sound/core/oss/pcm_plugin.c - linux/kernel/git/mellanox/linux - Git at Google

 /*
  *  PCM Plug-In shared (kernel/library) code
  *  Copyright (c) 1999 by Jaroslav Kysela <perex@suse.cz>
  *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
  *
  *
  *   This library is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU Library 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 Library General Public License for more details.
  *
  *   You should have received a copy of the GNU Library General Public
  *   License along with this library; if not, write to the Free Software
  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  *
  */

 #if 0
 #define PLUGIN_DEBUG
 #endif

 #include <sound/driver.h>

 #ifdef CONFIG_SND_PCM_OSS_PLUGINS

 #include <linux/slab.h>
 #include <linux/time.h>
 #include <linux/vmalloc.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>
 #include "pcm_plugin.h"

 #define snd_pcm_plug_first(plug) ((plug)->runtime->oss.plugin_first)
 #define snd_pcm_plug_last(plug) ((plug)->runtime->oss.plugin_last)

 /*
  *  because some cards might have rates "very close", we ignore
  *  all "resampling" requests within +-5%
  */
 static int rate_match(unsigned int src_rate, unsigned int dst_rate)
 {
 	unsigned int low = (src_rate * 95) / 100;
 	unsigned int high = (src_rate * 105) / 100;
 	return dst_rate >= low && dst_rate <= high;
 }

 static int snd_pcm_plugin_alloc(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
 {
 	struct snd_pcm_plugin_format *format;
 	ssize_t width;
 	size_t size;
 	unsigned int channel;
 	struct snd_pcm_plugin_channel *c;

 	if (plugin->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		format = &plugin->src_format;
 	} else {
 		format = &plugin->dst_format;
 	}
 	if ((width = snd_pcm_format_physical_width(format->format)) < 0)
 		return width;
 	size = frames * format->channels * width;
 	snd_assert((size % 8) == 0, return -ENXIO);
 	size /= 8;
 	if (plugin->buf_frames < frames) {
 		vfree(plugin->buf);
 		plugin->buf = vmalloc(size);
 		plugin->buf_frames = frames;
 	}
 	if (!plugin->buf) {
 		plugin->buf_frames = 0;
 		return -ENOMEM;
 	}
 	c = plugin->buf_channels;
 	if (plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED) {
 		for (channel = 0; channel < format->channels; channel++, c++) {
 			c->frames = frames;
 			c->enabled = 1;
 			c->wanted = 0;
 			c->area.addr = plugin->buf;
 			c->area.first = channel * width;
 			c->area.step = format->channels * width;
 		}
 	} else if (plugin->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED) {
 		snd_assert((size % format->channels) == 0,);
 		size /= format->channels;
 		for (channel = 0; channel < format->channels; channel++, c++) {
 			c->frames = frames;
 			c->enabled = 1;
 			c->wanted = 0;
 			c->area.addr = plugin->buf + (channel * size);
 			c->area.first = 0;
 			c->area.step = width;
 		}
 	} else
 		return -EINVAL;
 	return 0;
 }

 int snd_pcm_plug_alloc(struct snd_pcm_substream *plug, snd_pcm_uframes_t frames)
 {
 	int err;
 	snd_assert(snd_pcm_plug_first(plug) != NULL, return -ENXIO);
 	if (snd_pcm_plug_stream(plug) == SNDRV_PCM_STREAM_PLAYBACK) {
 		struct snd_pcm_plugin *plugin = snd_pcm_plug_first(plug);
 		while (plugin->next) {
 			if (plugin->dst_frames)
 				frames = plugin->dst_frames(plugin, frames);
 			snd_assert(frames > 0, return -ENXIO);
 			plugin = plugin->next;
 			err = snd_pcm_plugin_alloc(plugin, frames);
 			if (err < 0)
 				return err;
 		}
 	} else {
 		struct snd_pcm_plugin *plugin = snd_pcm_plug_last(plug);
 		while (plugin->prev) {
 			if (plugin->src_frames)
 				frames = plugin->src_frames(plugin, frames);
 			snd_assert(frames > 0, return -ENXIO);
 			plugin = plugin->prev;
 			err = snd_pcm_plugin_alloc(plugin, frames);
 			if (err < 0)
 				return err;
 		}
 	}
 	return 0;
 }


 snd_pcm_sframes_t snd_pcm_plugin_client_channels(struct snd_pcm_plugin *plugin,
 				       snd_pcm_uframes_t frames,
 				       struct snd_pcm_plugin_channel **channels)
 {
 	*channels = plugin->buf_channels;
 	return frames;
 }

 int snd_pcm_plugin_build(struct snd_pcm_substream *plug,
 			 const char *name,
 			 struct snd_pcm_plugin_format *src_format,
 			 struct snd_pcm_plugin_format *dst_format,
 			 size_t extra,
 			 struct snd_pcm_plugin **ret)
 {
 	struct snd_pcm_plugin *plugin;
 	unsigned int channels;

 	snd_assert(plug != NULL, return -ENXIO);
 	snd_assert(src_format != NULL && dst_format != NULL, return -ENXIO);
 	plugin = kzalloc(sizeof(*plugin) + extra, GFP_KERNEL);
 	if (plugin == NULL)
 		return -ENOMEM;
 	plugin->name = name;
 	plugin->plug = plug;
 	plugin->stream = snd_pcm_plug_stream(plug);
 	plugin->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
 	plugin->src_format = *src_format;
 	plugin->src_width = snd_pcm_format_physical_width(src_format->format);
 	snd_assert(plugin->src_width > 0, );
 	plugin->dst_format = *dst_format;
 	plugin->dst_width = snd_pcm_format_physical_width(dst_format->format);
 	snd_assert(plugin->dst_width > 0, );
 	if (plugin->stream == SNDRV_PCM_STREAM_PLAYBACK)
 		channels = src_format->channels;
 	else
 		channels = dst_format->channels;
 	plugin->buf_channels = kcalloc(channels, sizeof(*plugin->buf_channels), GFP_KERNEL);
 	if (plugin->buf_channels == NULL) {
 		snd_pcm_plugin_free(plugin);
 		return -ENOMEM;
 	}
 	plugin->client_channels = snd_pcm_plugin_client_channels;
 	*ret = plugin;
 	return 0;
 }

