xref: /freebsd/sys/dev/sound/pcm/buffer.c (revision 884a2a699669ec61e2366e3e358342dbc94be24a)
1 /*-
2  * Copyright (c) 2005-2009 Ariff Abdullah <ariff@FreeBSD.org>
3  * Portions Copyright (c) Ryan Beasley <ryan.beasley@gmail.com> - GSoC 2006
4  * Copyright (c) 1999 Cameron Grant <cg@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 
29 #ifdef HAVE_KERNEL_OPTION_HEADERS
30 #include "opt_snd.h"
31 #endif
32 
33 #include <dev/sound/pcm/sound.h>
34 
35 #include "feeder_if.h"
36 
37 #define SND_USE_FXDIV
38 #include "snd_fxdiv_gen.h"
39 
40 SND_DECLARE_FILE("$FreeBSD$");
41 
42 struct snd_dbuf *
43 sndbuf_create(device_t dev, char *drv, char *desc, struct pcm_channel *channel)
44 {
45 	struct snd_dbuf *b;
46 
47 	b = malloc(sizeof(*b), M_DEVBUF, M_WAITOK | M_ZERO);
48 	snprintf(b->name, SNDBUF_NAMELEN, "%s:%s", drv, desc);
49 	b->dev = dev;
50 	b->channel = channel;
51 
52 	return b;
53 }
54 
55 void
56 sndbuf_destroy(struct snd_dbuf *b)
57 {
58 	sndbuf_free(b);
59 	free(b, M_DEVBUF);
60 }
61 
62 bus_addr_t
63 sndbuf_getbufaddr(struct snd_dbuf *buf)
64 {
65 	return (buf->buf_addr);
66 }
67 
68 static void
69 sndbuf_setmap(void *arg, bus_dma_segment_t *segs, int nseg, int error)
70 {
71 	struct snd_dbuf *b = (struct snd_dbuf *)arg;
72 
73 	if (bootverbose) {
74 		device_printf(b->dev, "sndbuf_setmap %lx, %lx; ",
75 		    (u_long)segs[0].ds_addr, (u_long)segs[0].ds_len);
76 		printf("%p -> %lx\n", b->buf, (u_long)segs[0].ds_addr);
77 	}
78 	if (error == 0)
79 		b->buf_addr = segs[0].ds_addr;
80 	else
81 		b->buf_addr = 0;
82 }
83 
84 /*
85  * Allocate memory for DMA buffer. If the device does not use DMA transfers,
86  * the driver can call malloc(9) and sndbuf_setup() itself.
87  */
88 
89 int
90 sndbuf_alloc(struct snd_dbuf *b, bus_dma_tag_t dmatag, int dmaflags,
91     unsigned int size)
92 {
93 	int ret;
94 
95 	b->dmatag = dmatag;
96 	b->dmaflags = dmaflags | BUS_DMA_NOWAIT | BUS_DMA_COHERENT;
97 	b->maxsize = size;
98 	b->bufsize = b->maxsize;
99 	b->buf_addr = 0;
100 	b->flags |= SNDBUF_F_MANAGED;
101 	if (bus_dmamem_alloc(b->dmatag, (void **)&b->buf, b->dmaflags,
102 	    &b->dmamap)) {
103 		sndbuf_free(b);
104 		return (ENOMEM);
105 	}
106 	if (bus_dmamap_load(b->dmatag, b->dmamap, b->buf, b->maxsize,
107 	    sndbuf_setmap, b, 0) != 0 || b->buf_addr == 0) {
108 		sndbuf_free(b);
109 		return (ENOMEM);
110 	}
111 
112 	ret = sndbuf_resize(b, 2, b->maxsize / 2);
113 	if (ret != 0)
114 		sndbuf_free(b);
115 
116 	return (ret);
117 }
118 
119 int
120 sndbuf_setup(struct snd_dbuf *b, void *buf, unsigned int size)
121 {
122 	b->flags &= ~SNDBUF_F_MANAGED;
123 	if (buf)
124 		b->flags |= SNDBUF_F_MANAGED;
125 	b->buf = buf;
126 	b->maxsize = size;
127 	b->bufsize = b->maxsize;
128 	return sndbuf_resize(b, 2, b->maxsize / 2);
129 }
130 
131 void
132 sndbuf_free(struct snd_dbuf *b)
133 {
134 	if (b->tmpbuf)
135 		free(b->tmpbuf, M_DEVBUF);
136 
137 	if (b->shadbuf)
138 		free(b->shadbuf, M_DEVBUF);
139 
140 	if (b->buf) {
141 		if (b->flags & SNDBUF_F_MANAGED) {
142 			if (b->dmamap)
143 				bus_dmamap_unload(b->dmatag, b->dmamap);
144 			if (b->dmatag)
145 				bus_dmamem_free(b->dmatag, b->buf, b->dmamap);
146 		} else
