[libsigrok.git] / src / input / wav.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2013 Bert Vermeulen <bert@biot.com>
 *
 * 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 3 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 <config.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <string.h>
#include <stdint.h>
#include <libsigrok/libsigrok.h>
#include "libsigrok-internal.h"

#define LOG_PREFIX "input/wav"

/* How many bytes at a time to process and send to the session bus. */
#define CHUNK_SIZE               (1 * 1024 * 1024 * sizeof(float))

/* Minimum size of header + 1 8-bit mono PCM sample. */
#define MIN_DATA_CHUNK_OFFSET    45

/* Expect to find the "data" chunk within this offset from the start. */
#define MAX_DATA_CHUNK_OFFSET    1024

#define WAVE_FORMAT_PCM_         0x0001
#define WAVE_FORMAT_IEEE_FLOAT_  0x0003
#define WAVE_FORMAT_EXTENSIBLE_  0xfffe

struct context {
	gboolean started;
	int fmt_code;
	uint64_t samplerate;
	int samplesize;
	int num_channels;
	int unitsize;
	gboolean found_data;
	GSList *prev_sr_channels;
};

static int parse_wav_header(GString *buf, struct context *inc)
{
	uint64_t samplerate;
	unsigned int fmt_code, samplesize, num_channels, unitsize;

	if (buf->len < MIN_DATA_CHUNK_OFFSET)
		return SR_ERR_NA;

	fmt_code = RL16(buf->str + 20);
	samplerate = RL32(buf->str + 24);

	samplesize = RL16(buf->str + 32);
	num_channels = RL16(buf->str + 22);
	if (num_channels == 0)
		return SR_ERR;
	unitsize = samplesize / num_channels;
	if (unitsize != 1 && unitsize != 2 && unitsize != 4) {
		sr_err("Only 8, 16 or 32 bits per sample supported.");
		return SR_ERR_DATA;
	}

	if (fmt_code == WAVE_FORMAT_PCM_) {
	} else if (fmt_code == WAVE_FORMAT_IEEE_FLOAT_) {
		if (unitsize != 4) {
			sr_err("only 32-bit floats supported.");
			return SR_ERR_DATA;
		}
	} else if (fmt_code == WAVE_FORMAT_EXTENSIBLE_) {
		if (buf->len < 70)
			/* Not enough for extensible header and next chunk. */
			return SR_ERR_NA;

		if (RL16(buf->str + 16) != 40) {
			sr_err("WAV extensible format chunk must be 40 bytes.");
			return SR_ERR;
		}
		if (RL16(buf->str + 36) != 22) {
			sr_err("WAV extension must be 22 bytes.");
			return SR_ERR;
		}
		if (RL16(buf->str + 34) != RL16(buf->str + 38)) {
			sr_err("Reduced valid bits per sample not supported.");
			return SR_ERR_DATA;
		}
		/* Real format code is the first two bytes of the GUID. */
		fmt_code = RL16(buf->str + 44);
		if (fmt_code != WAVE_FORMAT_PCM_ && fmt_code != WAVE_FORMAT_IEEE_FLOAT_) {
			sr_err("Only PCM and floating point samples are supported.");
			return SR_ERR_DATA;
		}
		if (fmt_code == WAVE_FORMAT_IEEE_FLOAT_ && unitsize != 4) {
			sr_err("only 32-bit floats supported.");
			return SR_ERR_DATA;
		}
	} else {
		sr_err("Only PCM and floating point samples are supported.");
		return SR_ERR_DATA;
	}

	if (inc) {
		inc->fmt_code = fmt_code;
		inc->samplerate = samplerate;
		inc->samplesize = samplesize;
		inc->num_channels = num_channels;
		inc->unitsize = unitsize;
		inc->found_data = FALSE;
	}

	return SR_OK;
}

static int format_match(GHashTable *metadata, unsigned int *confidence)
{
	GString *buf;
	int ret;

	buf = g_hash_table_lookup(metadata, GINT_TO_POINTER(SR_INPUT_META_HEADER));
	if (strncmp(buf->str, "RIFF", 4))
		return SR_ERR;
	if (strncmp(buf->str + 8, "WAVE", 4))
		return SR_ERR;
	if (strncmp(buf->str + 12, "fmt ", 4))
		return SR_ERR;
	/*
	 * Only gets called when we already know this is a WAV file, so
	 * this parser can log error messages.
	 */
	if ((ret = parse_wav_header(buf, NULL)) != SR_OK)
		return ret;

