xref: /openbmc/linux/sound/core/oss/pcm_plugin.c (revision 828ff2ad)
1 /*
2  *  PCM Plug-In shared (kernel/library) code
3  *  Copyright (c) 1999 by Jaroslav Kysela <perex@perex.cz>
4  *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
5  *
6  *
7  *   This library is free software; you can redistribute it and/or modify
8  *   it under the terms of the GNU Library General Public License as
9  *   published by the Free Software Foundation; either version 2 of
10  *   the License, or (at your option) any later version.
11  *
12  *   This program is distributed in the hope that it will be useful,
13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  *   GNU Library General Public License for more details.
16  *
17  *   You should have received a copy of the GNU Library General Public
18  *   License along with this library; if not, write to the Free Software
19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
20  *
21  */
22 
23 #if 0
24 #define PLUGIN_DEBUG
25 #endif
26 
27 #include <linux/slab.h>
28 #include <linux/time.h>
29 #include <linux/vmalloc.h>
30 #include <sound/core.h>
31 #include <sound/pcm.h>
32 #include <sound/pcm_params.h>
33 #include "pcm_plugin.h"
34 
35 #define snd_pcm_plug_first(plug) ((plug)->runtime->oss.plugin_first)
36 #define snd_pcm_plug_last(plug) ((plug)->runtime->oss.plugin_last)
37 
38 /*
39  *  because some cards might have rates "very close", we ignore
40  *  all "resampling" requests within +-5%
41  */
42 static int rate_match(unsigned int src_rate, unsigned int dst_rate)
43 {
44 	unsigned int low = (src_rate * 95) / 100;
45 	unsigned int high = (src_rate * 105) / 100;
46 	return dst_rate >= low && dst_rate <= high;
47 }
48 
49 static int snd_pcm_plugin_alloc(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
50 {
51 	struct snd_pcm_plugin_format *format;
52 	ssize_t width;
53 	size_t size;
54 	unsigned int channel;
55 	struct snd_pcm_plugin_channel *c;
56 
57 	if (plugin->stream == SNDRV_PCM_STREAM_PLAYBACK) {
58 		format = &plugin->src_format;
59 	} else {
60 		format = &plugin->dst_format;
61 	}
62 	if ((width = snd_pcm_format_physical_width(format->format)) < 0)
63 		return width;
64 	size = frames * format->channels * width;
65 	if (snd_BUG_ON(size % 8))
66 		return -ENXIO;
67 	size /= 8;
68 	if (plugin->buf_frames < frames) {
69 		vfree(plugin->buf);
70 		plugin->buf = vmalloc(size);
71 		plugin->buf_frames = frames;
72 	}
73 	if (!plugin->buf) {
74 		plugin->buf_frames = 0;
75 		return -ENOMEM;
76 	}
77 	c = plugin->buf_channels;
78 	if (plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED) {
79 		for (channel = 0; channel < format->channels; channel++, c++) {
80 			c->frames = frames;
81 			c->enabled = 1;
82 			c->wanted = 0;
83 			c->area.addr = plugin->buf;
84 			c->area.first = channel * width;
85 			c->area.step = format->channels * width;
86 		}
87 	} else if (plugin->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED) {
88 		if (snd_BUG_ON(size % format->channels))
89 			return -EINVAL;
90 		size /= format->channels;
91 		for (channel = 0; channel < format->channels; channel++, c++) {
92 			c->frames = frames;
93 			c->enabled = 1;
94 			c->wanted = 0;
95 			c->area.addr = plugin->buf + (channel * size);
96 			c->area.first = 0;
97 			c->area.step = width;
98 		}
99 	} else
100 		return -EINVAL;
101 	return 0;
102 }
103 
104 int snd_pcm_plug_alloc(struct snd_pcm_substream *plug, snd_pcm_uframes_t frames)
105 {
106 	int err;
107 	if (snd_BUG_ON(!snd_pcm_plug_first(plug)))
108 		return -ENXIO;