147 			free(b->buf, M_DEVBUF);
148 	}
149 
150 	b->tmpbuf = NULL;
151 	b->shadbuf = NULL;
152 	b->buf = NULL;
153 	b->sl = 0;
154 	b->dmatag = NULL;
155 	b->dmamap = NULL;
156 }
157 
158 #define SNDBUF_CACHE_SHIFT	5
159 
160 int
161 sndbuf_resize(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz)
162 {
163 	unsigned int bufsize, allocsize;
164 	u_int8_t *tmpbuf;
165 
166 	CHN_LOCK(b->channel);
167 	if (b->maxsize == 0)
168 		goto out;
169 	if (blkcnt == 0)
170 		blkcnt = b->blkcnt;
171 	if (blksz == 0)
172 		blksz = b->blksz;
173 	if (blkcnt < 2 || blksz < 16 || (blkcnt * blksz) > b->maxsize) {
174 		CHN_UNLOCK(b->channel);
175 		return EINVAL;
176 	}
177 	if (blkcnt == b->blkcnt && blksz == b->blksz)
178 		goto out;
179 
180 	bufsize = blkcnt * blksz;
181 
182 	if (bufsize > b->allocsize ||
183 	    bufsize < (b->allocsize >> SNDBUF_CACHE_SHIFT)) {
184 		allocsize = round_page(bufsize);
185 		CHN_UNLOCK(b->channel);
186 		tmpbuf = malloc(allocsize, M_DEVBUF, M_WAITOK);
187 		CHN_LOCK(b->channel);
188 		if (snd_verbose > 3)
189 			printf("%s(): b=%p %p -> %p [%d -> %d : %d]\n",
190 			    __func__, b, b->tmpbuf, tmpbuf,
191 			    b->allocsize, allocsize, bufsize);
192 		if (b->tmpbuf != NULL)
193 			free(b->tmpbuf, M_DEVBUF);
194 		b->tmpbuf = tmpbuf;
195 		b->allocsize = allocsize;
196 	} else if (snd_verbose > 3)
197 		printf("%s(): b=%p %d [%d] NOCHANGE\n",
198 		    __func__, b, b->allocsize, b->bufsize);
199 
200 	b->blkcnt = blkcnt;
201 	b->blksz = blksz;
202 	b->bufsize = bufsize;
203 
204 	sndbuf_reset(b);
205 out:
206 	CHN_UNLOCK(b->channel);
207 	return 0;
208 }
209 
210 int
211 sndbuf_remalloc(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz)
212 {
213         unsigned int bufsize, allocsize;
214 	u_int8_t *buf, *tmpbuf, *shadbuf;
215 
216 	if (blkcnt < 2 || blksz < 16)
217 		return EINVAL;
218 
219 	bufsize = blksz * blkcnt;
220 
221 	if (bufsize > b->allocsize ||
222 	    bufsize < (b->allocsize >> SNDBUF_CACHE_SHIFT)) {
223 		allocsize = round_page(bufsize);
224 		CHN_UNLOCK(b->channel);
225 		buf = malloc(allocsize, M_DEVBUF, M_WAITOK);
226 		tmpbuf = malloc(allocsize, M_DEVBUF, M_WAITOK);
227 		shadbuf = malloc(allocsize, M_DEVBUF, M_WAITOK);
228 		CHN_LOCK(b->channel);
229 		if (b->buf != NULL)
230 			free(b->buf, M_DEVBUF);
231 		b->buf = buf;
232 		if (b->tmpbuf != NULL)
233 			free(b->tmpbuf, M_DEVBUF);
234 		b->tmpbuf = tmpbuf;
235 		if (b->shadbuf != NULL)
236 			free(b->shadbuf, M_DEVBUF);
237 		b->shadbuf = shadbuf;
238 		if (snd_verbose > 3)
239 			printf("%s(): b=%p %d -> %d [%d]\n",
240 			    __func__, b, b->allocsize, allocsize, bufsize);
241 		b->allocsize = allocsize;
242 	} else if (snd_verbose > 3)
243 		printf("%s(): b=%p %d [%d] NOCHANGE\n",
244 		    __func__, b, b->allocsize, b->bufsize);
245 
246 	b->blkcnt = blkcnt;
247 	b->blksz = blksz;
248 	b->bufsize = bufsize;
249 	b->maxsize = bufsize;
250 	b->sl = bufsize;
251 
252 	sndbuf_reset(b);
253 
254 	return 0;
255 }
256 
257 /**
258  * @brief Zero out space in buffer free area
259  *
260  * This function clears a chunk of @c length bytes in the buffer free area
261  * (i.e., where the next write will be placed).