	*confidence = 1;

	return SR_OK;
}

static int init(struct sr_input *in, GHashTable *options)
{
	(void)options;

	in->sdi = g_malloc0(sizeof(struct sr_dev_inst));
	in->priv = g_malloc0(sizeof(struct context));

	return SR_OK;
}

static int find_data_chunk(GString *buf, int initial_offset)
{
	unsigned int offset, i;

	offset = initial_offset;
	while (offset < MIN(MAX_DATA_CHUNK_OFFSET, buf->len)) {
		if (!memcmp(buf->str + offset, "data", 4))
			/* Skip into the samples. */
			return offset + 8;
		for (i = 0; i < 4; i++) {
			if (!isalnum(buf->str[offset + i])
					&& !isblank(buf->str[offset + i]))
				/* Doesn't look like a chunk ID. */
				return -1;
		}
		/* Skip past this chunk. */
		offset += 8 + RL32(buf->str + offset + 4);
	}

	if (offset > MAX_DATA_CHUNK_OFFSET)
		return -1;

	return offset;
}

static void send_chunk(const struct sr_input *in, int offset, int num_samples)
{
	struct sr_datafeed_packet packet;
	struct sr_datafeed_analog analog;
	struct sr_analog_encoding encoding;
	struct sr_analog_meaning meaning;
	struct sr_analog_spec spec;
	struct context *inc;
	float *fdata;
	int total_samples, samplenum;
	char *s, *d;

	inc = in->priv;

	total_samples = num_samples * inc->num_channels;
	fdata = g_malloc0(total_samples * sizeof(float));
	s = in->buf->str + offset;
	d = (char *)fdata;

	for (samplenum = 0; samplenum < total_samples; samplenum++) {
		if (inc->fmt_code == WAVE_FORMAT_PCM_) {
			switch (inc->unitsize) {
			case 1:
				/* 8-bit PCM samples are unsigned. */
				fdata[samplenum] = *(uint8_t*)(s) / (float)255;
				break;
			case 2:
				fdata[samplenum] = RL16S(s) / (float)INT16_MAX;
				break;
			case 4:
				fdata[samplenum] = RL32S(s) / (float)INT32_MAX;
				break;
			}
		} else {
			/* BINARY32 float */
#ifdef WORDS_BIGENDIAN
			int i;
			for (i = 0; i < inc->unitsize; i++)
				d[i] = s[inc->unitsize - 1 - i];
#else
			memcpy(d, s, inc->unitsize);
#endif
		}
		s += inc->unitsize;
		d += inc->unitsize;
	}

	/* TODO: Use proper 'digits' value for this device (and its modes). */
	sr_analog_init(&analog, &encoding, &meaning, &spec, 2);
	packet.type = SR_DF_ANALOG;
	packet.payload = &analog;
	analog.num_samples = num_samples;
	analog.data = fdata;
	analog.meaning->channels = in->sdi->channels;
	analog.meaning->mq = 0;
	analog.meaning->mqflags = 0;
	analog.meaning->unit = 0;
	sr_session_send(in->sdi, &packet);
	g_free(fdata);
}

static int process_buffer(struct sr_input *in)
{
	struct context *inc;
	int offset, chunk_samples, total_samples, processed, max_chunk_samples;
	int num_samples, i;

	inc = in->priv;
	if (!inc->started) {
		std_session_send_df_header(in->sdi);
		(void)sr_session_send_meta(in->sdi, SR_CONF_SAMPLERATE,
			g_variant_new_uint64(inc->samplerate));
		inc->started = TRUE;
	}

	if (!inc->found_data) {
		/* Skip past size of 'fmt ' chunk. */
		i = 20 + RL32(in->buf->str + 16);
		offset = find_data_chunk(in->buf, i);
		if (offset < 0) {
			if (in->buf->len > MAX_DATA_CHUNK_OFFSET) {
				sr_err("Couldn't find data chunk.");
				return SR_ERR;
			}
		}
		inc->found_data = TRUE;
	} else
		offset = 0;