109 	if (snd_pcm_plug_stream(plug) == SNDRV_PCM_STREAM_PLAYBACK) {
110 		struct snd_pcm_plugin *plugin = snd_pcm_plug_first(plug);
111 		while (plugin->next) {
112 			if (plugin->dst_frames)
113 				frames = plugin->dst_frames(plugin, frames);
114 			if (snd_BUG_ON((snd_pcm_sframes_t)frames <= 0))
115 				return -ENXIO;
116 			plugin = plugin->next;
117 			err = snd_pcm_plugin_alloc(plugin, frames);
118 			if (err < 0)
119 				return err;
120 		}
121 	} else {
122 		struct snd_pcm_plugin *plugin = snd_pcm_plug_last(plug);
123 		while (plugin->prev) {
124 			if (plugin->src_frames)
125 				frames = plugin->src_frames(plugin, frames);
126 			if (snd_BUG_ON((snd_pcm_sframes_t)frames <= 0))
127 				return -ENXIO;
128 			plugin = plugin->prev;
129 			err = snd_pcm_plugin_alloc(plugin, frames);
130 			if (err < 0)
131 				return err;
132 		}
133 	}
134 	return 0;
135 }
136 
137 
138 snd_pcm_sframes_t snd_pcm_plugin_client_channels(struct snd_pcm_plugin *plugin,
139 				       snd_pcm_uframes_t frames,
140 				       struct snd_pcm_plugin_channel **channels)
141 {
142 	*channels = plugin->buf_channels;
143 	return frames;
144 }
145 
146 int snd_pcm_plugin_build(struct snd_pcm_substream *plug,
147 			 const char *name,
148 			 struct snd_pcm_plugin_format *src_format,
149 			 struct snd_pcm_plugin_format *dst_format,
150 			 size_t extra,
151 			 struct snd_pcm_plugin **ret)
152 {
153 	struct snd_pcm_plugin *plugin;
154 	unsigned int channels;
155 
156 	if (snd_BUG_ON(!plug))
157 		return -ENXIO;
158 	if (snd_BUG_ON(!src_format || !dst_format))
159 		return -ENXIO;
160 	plugin = kzalloc(sizeof(*plugin) + extra, GFP_KERNEL);
161 	if (plugin == NULL)
162 		return -ENOMEM;
163 	plugin->name = name;
164 	plugin->plug = plug;
165 	plugin->stream = snd_pcm_plug_stream(plug);
166 	plugin->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
167 	plugin->src_format = *src_format;
168 	plugin->src_width = snd_pcm_format_physical_width(src_format->format);
169 	snd_BUG_ON(plugin->src_width <= 0);
170 	plugin->dst_format = *dst_format;
171 	plugin->dst_width = snd_pcm_format_physical_width(dst_format->format);
172 	snd_BUG_ON(plugin->dst_width <= 0);
173 	if (plugin->stream == SNDRV_PCM_STREAM_PLAYBACK)
174 		channels = src_format->channels;
175 	else
176 		channels = dst_format->channels;
177 	plugin->buf_channels = kcalloc(channels, sizeof(*plugin->buf_channels), GFP_KERNEL);
178 	if (plugin->buf_channels == NULL) {
179 		snd_pcm_plugin_free(plugin);
180 		return -ENOMEM;
181 	}
182 	plugin->client_channels = snd_pcm_plugin_client_channels;
183 	*ret = plugin;
184 	return 0;
185 }
186 
187 int snd_pcm_plugin_free(struct snd_pcm_plugin *plugin)
188 {
189 	if (! plugin)
190 		return 0;
191 	if (plugin->private_free)
192 		plugin->private_free(plugin);
193 	kfree(plugin->buf_channels);
194 	vfree(plugin->buf);
195 	kfree(plugin);
196 	return 0;
197 }
198 
199 snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t drv_frames)
200 {
201 	struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next;
202 	int stream;
203 
204 	if (snd_BUG_ON(!plug))
205 		return -ENXIO;
206 	if (drv_frames == 0)
207 		return 0;
208 	stream = snd_pcm_plug_stream(plug);
209 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
210 		plugin = snd_pcm_plug_last(plug);
211 		while (plugin && drv_frames > 0) {
212 			plugin_prev = plugin->prev;
213 			if (plugin->src_frames)
214 				drv_frames = plugin->src_frames(plugin, drv_frames);
215 			plugin = plugin_prev;
216 		}
217 	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
