->fd, cbuf, to_write);
	/* If play was paused the write returns -EBADFD */
	if (written == -EBADFD)
	break;
	if (written < 0)
	return oops(compress, errno, "write failed!");

	size -= written;
	cbuf += written;
	total += written;
	}
	return total;
	}

	int compress_read(struct compress compress, void buf, unsigned int size)
	{
	struct snd_compr_avail avail;
	struct pollfd fds;
	int to_read = 0;
	int num_read, total = 0, ret;
	char* cbuf = buf;
	const unsigned int frag_size = compress->config->fragment_size;

	if (!(compress->flags & COMPRESS_OUT))
	return oops(compress, EINVAL, "Invalid flag set");
	if (!is_compress_ready(compress))
	return oops(compress, ENODEV, "device not ready");
	fds.fd = compress->fd;
	fds.events = POLLIN;

	while (size) {
	if (ioctl(compress->fd, SNDRV_COMPRESS_AVAIL, &avail))
	return oops(compress, errno, "cannot get avail");

	if ( (avail.avail < frag_size) && (avail.avail < size) ) {
	/* Less than one fragment available and not at the
	* end of the read, so poll
	*/
	if (compress->nonblocking)
	return total;

	ret = poll(&fds, 1, compress->max_poll_wait_ms);
	if (fds.revents & POLLERR) {
	return oops(compress, EIO, "poll returned error!");
	}
	/* A pause will cause -EBADFD or zero.
	* This is not an error, just stop reading */
	if ((ret == 0) \|\| (ret == -EBADFD))
	break;
	if (ret < 0)
	return oops(compress, errno, "poll error");
	if (fds.revents & POLLIN) {
	continue;
	}
	}
	/* read avail bytes */
	if (size > avail.avail)
	to_read = avail.avail;
	else
	to_read = size;
	num_read = read(compress->fd, cbuf, to_read);
	/* If play was paused the read returns -EBADFD */
	if (num_read == -EBADFD)
	break;
	if (num_read < 0)
	return oops(compress, errno, "read failed!");

	size -= num_read;
	cbuf += num_read;
	total += num_read;
	}

	return total;
	}

	int compress_start(struct compress *compress)
	{
	if (!is_compress_ready(compress))
	return oops(compress, ENODEV, "device not ready");
	if (ioctl(compress->fd, SNDRV_COMPRESS_START))
	return oops(compress, errno, "cannot start the stream");
	compress->running = 1;
	return 0;

	}

	int compress_stop(struct compress *compress)
	{
	if (!is_compress_running(compress))
	return oops(compress, ENODEV, "device not ready");
	if (ioctl(compress->fd, SNDRV_COMPRESS_STOP))
	return oops(compress, errno, "cannot stop the stream");
	return 0;
	}

	int compress_pause(struct compress *compress)
	{
	if (!is_compress_running(compress))
	return oops(compress, ENODEV, "device not ready");
	if (ioctl(compress->fd, SNDRV_COMPRESS_PAUSE))
	return oops(compress, errno, "cannot pause the stream");
	return 0;
	}

	int compress_resume(struct compress *compress)
	{
	if (ioctl(compress->fd, SNDRV_COMPRESS_RESUME))
	return oops(compress, errno, "cannot resume the stream");
	return 0;
	}

	int compress_drain(struct compress *compress)
	{
	if (!is_compress_running(compress))
	return oops(compress, ENODEV, "device not ready");
	if (ioctl(compress->fd, SNDRV_COMPRESS_DRAIN))
	return oops(compress, errno, "cannot drain the stream");
	return 0;
	}

	int compress_partial_drain(struct compress *compress)
	{
	if (!is_compress_running(compress))
	return oops(compress, ENODEV, "device not ready");

	if (!compress->next_track)
	return oops(compress, EPERM, "next track not signalled");
	if (ioctl(compress->fd, SNDRV_COMPRESS_PARTIAL_DRAIN))
	return oops(compress, errno, "cannot drain the stream\n");
	compress->next_track = 0;
	return 0;
	}

	int compress_next_track(struct compress *compress)
	{
	if (!is_compress_running(compress))
	return oops(compress, ENODEV, "device not ready");

	if (!compress->gapless_metadata)
	return oops(compress, EPERM, "metadata not set");
	if (ioctl(compress->fd, SNDRV_COMPRESS_NEXT_TRACK))
	return oops(compress, errno, "cannot set next track\n");
	compress->next_track = 1;
	compress->gapless_metadata = 0;
	return 0;
	}

	int compress_set_gapless_metadata(struct compress *compress,
	struct compr_gapless_mdata *mdata)
	{
	struct snd_compr_metadata metadata;
	int version;

	if (!is_compress_ready(compress))
	return oops(compress, ENODEV, "device not ready");

	version = get_compress_version(compress);
	if (version <= 0)
	return -1;

	if (version < SNDRV_PROTOCOL_VERSION(0, 1, 1))
	return oops(compress, ENXIO, "gapless apis not supported in kernel");

	metadata.key = SNDRV_COMPRESS_ENCODER_PADDING;
	metadata.value[0] = mdata->encoder_padding;
	if (ioctl(compress->fd, SNDRV_COMPRESS_SET_METADATA, &metadata))
	return oops(compress, errno, "can't set metadata for stream\n");

	metadata.key = SNDRV_COMPRESS_ENCODER_DELAY;
	metadata.value[0] = mdata->encoder_delay;
	if (ioctl(compress->fd, SNDRV_COMPRESS_SET_METADATA, &metadata))
	return oops(compress, errno, "can't set metadata for stream\n");
	compress->gapless_metadata = 1;
	return 0;
	}

	bool is_codec_supported(unsigned int card, unsigned int device,
	unsigned int flags, struct snd_codec *codec)
	{
	unsigned int dev_flag;
	bool ret;
	int fd;
	char fn[256];

	snprintf(fn, sizeof(fn), "/dev/snd/comprC%uD%u", card, device);

	if (flags & COMPRESS_OUT)
	dev_flag = O_RDONLY;
	else
	dev_flag = O_WRONLY;

	fd = open(fn, dev_flag);
	if (fd < 0)
	return oops(&bad_compress, errno, "cannot open device '%s'", fn);

	ret = _is_codec_type_supported(fd, codec);

	close(fd);
	return ret;
	}

	void compress_set_max_poll_wait(struct compress *compress, int milliseconds)
	{
	compress->max_poll_wait_ms = milliseconds;
	}

	void compress_nonblock(struct compress *compress, int nonblock)
	{
	compress->nonblocking = !!nonblock;
	}

	int compress_wait(struct compress *compress, int timeout_ms)
	{
	struct pollfd fds;
	int ret;

	fds.fd = compress->fd;
	fds.events = POLLOUT \| POLLIN;

	ret = poll(&fds, 1, timeout_ms);
	if (ret > 0) {
	if (fds.revents & POLLERR)
	return oops(compress, EIO, "poll returned error!");
	if (fds.revents & (POLLOUT \| POLLIN))
	return 0;
	}
	if (ret == 0)
	return oops(compress, ETIME, "poll timed out");
	if (ret < 0)
	return oops(compress, errno, "poll error");

	return oops(compress, EIO, "poll signalled unhandled event");
	}