1 files changed, 799 insertions, 0 deletions

diff --git a/sound/core/oss/pcm_plugin.c b/sound/core/oss/pcm_plugin.c
new file mode 100644
index 000000000..8b7bbabee
--- /dev/null
+++ b/sound/core/oss/pcm_plugin.c
@@ -0,0 +1,799 @@
+/*
+ *  PCM Plug-In shared (kernel/library) code
+ *  Copyright (c) 1999 by Jaroslav Kysela <perex@perex.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 <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 = array3_size(frames, format->channels, width);
+	/* check for too large period size once again */
+	if (size > 1024 * 1024)
+		return -ENOMEM;
+	if (snd_BUG_ON(size % 8))
+		return -ENXIO;
+	size /= 8;
+	if (plugin->buf_frames < frames) {
+		kvfree(plugin->buf);
+		plugin->buf = kvzalloc(size, GFP_KERNEL);
+		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) {
+		if (snd_BUG_ON(size % format->channels))
+			return -EINVAL;
+		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;
+	if (snd_BUG_ON(!snd_pcm_plug_first(plug)))
+		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);
+			if ((snd_pcm_sframes_t)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);
+			if ((snd_pcm_sframes_t)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;
+	
+	if (snd_BUG_ON(!plug))
+		return -ENXIO;
+	if (snd_BUG_ON(!src_format || !dst_format))
+		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_BUG_ON(plugin->src_width <= 0);
+	plugin->dst_format = *dst_format;
+	plugin->dst_width = snd_pcm_format_physical_width(dst_format->format);
+	snd_BUG_ON(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);
+	kvfree(plugin->buf);
+	kfree(plugin);
+	return 0;
+}
+
+static snd_pcm_sframes_t plug_client_size(struct snd_pcm_substream *plug,
+					  snd_pcm_uframes_t drv_frames,
+					  bool check_size)
+{
+	struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next;
+	int stream;
+
+	if (snd_BUG_ON(!plug))
+		return -ENXIO;
+	if (drv_frames == 0)
+		return 0;
+	stream = snd_pcm_plug_stream(plug);
+	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);
+			if (check_size && plugin->buf_frames &&
+			    drv_frames > plugin->buf_frames)
+				drv_frames = plugin->buf_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 (check_size && plugin->buf_frames &&
+			    drv_frames > plugin->buf_frames)
+				drv_frames = plugin->buf_frames;
+			if (plugin->dst_frames)
+				drv_frames = plugin->dst_frames(plugin, drv_frames);
+			plugin = plugin_next;
+		}
+	} else
+		snd_BUG();
+	return drv_frames;
+}
+
+static snd_pcm_sframes_t plug_slave_size(struct snd_pcm_substream *plug,
+					 snd_pcm_uframes_t clt_frames,
+					 bool check_size)
+{
+	struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next;
+	snd_pcm_sframes_t frames;
+	int stream;
+	
+	if (snd_BUG_ON(!plug))
+		return -ENXIO;
+	if (clt_frames == 0)
+		return 0;
+	frames = clt_frames;
+	stream = snd_pcm_plug_stream(plug);
+	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		plugin = snd_pcm_plug_first(plug);
+		while (plugin && frames > 0) {
+			plugin_next = plugin->next;
+			if (check_size && plugin->buf_frames &&
+			    frames > plugin->buf_frames)
+				frames = plugin->buf_frames;
+			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;
+			}
+			if (check_size && plugin->buf_frames &&
+			    frames > plugin->buf_frames)
+				frames = plugin->buf_frames;
+			plugin = plugin_prev;
+		}
+	} else
+		snd_BUG();
+	return frames;
+}
+
+snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug,
+					   snd_pcm_uframes_t drv_frames)
+{
+	return plug_client_size(plug, drv_frames, false);
+}
+
+snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug,