218 		plugin = snd_pcm_plug_first(plug);
219 		while (plugin && drv_frames > 0) {
220 			plugin_next = plugin->next;
221 			if (plugin->dst_frames)
222 				drv_frames = plugin->dst_frames(plugin, drv_frames);
223 			plugin = plugin_next;
224 		}
225 	} else
226 		snd_BUG();
227 	return drv_frames;
228 }
229 
230 snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t clt_frames)
231 {
232 	struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next;
233 	snd_pcm_sframes_t frames;
234 	int stream;
235 
236 	if (snd_BUG_ON(!plug))
237 		return -ENXIO;
238 	if (clt_frames == 0)
239 		return 0;
240 	frames = clt_frames;
241 	stream = snd_pcm_plug_stream(plug);
242 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
243 		plugin = snd_pcm_plug_first(plug);
244 		while (plugin && frames > 0) {
245 			plugin_next = plugin->next;
246 			if (plugin->dst_frames) {
247 				frames = plugin->dst_frames(plugin, frames);
248 				if (frames < 0)
249 					return frames;
250 			}
251 			plugin = plugin_next;
252 		}
253 	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
254 		plugin = snd_pcm_plug_last(plug);
255 		while (plugin) {
256 			plugin_prev = plugin->prev;
257 			if (plugin->src_frames) {
258 				frames = plugin->src_frames(plugin, frames);
259 				if (frames < 0)
260 					return frames;
261 			}
262 			plugin = plugin_prev;
263 		}
264 	} else
265 		snd_BUG();
266 	return frames;
267 }
268 
269 static int snd_pcm_plug_formats(const struct snd_mask *mask,
270 				snd_pcm_format_t format)
271 {
272 	struct snd_mask formats = *mask;
273 	u64 linfmts = (SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S8 |
274 		       SNDRV_PCM_FMTBIT_U16_LE | SNDRV_PCM_FMTBIT_S16_LE |
275 		       SNDRV_PCM_FMTBIT_U16_BE | SNDRV_PCM_FMTBIT_S16_BE |
276 		       SNDRV_PCM_FMTBIT_U24_LE | SNDRV_PCM_FMTBIT_S24_LE |
277 		       SNDRV_PCM_FMTBIT_U24_BE | SNDRV_PCM_FMTBIT_S24_BE |
278 		       SNDRV_PCM_FMTBIT_U24_3LE | SNDRV_PCM_FMTBIT_S24_3LE |
279 		       SNDRV_PCM_FMTBIT_U24_3BE | SNDRV_PCM_FMTBIT_S24_3BE |
280 		       SNDRV_PCM_FMTBIT_U32_LE | SNDRV_PCM_FMTBIT_S32_LE |
281 		       SNDRV_PCM_FMTBIT_U32_BE | SNDRV_PCM_FMTBIT_S32_BE);
282 	snd_mask_set(&formats, (__force int)SNDRV_PCM_FORMAT_MU_LAW);
283 
284 	if (formats.bits[0] & lower_32_bits(linfmts))
285 		formats.bits[0] |= lower_32_bits(linfmts);
286 	if (formats.bits[1] & upper_32_bits(linfmts))
287 		formats.bits[1] |= upper_32_bits(linfmts);
288 	return snd_mask_test(&formats, (__force int)format);
289 }
290 
291 static snd_pcm_format_t preferred_formats[] = {
292 	SNDRV_PCM_FORMAT_S16_LE,
293 	SNDRV_PCM_FORMAT_S16_BE,
294 	SNDRV_PCM_FORMAT_U16_LE,
295 	SNDRV_PCM_FORMAT_U16_BE,
296 	SNDRV_PCM_FORMAT_S24_3LE,
297 	SNDRV_PCM_FORMAT_S24_3BE,
298 	SNDRV_PCM_FORMAT_U24_3LE,
299 	SNDRV_PCM_FORMAT_U24_3BE,
300 	SNDRV_PCM_FORMAT_S24_LE,
301 	SNDRV_PCM_FORMAT_S24_BE,
302 	SNDRV_PCM_FORMAT_U24_LE,
303 	SNDRV_PCM_FORMAT_U24_BE,
304 	SNDRV_PCM_FORMAT_S32_LE,
305 	SNDRV_PCM_FORMAT_S32_BE,
306 	SNDRV_PCM_FORMAT_U32_LE,
307 	SNDRV_PCM_FORMAT_U32_BE,
308 	SNDRV_PCM_FORMAT_S8,
309 	SNDRV_PCM_FORMAT_U8
310 };
311 
312 snd_pcm_format_t snd_pcm_plug_slave_format(snd_pcm_format_t format,
313 					   const struct snd_mask *format_mask)
314 {
315 	int i;
316 
317 	if (snd_mask_test(format_mask, (__force int)format))
318 		return format;
319 	if (!snd_pcm_plug_formats(format_mask, format))
320 		return (__force snd_pcm_format_t)-EINVAL;
321 	if (snd_pcm_format_linear(format)) {
322 		unsigned int width = snd_pcm_format_width(format);