 int snd_pcm_plugin_free(struct snd_pcm_plugin *plugin)
 {
 	if (! plugin)
 		return 0;
 	if (plugin->private_free)
 		plugin->private_free(plugin);
 	kfree(plugin->buf_channels);
 	vfree(plugin->buf);
 	kfree(plugin);
 	return 0;
 }

 snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t drv_frames)
 {
 	struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next;
 	int stream = snd_pcm_plug_stream(plug);

 	snd_assert(plug != NULL, return -ENXIO);
 	if (drv_frames == 0)
 		return 0;
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		plugin = snd_pcm_plug_last(plug);
 		while (plugin && drv_frames > 0) {
 			plugin_prev = plugin->prev;
 			if (plugin->src_frames)
 				drv_frames = plugin->src_frames(plugin, drv_frames);
 			plugin = plugin_prev;
 		}
 	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
 		plugin = snd_pcm_plug_first(plug);
 		while (plugin && drv_frames > 0) {
 			plugin_next = plugin->next;
 			if (plugin->dst_frames)
 				drv_frames = plugin->dst_frames(plugin, drv_frames);
 			plugin = plugin_next;
 		}
 	} else
 		snd_BUG();
 	return drv_frames;
 }

 snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t clt_frames)
 {
 	struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next;
 	snd_pcm_sframes_t frames;
 	int stream = snd_pcm_plug_stream(plug);

 	snd_assert(plug != NULL, return -ENXIO);
 	if (clt_frames == 0)
 		return 0;
 	frames = clt_frames;
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		plugin = snd_pcm_plug_first(plug);
 		while (plugin && frames > 0) {
 			plugin_next = plugin->next;
 			if (plugin->dst_frames) {
 				frames = plugin->dst_frames(plugin, frames);
 				if (frames < 0)
 					return frames;
 			}
 			plugin = plugin_next;
 		}
 	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
 		plugin = snd_pcm_plug_last(plug);
 		while (plugin) {
 			plugin_prev = plugin->prev;
 			if (plugin->src_frames) {
 				frames = plugin->src_frames(plugin, frames);
 				if (frames < 0)
 					return frames;
 			}
 			plugin = plugin_prev;
 		}
 	} else
 		snd_BUG();
 	return frames;
 }

 static int snd_pcm_plug_formats(struct snd_mask *mask, int format)
 {
 	struct snd_mask formats = *mask;
 	u64 linfmts = (SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S8 |
 		       SNDRV_PCM_FMTBIT_U16_LE | SNDRV_PCM_FMTBIT_S16_LE |
 		       SNDRV_PCM_FMTBIT_U16_BE | SNDRV_PCM_FMTBIT_S16_BE |
 		       SNDRV_PCM_FMTBIT_U24_LE | SNDRV_PCM_FMTBIT_S24_LE |
 		       SNDRV_PCM_FMTBIT_U24_BE | SNDRV_PCM_FMTBIT_S24_BE |
 		       SNDRV_PCM_FMTBIT_U32_LE | SNDRV_PCM_FMTBIT_S32_LE |
 		       SNDRV_PCM_FMTBIT_U32_BE | SNDRV_PCM_FMTBIT_S32_BE);
 	snd_mask_set(&formats, SNDRV_PCM_FORMAT_MU_LAW);

 	if (formats.bits[0] & (u32)linfmts)
 		formats.bits[0] |= (u32)linfmts;
 	if (formats.bits[1] & (u32)(linfmts >> 32))
 		formats.bits[1] |= (u32)(linfmts >> 32);
 	return snd_mask_test(&formats, format);
 }

 static int preferred_formats[] = {
 	SNDRV_PCM_FORMAT_S16_LE,
 	SNDRV_PCM_FORMAT_S16_BE,
 	SNDRV_PCM_FORMAT_U16_LE,
 	SNDRV_PCM_FORMAT_U16_BE,
 	SNDRV_PCM_FORMAT_S24_LE,
 	SNDRV_PCM_FORMAT_S24_BE,
 	SNDRV_PCM_FORMAT_U24_LE,
 	SNDRV_PCM_FORMAT_U24_BE,
 	SNDRV_PCM_FORMAT_S32_LE,
 	SNDRV_PCM_FORMAT_S32_BE,
 	SNDRV_PCM_FORMAT_U32_LE,
 	SNDRV_PCM_FORMAT_U32_BE,
 	SNDRV_PCM_FORMAT_S8,
 	SNDRV_PCM_FORMAT_U8
 };

 int snd_pcm_plug_slave_format(int format, struct snd_mask *format_mask)
 {
 	if (snd_mask_test(format_mask, format))
 		return format;
 	if (! snd_pcm_plug_formats(format_mask, format))
 		return -EINVAL;
 	if (snd_pcm_format_linear(format)) {
 		int width = snd_pcm_format_width(format);
 		int unsignd = snd_pcm_format_unsigned(format);
 		int big = snd_pcm_format_big_endian(format);
 		int format1;
 		int wid, width1=width;
 		int dwidth1 = 8;
 		for (wid = 0; wid < 4; ++wid) {
 			int end, big1 = big;
 			for (end = 0; end < 2; ++end) {
 				int sgn, unsignd1 = unsignd;
 				for (sgn = 0; sgn < 2; ++sgn) {
 					format1 = snd_pcm_build_linear_format(width1, unsignd1, big1);
 					if (format1 >= 0 &&
 					    snd_mask_test(format_mask, format1))
 						goto _found;
 					unsignd1 = !unsignd1;
 				}
 				big1 = !big1;
 			}
 			if (width1 == 32) {
 				dwidth1 = -dwidth1;
 				width1 = width;
 			}
 			width1 += dwidth1;
 		}
 		return -EINVAL;
 	_found:
 		return format1;
 	} else {
 		unsigned int i;
 		switch (format) {
 		case SNDRV_PCM_FORMAT_MU_LAW:
 			for (i = 0; i < ARRAY_SIZE(preferred_formats); ++i) {
 				int format1 = preferred_formats[i];
 				if (snd_mask_test(format_mask, format1))
 					return format1;
 			}
 		default:
 			return -EINVAL;
 		}
 	}
 }

