xref: /openbmc/linux/sound/core/oss/pcm_plugin.c (revision 1fa6ac37)
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(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(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 = snd_pcm_plug_stream(plug);
203 
204 	if (snd_BUG_ON(!plug))
205 		return -ENXIO;
206 	if (drv_frames == 0)
207 		return 0;
208 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
209 		plugin = snd_pcm_plug_last(plug);
210 		while (plugin && drv_frames > 0) {
211 			plugin_prev = plugin->prev;
212 			if (plugin->src_frames)
213 				drv_frames = plugin->src_frames(plugin, drv_frames);
214 			plugin = plugin_prev;
215 		}
216 	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
217 		plugin = snd_pcm_plug_first(plug);
218 		while (plugin && drv_frames > 0) {
219 			plugin_next = plugin->next;
220 			if (plugin->dst_frames)
221 				drv_frames = plugin->dst_frames(plugin, drv_frames);
222 			plugin = plugin_next;
223 		}
224 	} else
225 		snd_BUG();
226 	return drv_frames;
227 }
228 
229 snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t clt_frames)
230 {
231 	struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next;
232 	snd_pcm_sframes_t frames;
233 	int stream = snd_pcm_plug_stream(plug);
234 
235 	if (snd_BUG_ON(!plug))
236 		return -ENXIO;
237 	if (clt_frames == 0)
238 		return 0;
239 	frames = clt_frames;
240 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
241 		plugin = snd_pcm_plug_first(plug);
242 		while (plugin && frames > 0) {
243 			plugin_next = plugin->next;
244 			if (plugin->dst_frames) {
245 				frames = plugin->dst_frames(plugin, frames);
246 				if (frames < 0)
247 					return frames;
248 			}
249 			plugin = plugin_next;
250 		}
251 	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
252 		plugin = snd_pcm_plug_last(plug);
253 		while (plugin) {
254 			plugin_prev = plugin->prev;
255 			if (plugin->src_frames) {
256 				frames = plugin->src_frames(plugin, frames);
257 				if (frames < 0)
258 					return frames;
259 			}
260 			plugin = plugin_prev;
261 		}
262 	} else
263 		snd_BUG();
264 	return frames;
265 }
266 
267 static int snd_pcm_plug_formats(struct snd_mask *mask, int format)
268 {
269 	struct snd_mask formats = *mask;
270 	u64 linfmts = (SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S8 |
271 		       SNDRV_PCM_FMTBIT_U16_LE | SNDRV_PCM_FMTBIT_S16_LE |
272 		       SNDRV_PCM_FMTBIT_U16_BE | SNDRV_PCM_FMTBIT_S16_BE |
273 		       SNDRV_PCM_FMTBIT_U24_LE | SNDRV_PCM_FMTBIT_S24_LE |
274 		       SNDRV_PCM_FMTBIT_U24_BE | SNDRV_PCM_FMTBIT_S24_BE |
275 		       SNDRV_PCM_FMTBIT_U24_3LE | SNDRV_PCM_FMTBIT_S24_3LE |
276 		       SNDRV_PCM_FMTBIT_U24_3BE | SNDRV_PCM_FMTBIT_S24_3BE |
277 		       SNDRV_PCM_FMTBIT_U32_LE | SNDRV_PCM_FMTBIT_S32_LE |
278 		       SNDRV_PCM_FMTBIT_U32_BE | SNDRV_PCM_FMTBIT_S32_BE);
279 	snd_mask_set(&formats, SNDRV_PCM_FORMAT_MU_LAW);
280 
281 	if (formats.bits[0] & (u32)linfmts)
282 		formats.bits[0] |= (u32)linfmts;
283 	if (formats.bits[1] & (u32)(linfmts >> 32))
284 		formats.bits[1] |= (u32)(linfmts >> 32);
285 	return snd_mask_test(&formats, format);
286 }
287 
288 static int preferred_formats[] = {
289 	SNDRV_PCM_FORMAT_S16_LE,
290 	SNDRV_PCM_FORMAT_S16_BE,
291 	SNDRV_PCM_FORMAT_U16_LE,
292 	SNDRV_PCM_FORMAT_U16_BE,
293 	SNDRV_PCM_FORMAT_S24_3LE,
294 	SNDRV_PCM_FORMAT_S24_3BE,
295 	SNDRV_PCM_FORMAT_U24_3LE,
296 	SNDRV_PCM_FORMAT_U24_3BE,
297 	SNDRV_PCM_FORMAT_S24_LE,
298 	SNDRV_PCM_FORMAT_S24_BE,
299 	SNDRV_PCM_FORMAT_U24_LE,
