xref: /freebsd/sys/dev/sound/pcm/feeder_rate.c (revision f0a75d274af375d15b97b830966b99a02b7db911)
1 /*-
2  * Copyright (c) 1999 Cameron Grant <cg@FreeBSD.org>
3  * Copyright (c) 2003 Orion Hodson <orion@FreeBSD.org>
4  * Copyright (c) 2005 Ariff Abdullah <ariff@FreeBSD.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  *
28  * 2006-02-21:
29  * ==========
30  *
31  * Major cleanup and overhaul to remove much redundant codes.
32  * Highlights:
33  *	1) Support for signed / unsigned 16, 24 and 32 bit,
34  *	   big / little endian,
35  *	2) Unlimited channels.
36  *
37  * 2005-06-11:
38  * ==========
39  *
40  * *New* and rewritten soft sample rate converter supporting arbitrary sample
41  * rates, fine grained scaling/coefficients and a unified up/down stereo
42  * converter. Most of the disclaimers from orion's notes also applies
43  * here, regarding linear interpolation deficiencies and pre/post
44  * anti-aliasing filtering issues. This version comes with a much simpler and
45  * tighter interface, although it works almost exactly like the older one.
46  *
47  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
48  *                                                                         *
49  * This new implementation is fully dedicated in memory of Cameron Grant,  *
50  * the creator of the magnificent, highly addictive feeder infrastructure. *
51  *                                                                         *
52  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
53  *
54  * Orion's notes:
55  * =============
56  *
57  * This rate conversion code uses linear interpolation without any
58  * pre- or post- interpolation filtering to combat aliasing.  This
59  * greatly limits the sound quality and should be addressed at some
60  * stage in the future.
61  *
62  * Since this accuracy of interpolation is sensitive and examination
63  * of the algorithm output is harder from the kernel, the code is
64  * designed to be compiled in the kernel and in a userland test
65  * harness.  This is done by selectively including and excluding code
66  * with several portions based on whether _KERNEL is defined.  It's a
67  * little ugly, but exceedingly useful.  The testsuite and its
68  * revisions can be found at:
69  *		http://people.freebsd.org/~orion/files/feedrate/
70  *
71  * Special thanks to Ken Marx for exposing flaws in the code and for
72  * testing revisions.
73  */
74 
75 #include <dev/sound/pcm/sound.h>
76 #include "feeder_if.h"
77 
78 SND_DECLARE_FILE("$FreeBSD$");
79 
80 #define RATE_ASSERT(x, y)	/* KASSERT(x,y) */
81 #define RATE_TEST(x, y)		/* if (!(x)) printf y */
82 #define RATE_TRACE(x...)	/* printf(x) */
83 
84 MALLOC_DEFINE(M_RATEFEEDER, "ratefeed", "pcm rate feeder");
85 
86 /*
87  * Don't overflow 32bit integer, since everything is done
88  * within 32bit arithmetic.
89  */
90 #define RATE_FACTOR_MIN		1
91 #define RATE_FACTOR_MAX		PCM_S24_MAX
92 #define RATE_FACTOR_SAFE(val)	(!((val) < RATE_FACTOR_MIN || \
93 				(val) > RATE_FACTOR_MAX))
94 
95 struct feed_rate_info;
96 