+					  snd_pcm_uframes_t clt_frames)
+{
+	return plug_slave_size(plug, clt_frames, false);
+}
+
+static int snd_pcm_plug_formats(const struct snd_mask *mask,
+				snd_pcm_format_t 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_U24_3LE | SNDRV_PCM_FMTBIT_S24_3LE |
+		       SNDRV_PCM_FMTBIT_U24_3BE | SNDRV_PCM_FMTBIT_S24_3BE |
+		       SNDRV_PCM_FMTBIT_U32_LE | SNDRV_PCM_FMTBIT_S32_LE |
+		       SNDRV_PCM_FMTBIT_U32_BE | SNDRV_PCM_FMTBIT_S32_BE);
+	snd_mask_set(&formats, (__force int)SNDRV_PCM_FORMAT_MU_LAW);
+	
+	if (formats.bits[0] & lower_32_bits(linfmts))
+		formats.bits[0] |= lower_32_bits(linfmts);
+	if (formats.bits[1] & upper_32_bits(linfmts))
+		formats.bits[1] |= upper_32_bits(linfmts);
+	return snd_mask_test(&formats, (__force int)format);
+}
+
+static snd_pcm_format_t 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_3LE,
+	SNDRV_PCM_FORMAT_S24_3BE,
+	SNDRV_PCM_FORMAT_U24_3LE,
+	SNDRV_PCM_FORMAT_U24_3BE,
+	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
+};
+
+snd_pcm_format_t snd_pcm_plug_slave_format(snd_pcm_format_t format,
+					   const struct snd_mask *format_mask)
+{
+	int i;
+
+	if (snd_mask_test(format_mask, (__force int)format))
+		return format;
+	if (!snd_pcm_plug_formats(format_mask, format))
+		return (__force snd_pcm_format_t)-EINVAL;
+	if (snd_pcm_format_linear(format)) {
+		unsigned int width = snd_pcm_format_width(format);
+		int unsignd = snd_pcm_format_unsigned(format) > 0;
+		int big = snd_pcm_format_big_endian(format) > 0;
+		unsigned int badness, best = -1;
+		snd_pcm_format_t best_format = (__force snd_pcm_format_t)-1;
+		for (i = 0; i < ARRAY_SIZE(preferred_formats); i++) {
+			snd_pcm_format_t f = preferred_formats[i];
+			unsigned int w;
+			if (!snd_mask_test(format_mask, (__force int)f))
+				continue;
+			w = snd_pcm_format_width(f);
+			if (w >= width)
+				badness = w - width;
+			else
+				badness = width - w + 32;
+			badness += snd_pcm_format_unsigned(f) != unsignd;
+			badness += snd_pcm_format_big_endian(f) != big;
+			if (badness < best) {
+				best_format = f;
+				best = badness;
+			}
+		}
+		if ((__force int)best_format >= 0)
+			return best_format;
+		else
+			return (__force snd_pcm_format_t)-EINVAL;
+	} else {
+		switch (format) {
+		case SNDRV_PCM_FORMAT_MU_LAW:
+			for (i = 0; i < ARRAY_SIZE(preferred_formats); ++i) {
+				snd_pcm_format_t format1 = preferred_formats[i];
+				if (snd_mask_test(format_mask, (__force int)format1))
+					return format1;
+			}
+			/* fall through */
+		default:
+			return (__force snd_pcm_format_t)-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;
+	snd_pcm_access_t 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);
+
+	if (snd_BUG_ON(!buf))
+		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;
+	if (snd_BUG_ON(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) {
+		if (frames <= 0)
+			return frames;
+		if ((next = plugin->next) != NULL) {
+			snd_pcm_sframes_t frames1 = frames;
+			if (plugin->dst_frames) {
+				frames1 = plugin->dst_frames(plugin, frames);
+				if (frames1 <= 0)
+					return frames1;
+			}
+			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);
+					if (frames <= 0)
+						return frames;
+				}
+			}
+		} 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 plug_client_size(plug, frames, true);
+}
+
+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 = plug_slave_size(plug, frames, true);
+	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, snd_pcm_format_t 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, snd_pcm_format_t 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;
+}