	/* Round off up to the last channels * unitsize boundary. */
	chunk_samples = (in->buf->len - offset) / inc->samplesize;
	max_chunk_samples = CHUNK_SIZE / inc->samplesize;
	processed = 0;
	total_samples = chunk_samples;
	while (processed < total_samples) {
		if (chunk_samples > max_chunk_samples)
			num_samples = max_chunk_samples;
		else
			num_samples = chunk_samples;
		send_chunk(in, offset, num_samples);
		offset += num_samples * inc->samplesize;
		chunk_samples -= num_samples;
		processed += num_samples;
	}

	if ((unsigned int)offset < in->buf->len) {
		/*
		 * The incoming buffer wasn't processed completely. Stash
		 * the leftover data for next time.
		 */
		g_string_erase(in->buf, 0, offset);
	} else
		g_string_truncate(in->buf, 0);

	return SR_OK;
}

/*
 * Check the channel list for consistency across file re-import. See
 * the VCD input module for more details and motivation.
 */

static void keep_header_for_reread(const struct sr_input *in)
{
	struct context *inc;

	inc = in->priv;
	g_slist_free_full(inc->prev_sr_channels, sr_channel_free_cb);
	inc->prev_sr_channels = in->sdi->channels;
	in->sdi->channels = NULL;
}

static int check_header_in_reread(const struct sr_input *in)
{
	struct context *inc;

	if (!in)
		return FALSE;
	inc = in->priv;
	if (!inc)
		return FALSE;
	if (!inc->prev_sr_channels)
		return TRUE;

	if (sr_channel_lists_differ(inc->prev_sr_channels, in->sdi->channels)) {
		sr_err("Channel list change not supported for file re-read.");
		return FALSE;
	}
	g_slist_free_full(in->sdi->channels, sr_channel_free_cb);
	in->sdi->channels = inc->prev_sr_channels;
	inc->prev_sr_channels = NULL;

	return TRUE;
}

static int receive(struct sr_input *in, GString *buf)
{
	struct context *inc;
	int ret;
	char channelname[16];

	g_string_append_len(in->buf, buf->str, buf->len);

	if (in->buf->len < MIN_DATA_CHUNK_OFFSET) {
		/*
		 * Don't even try until there's enough room
		 * for the data segment to start.
		 */
		return SR_OK;
	}

	inc = in->priv;
	if (!in->sdi_ready) {
		if ((ret = parse_wav_header(in->buf, inc)) == SR_ERR_NA)
			/* Not enough data yet. */
			return SR_OK;
		else if (ret != SR_OK)
			return ret;

		for (int i = 0; i < inc->num_channels; i++) {
			snprintf(channelname, sizeof(channelname), "CH%d", i + 1);
			sr_channel_new(in->sdi, i, SR_CHANNEL_ANALOG, TRUE, channelname);
		}
		if (!check_header_in_reread(in))
			return SR_ERR_DATA;

		/* sdi is ready, notify frontend. */
		in->sdi_ready = TRUE;
		return SR_OK;
	}

	ret = process_buffer(in);

	return ret;
}

static int end(struct sr_input *in)
{
	struct context *inc;
	int ret;

	if (in->sdi_ready)
		ret = process_buffer(in);
	else
		ret = SR_OK;

	inc = in->priv;
	if (inc->started)
		std_session_send_df_end(in->sdi);

	return ret;
}

static int reset(struct sr_input *in)
{
	struct context *inc;

	inc = in->priv;
	memset(inc, 0, sizeof(*inc));