97 typedef uint32_t (*feed_rate_converter)(struct feed_rate_info *,
98 							uint8_t *, uint32_t);
99 
100 struct feed_rate_info {
101 	uint32_t src, dst;	/* rounded source / destination rates */
102 	uint32_t rsrc, rdst;	/* original source / destination rates */
103 	uint32_t gx, gy;	/* interpolation / decimation ratio */
104 	uint32_t alpha;		/* interpolation distance */
105 	uint32_t pos, bpos;	/* current sample / buffer positions */
106 	uint32_t bufsz;		/* total buffer size limit */
107 	uint32_t bufsz_init;	/* allocated buffer size */
108 	uint32_t channels;	/* total channels */
109 	uint32_t bps;		/* bytes-per-sample */
110 #ifdef FEEDRATE_STRAY
111 	uint32_t stray;		/* stray bytes */
112 #endif
113 	uint8_t  *buffer;
114 	feed_rate_converter convert;
115 };
116 
117 int feeder_rate_min = FEEDRATE_RATEMIN;
118 int feeder_rate_max = FEEDRATE_RATEMAX;
119 int feeder_rate_round = FEEDRATE_ROUNDHZ;
120 
121 TUNABLE_INT("hw.snd.feeder_rate_min", &feeder_rate_min);
122 TUNABLE_INT("hw.snd.feeder_rate_max", &feeder_rate_max);
123 TUNABLE_INT("hw.snd.feeder_rate_round", &feeder_rate_round);
124 
125 static int
126 sysctl_hw_snd_feeder_rate_min(SYSCTL_HANDLER_ARGS)
127 {
128 	int err, val;
129 
130 	val = feeder_rate_min;
131 	err = sysctl_handle_int(oidp, &val, sizeof(val), req);
132 	if (err != 0 || req->newptr == NULL)
133 		return (err);
134 	if (RATE_FACTOR_SAFE(val) && val < feeder_rate_max)
135 		feeder_rate_min = val;
136 	else
137 		err = EINVAL;
138 	return (err);
139 }
140 SYSCTL_PROC(_hw_snd, OID_AUTO, feeder_rate_min, CTLTYPE_INT | CTLFLAG_RW,
141 	0, sizeof(int), sysctl_hw_snd_feeder_rate_min, "I",
142 	"minimum allowable rate");
143 
144 static int
145 sysctl_hw_snd_feeder_rate_max(SYSCTL_HANDLER_ARGS)
146 {
147 	int err, val;
148 
149 	val = feeder_rate_max;
150 	err = sysctl_handle_int(oidp, &val, sizeof(val), req);
151 	if (err != 0 || req->newptr == NULL)
152 		return (err);
153 	if (RATE_FACTOR_SAFE(val) && val > feeder_rate_min)
154 		feeder_rate_max = val;
155 	else
156 		err = EINVAL;
157 	return (err);
158 }
159 SYSCTL_PROC(_hw_snd, OID_AUTO, feeder_rate_max, CTLTYPE_INT | CTLFLAG_RW,
160 	0, sizeof(int), sysctl_hw_snd_feeder_rate_max, "I",
161 	"maximum allowable rate");
162 
163 static int
164 sysctl_hw_snd_feeder_rate_round(SYSCTL_HANDLER_ARGS)
165 {
166 	int err, val;
167 
168 	val = feeder_rate_round;
169 	err = sysctl_handle_int(oidp, &val, sizeof(val), req);
170 	if (err != 0 || req->newptr == NULL)
171 		return (err);
172 	if (val < FEEDRATE_ROUNDHZ_MIN || val > FEEDRATE_ROUNDHZ_MAX)
173 		err = EINVAL;
174 	else
175 		feeder_rate_round = val - (val % FEEDRATE_ROUNDHZ);
176 	return (err);
177 }
178 SYSCTL_PROC(_hw_snd, OID_AUTO, feeder_rate_round, CTLTYPE_INT | CTLFLAG_RW,
179 	0, sizeof(int), sysctl_hw_snd_feeder_rate_round, "I",
180 	"sample rate converter rounding threshold");
181 
182 #define FEEDER_RATE_CONVERT(FMTBIT, RATE_INTCAST, SIGN, SIGNS, ENDIAN, ENDIANS)	\
183 static uint32_t									\
184 feed_convert_##SIGNS##FMTBIT##ENDIANS(struct feed_rate_info *info,		\
185 						uint8_t *dst, uint32_t max)	\
186 {										\