262  *
263  * @param b		buffer context
264  * @param length	number of bytes to blank
265  */
266 void
267 sndbuf_clear(struct snd_dbuf *b, unsigned int length)
268 {
269 	int i;
270 	u_char data, *p;
271 
272 	if (length == 0)
273 		return;
274 	if (length > b->bufsize)
275 		length = b->bufsize;
276 
277 	data = sndbuf_zerodata(b->fmt);
278 
279 	i = sndbuf_getfreeptr(b);
280 	p = sndbuf_getbuf(b);
281 	while (length > 0) {
282 		p[i] = data;
283 		length--;
284 		i++;
285 		if (i >= b->bufsize)
286 			i = 0;
287 	}
288 }
289 
290 /**
291  * @brief Zap buffer contents, resetting "ready area" fields
292  *
293  * @param b	buffer context
294  */
295 void
296 sndbuf_fillsilence(struct snd_dbuf *b)
297 {
298 	if (b->bufsize > 0)
299 		memset(sndbuf_getbuf(b), sndbuf_zerodata(b->fmt), b->bufsize);
300 	b->rp = 0;
301 	b->rl = b->bufsize;
302 }
303 
304 /**
305  * @brief Reset buffer w/o flushing statistics
306  *
307  * This function just zeroes out buffer contents and sets the "ready length"
308  * to zero.  This was originally to facilitate minimal playback interruption
309  * (i.e., dropped samples) in SNDCTL_DSP_SILENCE/SKIP ioctls.
310  *
311  * @param b	buffer context
312  */
313 void
314 sndbuf_softreset(struct snd_dbuf *b)
315 {
316 	b->rl = 0;
317 	if (b->buf && b->bufsize > 0)
318 		sndbuf_clear(b, b->bufsize);
319 }
320 
321 void
322 sndbuf_reset(struct snd_dbuf *b)
323 {
324 	b->hp = 0;
325 	b->rp = 0;
326 	b->rl = 0;
327 	b->dl = 0;
328 	b->prev_total = 0;
329 	b->total = 0;
330 	b->xrun = 0;
331 	if (b->buf && b->bufsize > 0)
332 		sndbuf_clear(b, b->bufsize);
333 	sndbuf_clearshadow(b);
334 }
335 
336 u_int32_t
337 sndbuf_getfmt(struct snd_dbuf *b)
338 {
339 	return b->fmt;
340 }
341 
342 int
343 sndbuf_setfmt(struct snd_dbuf *b, u_int32_t fmt)
344 {
345 	b->fmt = fmt;
346 	b->bps = AFMT_BPS(b->fmt);
347 	b->align = AFMT_ALIGN(b->fmt);
348 #if 0
349 	b->bps = AFMT_CHANNEL(b->fmt);
350 	if (b->fmt & AFMT_16BIT)
351 		b->bps <<= 1;
352 	else if (b->fmt & AFMT_24BIT)
353 		b->bps *= 3;
354 	else if (b->fmt & AFMT_32BIT)
355 		b->bps <<= 2;
356 #endif
357 	return 0;
358 }
359 
360 unsigned int
361 sndbuf_getspd(struct snd_dbuf *b)
362 {
363 	return b->spd;
364 }
365 
366 void
367 sndbuf_setspd(struct snd_dbuf *b, unsigned int spd)
368 {
369 	b->spd = spd;
370 }
371 
372 unsigned int
373 sndbuf_getalign(struct snd_dbuf *b)
374 {
375 	return (b->align);
376 }
377 
378 unsigned int
379 sndbuf_getblkcnt(struct snd_dbuf *b)
380 {
381 	return b->blkcnt;
382 }
383 
384 void
385 sndbuf_setblkcnt(struct snd_dbuf *b, unsigned int blkcnt)
386 {
387 	b->blkcnt = blkcnt;
388 }
389 
390 unsigned int
391 sndbuf_getblksz(struct snd_dbuf *b)
392 {
393 	return b->blksz;
394 }
395 
396 void
397 sndbuf_setblksz(struct snd_dbuf *b, unsigned int blksz)
398 {
399 	b->blksz = blksz;
400 }
401 
402 unsigned int
403 sndbuf_getbps(struct snd_dbuf *b)
404 {
405 	return b->bps;
406 }
407 
408 void *
409 sndbuf_getbuf(struct snd_dbuf *b)
410 {
411 	return b->buf;
412 }
413 
414 void *
415 sndbuf_getbufofs(struct snd_dbuf *b, unsigned int ofs)
416 {
417 	KASSERT(ofs < b->bufsize, ("%s: ofs invalid %d", __func__, ofs));