	/*
	 * Create, and re-create channels for every iteration of file
	 * import. Other logic will enforce a consistent set of channels
	 * across re-import, or an appropriate error message when file
	 * properties should change.
	 */
	keep_header_for_reread(in);

	g_string_truncate(in->buf, 0);

	return SR_OK;
}

SR_PRIV struct sr_input_module input_wav = {
	.id = "wav",
	.name = "WAV",
	.desc = "Microsoft WAV file format data",
	.exts = (const char*[]){"wav", NULL},
	.metadata = { SR_INPUT_META_HEADER | SR_INPUT_META_REQUIRED },
	.format_match = format_match,
	.init = init,
	.receive = receive,
	.end = end,
	.reset = reset,
};
Commit	Line	Data
	1	/*
	2	* This file is part of the libsigrok project.
	3	*
	4	* Copyright (C) 2013 Bert Vermeulen <bert@biot.com>
	5	*
	6	* This program is free software: you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation, either version 3 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	18	*/
	19
	20	#include <config.h>
	21	#include <sys/types.h>
	22	#include <sys/stat.h>
	23	#include <unistd.h>
	24	#include <fcntl.h>
	25	#include <ctype.h>
	26	#include <string.h>
	27	#include <stdint.h>
	28	#include <libsigrok/libsigrok.h>
	29	#include "libsigrok-internal.h"
	30
	31	#define LOG_PREFIX "input/wav"
	32
	33	/* How many bytes at a time to process and send to the session bus. */
	34	#define CHUNK_SIZE (1 * 1024 * 1024 * sizeof(float))
	35
	36	/* Minimum size of header + 1 8-bit mono PCM sample. */
	37	#define MIN_DATA_CHUNK_OFFSET 45
	38
	39	/* Expect to find the "data" chunk within this offset from the start. */
	40	#define MAX_DATA_CHUNK_OFFSET 1024
	41
	42	#define WAVE_FORMAT_PCM_ 0x0001
	43	#define WAVE_FORMAT_IEEE_FLOAT_ 0x0003
	44	#define WAVE_FORMAT_EXTENSIBLE_ 0xfffe
	45
	46	struct context {
	47	gboolean started;
	48	int fmt_code;
	49	uint64_t samplerate;
	50	int samplesize;
	51	int num_channels;
	52	int unitsize;
	53	gboolean found_data;
	54	GSList *prev_sr_channels;
	55	};
	56
	57	static int parse_wav_header(GString buf, struct context inc)
	58	{
	59	uint64_t samplerate;
	60	unsigned int fmt_code, samplesize, num_channels, unitsize;
	61
	62	if (buf->len < MIN_DATA_CHUNK_OFFSET)
	63	return SR_ERR_NA;
	64
	65	fmt_code = RL16(buf->str + 20);
	66	samplerate = RL32(buf->str + 24);
	67
	68	samplesize = RL16(buf->str + 32);
	69	num_channels = RL16(buf->str + 22);
	70	if (num_channels == 0)
	71	return SR_ERR;
	72	unitsize = samplesize / num_channels;
	73	if (unitsize != 1 && unitsize != 2 && unitsize != 4) {
	74	sr_err("Only 8, 16 or 32 bits per sample supported.");
	75	return SR_ERR_DATA;
	76	}
	77
	78	if (fmt_code == WAVE_FORMAT_PCM_) {
	79	} else if (fmt_code == WAVE_FORMAT_IEEE_FLOAT_) {
	80	if (unitsize != 4) {
	81	sr_err("only 32-bit floats supported.");
	82	return SR_ERR_DATA;
	83	}
	84	} else if (fmt_code == WAVE_FORMAT_EXTENSIBLE_) {
	85	if (buf->len < 70)
	86	/* Not enough for extensible header and next chunk. */
	87	return SR_ERR_NA;
	88
	89	if (RL16(buf->str + 16) != 40) {
	90	sr_err("WAV extensible format chunk must be 40 bytes.");
	91	return SR_ERR;
	92	}