323 		int unsignd = snd_pcm_format_unsigned(format) > 0;
324 		int big = snd_pcm_format_big_endian(format) > 0;
325 		unsigned int badness, best = -1;
326 		snd_pcm_format_t best_format = (__force snd_pcm_format_t)-1;
327 		for (i = 0; i < ARRAY_SIZE(preferred_formats); i++) {
328 			snd_pcm_format_t f = preferred_formats[i];
329 			unsigned int w;
330 			if (!snd_mask_test(format_mask, (__force int)f))
331 				continue;
332 			w = snd_pcm_format_width(f);
333 			if (w >= width)
334 				badness = w - width;
335 			else
336 				badness = width - w + 32;
337 			badness += snd_pcm_format_unsigned(f) != unsignd;
338 			badness += snd_pcm_format_big_endian(f) != big;
339 			if (badness < best) {
340 				best_format = f;
341 				best = badness;
342 			}
343 		}
344 		if ((__force int)best_format >= 0)
345 			return best_format;
346 		else
347 			return (__force snd_pcm_format_t)-EINVAL;
348 	} else {
349 		switch (format) {
350 		case SNDRV_PCM_FORMAT_MU_LAW:
351 			for (i = 0; i < ARRAY_SIZE(preferred_formats); ++i) {
352 				snd_pcm_format_t format1 = preferred_formats[i];
353 				if (snd_mask_test(format_mask, (__force int)format1))
354 					return format1;
355 			}
356 			/* fall through */
357 		default:
358 			return (__force snd_pcm_format_t)-EINVAL;
359 		}
360 	}
361 }
362 
363 int snd_pcm_plug_format_plugins(struct snd_pcm_substream *plug,
364 				struct snd_pcm_hw_params *params,
365 				struct snd_pcm_hw_params *slave_params)
366 {
367 	struct snd_pcm_plugin_format tmpformat;
368 	struct snd_pcm_plugin_format dstformat;
369 	struct snd_pcm_plugin_format srcformat;
370 	snd_pcm_access_t src_access, dst_access;
371 	struct snd_pcm_plugin *plugin = NULL;
372 	int err;
373 	int stream = snd_pcm_plug_stream(plug);
374 	int slave_interleaved = (params_channels(slave_params) == 1 ||
375 				 params_access(slave_params) == SNDRV_PCM_ACCESS_RW_INTERLEAVED);
376 
377 	switch (stream) {
378 	case SNDRV_PCM_STREAM_PLAYBACK:
379 		dstformat.format = params_format(slave_params);
380 		dstformat.rate = params_rate(slave_params);
381 		dstformat.channels = params_channels(slave_params);
382 		srcformat.format = params_format(params);
383 		srcformat.rate = params_rate(params);
384 		srcformat.channels = params_channels(params);
385 		src_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
386 		dst_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
387 						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
388 		break;
389 	case SNDRV_PCM_STREAM_CAPTURE:
390 		dstformat.format = params_format(params);
391 		dstformat.rate = params_rate(params);
392 		dstformat.channels = params_channels(params);
393 		srcformat.format = params_format(slave_params);
394 		srcformat.rate = params_rate(slave_params);
395 		srcformat.channels = params_channels(slave_params);
396 		src_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
397 						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
398 		dst_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
399 		break;
400 	default:
401 		snd_BUG();
402 		return -EINVAL;
403 	}
404 	tmpformat = srcformat;
405 
406 	pdprintf("srcformat: format=%i, rate=%i, channels=%i\n",
407 		 srcformat.format,
408 		 srcformat.rate,
409 		 srcformat.channels);
410 	pdprintf("dstformat: format=%i, rate=%i, channels=%i\n",
411 		 dstformat.format,
412 		 dstformat.rate,
413 		 dstformat.channels);
414 
415 	/* Format change (linearization) */
416 	if (! rate_match(srcformat.rate, dstformat.rate) &&
417 	    ! snd_pcm_format_linear(srcformat.format)) {