187 	uint32_t ret, smpsz, ch, pos, bpos, gx, gy, alpha, d1, d2;		\
188 	int32_t x, y;								\
189 	int i;									\
190 	uint8_t *src, *sx, *sy;							\
191 										\
192 	ret = 0;								\
193 	alpha = info->alpha;							\
194 	gx = info->gx;								\
195 	gy = info->gy;								\
196 	pos = info->pos;							\
197 	bpos = info->bpos;							\
198 	src = info->buffer + pos;						\
199 	ch = info->channels;							\
200 	smpsz = PCM_##FMTBIT##_BPS * ch;					\
201 	for (;;) {								\
202 		if (alpha < gx) {						\
203 			alpha += gy;						\
204 			pos += smpsz;						\
205 			if (pos == bpos)					\
206 				break;						\
207 			src += smpsz;						\
208 		} else {							\
209 			alpha -= gx;						\
210 			d1 = (alpha << PCM_FXSHIFT) / gy;			\
211 			d2 = (1U << PCM_FXSHIFT) - d1;				\
212 			sx = src - smpsz;					\
213 			sy = src;						\
214 			i = ch;							\
215 			do {							\
216 				x = PCM_READ_##SIGN##FMTBIT##_##ENDIAN(sx);	\
217 				y = PCM_READ_##SIGN##FMTBIT##_##ENDIAN(sy);	\
218 				x = (((RATE_INTCAST)x * d1) +			\
219 				    ((RATE_INTCAST)y * d2)) >> PCM_FXSHIFT;	\
220 				PCM_WRITE_##SIGN##FMTBIT##_##ENDIAN(dst, x);	\
221 				dst += PCM_##FMTBIT##_BPS;			\
222 				sx += PCM_##FMTBIT##_BPS;			\
223 				sy += PCM_##FMTBIT##_BPS;			\
224 				ret += PCM_##FMTBIT##_BPS;			\
225 			} while (--i != 0);					\
226 			if (ret == max)						\
227 				break;						\
228 		}								\
229 	}									\
230 	info->alpha = alpha;							\
231 	info->pos = pos;							\
232 	return (ret);								\
233 }
234 
235 FEEDER_RATE_CONVERT(8, int32_t, S, s, NE, ne)
236 FEEDER_RATE_CONVERT(16, int32_t, S, s, LE, le)
237 FEEDER_RATE_CONVERT(24, int32_t, S, s, LE, le)
238 FEEDER_RATE_CONVERT(32, intpcm_t, S, s, LE, le)
239 FEEDER_RATE_CONVERT(16, int32_t, S, s, BE, be)
240 FEEDER_RATE_CONVERT(24, int32_t, S, s, BE, be)
241 FEEDER_RATE_CONVERT(32, intpcm_t, S, s, BE, be)
242 FEEDER_RATE_CONVERT(8, int32_t, U, u, NE, ne)
243 FEEDER_RATE_CONVERT(16, int32_t, U, u, LE, le)
244 FEEDER_RATE_CONVERT(24, int32_t, U, u, LE, le)
245 FEEDER_RATE_CONVERT(32, intpcm_t, U, u, LE, le)
246 FEEDER_RATE_CONVERT(16, int32_t, U, u, BE, be)
247 FEEDER_RATE_CONVERT(24, int32_t, U, u, BE, be)
248 FEEDER_RATE_CONVERT(32, intpcm_t, U, u, BE, be)
249 
250 static void
251 feed_speed_ratio(uint32_t src, uint32_t dst, uint32_t *gx, uint32_t *gy)
252 {
253 	uint32_t w, x = src, y = dst;
254 
255 	while (y != 0) {
256 		w = x % y;
257 		x = y;
258 		y = w;
259 	}
260 	*gx = src / x;
261 	*gy = dst / x;
262 }
263 
264 static void
265 feed_rate_reset(struct feed_rate_info *info)
266 {
267 	info->src = info->rsrc - (info->rsrc %
268 	    ((feeder_rate_round > 0) ? feeder_rate_round : 1));
269 	info->dst = info->rdst - (info->rdst %
270 	    ((feeder_rate_round > 0) ? feeder_rate_round : 1));
271 	info->gx = 1;
272 	info->gy = 1;
273 	info->alpha = 0;
274 	info->channels = 1;
275 	info->bps = PCM_8_BPS;
276 	info->convert = NULL;
277 	info->bufsz = info->bufsz_init;
278 	info->pos = 1;
279 	info->bpos = 2;
280 #ifdef FEEDRATE_STRAY
281 	info->stray = 0;
282 #endif
283 }
284 
285 static int