 int snd_pcm_plug_format_plugins(struct snd_pcm_substream *plug,
 				struct snd_pcm_hw_params *params,
 				struct snd_pcm_hw_params *slave_params)
 {
 	struct snd_pcm_plugin_format tmpformat;
 	struct snd_pcm_plugin_format dstformat;
 	struct snd_pcm_plugin_format srcformat;
 	int src_access, dst_access;
 	struct snd_pcm_plugin *plugin = NULL;
 	int err;
 	int stream = snd_pcm_plug_stream(plug);
 	int slave_interleaved = (params_channels(slave_params) == 1 ||
 				 params_access(slave_params) == SNDRV_PCM_ACCESS_RW_INTERLEAVED);

 	switch (stream) {
 	case SNDRV_PCM_STREAM_PLAYBACK:
 		dstformat.format = params_format(slave_params);
 		dstformat.rate = params_rate(slave_params);
 		dstformat.channels = params_channels(slave_params);
 		srcformat.format = params_format(params);
 		srcformat.rate = params_rate(params);
 		srcformat.channels = params_channels(params);
 		src_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
 		dst_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
 						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
 		break;
 	case SNDRV_PCM_STREAM_CAPTURE:
 		dstformat.format = params_format(params);
 		dstformat.rate = params_rate(params);
 		dstformat.channels = params_channels(params);
 		srcformat.format = params_format(slave_params);
 		srcformat.rate = params_rate(slave_params);
 		srcformat.channels = params_channels(slave_params);
 		src_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
 						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
 		dst_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
 		break;
 	default:
 		snd_BUG();
 		return -EINVAL;
 	}
 	tmpformat = srcformat;

 	pdprintf("srcformat: format=%i, rate=%i, channels=%i\n",
 		 srcformat.format,
 		 srcformat.rate,
 		 srcformat.channels);
 	pdprintf("dstformat: format=%i, rate=%i, channels=%i\n",
 		 dstformat.format,
 		 dstformat.rate,
 		 dstformat.channels);

 	/* Format change (linearization) */
 	if (! rate_match(srcformat.rate, dstformat.rate) &&
 	    ! snd_pcm_format_linear(srcformat.format)) {
 		if (srcformat.format != SNDRV_PCM_FORMAT_MU_LAW)
 			return -EINVAL;
 		tmpformat.format = SNDRV_PCM_FORMAT_S16;
 		err = snd_pcm_plugin_build_mulaw(plug,
 						 &srcformat, &tmpformat,
 						 &plugin);
 		if (err < 0)
 			return err;
 		err = snd_pcm_plugin_append(plugin);
 		if (err < 0) {
 			snd_pcm_plugin_free(plugin);
 			return err;
 		}
 		srcformat = tmpformat;
 		src_access = dst_access;
 	}

 	/* channels reduction */
 	if (srcformat.channels > dstformat.channels) {
 		tmpformat.channels = dstformat.channels;
 		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
 		pdprintf("channels reduction: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
 		if (err < 0)
 			return err;
 		err = snd_pcm_plugin_append(plugin);
 		if (err < 0) {
 			snd_pcm_plugin_free(plugin);
 			return err;
 		}
 		srcformat = tmpformat;
 		src_access = dst_access;
 	}

 	/* rate resampling */
 	if (!rate_match(srcformat.rate, dstformat.rate)) {
 		if (srcformat.format != SNDRV_PCM_FORMAT_S16) {
 			/* convert to S16 for resampling */
 			tmpformat.format = SNDRV_PCM_FORMAT_S16;
 			err = snd_pcm_plugin_build_linear(plug,
 							  &srcformat, &tmpformat,
 							  &plugin);
 			if (err < 0)
 				return err;
 			err = snd_pcm_plugin_append(plugin);
 			if (err < 0) {
 				snd_pcm_plugin_free(plugin);
 				return err;
 			}
 			srcformat = tmpformat;
 			src_access = dst_access;
 		}
 		tmpformat.rate = dstformat.rate;
         	err = snd_pcm_plugin_build_rate(plug,
         					&srcformat, &tmpformat,
 						&plugin);
 		pdprintf("rate down resampling: src=%i, dst=%i returns %i\n", srcformat.rate, tmpformat.rate, err);
 		if (err < 0)
 			return err;
 		err = snd_pcm_plugin_append(plugin);
 		if (err < 0) {
 			snd_pcm_plugin_free(plugin);
 			return err;
 		}
 		srcformat = tmpformat;
 		src_access = dst_access;
         }

 	/* format change */
 	if (srcformat.format != dstformat.format) {
 		tmpformat.format = dstformat.format;
 		if (srcformat.format == SNDRV_PCM_FORMAT_MU_LAW ||
 		    tmpformat.format == SNDRV_PCM_FORMAT_MU_LAW) {
 			err = snd_pcm_plugin_build_mulaw(plug,
 							 &srcformat, &tmpformat,
 							 &plugin);
 		}
 		else if (snd_pcm_format_linear(srcformat.format) &&
 			 snd_pcm_format_linear(tmpformat.format)) {
 			err = snd_pcm_plugin_build_linear(plug,
 							  &srcformat, &tmpformat,
 							  &plugin);
 		}
 		else
 			return -EINVAL;
 		pdprintf("format change: src=%i, dst=%i returns %i\n", srcformat.format, tmpformat.format, err);
 		if (err < 0)
 			return err;
 		err = snd_pcm_plugin_append(plugin);
 		if (err < 0) {
 			snd_pcm_plugin_free(plugin);
 			return err;
 		}
 		srcformat = tmpformat;
 		src_access = dst_access;
 	}

 	/* channels extension */
 	if (srcformat.channels < dstformat.channels) {
 		tmpformat.channels = dstformat.channels;
 		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
 		pdprintf("channels extension: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
 		if (err < 0)
 			return err;
 		err = snd_pcm_plugin_append(plugin);
 		if (err < 0) {
 			snd_pcm_plugin_free(plugin);
 			return err;
 		}
 		srcformat = tmpformat;
 		src_access = dst_access;
 	}