418 		if (srcformat.format != SNDRV_PCM_FORMAT_MU_LAW)
419 			return -EINVAL;
420 		tmpformat.format = SNDRV_PCM_FORMAT_S16;
421 		err = snd_pcm_plugin_build_mulaw(plug,
422 						 &srcformat, &tmpformat,
423 						 &plugin);
424 		if (err < 0)
425 			return err;
426 		err = snd_pcm_plugin_append(plugin);
427 		if (err < 0) {
428 			snd_pcm_plugin_free(plugin);
429 			return err;
430 		}
431 		srcformat = tmpformat;
432 		src_access = dst_access;
433 	}
434 
435 	/* channels reduction */
436 	if (srcformat.channels > dstformat.channels) {
437 		tmpformat.channels = dstformat.channels;
438 		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
439 		pdprintf("channels reduction: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
440 		if (err < 0)
441 			return err;
442 		err = snd_pcm_plugin_append(plugin);
443 		if (err < 0) {
444 			snd_pcm_plugin_free(plugin);
445 			return err;
446 		}
447 		srcformat = tmpformat;
448 		src_access = dst_access;
449 	}
450 
451 	/* rate resampling */
452 	if (!rate_match(srcformat.rate, dstformat.rate)) {
453 		if (srcformat.format != SNDRV_PCM_FORMAT_S16) {
454 			/* convert to S16 for resampling */
455 			tmpformat.format = SNDRV_PCM_FORMAT_S16;
456 			err = snd_pcm_plugin_build_linear(plug,
457 							  &srcformat, &tmpformat,
458 							  &plugin);
459 			if (err < 0)
460 				return err;
461 			err = snd_pcm_plugin_append(plugin);
462 			if (err < 0) {
463 				snd_pcm_plugin_free(plugin);
464 				return err;
465 			}
466 			srcformat = tmpformat;
467 			src_access = dst_access;
468 		}
469 		tmpformat.rate = dstformat.rate;
470         	err = snd_pcm_plugin_build_rate(plug,
471         					&srcformat, &tmpformat,
472 						&plugin);
473 		pdprintf("rate down resampling: src=%i, dst=%i returns %i\n", srcformat.rate, tmpformat.rate, err);
474 		if (err < 0)
475 			return err;
476 		err = snd_pcm_plugin_append(plugin);
477 		if (err < 0) {
478 			snd_pcm_plugin_free(plugin);
479 			return err;
480 		}
481 		srcformat = tmpformat;
482 		src_access = dst_access;
483         }
484 
485 	/* format change */
486 	if (srcformat.format != dstformat.format) {
487 		tmpformat.format = dstformat.format;
488 		if (srcformat.format == SNDRV_PCM_FORMAT_MU_LAW ||
489 		    tmpformat.format == SNDRV_PCM_FORMAT_MU_LAW) {
490 			err = snd_pcm_plugin_build_mulaw(plug,
491 							 &srcformat, &tmpformat,
492 							 &plugin);
493 		}
494 		else if (snd_pcm_format_linear(srcformat.format) &&
495 			 snd_pcm_format_linear(tmpformat.format)) {
496 			err = snd_pcm_plugin_build_linear(plug,
497 							  &srcformat, &tmpformat,
498 							  &plugin);
499 		}
500 		else
501 			return -EINVAL;
502 		pdprintf("format change: src=%i, dst=%i returns %i\n", srcformat.format, tmpformat.format, err);
503 		if (err < 0)
504 			return err;
505 		err = snd_pcm_plugin_append(plugin);
506 		if (err < 0) {
507 			snd_pcm_plugin_free(plugin);
508 			return err;
509 		}
510 		srcformat = tmpformat;
511 		src_access = dst_access;
512 	}
513 
514 	/* channels extension */
515 	if (srcformat.channels < dstformat.channels) {
516 		tmpformat.channels = dstformat.channels;
517 		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
518 		pdprintf("channels extension: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
519 		if (err < 0)
520 			return err;
521 		err = snd_pcm_plugin_append(plugin);
522 		if (err < 0) {
523 			snd_pcm_plugin_free(plugin);
524 			return err;
525 		}
526 		srcformat = tmpformat;
527 		src_access = dst_access;
528 	}
529 
