xref: /openbmc/linux/sound/core/oss/pcm_plugin.c (revision 287dcc2b)
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 	width = snd_pcm_format_physical_width(format->format);
63 	if (width < 0)
64 		return width;
65 	size = array3_size(frames, format->channels, width);
66 	/* check for too large period size once again */
67 	if (size > 1024 * 1024)
68 		return -ENOMEM;
69 	if (snd_BUG_ON(size % 8))
70 		return -ENXIO;
71 	size /= 8;
72 	if (plugin->buf_frames < frames) {
73 		kvfree(plugin->buf);
74 		plugin->buf = kvzalloc(size, GFP_KERNEL);
75 		plugin->buf_frames = frames;
76 	}
77 	if (!plugin->buf) {
78 		plugin->buf_frames = 0;
79 		return -ENOMEM;
80 	}
81 	c = plugin->buf_channels;
82 	if (plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED) {
83 		for (channel = 0; channel < format->channels; channel++, c++) {
84 			c->frames = frames;
85 			c->enabled = 1;
86 			c->wanted = 0;
87 			c->area.addr = plugin->buf;
88 			c->area.first = channel * width;
89 			c->area.step = format->channels * width;
90 		}
91 	} else if (plugin->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED) {
92 		if (snd_BUG_ON(size % format->channels))
93 			return -EINVAL;
94 		size /= format->channels;
95 		for (channel = 0; channel < format->channels; channel++, c++) {
96 			c->frames = frames;
97 			c->enabled = 1;
98 			c->wanted = 0;
99 			c->area.addr = plugin->buf + (channel * size);
100 			c->area.first = 0;
101 			c->area.step = width;
102 		}
103 	} else
104 		return -EINVAL;
105 	return 0;
106 }
107 
108 int snd_pcm_plug_alloc(struct snd_pcm_substream *plug, snd_pcm_uframes_t frames)
109 {
110 	int err;
111 	if (snd_BUG_ON(!snd_pcm_plug_first(plug)))
112 		return -ENXIO;
113 	if (snd_pcm_plug_stream(plug) == SNDRV_PCM_STREAM_PLAYBACK) {
114 		struct snd_pcm_plugin *plugin = snd_pcm_plug_first(plug);
115 		while (plugin->next) {
116 			if (plugin->dst_frames)
117 				frames = plugin->dst_frames(plugin, frames);
118 			if ((snd_pcm_sframes_t)frames <= 0)
119 				return -ENXIO;
120 			plugin = plugin->next;
121 			err = snd_pcm_plugin_alloc(plugin, frames);
122 			if (err < 0)
123 				return err;
124 		}
125 	} else {
126 		struct snd_pcm_plugin *plugin = snd_pcm_plug_last(plug);
127 		while (plugin->prev) {
128 			if (plugin->src_frames)
129 				frames = plugin->src_frames(plugin, frames);
130 			if ((snd_pcm_sframes_t)frames <= 0)
131 				return -ENXIO;
132 			plugin = plugin->prev;
133 			err = snd_pcm_plugin_alloc(plugin, frames);
134 			if (err < 0)
135 				return err;
136 		}
137 	}
138 	return 0;
139 }
140 
141 
142 snd_pcm_sframes_t snd_pcm_plugin_client_channels(struct snd_pcm_plugin *plugin,
143 				       snd_pcm_uframes_t frames,
144 				       struct snd_pcm_plugin_channel **channels)
145 {
146 	*channels = plugin->buf_channels;
147 	return frames;
148 }
149 
150 int snd_pcm_plugin_build(struct snd_pcm_substream *plug,
151 			 const char *name,
152 			 struct snd_pcm_plugin_format *src_format,
153 			 struct snd_pcm_plugin_format *dst_format,
154 			 size_t extra,
155 			 struct snd_pcm_plugin **ret)
156 {
157 	struct snd_pcm_plugin *plugin;
158 	unsigned int channels;
159 
160 	if (snd_BUG_ON(!plug))
161 		return -ENXIO;
162 	if (snd_BUG_ON(!src_format || !dst_format))
163 		return -ENXIO;