 	/* de-interleave */
 	if (src_access != dst_access) {
 		err = snd_pcm_plugin_build_copy(plug,
 						&srcformat,
 						&tmpformat,
 						&plugin);
 		pdprintf("interleave change (copy: returns %i)\n", err);
 		if (err < 0)
 			return err;
 		err = snd_pcm_plugin_append(plugin);
 		if (err < 0) {
 			snd_pcm_plugin_free(plugin);
 			return err;
 		}
 	}

 	return 0;
 }

 snd_pcm_sframes_t snd_pcm_plug_client_channels_buf(struct snd_pcm_substream *plug,
 					 char *buf,
 					 snd_pcm_uframes_t count,
 					 struct snd_pcm_plugin_channel **channels)
 {
 	struct snd_pcm_plugin *plugin;
 	struct snd_pcm_plugin_channel *v;
 	struct snd_pcm_plugin_format *format;
 	int width, nchannels, channel;
 	int stream = snd_pcm_plug_stream(plug);

 	snd_assert(buf != NULL, return -ENXIO);
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		plugin = snd_pcm_plug_first(plug);
 		format = &plugin->src_format;
 	} else {
 		plugin = snd_pcm_plug_last(plug);
 		format = &plugin->dst_format;
 	}
 	v = plugin->buf_channels;
 	*channels = v;
 	if ((width = snd_pcm_format_physical_width(format->format)) < 0)
 		return width;
 	nchannels = format->channels;
 	snd_assert(plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED || format->channels <= 1, return -ENXIO);
 	for (channel = 0; channel < nchannels; channel++, v++) {
 		v->frames = count;
 		v->enabled = 1;
 		v->wanted = (stream == SNDRV_PCM_STREAM_CAPTURE);
 		v->area.addr = buf;
 		v->area.first = channel * width;
 		v->area.step = nchannels * width;
 	}
 	return count;
 }

 snd_pcm_sframes_t snd_pcm_plug_write_transfer(struct snd_pcm_substream *plug, struct snd_pcm_plugin_channel *src_channels, snd_pcm_uframes_t size)
 {
 	struct snd_pcm_plugin *plugin, *next;
 	struct snd_pcm_plugin_channel *dst_channels;
 	int err;
 	snd_pcm_sframes_t frames = size;

 	plugin = snd_pcm_plug_first(plug);
 	while (plugin && frames > 0) {
 		if ((next = plugin->next) != NULL) {
 			snd_pcm_sframes_t frames1 = frames;
 			if (plugin->dst_frames)
 				frames1 = plugin->dst_frames(plugin, frames);
 			if ((err = next->client_channels(next, frames1, &dst_channels)) < 0) {
 				return err;
 			}
 			if (err != frames1) {
 				frames = err;
 				if (plugin->src_frames)
 					frames = plugin->src_frames(plugin, frames1);
 			}
 		} else
 			dst_channels = NULL;
 		pdprintf("write plugin: %s, %li\n", plugin->name, frames);
 		if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
 			return frames;
 		src_channels = dst_channels;
 		plugin = next;
 	}
 	return snd_pcm_plug_client_size(plug, frames);
 }

 snd_pcm_sframes_t snd_pcm_plug_read_transfer(struct snd_pcm_substream *plug, struct snd_pcm_plugin_channel *dst_channels_final, snd_pcm_uframes_t size)
 {
 	struct snd_pcm_plugin *plugin, *next;
 	struct snd_pcm_plugin_channel *src_channels, *dst_channels;
 	snd_pcm_sframes_t frames = size;
 	int err;

 	frames = snd_pcm_plug_slave_size(plug, frames);
 	if (frames < 0)
 		return frames;

 	src_channels = NULL;
 	plugin = snd_pcm_plug_first(plug);
 	while (plugin && frames > 0) {
 		if ((next = plugin->next) != NULL) {
 			if ((err = plugin->client_channels(plugin, frames, &dst_channels)) < 0) {
 				return err;
 			}
 			frames = err;
 		} else {
 			dst_channels = dst_channels_final;
 		}
 		pdprintf("read plugin: %s, %li\n", plugin->name, frames);
 		if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
 			return frames;
 		plugin = next;
 		src_channels = dst_channels;
 	}
 	return frames;
 }

 int snd_pcm_area_silence(const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
 			 size_t samples, int format)
 {
 	/* FIXME: sub byte resolution and odd dst_offset */
 	unsigned char *dst;
 	unsigned int dst_step;
 	int width;
 	const unsigned char *silence;
 	if (!dst_area->addr)
 		return 0;
 	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
 	width = snd_pcm_format_physical_width(format);
 	if (width <= 0)
 		return -EINVAL;
 	if (dst_area->step == (unsigned int) width && width >= 8)
 		return snd_pcm_format_set_silence(format, dst, samples);
 	silence = snd_pcm_format_silence_64(format);
 	if (! silence)
 		return -EINVAL;
 	dst_step = dst_area->step / 8;
 	if (width == 4) {
 		/* Ima ADPCM */
 		int dstbit = dst_area->first % 8;
 		int dstbit_step = dst_area->step % 8;
 		while (samples-- > 0) {
 			if (dstbit)
 				*dst &= 0xf0;
 			else
 				*dst &= 0x0f;
 			dst += dst_step;
 			dstbit += dstbit_step;
 			if (dstbit == 8) {
 				dst++;
 				dstbit = 0;
 			}
 		}
 	} else {
 		width /= 8;
 		while (samples-- > 0) {
 			memcpy(dst, silence, width);
 			dst += dst_step;
 		}
 	}
 	return 0;
 }

 int snd_pcm_area_copy(const struct snd_pcm_channel_area *src_area, size_t src_offset,
 		      const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
 		      size_t samples, int format)
 {
 	/* FIXME: sub byte resolution and odd dst_offset */
 	char *src, *dst;
 	int width;
 	int src_step, dst_step;
 	src = src_area->addr + (src_area->first + src_area->step * src_offset) / 8;
 	if (!src_area->addr)
 		return snd_pcm_area_silence(dst_area, dst_offset, samples, format);
 	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
 	if (!dst_area->addr)
 		return 0;
 	width = snd_pcm_format_physical_width(format);
 	if (width <= 0)
 		return -EINVAL;
 	if (src_area->step == (unsigned int) width &&
 	    dst_area->step == (unsigned int) width && width >= 8) {
 		size_t bytes = samples * width / 8;
 		memcpy(dst, src, bytes);
 		return 0;
 	}
 	src_step = src_area->step / 8;
 	dst_step = dst_area->step / 8;
 	if (width == 4) {
 		/* Ima ADPCM */
 		int srcbit = src_area->first % 8;
 		int srcbit_step = src_area->step % 8;
 		int dstbit = dst_area->first % 8;
 		int dstbit_step = dst_area->step % 8;
 		while (samples-- > 0) {
 			unsigned char srcval;
 			if (srcbit)
 				srcval = *src & 0x0f;
 			else
 				srcval = (*src & 0xf0) >> 4;
 			if (dstbit)
 				*dst = (*dst & 0xf0) | srcval;
 			else
 				*dst = (*dst & 0x0f) | (srcval << 4);
 			src += src_step;
 			srcbit += srcbit_step;
 			if (srcbit == 8) {
 				src++;
 				srcbit = 0;
 			}
 			dst += dst_step;
 			dstbit += dstbit_step;
 			if (dstbit == 8) {
 				dst++;
 				dstbit = 0;
 			}
 		}
 	} else {
 		width /= 8;
 		while (samples-- > 0) {
 			memcpy(dst, src, width);
 			src += src_step;
 			dst += dst_step;
 		}
 	}
 	return 0;
 }