530 	/* de-interleave */
531 	if (src_access != dst_access) {
532 		err = snd_pcm_plugin_build_copy(plug,
533 						&srcformat,
534 						&tmpformat,
535 						&plugin);
536 		pdprintf("interleave change (copy: returns %i)\n", err);
537 		if (err < 0)
538 			return err;
539 		err = snd_pcm_plugin_append(plugin);
540 		if (err < 0) {
541 			snd_pcm_plugin_free(plugin);
542 			return err;
543 		}
544 	}
545 
546 	return 0;
547 }
548 
549 snd_pcm_sframes_t snd_pcm_plug_client_channels_buf(struct snd_pcm_substream *plug,
550 					 char *buf,
551 					 snd_pcm_uframes_t count,
552 					 struct snd_pcm_plugin_channel **channels)
553 {
554 	struct snd_pcm_plugin *plugin;
555 	struct snd_pcm_plugin_channel *v;
556 	struct snd_pcm_plugin_format *format;
557 	int width, nchannels, channel;
558 	int stream = snd_pcm_plug_stream(plug);
559 
560 	if (snd_BUG_ON(!buf))
561 		return -ENXIO;
562 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
563 		plugin = snd_pcm_plug_first(plug);
564 		format = &plugin->src_format;
565 	} else {
566 		plugin = snd_pcm_plug_last(plug);
567 		format = &plugin->dst_format;
568 	}
569 	v = plugin->buf_channels;
570 	*channels = v;
571 	if ((width = snd_pcm_format_physical_width(format->format)) < 0)
572 		return width;
573 	nchannels = format->channels;
574 	if (snd_BUG_ON(plugin->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED &&
575 		       format->channels > 1))
576 		return -ENXIO;
577 	for (channel = 0; channel < nchannels; channel++, v++) {
578 		v->frames = count;
579 		v->enabled = 1;
580 		v->wanted = (stream == SNDRV_PCM_STREAM_CAPTURE);
581 		v->area.addr = buf;
582 		v->area.first = channel * width;
583 		v->area.step = nchannels * width;
584 	}
585 	return count;
586 }
587 
588 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)
589 {
590 	struct snd_pcm_plugin *plugin, *next;
591 	struct snd_pcm_plugin_channel *dst_channels;
592 	int err;
593 	snd_pcm_sframes_t frames = size;
594 
595 	plugin = snd_pcm_plug_first(plug);
596 	while (plugin) {
597 		if (frames <= 0)
598 			return frames;
599 		if ((next = plugin->next) != NULL) {
600 			snd_pcm_sframes_t frames1 = frames;
601 			if (plugin->dst_frames) {
602 				frames1 = plugin->dst_frames(plugin, frames);
603 				if (frames1 <= 0)
604 					return frames1;
605 			}
606 			if ((err = next->client_channels(next, frames1, &dst_channels)) < 0) {
607 				return err;
608 			}
609 			if (err != frames1) {
610 				frames = err;
611 				if (plugin->src_frames) {
612 					frames = plugin->src_frames(plugin, frames1);
613 					if (frames <= 0)
614 						return frames;
615 				}
616 			}
617 		} else
618 			dst_channels = NULL;
619 		pdprintf("write plugin: %s, %li\n", plugin->name, frames);
620 		if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
621 			return frames;
622 		src_channels = dst_channels;
623 		plugin = next;
624 	}
625 	return snd_pcm_plug_client_size(plug, frames);
626 }
627 
628 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)
629 {
630 	struct snd_pcm_plugin *plugin, *next;
631 	struct snd_pcm_plugin_channel *src_channels, *dst_channels;
632 	snd_pcm_sframes_t frames = size;
633 	int err;
634 
635 	frames = snd_pcm_plug_slave_size(plug, frames);
636 	if (frames < 0)
637 		return frames;
638 
639 	src_channels = NULL;
640 	plugin = snd_pcm_plug_first(plug);
641 	while (plugin && frames > 0) {
642 		if ((next = plugin->next) != NULL) {
643 			if ((err = plugin->client_channels(plugin, frames, &dst_channels)) < 0) {
644 				return err;
645 			}