300 	SNDRV_PCM_FORMAT_U24_BE,
301 	SNDRV_PCM_FORMAT_S32_LE,
302 	SNDRV_PCM_FORMAT_S32_BE,
303 	SNDRV_PCM_FORMAT_U32_LE,
304 	SNDRV_PCM_FORMAT_U32_BE,
305 	SNDRV_PCM_FORMAT_S8,
306 	SNDRV_PCM_FORMAT_U8
307 };
308 
309 int snd_pcm_plug_slave_format(int format, struct snd_mask *format_mask)
310 {
311 	int i;
312 
313 	if (snd_mask_test(format_mask, format))
314 		return format;
315 	if (! snd_pcm_plug_formats(format_mask, format))
316 		return -EINVAL;
317 	if (snd_pcm_format_linear(format)) {
318 		unsigned int width = snd_pcm_format_width(format);
319 		int unsignd = snd_pcm_format_unsigned(format) > 0;
320 		int big = snd_pcm_format_big_endian(format) > 0;
321 		unsigned int badness, best = -1;
322 		int best_format = -1;
323 		for (i = 0; i < ARRAY_SIZE(preferred_formats); i++) {
324 			int f = preferred_formats[i];
325 			unsigned int w;
326 			if (!snd_mask_test(format_mask, f))
327 				continue;
328 			w = snd_pcm_format_width(f);
329 			if (w >= width)
330 				badness = w - width;
331 			else
332 				badness = width - w + 32;
333 			badness += snd_pcm_format_unsigned(f) != unsignd;
334 			badness += snd_pcm_format_big_endian(f) != big;
335 			if (badness < best) {
336 				best_format = f;
337 				best = badness;
338 			}
339 		}
340 		return best_format >= 0 ? best_format : -EINVAL;
341 	} else {
342 		switch (format) {
343 		case SNDRV_PCM_FORMAT_MU_LAW:
344 			for (i = 0; i < ARRAY_SIZE(preferred_formats); ++i) {
345 				int format1 = preferred_formats[i];
346 				if (snd_mask_test(format_mask, format1))
347 					return format1;
348 			}
349 		default:
350 			return -EINVAL;
351 		}
352 	}
353 }
354 
355 int snd_pcm_plug_format_plugins(struct snd_pcm_substream *plug,
356 				struct snd_pcm_hw_params *params,
357 				struct snd_pcm_hw_params *slave_params)
358 {
359 	struct snd_pcm_plugin_format tmpformat;
360 	struct snd_pcm_plugin_format dstformat;
361 	struct snd_pcm_plugin_format srcformat;
362 	int src_access, dst_access;
363 	struct snd_pcm_plugin *plugin = NULL;
364 	int err;
365 	int stream = snd_pcm_plug_stream(plug);
366 	int slave_interleaved = (params_channels(slave_params) == 1 ||
367 				 params_access(slave_params) == SNDRV_PCM_ACCESS_RW_INTERLEAVED);
368 
369 	switch (stream) {
370 	case SNDRV_PCM_STREAM_PLAYBACK:
371 		dstformat.format = params_format(slave_params);
372 		dstformat.rate = params_rate(slave_params);
373 		dstformat.channels = params_channels(slave_params);
374 		srcformat.format = params_format(params);
375 		srcformat.rate = params_rate(params);
376 		srcformat.channels = params_channels(params);
377 		src_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
378 		dst_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
379 						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
380 		break;
381 	case SNDRV_PCM_STREAM_CAPTURE:
382 		dstformat.format = params_format(params);
383 		dstformat.rate = params_rate(params);
384 		dstformat.channels = params_channels(params);
385 		srcformat.format = params_format(slave_params);
386 		srcformat.rate = params_rate(slave_params);
387 		srcformat.channels = params_channels(slave_params);
388 		src_access = (slave_interleaved ? SNDRV_PCM_ACCESS_RW_INTERLEAVED :
389 						  SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
390 		dst_access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
391 		break;
392 	default:
393 		snd_BUG();
394 		return -EINVAL;
395 	}
396 	tmpformat = srcformat;
397 
398 	pdprintf("srcformat: format=%i, rate=%i, channels=%i\n",