164 	plugin = kzalloc(sizeof(*plugin) + extra, GFP_KERNEL);
165 	if (plugin == NULL)
166 		return -ENOMEM;
167 	plugin->name = name;
168 	plugin->plug = plug;
169 	plugin->stream = snd_pcm_plug_stream(plug);
170 	plugin->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
171 	plugin->src_format = *src_format;
172 	plugin->src_width = snd_pcm_format_physical_width(src_format->format);
173 	snd_BUG_ON(plugin->src_width <= 0);
174 	plugin->dst_format = *dst_format;
175 	plugin->dst_width = snd_pcm_format_physical_width(dst_format->format);
176 	snd_BUG_ON(plugin->dst_width <= 0);
177 	if (plugin->stream == SNDRV_PCM_STREAM_PLAYBACK)
178 		channels = src_format->channels;
179 	else
180 		channels = dst_format->channels;
181 	plugin->buf_channels = kcalloc(channels, sizeof(*plugin->buf_channels), GFP_KERNEL);
182 	if (plugin->buf_channels == NULL) {
183 		snd_pcm_plugin_free(plugin);
184 		return -ENOMEM;
185 	}
186 	plugin->client_channels = snd_pcm_plugin_client_channels;
187 	*ret = plugin;
188 	return 0;
189 }
190 
191 int snd_pcm_plugin_free(struct snd_pcm_plugin *plugin)
192 {
193 	if (! plugin)
194 		return 0;
195 	if (plugin->private_free)
196 		plugin->private_free(plugin);
197 	kfree(plugin->buf_channels);
198 	kvfree(plugin->buf);
199 	kfree(plugin);
200 	return 0;
201 }
202 
203 static snd_pcm_sframes_t calc_dst_frames(struct snd_pcm_substream *plug,
204 					 snd_pcm_sframes_t frames,
205 					 bool check_size)
206 {
207 	struct snd_pcm_plugin *plugin, *plugin_next;
208 
209 	plugin = snd_pcm_plug_first(plug);
210 	while (plugin && frames > 0) {
211 		plugin_next = plugin->next;
212 		if (check_size && plugin->buf_frames &&
213 		    frames > plugin->buf_frames)
214 			frames = plugin->buf_frames;
215 		if (plugin->dst_frames) {
216 			frames = plugin->dst_frames(plugin, frames);
217 			if (frames < 0)
218 				return frames;
219 		}
220 		plugin = plugin_next;
221 	}
222 	return frames;
223 }
224 
225 static snd_pcm_sframes_t calc_src_frames(struct snd_pcm_substream *plug,
226 					 snd_pcm_sframes_t frames,
227 					 bool check_size)
228 {
229 	struct snd_pcm_plugin *plugin, *plugin_prev;
230 
231 	plugin = snd_pcm_plug_last(plug);
232 	while (plugin && frames > 0) {
233 		plugin_prev = plugin->prev;
234 		if (plugin->src_frames) {
235 			frames = plugin->src_frames(plugin, frames);
236 			if (frames < 0)
237 				return frames;
238 		}
239 		if (check_size && plugin->buf_frames &&
240 		    frames > plugin->buf_frames)
241 			frames = plugin->buf_frames;
242 		plugin = plugin_prev;
243 	}
244 	return frames;
245 }
246 
247 snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t drv_frames)
248 {
249 	if (snd_BUG_ON(!plug))
250 		return -ENXIO;
251 	switch (snd_pcm_plug_stream(plug)) {
252 	case SNDRV_PCM_STREAM_PLAYBACK:
253 		return calc_src_frames(plug, drv_frames, false);
254 	case SNDRV_PCM_STREAM_CAPTURE:
255 		return calc_dst_frames(plug, drv_frames, false);
256 	default:
257 		snd_BUG();
258 		return -EINVAL;
259 	}
260 }
261 
262 snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t clt_frames)
263 {
264 	if (snd_BUG_ON(!plug))
265 		return -ENXIO;
266 	switch (snd_pcm_plug_stream(plug)) {
267 	case SNDRV_PCM_STREAM_PLAYBACK:
268 		return calc_dst_frames(plug, clt_frames, false);
269 	case SNDRV_PCM_STREAM_CAPTURE:
270 		return calc_src_frames(plug, clt_frames, false);
271 	default:
272 		snd_BUG();
273 		return -EINVAL;
274 	}
275 }
276 
277 static int snd_pcm_plug_formats(const struct snd_mask *mask,
278 				snd_pcm_format_t format)
279 {
280 	struct snd_mask formats = *mask;
281 	u64 linfmts = (SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S8 |
282 		       SNDRV_PCM_FMTBIT_U16_LE | SNDRV_PCM_FMTBIT_S16_LE |
283 		       SNDRV_PCM_FMTBIT_U16_BE | SNDRV_PCM_FMTBIT_S16_BE |
284 		       SNDRV_PCM_FMTBIT_U24_LE | SNDRV_PCM_FMTBIT_S24_LE |
285 		       SNDRV_PCM_FMTBIT_U24_BE | SNDRV_PCM_FMTBIT_S24_BE |
286 		       SNDRV_PCM_FMTBIT_U24_3LE | SNDRV_PCM_FMTBIT_S24_3LE |
287 		       SNDRV_PCM_FMTBIT_U24_3BE | SNDRV_PCM_FMTBIT_S24_3BE |
288 		       SNDRV_PCM_FMTBIT_U32_LE | SNDRV_PCM_FMTBIT_S32_LE |
289 		       SNDRV_PCM_FMTBIT_U32_BE | SNDRV_PCM_FMTBIT_S32_BE);
290 	snd_mask_set(&formats, (__force int)SNDRV_PCM_FORMAT_MU_LAW);
291 
292 	if (formats.bits[0] & lower_32_bits(linfmts))
293 		formats.bits[0] |= lower_32_bits(linfmts);
294 	if (formats.bits[1] & upper_32_bits(linfmts))
295 		formats.bits[1] |= upper_32_bits(linfmts);
296 	return snd_mask_test(&formats, (__force int)format);
297 }
298 
299 static const snd_pcm_format_t preferred_formats[] = {
300 	SNDRV_PCM_FORMAT_S16_LE,
301 	SNDRV_PCM_FORMAT_S16_BE,
302 	SNDRV_PCM_FORMAT_U16_LE,
303 	SNDRV_PCM_FORMAT_U16_BE,
304 	SNDRV_PCM_FORMAT_S24_3LE,
305 	SNDRV_PCM_FORMAT_S24_3BE,
306 	SNDRV_PCM_FORMAT_U24_3LE,
307 	SNDRV_PCM_FORMAT_U24_3BE,
308 	SNDRV_PCM_FORMAT_S24_LE,
309 	SNDRV_PCM_FORMAT_S24_BE,
310 	SNDRV_PCM_FORMAT_U24_LE,
311 	SNDRV_PCM_FORMAT_U24_BE,
312 	SNDRV_PCM_FORMAT_S32_LE,
313 	SNDRV_PCM_FORMAT_S32_BE,
314 	SNDRV_PCM_FORMAT_U32_LE,
315 	SNDRV_PCM_FORMAT_U32_BE,
316 	SNDRV_PCM_FORMAT_S8,
317 	SNDRV_PCM_FORMAT_U8
318 };
319 
320 snd_pcm_format_t snd_pcm_plug_slave_format(snd_pcm_format_t format,
321 					   const struct snd_mask *format_mask)
322 {
323 	int i;
324 
325 	if (snd_mask_test(format_mask, (__force int)format))
326 		return format;
327 	if (!snd_pcm_plug_formats(format_mask, format))
328 		return (__force snd_pcm_format_t)-EINVAL;
329 	if (snd_pcm_format_linear(format)) {
330 		unsigned int width = snd_pcm_format_width(format);
331 		int unsignd = snd_pcm_format_unsigned(format) > 0;
332 		int big = snd_pcm_format_big_endian(format) > 0;
333 		unsigned int badness, best = -1;
334 		snd_pcm_format_t best_format = (__force snd_pcm_format_t)-1;
335 		for (i = 0; i < ARRAY_SIZE(preferred_formats); i++) {
336 			snd_pcm_format_t f = preferred_formats[i];
337 			unsigned int w;
338 			if (!snd_mask_test(format_mask, (__force int)f))
339 				continue;
340 			w = snd_pcm_format_width(f);
341 			if (w >= width)
342 				badness = w - width;
343 			else
344 				badness = width - w + 32;
345 			badness += snd_pcm_format_unsigned(f) != unsignd;
346 			badness += snd_pcm_format_big_endian(f) != big;
347 			if (badness < best) {
348 				best_format = f;
349 				best = badness;
350 			}
351 		}
352 		if ((__force int)best_format >= 0)
353 			return best_format;
354 		else
355 			return (__force snd_pcm_format_t)-EINVAL;
356 	} else {
357 		switch (format) {
358 		case SNDRV_PCM_FORMAT_MU_LAW:
359 			for (i = 0; i < ARRAY_SIZE(preferred_formats); ++i) {