	93	if (RL16(buf->str + 36) != 22) {
	94	sr_err("WAV extension must be 22 bytes.");
	95	return SR_ERR;
	96	}
	97	if (RL16(buf->str + 34) != RL16(buf->str + 38)) {
	98	sr_err("Reduced valid bits per sample not supported.");
	99	return SR_ERR_DATA;
	100	}
	101	/* Real format code is the first two bytes of the GUID. */
	102	fmt_code = RL16(buf->str + 44);
	103	if (fmt_code != WAVE_FORMAT_PCM_ && fmt_code != WAVE_FORMAT_IEEE_FLOAT_) {
	104	sr_err("Only PCM and floating point samples are supported.");
	105	return SR_ERR_DATA;
	106	}
	107	if (fmt_code == WAVE_FORMAT_IEEE_FLOAT_ && unitsize != 4) {
	108	sr_err("only 32-bit floats supported.");
	109	return SR_ERR_DATA;
	110	}
	111	} else {
	112	sr_err("Only PCM and floating point samples are supported.");
	113	return SR_ERR_DATA;
	114	}
	115
	116	if (inc) {
	117	inc->fmt_code = fmt_code;
	118	inc->samplerate = samplerate;
	119	inc->samplesize = samplesize;
	120	inc->num_channels = num_channels;
	121	inc->unitsize = unitsize;
	122	inc->found_data = FALSE;
	123	}
	124
	125	return SR_OK;
	126	}
	127
	128	static int format_match(GHashTable metadata, unsigned int confidence)
	129	{
	130	GString *buf;
	131	int ret;
	132
	133	buf = g_hash_table_lookup(metadata, GINT_TO_POINTER(SR_INPUT_META_HEADER));
	134	if (strncmp(buf->str, "RIFF", 4))
	135	return SR_ERR;
	136	if (strncmp(buf->str + 8, "WAVE", 4))
	137	return SR_ERR;
	138	if (strncmp(buf->str + 12, "fmt ", 4))
	139	return SR_ERR;
	140	/*
	141	* Only gets called when we already know this is a WAV file, so
	142	* this parser can log error messages.
	143	*/
	144	if ((ret = parse_wav_header(buf, NULL)) != SR_OK)
	145	return ret;
	146
	147	*confidence = 1;
	148
	149	return SR_OK;
	150	}
	151
	152	static int init(struct sr_input in, GHashTable options)
	153	{
	154	(void)options;
	155
	156	in->sdi = g_malloc0(sizeof(struct sr_dev_inst));
	157	in->priv = g_malloc0(sizeof(struct context));
	158
	159	return SR_OK;
	160	}
	161
	162	static int find_data_chunk(GString *buf, int initial_offset)
	163	{
	164	unsigned int offset, i;
	165
	166	offset = initial_offset;
	167	while (offset < MIN(MAX_DATA_CHUNK_OFFSET, buf->len)) {
	168	if (!memcmp(buf->str + offset, "data", 4))
	169	/* Skip into the samples. */
	170	return offset + 8;
	171	for (i = 0; i < 4; i++) {
	172	if (!isalnum(buf->str[offset + i])
	173	&& !isblank(buf->str[offset + i]))
	174	/* Doesn't look like a chunk ID. */
	175	return -1;
	176	}
	177	/* Skip past this chunk. */
	178	offset += 8 + RL32(buf->str + offset + 4);
	179	}
	180
	181	if (offset > MAX_DATA_CHUNK_OFFSET)
	182	return -1;
	183
	184	return offset;
	185	}
	186
	187	static void send_chunk(const struct sr_input *in, int offset, int num_samples)
	188	{
	189	struct sr_datafeed_packet packet;
	190	struct sr_datafeed_analog analog;
	191	struct sr_analog_encoding encoding;
	192	struct sr_analog_meaning meaning;
	193	struct sr_analog_spec spec;
	194	struct context *inc;
	195	float *fdata;
	196	int total_samples, samplenum;
	197	char s, d;
	198
	199	inc = in->priv;
	200
	201	total_samples = num_samples * inc->num_channels;
	202	fdata = g_malloc0(total_samples * sizeof(float));