399 		 srcformat.format,
400 		 srcformat.rate,
401 		 srcformat.channels);
402 	pdprintf("dstformat: format=%i, rate=%i, channels=%i\n",
403 		 dstformat.format,
404 		 dstformat.rate,
405 		 dstformat.channels);
406 
407 	/* Format change (linearization) */
408 	if (! rate_match(srcformat.rate, dstformat.rate) &&
409 	    ! snd_pcm_format_linear(srcformat.format)) {
410 		if (srcformat.format != SNDRV_PCM_FORMAT_MU_LAW)
411 			return -EINVAL;
412 		tmpformat.format = SNDRV_PCM_FORMAT_S16;
413 		err = snd_pcm_plugin_build_mulaw(plug,
414 						 &srcformat, &tmpformat,
415 						 &plugin);
416 		if (err < 0)
417 			return err;
418 		err = snd_pcm_plugin_append(plugin);
419 		if (err < 0) {
420 			snd_pcm_plugin_free(plugin);
421 			return err;
422 		}
423 		srcformat = tmpformat;
424 		src_access = dst_access;
425 	}
426 
427 	/* channels reduction */
428 	if (srcformat.channels > dstformat.channels) {
429 		tmpformat.channels = dstformat.channels;
430 		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
431 		pdprintf("channels reduction: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, err);
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 	/* rate resampling */
444 	if (!rate_match(srcformat.rate, dstformat.rate)) {
445 		if (srcformat.format != SNDRV_PCM_FORMAT_S16) {
446 			/* convert to S16 for resampling */
447 			tmpformat.format = SNDRV_PCM_FORMAT_S16;
448 			err = snd_pcm_plugin_build_linear(plug,
449 							  &srcformat, &tmpformat,
450 							  &plugin);
451 			if (err < 0)
452 				return err;
453 			err = snd_pcm_plugin_append(plugin);
454 			if (err < 0) {
455 				snd_pcm_plugin_free(plugin);
456 				return err;
457 			}
458 			srcformat = tmpformat;
459 			src_access = dst_access;
460 		}
461 		tmpformat.rate = dstformat.rate;
462         	err = snd_pcm_plugin_build_rate(plug,
463         					&srcformat, &tmpformat,
464 						&plugin);
465 		pdprintf("rate down resampling: src=%i, dst=%i returns %i\n", srcformat.rate, tmpformat.rate, err);
466 		if (err < 0)
467 			return err;
468 		err = snd_pcm_plugin_append(plugin);
469 		if (err < 0) {
470 			snd_pcm_plugin_free(plugin);
471 			return err;
472 		}
473 		srcformat = tmpformat;
474 		src_access = dst_access;
475         }
476 
477 	/* format change */
478 	if (srcformat.format != dstformat.format) {
479 		tmpformat.format = dstformat.format;
480 		if (srcformat.format == SNDRV_PCM_FORMAT_MU_LAW ||
481 		    tmpformat.format == SNDRV_PCM_FORMAT_MU_LAW) {
482 			err = snd_pcm_plugin_build_mulaw(plug,
483 							 &srcformat, &tmpformat,
484 							 &plugin);
485 		}
486 		else if (snd_pcm_format_linear(srcformat.format) &&
487 			 snd_pcm_format_linear(tmpformat.format)) {
488 			err = snd_pcm_plugin_build_linear(plug,
489 							  &srcformat, &tmpformat,
490 							  &plugin);
491 		}
492 		else
493 			return -EINVAL;
494 		pdprintf("format change: src=%i, dst=%i returns %i\n", srcformat.format, tmpformat.format, err);
495 		if (err < 0)
496 			return err;
497 		err = snd_pcm_plugin_append(plugin);
498 		if (err < 0) {
499 			snd_pcm_plugin_free(plugin);
500 			return err;
501 		}
502 		srcformat = tmpformat;
503 		src_access = dst_access;
504 	}
505 
506 	/* channels extension */
507 	if (srcformat.channels < dstformat.channels) {
508 		tmpformat.channels = dstformat.channels;
509 		err = snd_pcm_plugin_build_route(plug, &srcformat, &tmpformat, &plugin);