286 feed_rate_setup(struct pcm_feeder *f)
287 {
288 	struct feed_rate_info *info = f->data;
289 	static const struct {
290 		uint32_t format;	/* pcm / audio format */
291 		uint32_t bps;		/* bytes-per-sample, regardless of
292 					   total channels */
293 		feed_rate_converter convert;
294 	} convtbl[] = {
295 		{ AFMT_S8,     PCM_8_BPS,  feed_convert_s8ne  },
296 		{ AFMT_S16_LE, PCM_16_BPS, feed_convert_s16le },
297 		{ AFMT_S24_LE, PCM_24_BPS, feed_convert_s24le },
298 		{ AFMT_S32_LE, PCM_32_BPS, feed_convert_s32le },
299 		{ AFMT_S16_BE, PCM_16_BPS, feed_convert_s16be },
300 		{ AFMT_S24_BE, PCM_24_BPS, feed_convert_s24be },
301 		{ AFMT_S32_BE, PCM_32_BPS, feed_convert_s32be },
302 		{ AFMT_U8,     PCM_8_BPS,  feed_convert_u8ne  },
303 		{ AFMT_U16_LE, PCM_16_BPS, feed_convert_u16le },
304 		{ AFMT_U24_LE, PCM_24_BPS, feed_convert_u24le },
305 		{ AFMT_U32_LE, PCM_32_BPS, feed_convert_u32le },
306 		{ AFMT_U16_BE, PCM_16_BPS, feed_convert_u16be },
307 		{ AFMT_U24_BE, PCM_24_BPS, feed_convert_u24be },
308 		{ AFMT_U32_BE, PCM_32_BPS, feed_convert_u32be },
309 		{ 0, 0, NULL },
310 	};
311 	uint32_t i;
312 
313 	feed_rate_reset(info);
314 
315 	if (info->src != info->dst)
316 		feed_speed_ratio(info->src, info->dst, &info->gx, &info->gy);
317 
318 	if (!(RATE_FACTOR_SAFE(info->gx) && RATE_FACTOR_SAFE(info->gy)))
319 		return (-1);
320 
321 	for (i = 0; i < sizeof(convtbl) / sizeof(*convtbl); i++) {
322 		if (convtbl[i].format == 0)
323 			return (-1);
324 		if ((f->desc->out & ~AFMT_STEREO) == convtbl[i].format) {
325 			info->bps = convtbl[i].bps;
326 			info->convert = convtbl[i].convert;
327 			break;
328 		}
329 	}
330 
331 	/*
332 	 * No need to interpolate/decimate, just do plain copy.
333 	 */
334 	if (info->gx == info->gy)
335 		info->convert = NULL;
336 
337 	info->channels = (f->desc->out & AFMT_STEREO) ? 2 : 1;
338 	info->pos = info->bps * info->channels;
339 	info->bpos = info->pos << 1;
340 	info->bufsz -= info->bufsz % info->pos;
341 
342 	memset(info->buffer, sndbuf_zerodata(f->desc->out), info->bpos);
343 
344 	RATE_TRACE("%s: %u (%u) -> %u (%u) [%u/%u] , "
345 	    "format=0x%08x, channels=%u, bufsz=%u\n",
346 	    __func__, info->src, info->rsrc, info->dst, info->rdst,
347 	    info->gx, info->gy, f->desc->out, info->channels,
348 	    info->bufsz - info->pos);
349 
350 	return (0);
351 }
352 
353 static int
354 feed_rate_set(struct pcm_feeder *f, int what, int32_t value)
355 {
356 	struct feed_rate_info *info = f->data;
357 
358 	if (value < feeder_rate_min || value > feeder_rate_max)
359 		return (-1);
360 
361 	switch (what) {
362 	case FEEDRATE_SRC:
363 		info->rsrc = value;
364 		break;
365 	case FEEDRATE_DST:
366 		info->rdst = value;
367 		break;
368 	default:
369 		return (-1);
370 	}
371 	return (feed_rate_setup(f));
372 }
373 
374 static int
375 feed_rate_get(struct pcm_feeder *f, int what)
376 {
377 	struct feed_rate_info *info = f->data;
378 
379 	switch (what) {
380 	case FEEDRATE_SRC:
381 		return (info->rsrc);
382 	case FEEDRATE_DST:
383 		return (info->rdst);
384 	default:
385 		return (-1);
386 	}
387 	return (-1);