	203	s = in->buf->str + offset;
	204	d = (char *)fdata;
	205
	206	for (samplenum = 0; samplenum < total_samples; samplenum++) {
	207	if (inc->fmt_code == WAVE_FORMAT_PCM_) {
	208	switch (inc->unitsize) {
	209	case 1:
	210	/* 8-bit PCM samples are unsigned. */
	211	fdata[samplenum] = (uint8_t)(s) / (float)255;
	212	break;
	213	case 2:
	214	fdata[samplenum] = RL16S(s) / (float)INT16_MAX;
	215	break;
	216	case 4:
	217	fdata[samplenum] = RL32S(s) / (float)INT32_MAX;
	218	break;
	219	}
	220	} else {
	221	/* BINARY32 float */
	222	#ifdef WORDS_BIGENDIAN
	223	int i;
	224	for (i = 0; i < inc->unitsize; i++)
	225	d[i] = s[inc->unitsize - 1 - i];
	226	#else
	227	memcpy(d, s, inc->unitsize);
	228	#endif
	229	}
	230	s += inc->unitsize;
	231	d += inc->unitsize;
	232	}
	233
	234	/* TODO: Use proper 'digits' value for this device (and its modes). */
	235	sr_analog_init(&analog, &encoding, &meaning, &spec, 2);
	236	packet.type = SR_DF_ANALOG;
	237	packet.payload = &analog;
	238	analog.num_samples = num_samples;
	239	analog.data = fdata;
	240	analog.meaning->channels = in->sdi->channels;
	241	analog.meaning->mq = 0;
	242	analog.meaning->mqflags = 0;
	243	analog.meaning->unit = 0;
	244	sr_session_send(in->sdi, &packet);
	245	g_free(fdata);
	246	}
	247
	248	static int process_buffer(struct sr_input *in)
	249	{
	250	struct context *inc;
	251	int offset, chunk_samples, total_samples, processed, max_chunk_samples;
	252	int num_samples, i;
	253
	254	inc = in->priv;
	255	if (!inc->started) {
	256	std_session_send_df_header(in->sdi);
	257	(void)sr_session_send_meta(in->sdi, SR_CONF_SAMPLERATE,
	258	g_variant_new_uint64(inc->samplerate));
	259	inc->started = TRUE;
	260	}
	261
	262	if (!inc->found_data) {
	263	/* Skip past size of 'fmt ' chunk. */
	264	i = 20 + RL32(in->buf->str + 16);
	265	offset = find_data_chunk(in->buf, i);
	266	if (offset < 0) {
	267	if (in->buf->len > MAX_DATA_CHUNK_OFFSET) {
	268	sr_err("Couldn't find data chunk.");
	269	return SR_ERR;
	270	}
	271	}
	272	inc->found_data = TRUE;
	273	} else
	274	offset = 0;
	275
	276	/* Round off up to the last channels * unitsize boundary. */
	277	chunk_samples = (in->buf->len - offset) / inc->samplesize;
	278	max_chunk_samples = CHUNK_SIZE / inc->samplesize;
	279	processed = 0;
	280	total_samples = chunk_samples;
	281	while (processed < total_samples) {
	282	if (chunk_samples > max_chunk_samples)
	283	num_samples = max_chunk_samples;
	284	else
	285	num_samples = chunk_samples;
	286	send_chunk(in, offset, num_samples);
	287	offset += num_samples * inc->samplesize;
	288	chunk_samples -= num_samples;
	289	processed += num_samples;
	290	}
	291
	292	if ((unsigned int)offset < in->buf->len) {
	293	/*
	294	* The incoming buffer wasn't processed completely. Stash
	295	* the leftover data for next time.
	296	*/
	297	g_string_erase(in->buf, 0, offset);
	298	} else
	299	g_string_truncate(in->buf, 0);
	300
	301	return SR_OK;
	302	}
	303
	304	/*
	305	* Check the channel list for consistency across file re-import. See
	306	* the VCD input module for more details and motivation.
	307	*/