510 		pdprintf("channels extension: src=%i, dst=%i returns %i\n", srcformat.channels, tmpformat.channels, 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 	/* de-interleave */
523 	if (src_access != dst_access) {
524 		err = snd_pcm_plugin_build_copy(plug,
525 						&srcformat,
526 						&tmpformat,
527 						&plugin);
528 		pdprintf("interleave change (copy: returns %i)\n", err);
529 		if (err < 0)
530 			return err;
531 		err = snd_pcm_plugin_append(plugin);
532 		if (err < 0) {
533 			snd_pcm_plugin_free(plugin);
534 			return err;
535 		}
536 	}
537 
538 	return 0;
539 }
540 
541 snd_pcm_sframes_t snd_pcm_plug_client_channels_buf(struct snd_pcm_substream *plug,
542 					 char *buf,
543 					 snd_pcm_uframes_t count,
544 					 struct snd_pcm_plugin_channel **channels)
545 {
546 	struct snd_pcm_plugin *plugin;
547 	struct snd_pcm_plugin_channel *v;
548 	struct snd_pcm_plugin_format *format;
549 	int width, nchannels, channel;
550 	int stream = snd_pcm_plug_stream(plug);
551 
552 	if (snd_BUG_ON(!buf))
553 		return -ENXIO;
554 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
555 		plugin = snd_pcm_plug_first(plug);
556 		format = &plugin->src_format;
557 	} else {
558 		plugin = snd_pcm_plug_last(plug);
559 		format = &plugin->dst_format;
560 	}
561 	v = plugin->buf_channels;
562 	*channels = v;
563 	if ((width = snd_pcm_format_physical_width(format->format)) < 0)
564 		return width;
565 	nchannels = format->channels;
566 	if (snd_BUG_ON(plugin->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED &&
567 		       format->channels > 1))
568 		return -ENXIO;
569 	for (channel = 0; channel < nchannels; channel++, v++) {
570 		v->frames = count;
571 		v->enabled = 1;
572 		v->wanted = (stream == SNDRV_PCM_STREAM_CAPTURE);
573 		v->area.addr = buf;
574 		v->area.first = channel * width;
575 		v->area.step = nchannels * width;
576 	}
577 	return count;
578 }
579 
580 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)
581 {
582 	struct snd_pcm_plugin *plugin, *next;
583 	struct snd_pcm_plugin_channel *dst_channels;
584 	int err;
585 	snd_pcm_sframes_t frames = size;
586 
587 	plugin = snd_pcm_plug_first(plug);
588 	while (plugin && frames > 0) {
589 		if ((next = plugin->next) != NULL) {
590 			snd_pcm_sframes_t frames1 = frames;
591 			if (plugin->dst_frames)
592 				frames1 = plugin->dst_frames(plugin, frames);
593 			if ((err = next->client_channels(next, frames1, &dst_channels)) < 0) {
594 				return err;
595 			}
596 			if (err != frames1) {
597 				frames = err;
598 				if (plugin->src_frames)
599 					frames = plugin->src_frames(plugin, frames1);
600 			}
601 		} else
602 			dst_channels = NULL;
603 		pdprintf("write plugin: %s, %li\n", plugin->name, frames);
604 		if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
605 			return frames;
606 		src_channels = dst_channels;
607 		plugin = next;
608 	}
609 	return snd_pcm_plug_client_size(plug, frames);
610 }
611 
612 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)
613 {
614 	struct snd_pcm_plugin *plugin, *next;
615 	struct snd_pcm_plugin_channel *src_channels, *dst_channels;
616 	snd_pcm_sframes_t frames = size;
617 	int err;
618 
619 	frames = snd_pcm_plug_slave_size(plug, frames);
620 	if (frames < 0)
621 		return frames;
622 
623 	src_channels = NULL;
624 	plugin = snd_pcm_plug_first(plug);
625 	while (plugin && frames > 0) {
626 		if ((next = plugin->next) != NULL) {
627 			if ((err = plugin->client_channels(plugin, frames, &dst_channels)) < 0) {
628 				return err;
629 			}
630 			frames = err;
631 		} else {
632 			dst_channels = dst_channels_final;