388 }
389 
390 static int
391 feed_rate_init(struct pcm_feeder *f)
392 {
393 	struct feed_rate_info *info;
394 
395 	if (f->desc->out != f->desc->in)
396 		return (EINVAL);
397 
398 	info = malloc(sizeof(*info), M_RATEFEEDER, M_NOWAIT | M_ZERO);
399 	if (info == NULL)
400 		return (ENOMEM);
401 	/*
402 	 * bufsz = sample from last cycle + conversion space
403 	 */
404 	info->bufsz_init = 8 + feeder_buffersize;
405 	info->buffer = malloc(sizeof(*info->buffer) * info->bufsz_init,
406 	    M_RATEFEEDER, M_NOWAIT | M_ZERO);
407 	if (info->buffer == NULL) {
408 		free(info, M_RATEFEEDER);
409 		return (ENOMEM);
410 	}
411 	info->rsrc = DSP_DEFAULT_SPEED;
412 	info->rdst = DSP_DEFAULT_SPEED;
413 	f->data = info;
414 	return (feed_rate_setup(f));
415 }
416 
417 static int
418 feed_rate_free(struct pcm_feeder *f)
419 {
420 	struct feed_rate_info *info = f->data;
421 
422 	if (info != NULL) {
423 		if (info->buffer != NULL)
424 			free(info->buffer, M_RATEFEEDER);
425 		free(info, M_RATEFEEDER);
426 	}
427 	f->data = NULL;
428 	return (0);
429 }
430 
431 static int
432 feed_rate(struct pcm_feeder *f, struct pcm_channel *c, uint8_t *b,
433 						uint32_t count, void *source)
434 {
435 	struct feed_rate_info *info = f->data;
436 	uint32_t i, smpsz;
437 	int32_t fetch, slot;
438 
439 	if (info->convert == NULL)
440 		return (FEEDER_FEED(f->source, c, b, count, source));
441 
442 	/*
443 	 * This loop has been optimized to generalize both up / down
444 	 * sampling without causing missing samples or excessive buffer
445 	 * feeding. The tricky part is to calculate *precise* (slot) value
446 	 * needed for the entire conversion space since we are bound to
447 	 * return and fill up the buffer according to the requested 'count'.
448 	 * Too much feeding will cause the extra buffer stay within temporary
449 	 * circular buffer forever and always manifest itself as a truncated
450 	 * sound during end of playback / recording. Too few, and we end up
451 	 * with possible underruns and waste of cpu cycles.
452 	 *
453 	 * 'Stray' management exist to combat with possible unaligned
454 	 * buffering by the caller.
455 	 */
456 	smpsz = info->bps * info->channels;
457 	RATE_TEST(count >= smpsz && (count % smpsz) == 0,
458 	    ("%s: Count size not sample integral (%d)\n", __func__, count));
459 	if (count < smpsz)
460 		return (0);
461 	count -= count % smpsz;
462 	/*
463 	 * This slot count formula will stay here for the next million years
464 	 * to come. This is the key of our circular buffering precision.
465 	 */
466 	slot = (((info->gx * (count / smpsz)) + info->gy - info->alpha - 1) /
467 	    info->gy) * smpsz;
468 	RATE_TEST((slot % smpsz) == 0,
469 	    ("%s: Slot count not sample integral (%d)\n", __func__, slot));
470 #ifdef FEEDRATE_STRAY
471 	RATE_TEST(info->stray == 0, ("%s: [1] Stray bytes: %u\n", __func__,
472 	    info->stray));
473 #endif
474 	if (info->pos != smpsz && info->bpos - info->pos == smpsz &&
475 	    info->bpos + slot > info->bufsz) {
476 		/*
477 		 * Copy last unit sample and its previous to
478 		 * beginning of buffer.