418 
419 	return b->buf + ofs;
420 }
421 
422 unsigned int
423 sndbuf_getsize(struct snd_dbuf *b)
424 {
425 	return b->bufsize;
426 }
427 
428 unsigned int
429 sndbuf_getmaxsize(struct snd_dbuf *b)
430 {
431 	return b->maxsize;
432 }
433 
434 unsigned int
435 sndbuf_getallocsize(struct snd_dbuf *b)
436 {
437 	return b->allocsize;
438 }
439 
440 unsigned int
441 sndbuf_runsz(struct snd_dbuf *b)
442 {
443 	return b->dl;
444 }
445 
446 void
447 sndbuf_setrun(struct snd_dbuf *b, int go)
448 {
449 	b->dl = go? b->blksz : 0;
450 }
451 
452 struct selinfo *
453 sndbuf_getsel(struct snd_dbuf *b)
454 {
455 	return &b->sel;
456 }
457 
458 /************************************************************/
459 unsigned int
460 sndbuf_getxrun(struct snd_dbuf *b)
461 {
462 	SNDBUF_LOCKASSERT(b);
463 
464 	return b->xrun;
465 }
466 
467 void
468 sndbuf_setxrun(struct snd_dbuf *b, unsigned int xrun)
469 {
470 	SNDBUF_LOCKASSERT(b);
471 
472 	b->xrun = xrun;
473 }
474 
475 unsigned int
476 sndbuf_gethwptr(struct snd_dbuf *b)
477 {
478 	SNDBUF_LOCKASSERT(b);
479 
480 	return b->hp;
481 }
482 
483 void
484 sndbuf_sethwptr(struct snd_dbuf *b, unsigned int ptr)
485 {
486 	SNDBUF_LOCKASSERT(b);
487 
488 	b->hp = ptr;
489 }
490 
491 unsigned int
492 sndbuf_getready(struct snd_dbuf *b)
493 {
494 	SNDBUF_LOCKASSERT(b);
495 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
496 
497 	return b->rl;
498 }
499 
500 unsigned int
501 sndbuf_getreadyptr(struct snd_dbuf *b)
502 {
503 	SNDBUF_LOCKASSERT(b);
504 	KASSERT((b->rp >= 0) && (b->rp <= b->bufsize), ("%s: b->rp invalid %d", __func__, b->rp));
505 
506 	return b->rp;
507 }
508 
509 unsigned int
510 sndbuf_getfree(struct snd_dbuf *b)
511 {
512 	SNDBUF_LOCKASSERT(b);
513 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
514 
515 	return b->bufsize - b->rl;
516 }
517 
518 unsigned int
519 sndbuf_getfreeptr(struct snd_dbuf *b)
520 {
521 	SNDBUF_LOCKASSERT(b);
522 	KASSERT((b->rp >= 0) && (b->rp <= b->bufsize), ("%s: b->rp invalid %d", __func__, b->rp));
523 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
524 
525 	return (b->rp + b->rl) % b->bufsize;
526 }
527 
528 u_int64_t
529 sndbuf_getblocks(struct snd_dbuf *b)
530 {
531 	SNDBUF_LOCKASSERT(b);
532 
533 	return b->total / b->blksz;
534 }
535 
536 u_int64_t
537 sndbuf_getprevblocks(struct snd_dbuf *b)
538 {
539 	SNDBUF_LOCKASSERT(b);
540 
541 	return b->prev_total / b->blksz;
542 }
543 
544 u_int64_t
545 sndbuf_gettotal(struct snd_dbuf *b)
546 {
547 	SNDBUF_LOCKASSERT(b);
548 
549 	return b->total;
550 }
551 
552 u_int64_t
553 sndbuf_getprevtotal(struct snd_dbuf *b)
554 {
555 	SNDBUF_LOCKASSERT(b);
556 
557 	return b->prev_total;
558 }
559 
560 void
561 sndbuf_updateprevtotal(struct snd_dbuf *b)
562 {
563 	SNDBUF_LOCKASSERT(b);
564 
565 	b->prev_total = b->total;
566 }
567 
568 unsigned int
569 sndbuf_xbytes(unsigned int v, struct snd_dbuf *from, struct snd_dbuf *to)
570 {
571 	if (from == NULL || to == NULL || v == 0)
572 		return 0;
573 
574 	return snd_xbytes(v, sndbuf_getalign(from) * sndbuf_getspd(from),
575 	    sndbuf_getalign(to) * sndbuf_getspd(to));
576 }
577 
578 u_int8_t
579 sndbuf_zerodata(u_int32_t fmt)