633 		}
634 		pdprintf("read plugin: %s, %li\n", plugin->name, frames);
635 		if ((frames = plugin->transfer(plugin, src_channels, dst_channels, frames)) < 0)
636 			return frames;
637 		plugin = next;
638 		src_channels = dst_channels;
639 	}
640 	return frames;
641 }
642 
643 int snd_pcm_area_silence(const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
644 			 size_t samples, int format)
645 {
646 	/* FIXME: sub byte resolution and odd dst_offset */
647 	unsigned char *dst;
648 	unsigned int dst_step;
649 	int width;
650 	const unsigned char *silence;
651 	if (!dst_area->addr)
652 		return 0;
653 	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
654 	width = snd_pcm_format_physical_width(format);
655 	if (width <= 0)
656 		return -EINVAL;
657 	if (dst_area->step == (unsigned int) width && width >= 8)
658 		return snd_pcm_format_set_silence(format, dst, samples);
659 	silence = snd_pcm_format_silence_64(format);
660 	if (! silence)
661 		return -EINVAL;
662 	dst_step = dst_area->step / 8;
663 	if (width == 4) {
664 		/* Ima ADPCM */
665 		int dstbit = dst_area->first % 8;
666 		int dstbit_step = dst_area->step % 8;
667 		while (samples-- > 0) {
668 			if (dstbit)
669 				*dst &= 0xf0;
670 			else
671 				*dst &= 0x0f;
672 			dst += dst_step;
673 			dstbit += dstbit_step;
674 			if (dstbit == 8) {
675 				dst++;
676 				dstbit = 0;
677 			}
678 		}
679 	} else {
680 		width /= 8;
681 		while (samples-- > 0) {
682 			memcpy(dst, silence, width);
683 			dst += dst_step;
684 		}
685 	}
686 	return 0;
687 }
688 
689 int snd_pcm_area_copy(const struct snd_pcm_channel_area *src_area, size_t src_offset,
690 		      const struct snd_pcm_channel_area *dst_area, size_t dst_offset,
691 		      size_t samples, int format)
692 {
693 	/* FIXME: sub byte resolution and odd dst_offset */
694 	char *src, *dst;
695 	int width;
696 	int src_step, dst_step;
697 	src = src_area->addr + (src_area->first + src_area->step * src_offset) / 8;
698 	if (!src_area->addr)
699 		return snd_pcm_area_silence(dst_area, dst_offset, samples, format);
700 	dst = dst_area->addr + (dst_area->first + dst_area->step * dst_offset) / 8;
701 	if (!dst_area->addr)
702 		return 0;
703 	width = snd_pcm_format_physical_width(format);
704 	if (width <= 0)
705 		return -EINVAL;
706 	if (src_area->step == (unsigned int) width &&
707 	    dst_area->step == (unsigned int) width && width >= 8) {
708 		size_t bytes = samples * width / 8;
709 		memcpy(dst, src, bytes);
710 		return 0;
711 	}
712 	src_step = src_area->step / 8;
713 	dst_step = dst_area->step / 8;
714 	if (width == 4) {
715 		/* Ima ADPCM */
716 		int srcbit = src_area->first % 8;
717 		int srcbit_step = src_area->step % 8;
718 		int dstbit = dst_area->first % 8;
719 		int dstbit_step = dst_area->step % 8;
720 		while (samples-- > 0) {
721 			unsigned char srcval;
722 			if (srcbit)
723 				srcval = *src & 0x0f;
724 			else
725 				srcval = (*src & 0xf0) >> 4;
726 			if (dstbit)
727 				*dst = (*dst & 0xf0) | srcval;
728 			else
729 				*dst = (*dst & 0x0f) | (srcval << 4);
730 			src += src_step;
731 			srcbit += srcbit_step;
732 			if (srcbit == 8) {
733 				src++;
734 				srcbit = 0;
735 			}
736 			dst += dst_step;
737 			dstbit += dstbit_step;
738 			if (dstbit == 8) {
739 				dst++;
740 				dstbit = 0;
741 			}
742 		}
743 	} else {
744 		width /= 8;
745 		while (samples-- > 0) {
746 			memcpy(dst, src, width);
747 			src += src_step;
748 			dst += dst_step;
749 		}
750 	}
751 	return 0;
752 }
753