479 		 */
480 		bcopy(info->buffer + info->pos - smpsz, info->buffer,
481 		    sizeof(*info->buffer) * (smpsz << 1));
482 		info->pos = smpsz;
483 		info->bpos = smpsz << 1;
484 	}
485 	RATE_ASSERT(slot >= 0, ("%s: Negative Slot: %d\n", __func__, slot));
486 	i = 0;
487 	for (;;) {
488 		for (;;) {
489 			fetch = info->bufsz - info->bpos;
490 #ifdef FEEDRATE_STRAY
491 			fetch -= info->stray;
492 #endif
493 			RATE_ASSERT(fetch >= 0,
494 			    ("%s: [1] Buffer overrun: %d > %d\n", __func__,
495 			    info->bpos, info->bufsz));
496 			if (slot < fetch)
497 				fetch = slot;
498 #ifdef FEEDRATE_STRAY
499 			if (fetch < 1)
500 #else
501 			if (fetch < smpsz)
502 #endif
503 				break;
504 			RATE_ASSERT((int)(info->bpos
505 #ifdef FEEDRATE_STRAY
506 			    - info->stray
507 #endif
508 			    ) >= 0 &&
509 			    (info->bpos  - info->stray) < info->bufsz,
510 			    ("%s: DANGER - BUFFER OVERRUN! bufsz=%d, pos=%d\n",
511 			    __func__, info->bufsz, info->bpos
512 #ifdef FEEDRATE_STRAY
513 			    - info->stray
514 #endif
515 			    ));
516 			fetch = FEEDER_FEED(f->source, c,
517 			    info->buffer + info->bpos
518 #ifdef FEEDRATE_STRAY
519 			    - info->stray
520 #endif
521 			    , fetch, source);
522 #ifdef FEEDRATE_STRAY
523 			info->stray = 0;
524 			if (fetch == 0)
525 #else
526 			if (fetch < smpsz)
527 #endif
528 				break;
529 			RATE_TEST((fetch % smpsz) == 0,
530 			    ("%s: Fetch size not sample integral (%d)\n",
531 			    __func__, fetch));
532 #ifdef FEEDRATE_STRAY
533 			info->stray += fetch % smpsz;
534 			RATE_TEST(info->stray == 0,
535 			    ("%s: Stray bytes detected (%d)\n", __func__,
536 			    info->stray));
537 #endif
538 			fetch -= fetch % smpsz;
539 			info->bpos += fetch;
540 			slot -= fetch;
541 			RATE_ASSERT(slot >= 0, ("%s: Negative Slot: %d\n",
542 			    __func__, slot));
543 			if (slot == 0 || info->bpos == info->bufsz)
544 				break;
545 		}
546 		if (info->pos == info->bpos) {
547 			RATE_TEST(info->pos == smpsz,
548 			    ("%s: EOF while in progress\n", __func__));
549 			break;
550 		}
551 		RATE_ASSERT(info->pos <= info->bpos,
552 		    ("%s: [2] Buffer overrun: %d > %d\n", __func__, info->pos,
553 		    info->bpos));
554 		RATE_ASSERT(info->pos < info->bpos,
555 		    ("%s: Zero buffer!\n", __func__));
556 		RATE_ASSERT(((info->bpos - info->pos) % smpsz) == 0,
557 		    ("%s: Buffer not sample integral (%d)\n", __func__,
558 		    info->bpos - info->pos));
559 		i += info->convert(info, b + i, count - i);
560 		RATE_ASSERT(info->pos <= info->bpos,
561 		    ("%s: [3] Buffer overrun: %d > %d\n", __func__, info->pos,
562 		    info->bpos));
563 		if (info->pos == info->bpos) {
564 			/*
565 			 * End of buffer cycle. Copy last unit sample
566 			 * to beginning of buffer so next cycle can
567 			 * interpolate using it.