360 				snd_pcm_format_t format1 = preferred_formats[i];
361 				if (snd_mask_test(format_mask, (__force int)format1))
362 					return format1;
363 			}
364 			fallthrough;
365 		default:
366 			return (__force snd_pcm_format_t)-EINVAL;
367 		}
368 	}
369 }
370 
371 int snd_pcm_plug_format_plugins(struct snd_pcm_substream *plug,
372 				struct snd_pcm_hw_params *params,
373 				struct snd_pcm_hw_params *slave_params)
374 {
375 	struct snd_pcm_plugin_format tmpformat;
376 	struct snd_pcm_plugin_format dstformat;
377 	struct snd_pcm_plugin_format srcformat;
378 	snd_pcm_access_t src_access, dst_access;
379 	struct snd_pcm_plugin *plugin = NULL;
380 	int err;
381 	int stream = snd_pcm_plug_stream(plug);
382 	int slave_interleaved = (params_channels(slave_params) == 1 ||
383 				 params_access(slave_params) == SNDRV_PCM_ACCESS_RW_INTERLEAVED);
384 
385 	switch (stream) {
386 	case SNDRV_PCM_STREAM_PLAYBACK:
387 		dstformat.format = params_format(slave_params);
388 		dstformat.rate = params_rate(slave_params);
389 		dstformat.channels = params_channels(slave_params);
390 		srcformat.format = params_format(params);
391 		srcformat.rate = params_rate(params);
392 		srcformat.channels = params_channels(params);
393 		src_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
394 		dst_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
395 						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
396 		break;
397 	case SNDRV_PCM_STREAM_CAPTURE:
398 		dstformat.format = params_format(params);
399 		dstformat.rate = params_rate(params);
400 		dstformat.channels = params_channels(params);
401 		srcformat.format = params_format(slave_params);
402 		srcformat.rate = params_rate(slave_params);
403 		srcformat.channels = params_channels(slave_params);
404 		src_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
405 						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
406 		dst_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
407 		break;
408 	default:
409 		snd_BUG();
410 		return -EINVAL;
411 	}
412 	tmpformat = srcformat;
413 
414 	pdprintf("srcformat: format=%i, rate=%i, channels=%i\n",
415 		 srcformat.format,
416 		 srcformat.rate,
417 		 srcformat.channels);
418 	pdprintf("dstformat: format=%i, rate=%i, channels=%i\n",
419 		 dstformat.format,
420 		 dstformat.rate,
421 		 dstformat.channels);
422 
423 	/* Format change (linearization) */
424 	if (! rate_match(srcformat.rate, dstformat.rate) &&
425 	    ! snd_pcm_format_linear(srcformat.format)) {
426 		if (srcformat.format != SNDRV_PCM_FORMAT_MU_LAW)
427 			return -EINVAL;
428 		tmpformat.format = SNDRV_PCM_FORMAT_S16;
429 		err = snd_pcm_plugin_build_mulaw(plug,
430 						 &srcformat, &tmpformat,
431 						 &plugin);
432 		if (err < 0)
433 			return err;
434 		err = snd_pcm_plugin_append(plugin);
435 		if (err < 0) {
436 			snd_pcm_plugin_free(plugin);
437 			return err;
438 		}
439 		srcformat = tmpformat;
440 		src_access = dst_access;
441 	}
442 
443 	/* channels reduction */
444 	if (srcformat.channels > dstformat.channels) {
445 		tmpformat.channels = dstformat.channels;
446 		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
447 		pdprintf("channels reduction: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
448 		if (err < 0)
449 			return err;
450 		err = snd_pcm_plugin_append(plugin);