646 			frames = err;
647 		} else {
648 			dst_channels = dst_channels_final;
649 		}
650 		pdprintf("read plugin: %s, %li\n", plugin->name, frames);
651 		if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
652 			return frames;
653 		plugin = next;
654 		src_channels = dst_channels;
655 	}
656 	return frames;
657 }
658 
659 int snd_pcm_area_silence(const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
660 			 size_t samples, snd_pcm_format_t format)
661 {
662 	/* FIXME: sub byte resolution and odd dst_offset */
663 	unsigned char *dst;
664 	unsigned int dst_step;
665 	int width;
666 	const unsigned char *silence;
667 	if (!dst_area->addr)
668 		return 0;
669 	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
670 	width = snd_pcm_format_physical_width(format);
671 	if (width <= 0)
672 		return -EINVAL;
673 	if (dst_area->step == (unsigned int) width && width >= 8)
674 		return snd_pcm_format_set_silence(format, dst, samples);
675 	silence = snd_pcm_format_silence_64(format);
676 	if (! silence)
677 		return -EINVAL;
678 	dst_step = dst_area->step / 8;
679 	if (width == 4) {
680 		/* Ima ADPCM */
681 		int dstbit = dst_area->first % 8;
682 		int dstbit_step = dst_area->step % 8;
683 		while (samples-- > 0) {
684 			if (dstbit)
685 				*dst &= 0xf0;
686 			else
687 				*dst &= 0x0f;
688 			dst += dst_step;
689 			dstbit += dstbit_step;
690 			if (dstbit == 8) {
691 				dst++;
692 				dstbit = 0;
693 			}
694 		}
695 	} else {
696 		width /= 8;
697 		while (samples-- > 0) {
698 			memcpy(dst, silence, width);
699 			dst += dst_step;
700 		}
701 	}
702 	return 0;
703 }
704 
705 int snd_pcm_area_copy(const struct snd_pcm_channel_area *src_area, size_t src_offset,
706 		      const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
707 		      size_t samples, snd_pcm_format_t format)
708 {
709 	/* FIXME: sub byte resolution and odd dst_offset */
710 	char *src, *dst;
711 	int width;
712 	int src_step, dst_step;
713 	src = src_area->addr + (src_area->first + src_area->step * src_offset) / 8;
714 	if (!src_area->addr)
715 		return snd_pcm_area_silence(dst_area, dst_offset, samples, format);
716 	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
717 	if (!dst_area->addr)
718 		return 0;
719 	width = snd_pcm_format_physical_width(format);
720 	if (width <= 0)
721 		return -EINVAL;
722 	if (src_area->step == (unsigned int) width &&
723 	    dst_area->step == (unsigned int) width && width >= 8) {
724 		size_t bytes = samples * width / 8;
725 		memcpy(dst, src, bytes);
726 		return 0;
727 	}
728 	src_step = src_area->step / 8;
729 	dst_step = dst_area->step / 8;
730 	if (width == 4) {
731 		/* Ima ADPCM */
732 		int srcbit = src_area->first % 8;
733 		int srcbit_step = src_area->step % 8;
734 		int dstbit = dst_area->first % 8;
735 		int dstbit_step = dst_area->step % 8;
736 		while (samples-- > 0) {
737 			unsigned char srcval;
738 			if (srcbit)
739 				srcval = *src & 0x0f;
740 			else
741 				srcval = (*src & 0xf0) >> 4;
742 			if (dstbit)
743 				*dst = (*dst & 0xf0) | srcval;
744 			else
745 				*dst = (*dst & 0x0f) | (srcval << 4);
746 			src += src_step;
747 			srcbit += srcbit_step;
748 			if (srcbit == 8) {
749 				src++;
750 				srcbit = 0;
751 			}
752 			dst += dst_step;
753 			dstbit += dstbit_step;
754 			if (dstbit == 8) {
755 				dst++;
756 				dstbit = 0;
757 			}
758 		}
759 	} else {
760 		width /= 8;
761 		while (samples-- > 0) {
762 			memcpy(dst, src, width);
763 			src += src_step;
764 			dst += dst_step;
765 		}
766 	}
767 	return 0;
768 }
769