568 			 */
569 #ifdef FEEDRATE_STRAY
570 			RATE_TEST(info->stray == 0,
571 			    ("%s: [2] Stray bytes: %u\n", __func__,
572 			    info->stray));
573 #endif
574 			bcopy(info->buffer + info->pos - smpsz, info->buffer,
575 			    sizeof(*info->buffer) * smpsz);
576 			info->bpos = smpsz;
577 			info->pos = smpsz;
578 		}
579 		if (i == count)
580 			break;
581 	}
582 
583 	RATE_TEST((slot == 0 && count == i) || (slot > 0 && count > i &&
584 	    info->pos == info->bpos && info->pos == smpsz),
585 	    ("%s: Inconsistent slot/count! "
586 	    "Count Expect: %u , Got: %u, Slot Left: %d\n", __func__, count, i,
587 	    slot));
588 
589 #ifdef FEEDRATE_STRAY
590 	RATE_TEST(info->stray == 0, ("%s: [3] Stray bytes: %u\n", __func__,
591 	    info->stray));
592 #endif
593 
594 	return (i);
595 }
596 
597 static struct pcm_feederdesc feeder_rate_desc[] = {
598 	{FEEDER_RATE, AFMT_S8, AFMT_S8, 0},
599 	{FEEDER_RATE, AFMT_S16_LE, AFMT_S16_LE, 0},
600 	{FEEDER_RATE, AFMT_S24_LE, AFMT_S24_LE, 0},
601 	{FEEDER_RATE, AFMT_S32_LE, AFMT_S32_LE, 0},
602 	{FEEDER_RATE, AFMT_S16_BE, AFMT_S16_BE, 0},
603 	{FEEDER_RATE, AFMT_S24_BE, AFMT_S24_BE, 0},
604 	{FEEDER_RATE, AFMT_S32_BE, AFMT_S32_BE, 0},
605 	{FEEDER_RATE, AFMT_S8 | AFMT_STEREO, AFMT_S8 | AFMT_STEREO, 0},
606 	{FEEDER_RATE, AFMT_S16_LE | AFMT_STEREO, AFMT_S16_LE | AFMT_STEREO, 0},
607 	{FEEDER_RATE, AFMT_S24_LE | AFMT_STEREO, AFMT_S24_LE | AFMT_STEREO, 0},
608 	{FEEDER_RATE, AFMT_S32_LE | AFMT_STEREO, AFMT_S32_LE | AFMT_STEREO, 0},
609 	{FEEDER_RATE, AFMT_S16_BE | AFMT_STEREO, AFMT_S16_BE | AFMT_STEREO, 0},
610 	{FEEDER_RATE, AFMT_S24_BE | AFMT_STEREO, AFMT_S24_BE | AFMT_STEREO, 0},
611 	{FEEDER_RATE, AFMT_S32_BE | AFMT_STEREO, AFMT_S32_BE | AFMT_STEREO, 0},
612 	{FEEDER_RATE, AFMT_U8, AFMT_U8, 0},
613 	{FEEDER_RATE, AFMT_U16_LE, AFMT_U16_LE, 0},
614 	{FEEDER_RATE, AFMT_U24_LE, AFMT_U24_LE, 0},
615 	{FEEDER_RATE, AFMT_U32_LE, AFMT_U32_LE, 0},
616 	{FEEDER_RATE, AFMT_U16_BE, AFMT_U16_BE, 0},
617 	{FEEDER_RATE, AFMT_U24_BE, AFMT_U24_BE, 0},
618 	{FEEDER_RATE, AFMT_U32_BE, AFMT_U32_BE, 0},
619 	{FEEDER_RATE, AFMT_U8 | AFMT_STEREO, AFMT_U8 | AFMT_STEREO, 0},
620 	{FEEDER_RATE, AFMT_U16_LE | AFMT_STEREO, AFMT_U16_LE | AFMT_STEREO, 0},
621 	{FEEDER_RATE, AFMT_U24_LE | AFMT_STEREO, AFMT_U24_LE | AFMT_STEREO, 0},
622 	{FEEDER_RATE, AFMT_U32_LE | AFMT_STEREO, AFMT_U32_LE | AFMT_STEREO, 0},
623 	{FEEDER_RATE, AFMT_U16_BE | AFMT_STEREO, AFMT_U16_BE | AFMT_STEREO, 0},
624 	{FEEDER_RATE, AFMT_U24_BE | AFMT_STEREO, AFMT_U24_BE | AFMT_STEREO, 0},
625 	{FEEDER_RATE, AFMT_U32_BE | AFMT_STEREO, AFMT_U32_BE | AFMT_STEREO, 0},
626 	{0, 0, 0, 0},
627 };
628 
629 static kobj_method_t feeder_rate_methods[] = {
630 	KOBJMETHOD(feeder_init,		feed_rate_init),
631 	KOBJMETHOD(feeder_free,		feed_rate_free),
632 	KOBJMETHOD(feeder_set,		feed_rate_set),
633 	KOBJMETHOD(feeder_get,		feed_rate_get),
634 	KOBJMETHOD(feeder_feed,		feed_rate),
635 	{0, 0}
636 };
637 
638 FEEDER_DECLARE(feeder_rate, 2, NULL);
639