 #endif
	/*
	* PCM Plug-In shared (kernel/library) code
	* Copyright (c) 1999 by Jaroslav Kysela <perex@suse.cz>
	* Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
	*
	*
	* This library is free software; you can redistribute it and/or modify
	* it under the terms of the GNU Library 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 Library General Public License for more details.
	*
	* You should have received a copy of the GNU Library General Public
	* License along with this library; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*
	*/

	#if 0
	#define PLUGIN_DEBUG
	#endif

	#include <sound/driver.h>

	#ifdef CONFIG_SND_PCM_OSS_PLUGINS

	#include <linux/slab.h>
	#include <linux/time.h>
	#include <linux/vmalloc.h>
	#include <sound/core.h>
	#include <sound/pcm.h>
	#include <sound/pcm_params.h>
	#include "pcm_plugin.h"

	#define snd_pcm_plug_first(plug) ((plug)->runtime->oss.plugin_first)
	#define snd_pcm_plug_last(plug) ((plug)->runtime->oss.plugin_last)

	/*
	* because some cards might have rates "very close", we ignore
	* all "resampling" requests within +-5%
	*/
	static int rate_match(unsigned int src_rate, unsigned int dst_rate)
	{
	unsigned int low = (src_rate * 95) / 100;
	unsigned int high = (src_rate * 105) / 100;
	return dst_rate >= low && dst_rate <= high;
	}

	static int snd_pcm_plugin_alloc(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
	{
	struct snd_pcm_plugin_format *format;
	ssize_t width;
	size_t size;
	unsigned int channel;
	struct snd_pcm_plugin_channel *c;

	if (plugin->stream == SNDRV_PCM_STREAM_PLAYBACK) {
	format = &plugin->src_format;
	} else {
	format = &plugin->dst_format;
	}
	if ((width = snd_pcm_format_physical_width(format->format)) < 0)
	return width;
	size = frames * format->channels * width;
	snd_assert((size % 8) == 0, return -ENXIO);
	size /= 8;
	if (plugin->buf_frames < frames) {
	vfree(plugin->buf);
	plugin->buf = vmalloc(size);
	plugin->buf_frames = frames;
	}
	if (!plugin->buf) {
	plugin->buf_frames = 0;
	return -ENOMEM;
	}
	c = plugin->buf_channels;
	if (plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED) {
	for (channel = 0; channel < format->channels; channel++, c++) {
	c->frames = frames;
	c->enabled = 1;
	c->wanted = 0;
	c->area.addr = plugin->buf;
	c->area.first = channel * width;
	c->area.step = format->channels * width;
	}
	} else if (plugin->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED) {
	snd_assert((size % format->channels) == 0,);
	size /= format->channels;
	for (channel = 0; channel < format->channels; channel++, c++) {
	c->frames = frames;
	c->enabled = 1;
	c->wanted = 0;
	c->area.addr = plugin->buf + (channel * size);
	c->area.first = 0;
	c->area.step = width;
	}
	} else
	return -EINVAL;
	return 0;
	}

	int snd_pcm_plug_alloc(struct snd_pcm_substream *plug, snd_pcm_uframes_t frames)
	{
	int err;
	snd_assert(snd_pcm_plug_first(plug) != NULL, return -ENXIO);
	if (snd_pcm_plug_stream(plug) == SNDRV_PCM_STREAM_PLAYBACK) {
	struct snd_pcm_plugin *plugin = snd_pcm_plug_first(plug);
	while (plugin->next) {
	if (plugin->dst_frames)
	frames = plugin->dst_frames(plugin, frames);
	snd_assert(frames > 0, return -ENXIO);
	plugin = plugin->next;
	err = snd_pcm_plugin_alloc(plugin, frames);
	if (err < 0)
	return err;
	}
	} else {
	struct snd_pcm_plugin *plugin = snd_pcm_plug_last(plug);
	while (plugin->prev) {
	if (plugin->src_frames)
	frames = plugin->src_frames(plugin, frames);
	snd_assert(frames > 0, return -ENXIO);
	plugin = plugin->prev;
	err = snd_pcm_plugin_alloc(plugin, frames);
	if (err < 0)
	return err;
	}
	}
	return 0;
	}


	snd_pcm_sframes_t snd_pcm_plugin_client_channels(struct snd_pcm_plugin *plugin,
	snd_pcm_uframes_t frames,
	struct snd_pcm_plugin_channel **channels)
	{
	*channels = plugin->buf_channels;
	return frames;
	}

	int snd_pcm_plugin_build(struct snd_pcm_substream *plug,
	const char *name,
	struct snd_pcm_plugin_format *src_format,
	struct snd_pcm_plugin_format *dst_format,
	size_t extra,
	struct snd_pcm_plugin **ret)
	{
	struct snd_pcm_plugin *plugin;
	unsigned int channels;

	snd_assert(plug != NULL, return -ENXIO);
	snd_assert(src_format != NULL && dst_format != NULL, return -ENXIO);
	plugin = kzalloc(sizeof(*plugin) + extra, GFP_KERNEL);
	if (plugin == NULL)
	return -ENOMEM;
	plugin->name = name;
	plugin->plug = plug;
	plugin->stream = snd_pcm_plug_stream(plug);
	plugin->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
	plugin->src_format = *src_format;
	plugin->src_width = snd_pcm_format_physical_width(src_format->format);
	snd_assert(plugin->src_width > 0, );
	plugin->dst_format = *dst_format;
	plugin->dst_width = snd_pcm_format_physical_width(dst_format->format);
	snd_assert(plugin->dst_width > 0, );
	if (plugin->stream == SNDRV_PCM_STREAM_PLAYBACK)
	channels = src_format->channels;
	else
	channels = dst_format->channels;
	plugin->buf_channels = kcalloc(channels, sizeof(*plugin->buf_channels), GFP_KERNEL);
	if (plugin->buf_channels == NULL) {
	snd_pcm_plugin_free(plugin);
	return -ENOMEM;
	}
	plugin->client_channels = snd_pcm_plugin_client_channels;
	*ret = plugin;
	return 0;
	}