580 {
581 	if (fmt & (AFMT_SIGNED | AFMT_PASSTHROUGH))
582 		return (0x00);
583 	else if (fmt & AFMT_MU_LAW)
584 		return (0x7f);
585 	else if (fmt & AFMT_A_LAW)
586 		return (0x55);
587 	return (0x80);
588 }
589 
590 /************************************************************/
591 
592 /**
593  * @brief Acquire buffer space to extend ready area
594  *
595  * This function extends the ready area length by @c count bytes, and may
596  * optionally copy samples from another location stored in @c from.  The
597  * counter @c snd_dbuf::total is also incremented by @c count bytes.
598  *
599  * @param b	audio buffer
600  * @param from	sample source (optional)
601  * @param count	number of bytes to acquire
602  *
603  * @retval 0	Unconditional
604  */
605 int
606 sndbuf_acquire(struct snd_dbuf *b, u_int8_t *from, unsigned int count)
607 {
608 	int l;
609 
610 	KASSERT(count <= sndbuf_getfree(b), ("%s: count %d > free %d", __func__, count, sndbuf_getfree(b)));
611 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
612 	b->total += count;
613 	if (from != NULL) {
614 		while (count > 0) {
615 			l = min(count, sndbuf_getsize(b) - sndbuf_getfreeptr(b));
616 			bcopy(from, sndbuf_getbufofs(b, sndbuf_getfreeptr(b)), l);
617 			from += l;
618 			b->rl += l;
619 			count -= l;
620 		}
621 	} else
622 		b->rl += count;
623 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count));
624 
625 	return 0;
626 }
627 
628 /**
629  * @brief Dispose samples from channel buffer, increasing size of ready area
630  *
631  * This function discards samples from the supplied buffer by advancing the
632  * ready area start pointer and decrementing the ready area length.  If
633  * @c to is not NULL, then the discard samples will be copied to the location
634  * it points to.
635  *
636  * @param b	PCM channel sound buffer
637  * @param to	destination buffer (optional)
638  * @param count	number of bytes to discard
639  *
640  * @returns 0 unconditionally
641  */
642 int
643 sndbuf_dispose(struct snd_dbuf *b, u_int8_t *to, unsigned int count)
644 {
645 	int l;
646 
647 	KASSERT(count <= sndbuf_getready(b), ("%s: count %d > ready %d", __func__, count, sndbuf_getready(b)));
648 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
649 	if (to != NULL) {
650 		while (count > 0) {
651 			l = min(count, sndbuf_getsize(b) - sndbuf_getreadyptr(b));
652 			bcopy(sndbuf_getbufofs(b, sndbuf_getreadyptr(b)), to, l);
653 			to += l;
654 			b->rl -= l;
655 			b->rp = (b->rp + l) % b->bufsize;
656 			count -= l;
657 		}
658 	} else {
659 		b->rl -= count;
660 		b->rp = (b->rp + count) % b->bufsize;
661 	}
662 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count));
663 
664 	return 0;
665 }
666 
667 #ifdef SND_DIAGNOSTIC
668 static uint32_t snd_feeder_maxfeed = 0;
669 SYSCTL_UINT(_hw_snd, OID_AUTO, feeder_maxfeed, CTLFLAG_RD,
670     &snd_feeder_maxfeed, 0, "maximum feeder count request");
671 
672 static uint32_t snd_feeder_maxcycle = 0;
673 SYSCTL_UINT(_hw_snd, OID_AUTO, feeder_maxcycle, CTLFLAG_RD,
674     &snd_feeder_maxcycle, 0, "maximum feeder cycle");
675 #endif
676 
677 /* count is number of bytes we want added to destination buffer */