451 		if (err < 0) {
452 			snd_pcm_plugin_free(plugin);
453 			return err;
454 		}
455 		srcformat = tmpformat;
456 		src_access = dst_access;
457 	}
458 
459 	/* rate resampling */
460 	if (!rate_match(srcformat.rate, dstformat.rate)) {
461 		if (srcformat.format != SNDRV_PCM_FORMAT_S16) {
462 			/* convert to S16 for resampling */
463 			tmpformat.format = SNDRV_PCM_FORMAT_S16;
464 			err = snd_pcm_plugin_build_linear(plug,
465 							  &srcformat, &tmpformat,
466 							  &plugin);
467 			if (err < 0)
468 				return err;
469 			err = snd_pcm_plugin_append(plugin);
470 			if (err < 0) {
471 				snd_pcm_plugin_free(plugin);
472 				return err;
473 			}
474 			srcformat = tmpformat;
475 			src_access = dst_access;
476 		}
477 		tmpformat.rate = dstformat.rate;
478         	err = snd_pcm_plugin_build_rate(plug,
479         					&srcformat, &tmpformat,
480 						&plugin);
481 		pdprintf("rate down resampling: src=%i, dst=%i returns %i\n", srcformat.rate, tmpformat.rate, err);
482 		if (err < 0)
483 			return err;
484 		err = snd_pcm_plugin_append(plugin);
485 		if (err < 0) {
486 			snd_pcm_plugin_free(plugin);
487 			return err;
488 		}
489 		srcformat = tmpformat;
490 		src_access = dst_access;
491         }
492 
493 	/* format change */
494 	if (srcformat.format != dstformat.format) {
495 		tmpformat.format = dstformat.format;
496 		if (srcformat.format == SNDRV_PCM_FORMAT_MU_LAW ||
497 		    tmpformat.format == SNDRV_PCM_FORMAT_MU_LAW) {
498 			err = snd_pcm_plugin_build_mulaw(plug,
499 							 &srcformat, &tmpformat,
500 							 &plugin);
501 		}
502 		else if (snd_pcm_format_linear(srcformat.format) &&
503 			 snd_pcm_format_linear(tmpformat.format)) {
504 			err = snd_pcm_plugin_build_linear(plug,
505 							  &srcformat, &tmpformat,
506 							  &plugin);
507 		}
508 		else
509 			return -EINVAL;
510 		pdprintf("format change: src=%i, dst=%i returns %i\n", srcformat.format, tmpformat.format, err);
511 		if (err < 0)
512 			return err;
513 		err = snd_pcm_plugin_append(plugin);
514 		if (err < 0) {
515 			snd_pcm_plugin_free(plugin);
516 			return err;
517 		}
518 		srcformat = tmpformat;
519 		src_access = dst_access;
520 	}
521 
522 	/* channels extension */
523 	if (srcformat.channels < dstformat.channels) {
524 		tmpformat.channels = dstformat.channels;
525 		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
526 		pdprintf("channels extension: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
527 		if (err < 0)
528 			return err;
529 		err = snd_pcm_plugin_append(plugin);
530 		if (err < 0) {
531 			snd_pcm_plugin_free(plugin);
532 			return err;
533 		}
534 		srcformat = tmpformat;
535 		src_access = dst_access;
536 	}
537 
538 	/* de-interleave */
539 	if (src_access != dst_access) {
540 		err = snd_pcm_plugin_build_copy(plug,
541 						&srcformat,
542 						&tmpformat,
543 						&plugin);
544 		pdprintf("interleave change (copy: returns %i)\n", err);
545 		if (err < 0)
546 			return err;
547 		err = snd_pcm_plugin_append(plugin);
548 		if (err < 0) {
549 			snd_pcm_plugin_free(plugin);
550 			return err;
551 		}
552 	}
553 
554 	return 0;
555 }
556 
557 snd_pcm_sframes_t snd_pcm_plug_client_channels_buf(struct snd_pcm_substream *plug,
558 					 char *buf,
559 					 snd_pcm_uframes_t count,