	int snd_pcm_plugin_free(struct snd_pcm_plugin *plugin)
	{
	if (! plugin)
	return 0;
	if (plugin->private_free)
	plugin->private_free(plugin);
	kfree(plugin->buf_channels);
	vfree(plugin->buf);
	kfree(plugin);
	return 0;
	}

	snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t drv_frames)
	{
	struct snd_pcm_plugin plugin, plugin_prev, *plugin_next;
	int stream = snd_pcm_plug_stream(plug);

	snd_assert(plug != NULL, return -ENXIO);
	if (drv_frames == 0)
	return 0;
	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
	plugin = snd_pcm_plug_last(plug);
	while (plugin && drv_frames > 0) {
	plugin_prev = plugin->prev;
	if (plugin->src_frames)
	drv_frames = plugin->src_frames(plugin, drv_frames);
	plugin = plugin_prev;
	}
	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
	plugin = snd_pcm_plug_first(plug);
	while (plugin && drv_frames > 0) {
	plugin_next = plugin->next;
	if (plugin->dst_frames)
	drv_frames = plugin->dst_frames(plugin, drv_frames);
	plugin = plugin_next;
	}
	} else
	snd_BUG();
	return drv_frames;
	}

	snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t clt_frames)
	{
	struct snd_pcm_plugin plugin, plugin_prev, *plugin_next;
	snd_pcm_sframes_t frames;
	int stream = snd_pcm_plug_stream(plug);

	snd_assert(plug != NULL, return -ENXIO);
	if (clt_frames == 0)
	return 0;
	frames = clt_frames;
	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
	plugin = snd_pcm_plug_first(plug);
	while (plugin && frames > 0) {
	plugin_next = plugin->next;
	if (plugin->dst_frames) {
	frames = plugin->dst_frames(plugin, frames);
	if (frames < 0)
	return frames;
	}
	plugin = plugin_next;
	}
	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
	plugin = snd_pcm_plug_last(plug);
	while (plugin) {
	plugin_prev = plugin->prev;
	if (plugin->src_frames) {
	frames = plugin->src_frames(plugin, frames);
	if (frames < 0)
	return frames;
	}
	plugin = plugin_prev;
	}
	} else
	snd_BUG();
	return frames;
	}

	static int snd_pcm_plug_formats(struct snd_mask *mask, int format)
	{
	struct snd_mask formats = *mask;
	u64 linfmts = (SNDRV_PCM_FMTBIT_U8 \| SNDRV_PCM_FMTBIT_S8 \|
	SNDRV_PCM_FMTBIT_U16_LE \| SNDRV_PCM_FMTBIT_S16_LE \|
	SNDRV_PCM_FMTBIT_U16_BE \| SNDRV_PCM_FMTBIT_S16_BE \|
	SNDRV_PCM_FMTBIT_U24_LE \| SNDRV_PCM_FMTBIT_S24_LE \|
	SNDRV_PCM_FMTBIT_U24_BE \| SNDRV_PCM_FMTBIT_S24_BE \|
	SNDRV_PCM_FMTBIT_U32_LE \| SNDRV_PCM_FMTBIT_S32_LE \|
	SNDRV_PCM_FMTBIT_U32_BE \| SNDRV_PCM_FMTBIT_S32_BE);
	snd_mask_set(&formats, SNDRV_PCM_FORMAT_MU_LAW);

	if (formats.bits[0] & (u32)linfmts)
	formats.bits[0] \|= (u32)linfmts;
	if (formats.bits[1] & (u32)(linfmts >> 32))
	formats.bits[1] \|= (u32)(linfmts >> 32);
	return snd_mask_test(&formats, format);
	}

	static int preferred_formats[] = {
	SNDRV_PCM_FORMAT_S16_LE,
	SNDRV_PCM_FORMAT_S16_BE,
	SNDRV_PCM_FORMAT_U16_LE,
	SNDRV_PCM_FORMAT_U16_BE,
	SNDRV_PCM_FORMAT_S24_LE,
	SNDRV_PCM_FORMAT_S24_BE,
	SNDRV_PCM_FORMAT_U24_LE,
	SNDRV_PCM_FORMAT_U24_BE,
	SNDRV_PCM_FORMAT_S32_LE,
	SNDRV_PCM_FORMAT_S32_BE,
	SNDRV_PCM_FORMAT_U32_LE,
	SNDRV_PCM_FORMAT_U32_BE,
	SNDRV_PCM_FORMAT_S8,
	SNDRV_PCM_FORMAT_U8
	};

	int snd_pcm_plug_slave_format(int format, struct snd_mask *format_mask)
	{
	if (snd_mask_test(format_mask, format))
	return format;
	if (! snd_pcm_plug_formats(format_mask, format))
	return -EINVAL;
	if (snd_pcm_format_linear(format)) {
	int width = snd_pcm_format_width(format);
	int unsignd = snd_pcm_format_unsigned(format);
	int big = snd_pcm_format_big_endian(format);
	int format1;
	int wid, width1=width;
	int dwidth1 = 8;
	for (wid = 0; wid < 4; ++wid) {
	int end, big1 = big;
	for (end = 0; end < 2; ++end) {
	int sgn, unsignd1 = unsignd;
	for (sgn = 0; sgn < 2; ++sgn) {
	format1 = snd_pcm_build_linear_format(width1, unsignd1, big1);
	if (format1 >= 0 &&
	snd_mask_test(format_mask, format1))
	goto _found;
	unsignd1 = !unsignd1;
	}
	big1 = !big1;
	}
	if (width1 == 32) {
	dwidth1 = -dwidth1;
	width1 = width;
	}
	width1 += dwidth1;
	}
	return -EINVAL;
	_found:
	return format1;
	} else {
	unsigned int i;
	switch (format) {
	case SNDRV_PCM_FORMAT_MU_LAW:
	for (i = 0; i < ARRAY_SIZE(preferred_formats); ++i) {
	int format1 = preferred_formats[i];
	if (snd_mask_test(format_mask, format1))
	return format1;
	}
	default:
	return -EINVAL;
	}
	}
	}