	308
	309	static void keep_header_for_reread(const struct sr_input *in)
	310	{
	311	struct context *inc;
	312
	313	inc = in->priv;
	314	g_slist_free_full(inc->prev_sr_channels, sr_channel_free_cb);
	315	inc->prev_sr_channels = in->sdi->channels;
	316	in->sdi->channels = NULL;
	317	}
	318
	319	static int check_header_in_reread(const struct sr_input *in)
	320	{
	321	struct context *inc;
	322
	323	if (!in)
	324	return FALSE;
	325	inc = in->priv;
	326	if (!inc)
	327	return FALSE;
	328	if (!inc->prev_sr_channels)
	329	return TRUE;
	330
	331	if (sr_channel_lists_differ(inc->prev_sr_channels, in->sdi->channels)) {
	332	sr_err("Channel list change not supported for file re-read.");
	333	return FALSE;
	334	}
	335	g_slist_free_full(in->sdi->channels, sr_channel_free_cb);
	336	in->sdi->channels = inc->prev_sr_channels;
	337	inc->prev_sr_channels = NULL;
	338
	339	return TRUE;
	340	}
	341
	342	static int receive(struct sr_input in, GString buf)
	343	{
	344	struct context *inc;
	345	int ret;
	346	char channelname[16];
	347
	348	g_string_append_len(in->buf, buf->str, buf->len);
	349
	350	if (in->buf->len < MIN_DATA_CHUNK_OFFSET) {
	351	/*
	352	* Don't even try until there's enough room
	353	* for the data segment to start.
	354	*/
	355	return SR_OK;
	356	}
	357
	358	inc = in->priv;
	359	if (!in->sdi_ready) {
	360	if ((ret = parse_wav_header(in->buf, inc)) == SR_ERR_NA)
	361	/* Not enough data yet. */
	362	return SR_OK;
	363	else if (ret != SR_OK)
	364	return ret;
	365
	366	for (int i = 0; i < inc->num_channels; i++) {
	367	snprintf(channelname, sizeof(channelname), "CH%d", i + 1);
	368	sr_channel_new(in->sdi, i, SR_CHANNEL_ANALOG, TRUE, channelname);
	369	}
	370	if (!check_header_in_reread(in))
	371	return SR_ERR_DATA;
	372
	373	/* sdi is ready, notify frontend. */
	374	in->sdi_ready = TRUE;
	375	return SR_OK;
	376	}
	377
	378	ret = process_buffer(in);
	379
	380	return ret;
	381	}
	382
	383	static int end(struct sr_input *in)
	384	{
	385	struct context *inc;
	386	int ret;
	387
	388	if (in->sdi_ready)
	389	ret = process_buffer(in);
	390	else
	391	ret = SR_OK;
	392
	393	inc = in->priv;
	394	if (inc->started)
	395	std_session_send_df_end(in->sdi);
	396
	397	return ret;
	398	}
	399
	400	static int reset(struct sr_input *in)
	401	{
	402	struct context *inc;
	403
	404	inc = in->priv;
	405	memset(inc, 0, sizeof(*inc));
	406
	407	/*
	408	* Create, and re-create channels for every iteration of file
	409	* import. Other logic will enforce a consistent set of channels
	410	* across re-import, or an appropriate error message when file
	411	* properties should change.
	412	*/
	413	keep_header_for_reread(in);
	414
	415	g_string_truncate(in->buf, 0);
	416
	417	return SR_OK;
	418	}
	419
	420	SR_PRIV struct sr_input_module input_wav = {
	421	.id = "wav",
	422	.name = "WAV",
	423	.desc = "Microsoft WAV file format data",
	424	.exts = (const char*[]){"wav", NULL},
	425	.metadata = { SR_INPUT_META_HEADER \| SR_INPUT_META_REQUIRED },
	426	.format_match = format_match,
	427	.init = init,
	428	.receive = receive,
	429	.end = end,
	430	.reset = reset,
	431	};