560 					 struct snd_pcm_plugin_channel **channels)
561 {
562 	struct snd_pcm_plugin *plugin;
563 	struct snd_pcm_plugin_channel *v;
564 	struct snd_pcm_plugin_format *format;
565 	int width, nchannels, channel;
566 	int stream = snd_pcm_plug_stream(plug);
567 
568 	if (snd_BUG_ON(!buf))
569 		return -ENXIO;
570 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
571 		plugin = snd_pcm_plug_first(plug);
572 		format = &plugin->src_format;
573 	} else {
574 		plugin = snd_pcm_plug_last(plug);
575 		format = &plugin->dst_format;
576 	}
577 	v = plugin->buf_channels;
578 	*channels = v;
579 	width = snd_pcm_format_physical_width(format->format);
580 	if (width < 0)
581 		return width;
582 	nchannels = format->channels;
583 	if (snd_BUG_ON(plugin->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED &&
584 		       format->channels > 1))
585 		return -ENXIO;
586 	for (channel = 0; channel < nchannels; channel++, v++) {
587 		v->frames = count;
588 		v->enabled = 1;
589 		v->wanted = (stream == SNDRV_PCM_STREAM_CAPTURE);
590 		v->area.addr = buf;
591 		v->area.first = channel * width;
592 		v->area.step = nchannels * width;
593 	}
594 	return count;
595 }
596 
597 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)
598 {
599 	struct snd_pcm_plugin *plugin, *next;
600 	struct snd_pcm_plugin_channel *dst_channels;
601 	int err;
602 	snd_pcm_sframes_t frames = size;
603 
604 	plugin = snd_pcm_plug_first(plug);
605 	while (plugin) {
606 		if (frames <= 0)
607 			return frames;
608 		next = plugin->next;
609 		if (next) {
610 			snd_pcm_sframes_t frames1 = frames;
611 			if (plugin->dst_frames) {
612 				frames1 = plugin->dst_frames(plugin, frames);
613 				if (frames1 <= 0)
614 					return frames1;
615 			}
616 			err = next->client_channels(next, frames1, &dst_channels);
617 			if (err < 0)
618 				return err;
619 			if (err != frames1) {
620 				frames = err;
621 				if (plugin->src_frames) {
622 					frames = plugin->src_frames(plugin, frames1);
623 					if (frames <= 0)
624 						return frames;
625 				}
626 			}
627 		} else
628 			dst_channels = NULL;
629 		pdprintf("write plugin: %s, %li\n", plugin->name, frames);
630 		frames = plugin->transfer(plugin, src_channels, dst_channels, frames);
631 		if (frames < 0)
632 			return frames;
633 		src_channels = dst_channels;
634 		plugin = next;
635 	}
636 	return calc_src_frames(plug, frames, true);
637 }
638 
639 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)
640 {
641 	struct snd_pcm_plugin *plugin, *next;
642 	struct snd_pcm_plugin_channel *src_channels, *dst_channels;
643 	snd_pcm_sframes_t frames = size;
644 	int err;
645 
646 	frames = calc_src_frames(plug, frames, true);
647 	if (frames < 0)
648 		return frames;
649 
650 	src_channels = NULL;
651 	plugin = snd_pcm_plug_first(plug);
652 	while (plugin && frames > 0) {
653 		next = plugin->next;
654 		if (next) {
655 			err = plugin->client_channels(plugin, frames, &dst_channels);
656 			if (err < 0)
657 				return err;
658 			frames = err;
659 		} else {
660 			dst_channels = dst_channels_final;
661 		}
662 		pdprintf("read plugin: %s, %li\n", plugin->name, frames);
663 		frames = plugin->transfer(plugin, src_channels, dst_channels, frames);
664 		if (frames < 0)
665 			return frames;
666 		plugin = next;