	int snd_pcm_plug_format_plugins(struct snd_pcm_substream *plug,
	struct snd_pcm_hw_params *params,
	struct snd_pcm_hw_params *slave_params)
	{
	struct snd_pcm_plugin_format tmpformat;
	struct snd_pcm_plugin_format dstformat;
	struct snd_pcm_plugin_format srcformat;
	int src_access, dst_access;
	struct snd_pcm_plugin *plugin = NULL;
	int err;
	int stream = snd_pcm_plug_stream(plug);
	int slave_interleaved = (params_channels(slave_params) == 1 \|\|
	params_access(slave_params) == SNDRV_PCM_ACCESS_RW_INTERLEAVED);

	switch (stream) {
	case SNDRV_PCM_STREAM_PLAYBACK:
	dstformat.format = params_format(slave_params);
	dstformat.rate = params_rate(slave_params);
	dstformat.channels = params_channels(slave_params);
	srcformat.format = params_format(params);
	srcformat.rate = params_rate(params);
	srcformat.channels = params_channels(params);
	src_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
	dst_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
	SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
	break;
	case SNDRV_PCM_STREAM_CAPTURE:
	dstformat.format = params_format(params);
	dstformat.rate = params_rate(params);
	dstformat.channels = params_channels(params);
	srcformat.format = params_format(slave_params);
	srcformat.rate = params_rate(slave_params);
	srcformat.channels = params_channels(slave_params);
	src_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
	SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
	dst_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
	break;
	default:
	snd_BUG();
	return -EINVAL;
	}
	tmpformat = srcformat;

	pdprintf("srcformat: format=%i, rate=%i, channels=%i\n",
	srcformat.format,
	srcformat.rate,
	srcformat.channels);
	pdprintf("dstformat: format=%i, rate=%i, channels=%i\n",
	dstformat.format,
	dstformat.rate,
	dstformat.channels);

	/* Format change (linearization) */
	if (! rate_match(srcformat.rate, dstformat.rate) &&
	! snd_pcm_format_linear(srcformat.format)) {
	if (srcformat.format != SNDRV_PCM_FORMAT_MU_LAW)
	return -EINVAL;
	tmpformat.format = SNDRV_PCM_FORMAT_S16;
	err = snd_pcm_plugin_build_mulaw(plug,
	&srcformat, &tmpformat,
	&plugin);
	if (err < 0)
	return err;
	err = snd_pcm_plugin_append(plugin);
	if (err < 0) {
	snd_pcm_plugin_free(plugin);
	return err;
	}
	srcformat = tmpformat;
	src_access = dst_access;
	}

	/* channels reduction */
	if (srcformat.channels > dstformat.channels) {
	tmpformat.channels = dstformat.channels;
	err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
	pdprintf("channels reduction: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
	if (err < 0)
	return err;
	err = snd_pcm_plugin_append(plugin);
	if (err < 0) {
	snd_pcm_plugin_free(plugin);
	return err;
	}
	srcformat = tmpformat;
	src_access = dst_access;
	}

	/* rate resampling */
	if (!rate_match(srcformat.rate, dstformat.rate)) {
	if (srcformat.format != SNDRV_PCM_FORMAT_S16) {
	/* convert to S16 for resampling */
	tmpformat.format = SNDRV_PCM_FORMAT_S16;
	err = snd_pcm_plugin_build_linear(plug,
	&srcformat, &tmpformat,
	&plugin);
	if (err < 0)
	return err;
	err = snd_pcm_plugin_append(plugin);
	if (err < 0) {
	snd_pcm_plugin_free(plugin);
	return err;
	}
	srcformat = tmpformat;
	src_access = dst_access;
	}
	tmpformat.rate = dstformat.rate;
	err = snd_pcm_plugin_build_rate(plug,
	&srcformat, &tmpformat,
	&plugin);
	pdprintf("rate down resampling: src=%i, dst=%i returns %i\n", srcformat.rate, tmpformat.rate, err);
	if (err < 0)
	return err;
	err = snd_pcm_plugin_append(plugin);
	if (err < 0) {
	snd_pcm_plugin_free(plugin);
	return err;
	}
	srcformat = tmpformat;
	src_access = dst_access;
	}

	/* format change */
	if (srcformat.format != dstformat.format) {
	tmpformat.format = dstformat.format;
	if (srcformat.format == SNDRV_PCM_FORMAT_MU_LAW \|\|
	tmpformat.format == SNDRV_PCM_FORMAT_MU_LAW) {
	err = snd_pcm_plugin_build_mulaw(plug,
	&srcformat, &tmpformat,
	&plugin);
	}
	else if (snd_pcm_format_linear(srcformat.format) &&
	snd_pcm_format_linear(tmpformat.format)) {
	err = snd_pcm_plugin_build_linear(plug,
	&srcformat, &tmpformat,
	&plugin);
	}
	else
	return -EINVAL;
	pdprintf("format change: src=%i, dst=%i returns %i\n", srcformat.format, tmpformat.format, err);
	if (err < 0)
	return err;
	err = snd_pcm_plugin_append(plugin);
	if (err < 0) {
	snd_pcm_plugin_free(plugin);
	return err;
	}
	srcformat = tmpformat;
	src_access = dst_access;
	}

	/* channels extension */
	if (srcformat.channels < dstformat.channels) {
	tmpformat.channels = dstformat.channels;
	err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
	pdprintf("channels extension: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
	if (err < 0)
	return err;
	err = snd_pcm_plugin_append(plugin);
	if (err < 0) {
	snd_pcm_plugin_free(plugin);
	return err;
	}
	srcformat = tmpformat;
	src_access = dst_access;
	}