678 int
679 sndbuf_feed(struct snd_dbuf *from, struct snd_dbuf *to, struct pcm_channel *channel, struct pcm_feeder *feeder, unsigned int count)
680 {
681 	unsigned int cnt, maxfeed;
682 #ifdef SND_DIAGNOSTIC
683 	unsigned int cycle;
684 
685 	if (count > snd_feeder_maxfeed)
686 		snd_feeder_maxfeed = count;
687 
688 	cycle = 0;
689 #endif
690 
691 	KASSERT(count > 0, ("can't feed 0 bytes"));
692 
693 	if (sndbuf_getfree(to) < count)
694 		return (EINVAL);
695 
696 	maxfeed = SND_FXROUND(SND_FXDIV_MAX, sndbuf_getalign(to));
697 
698 	do {
699 		cnt = FEEDER_FEED(feeder, channel, to->tmpbuf,
700 		    min(count, maxfeed), from);
701 		if (cnt == 0)
702 			break;
703 		sndbuf_acquire(to, to->tmpbuf, cnt);
704 		count -= cnt;
705 #ifdef SND_DIAGNOSTIC
706 		cycle++;
707 #endif
708 	} while (count != 0);
709 
710 #ifdef SND_DIAGNOSTIC
711 	if (cycle > snd_feeder_maxcycle)
712 		snd_feeder_maxcycle = cycle;
713 #endif
714 
715 	return (0);
716 }
717 
718 /************************************************************/
719 
720 void
721 sndbuf_dump(struct snd_dbuf *b, char *s, u_int32_t what)
722 {
723 	printf("%s: [", s);
724 	if (what & 0x01)
725 		printf(" bufsize: %d, maxsize: %d", b->bufsize, b->maxsize);
726 	if (what & 0x02)
727 		printf(" dl: %d, rp: %d, rl: %d, hp: %d", b->dl, b->rp, b->rl, b->hp);
728 	if (what & 0x04)
729 		printf(" total: %ju, prev_total: %ju, xrun: %d", (uintmax_t)b->total, (uintmax_t)b->prev_total, b->xrun);
730    	if (what & 0x08)
731 		printf(" fmt: 0x%x, spd: %d", b->fmt, b->spd);
732 	if (what & 0x10)
733 		printf(" blksz: %d, blkcnt: %d, flags: 0x%x", b->blksz, b->blkcnt, b->flags);
734 	printf(" ]\n");
735 }
736 
737 /************************************************************/
738 u_int32_t
739 sndbuf_getflags(struct snd_dbuf *b)
740 {
741 	return b->flags;
742 }
743 
744 void
745 sndbuf_setflags(struct snd_dbuf *b, u_int32_t flags, int on)
746 {
747 	b->flags &= ~flags;
748 	if (on)
749 		b->flags |= flags;
750 }
751 
752 /**
753  * @brief Clear the shadow buffer by filling with samples equal to zero.
754  *
755  * @param b buffer to clear
756  */
757 void
758 sndbuf_clearshadow(struct snd_dbuf *b)
759 {
760 	KASSERT(b != NULL, ("b is a null pointer"));
761 	KASSERT(b->sl >= 0, ("illegal shadow length"));
762 
763 	if ((b->shadbuf != NULL) && (b->sl > 0))
764 		memset(b->shadbuf, sndbuf_zerodata(b->fmt), b->sl);
765 }
766 
767 #ifdef OSSV4_EXPERIMENT
768 /**
769  * @brief Return peak value from samples in buffer ready area.
770  *
771  * Peak ranges from 0-32767.  If channel is monaural, most significant 16
772  * bits will be zero.  For now, only expects to work with 1-2 channel
773  * buffers.
774  *
775  * @note  Currently only operates with linear PCM formats.
776  *
777  * @param b buffer to analyze
778  * @param lpeak pointer to store left peak value
779  * @param rpeak pointer to store right peak value
780  */
781 void
782 sndbuf_getpeaks(struct snd_dbuf *b, int *lp, int *rp)
783 {
784 	u_int32_t lpeak, rpeak;
785 
786 	lpeak = 0;
787 	rpeak = 0;
788 
789 	/**
790 	 * @todo fill this in later
791 	 */
792 }
793 #endif
794