667 		src_channels = dst_channels;
668 	}
669 	return frames;
670 }
671 
672 int snd_pcm_area_silence(const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
673 			 size_t samples, snd_pcm_format_t format)
674 {
675 	/* FIXME: sub byte resolution and odd dst_offset */
676 	unsigned char *dst;
677 	unsigned int dst_step;
678 	int width;
679 	const unsigned char *silence;
680 	if (!dst_area->addr)
681 		return 0;
682 	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
683 	width = snd_pcm_format_physical_width(format);
684 	if (width <= 0)
685 		return -EINVAL;
686 	if (dst_area->step == (unsigned int) width && width >= 8)
687 		return snd_pcm_format_set_silence(format, dst, samples);
688 	silence = snd_pcm_format_silence_64(format);
689 	if (! silence)
690 		return -EINVAL;
691 	dst_step = dst_area->step / 8;
692 	if (width == 4) {
693 		/* Ima ADPCM */
694 		int dstbit = dst_area->first % 8;
695 		int dstbit_step = dst_area->step % 8;
696 		while (samples-- > 0) {
697 			if (dstbit)
698 				*dst &= 0xf0;
699 			else
700 				*dst &= 0x0f;
701 			dst += dst_step;
702 			dstbit += dstbit_step;
703 			if (dstbit == 8) {
704 				dst++;
705 				dstbit = 0;
706 			}
707 		}
708 	} else {
709 		width /= 8;
710 		while (samples-- > 0) {
711 			memcpy(dst, silence, width);
712 			dst += dst_step;
713 		}
714 	}
715 	return 0;
716 }
717 
718 int snd_pcm_area_copy(const struct snd_pcm_channel_area *src_area, size_t src_offset,
719 		      const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
720 		      size_t samples, snd_pcm_format_t format)
721 {
722 	/* FIXME: sub byte resolution and odd dst_offset */
723 	char *src, *dst;
724 	int width;
725 	int src_step, dst_step;
726 	src = src_area->addr + (src_area->first + src_area->step * src_offset) / 8;
727 	if (!src_area->addr)
728 		return snd_pcm_area_silence(dst_area, dst_offset, samples, format);
729 	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
730 	if (!dst_area->addr)
731 		return 0;
732 	width = snd_pcm_format_physical_width(format);
733 	if (width <= 0)
734 		return -EINVAL;
735 	if (src_area->step == (unsigned int) width &&
736 	    dst_area->step == (unsigned int) width && width >= 8) {
737 		size_t bytes = samples * width / 8;
738 		memcpy(dst, src, bytes);
739 		return 0;
740 	}
741 	src_step = src_area->step / 8;
742 	dst_step = dst_area->step / 8;
743 	if (width == 4) {
744 		/* Ima ADPCM */
745 		int srcbit = src_area->first % 8;
746 		int srcbit_step = src_area->step % 8;
747 		int dstbit = dst_area->first % 8;
748 		int dstbit_step = dst_area->step % 8;
749 		while (samples-- > 0) {
750 			unsigned char srcval;
751 			if (srcbit)
752 				srcval = *src & 0x0f;
753 			else
754 				srcval = (*src & 0xf0) >> 4;
755 			if (dstbit)
756 				*dst = (*dst & 0xf0) | srcval;
757 			else
758 				*dst = (*dst & 0x0f) | (srcval << 4);
759 			src += src_step;
760 			srcbit += srcbit_step;
761 			if (srcbit == 8) {
762 				src++;
763 				srcbit = 0;
764 			}
765 			dst += dst_step;
766 			dstbit += dstbit_step;
767 			if (dstbit == 8) {
768 				dst++;
769 				dstbit = 0;
770 			}
771 		}
772 	} else {
773 		width /= 8;
774 		while (samples-- > 0) {
775 			memcpy(dst, src, width);
776 			src += src_step;
777 			dst += dst_step;
778 		}
779 	}
780 	return 0;
781 }
782