	/* de-interleave */
	if (src_access != dst_access) {
	err = snd_pcm_plugin_build_copy(plug,
	&srcformat,
	&tmpformat,
	&plugin);
	pdprintf("interleave change (copy: returns %i)\n", err);
	if (err < 0)
	return err;
	err = snd_pcm_plugin_append(plugin);
	if (err < 0) {
	snd_pcm_plugin_free(plugin);
	return err;
	}
	}

	return 0;
	}

	snd_pcm_sframes_t snd_pcm_plug_client_channels_buf(struct snd_pcm_substream *plug,
	char *buf,
	snd_pcm_uframes_t count,
	struct snd_pcm_plugin_channel **channels)
	{
	struct snd_pcm_plugin *plugin;
	struct snd_pcm_plugin_channel *v;
	struct snd_pcm_plugin_format *format;
	int width, nchannels, channel;
	int stream = snd_pcm_plug_stream(plug);

	snd_assert(buf != NULL, return -ENXIO);
	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
	plugin = snd_pcm_plug_first(plug);
	format = &plugin->src_format;
	} else {
	plugin = snd_pcm_plug_last(plug);
	format = &plugin->dst_format;
	}
	v = plugin->buf_channels;
	*channels = v;
	if ((width = snd_pcm_format_physical_width(format->format)) < 0)
	return width;
	nchannels = format->channels;
	snd_assert(plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED \|\| format->channels <= 1, return -ENXIO);
	for (channel = 0; channel < nchannels; channel++, v++) {
	v->frames = count;
	v->enabled = 1;
	v->wanted = (stream == SNDRV_PCM_STREAM_CAPTURE);
	v->area.addr = buf;
	v->area.first = channel * width;
	v->area.step = nchannels * width;
	}
	return count;
	}

	snd_pcm_sframes_t snd_pcm_plug_write_transfer(struct snd_pcm_substream plug, struct snd_pcm_plugin_channel src_channels, snd_pcm_uframes_t size)
	{
	struct snd_pcm_plugin plugin, next;
	struct snd_pcm_plugin_channel *dst_channels;
	int err;
	snd_pcm_sframes_t frames = size;

	plugin = snd_pcm_plug_first(plug);
	while (plugin && frames > 0) {
	if ((next = plugin->next) != NULL) {
	snd_pcm_sframes_t frames1 = frames;
	if (plugin->dst_frames)
	frames1 = plugin->dst_frames(plugin, frames);
	if ((err = next->client_channels(next, frames1, &dst_channels)) < 0) {
	return err;
	}
	if (err != frames1) {
	frames = err;
	if (plugin->src_frames)
	frames = plugin->src_frames(plugin, frames1);
	}
	} else
	dst_channels = NULL;
	pdprintf("write plugin: %s, %li\n", plugin->name, frames);
	if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
	return frames;
	src_channels = dst_channels;
	plugin = next;
	}
	return snd_pcm_plug_client_size(plug, frames);
	}

	snd_pcm_sframes_t snd_pcm_plug_read_transfer(struct snd_pcm_substream plug, struct snd_pcm_plugin_channel dst_channels_final, snd_pcm_uframes_t size)
	{
	struct snd_pcm_plugin plugin, next;
	struct snd_pcm_plugin_channel src_channels, dst_channels;
	snd_pcm_sframes_t frames = size;
	int err;

	frames = snd_pcm_plug_slave_size(plug, frames);
	if (frames < 0)
	return frames;

	src_channels = NULL;
	plugin = snd_pcm_plug_first(plug);
	while (plugin && frames > 0) {
	if ((next = plugin->next) != NULL) {
	if ((err = plugin->client_channels(plugin, frames, &dst_channels)) < 0) {
	return err;
	}
	frames = err;
	} else {
	dst_channels = dst_channels_final;
	}
	pdprintf("read plugin: %s, %li\n", plugin->name, frames);
	if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
	return frames;
	plugin = next;
	src_channels = dst_channels;
	}
	return frames;
	}

	int snd_pcm_area_silence(const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
	size_t samples, int format)
	{
	/* FIXME: sub byte resolution and odd dst_offset */
	unsigned char *dst;
	unsigned int dst_step;
	int width;
	const unsigned char *silence;
	if (!dst_area->addr)
	return 0;
	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
	width = snd_pcm_format_physical_width(format);
	if (width <= 0)
	return -EINVAL;
	if (dst_area->step == (unsigned int) width && width >= 8)
	return snd_pcm_format_set_silence(format, dst, samples);
	silence = snd_pcm_format_silence_64(format);
	if (! silence)
	return -EINVAL;
	dst_step = dst_area->step / 8;
	if (width == 4) {
	/* Ima ADPCM */
	int dstbit = dst_area->first % 8;
	int dstbit_step = dst_area->step % 8;
	while (samples-- > 0) {
	if (dstbit)
	*dst &= 0xf0;
	else
	*dst &= 0x0f;
	dst += dst_step;
	dstbit += dstbit_step;
	if (dstbit == 8) {
	dst++;
	dstbit = 0;
	}
	}
	} else {
	width /= 8;
	while (samples-- > 0) {
	memcpy(dst, silence, width);
	dst += dst_step;
	}
	}
	return 0;
	}

	int snd_pcm_area_copy(const struct snd_pcm_channel_area *src_area, size_t src_offset,
	const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
	size_t samples, int format)
	{
	/* FIXME: sub byte resolution and odd dst_offset */
	char src, dst;
	int width;
	int src_step, dst_step;
	src = src_area->addr + (src_area->first + src_area->step * src_offset) / 8;
	if (!src_area->addr)
	return snd_pcm_area_silence(dst_area, dst_offset, samples, format);
	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
	if (!dst_area->addr)
	return 0;
	width = snd_pcm_format_physical_width(format);
	if (width <= 0)
	return -EINVAL;
	if (src_area->step == (unsigned int) width &&
	dst_area->step == (unsigned int) width && width >= 8) {
	size_t bytes = samples * width / 8;
	memcpy(dst, src, bytes);
	return 0;
	}
	src_step = src_area->step / 8;
	dst_step = dst_area->step / 8;
	if (width == 4) {
	/* Ima ADPCM */
	int srcbit = src_area->first % 8;
	int srcbit_step = src_area->step % 8;
	int dstbit = dst_area->first % 8;
	int dstbit_step = dst_area->step % 8;
	while (samples-- > 0) {
	unsigned char srcval;
	if (srcbit)
	srcval = *src & 0x0f;
	else
	srcval = (*src & 0xf0) >> 4;
	if (dstbit)
	dst = (dst & 0xf0) \| srcval;
	else
	dst = (dst & 0x0f) \| (srcval << 4);
	src += src_step;
	srcbit += srcbit_step;
	if (srcbit == 8) {
	src++;
	srcbit = 0;
	}
	dst += dst_step;
	dstbit += dstbit_step;
	if (dstbit == 8) {
	dst++;
	dstbit = 0;
	}
	}
	} else {
	width /= 8;
	while (samples-- > 0) {
	memcpy(dst, src, width);
	src += src_step;
	dst += dst_step;
	}
	}
	return 0;
	}

	#endif