xref: /freebsd/sys/dev/sound/pcm/buffer.c (revision 193d9e768ba63fcfb187cfd17f461f7d41345048)
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 (snd_verbose > 3) {
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->buf_addr)
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 void
305 sndbuf_fillsilence_rl(struct snd_dbuf *b, u_int rl)
306 {
307 	if (b->bufsize > 0)
308 		memset(sndbuf_getbuf(b), sndbuf_zerodata(b->fmt), b->bufsize);
309 	b->rp = 0;
310 	b->rl = min(b->bufsize, rl);
311 }
312 
313 /**
314  * @brief Reset buffer w/o flushing statistics
315  *
316  * This function just zeroes out buffer contents and sets the "ready length"
317  * to zero.  This was originally to facilitate minimal playback interruption
318  * (i.e., dropped samples) in SNDCTL_DSP_SILENCE/SKIP ioctls.
319  *
320  * @param b	buffer context
321  */
322 void
323 sndbuf_softreset(struct snd_dbuf *b)
324 {
325 	b->rl = 0;
326 	if (b->buf && b->bufsize > 0)
327 		sndbuf_clear(b, b->bufsize);
328 }
329 
330 void
331 sndbuf_reset(struct snd_dbuf *b)
332 {
333 	b->hp = 0;
334 	b->rp = 0;
335 	b->rl = 0;
336 	b->dl = 0;
337 	b->prev_total = 0;
338 	b->total = 0;
339 	b->xrun = 0;
340 	if (b->buf && b->bufsize > 0)
341 		sndbuf_clear(b, b->bufsize);
342 	sndbuf_clearshadow(b);
343 }
344 
345 u_int32_t
346 sndbuf_getfmt(struct snd_dbuf *b)
347 {
348 	return b->fmt;
349 }
350 
351 int
352 sndbuf_setfmt(struct snd_dbuf *b, u_int32_t fmt)
353 {
354 	b->fmt = fmt;
355 	b->bps = AFMT_BPS(b->fmt);
356 	b->align = AFMT_ALIGN(b->fmt);
357 #if 0
358 	b->bps = AFMT_CHANNEL(b->fmt);
359 	if (b->fmt & AFMT_16BIT)
360 		b->bps <<= 1;
361 	else if (b->fmt & AFMT_24BIT)
362 		b->bps *= 3;
363 	else if (b->fmt & AFMT_32BIT)
364 		b->bps <<= 2;
365 #endif
366 	return 0;
367 }
368 
369 unsigned int
370 sndbuf_getspd(struct snd_dbuf *b)
371 {
372 	return b->spd;
373 }
374 
375 void
376 sndbuf_setspd(struct snd_dbuf *b, unsigned int spd)
377 {
378 	b->spd = spd;
379 }
380 
381 unsigned int
382 sndbuf_getalign(struct snd_dbuf *b)
383 {
384 	return (b->align);
385 }
386 
387 unsigned int
388 sndbuf_getblkcnt(struct snd_dbuf *b)
389 {
390 	return b->blkcnt;
391 }
392 
393 void
394 sndbuf_setblkcnt(struct snd_dbuf *b, unsigned int blkcnt)
395 {
396 	b->blkcnt = blkcnt;
397 }
398 
399 unsigned int
400 sndbuf_getblksz(struct snd_dbuf *b)
401 {
402 	return b->blksz;
403 }
404 
405 void
406 sndbuf_setblksz(struct snd_dbuf *b, unsigned int blksz)
407 {
408 	b->blksz = blksz;
409 }
410 
411 unsigned int
412 sndbuf_getbps(struct snd_dbuf *b)
413 {
414 	return b->bps;
415 }
416 
417 void *
418 sndbuf_getbuf(struct snd_dbuf *b)
419 {
420 	return b->buf;
421 }
422 
423 void *
424 sndbuf_getbufofs(struct snd_dbuf *b, unsigned int ofs)
425 {
426 	KASSERT(ofs < b->bufsize, ("%s: ofs invalid %d", __func__, ofs));
427 
428 	return b->buf + ofs;
429 }
430 
431 unsigned int
432 sndbuf_getsize(struct snd_dbuf *b)
433 {
434 	return b->bufsize;
435 }
436 
437 unsigned int
438 sndbuf_getmaxsize(struct snd_dbuf *b)
439 {
440 	return b->maxsize;
441 }
442 
443 unsigned int
444 sndbuf_getallocsize(struct snd_dbuf *b)
445 {
446 	return b->allocsize;
447 }
448 
449 unsigned int
450 sndbuf_runsz(struct snd_dbuf *b)
451 {
452 	return b->dl;
453 }
454 
455 void
456 sndbuf_setrun(struct snd_dbuf *b, int go)
457 {
458 	b->dl = go? b->blksz : 0;
459 }
460 
461 struct selinfo *
462 sndbuf_getsel(struct snd_dbuf *b)
463 {
464 	return &b->sel;
465 }
466 
467 /************************************************************/
468 unsigned int
469 sndbuf_getxrun(struct snd_dbuf *b)
470 {
471 	SNDBUF_LOCKASSERT(b);
472 
473 	return b->xrun;
474 }
475 
476 void
477 sndbuf_setxrun(struct snd_dbuf *b, unsigned int xrun)
478 {
479 	SNDBUF_LOCKASSERT(b);
480 
481 	b->xrun = xrun;
482 }
483 
484 unsigned int
485 sndbuf_gethwptr(struct snd_dbuf *b)
486 {
487 	SNDBUF_LOCKASSERT(b);
488 
489 	return b->hp;
490 }
491 
492 void
493 sndbuf_sethwptr(struct snd_dbuf *b, unsigned int ptr)
494 {
495 	SNDBUF_LOCKASSERT(b);
496 
497 	b->hp = ptr;
498 }
499 
500 unsigned int
501 sndbuf_getready(struct snd_dbuf *b)
502 {
503 	SNDBUF_LOCKASSERT(b);
504 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
505 
506 	return b->rl;
507 }
508 
509 unsigned int
510 sndbuf_getreadyptr(struct snd_dbuf *b)
511 {
512 	SNDBUF_LOCKASSERT(b);
513 	KASSERT((b->rp >= 0) && (b->rp <= b->bufsize), ("%s: b->rp invalid %d", __func__, b->rp));
514 
515 	return b->rp;
516 }
517 
518 unsigned int
519 sndbuf_getfree(struct snd_dbuf *b)
520 {
521 	SNDBUF_LOCKASSERT(b);
522 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
523 
524 	return b->bufsize - b->rl;
525 }
526 
527 unsigned int
528 sndbuf_getfreeptr(struct snd_dbuf *b)
529 {
530 	SNDBUF_LOCKASSERT(b);
531 	KASSERT((b->rp >= 0) && (b->rp <= b->bufsize), ("%s: b->rp invalid %d", __func__, b->rp));
532 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
533 
534 	return (b->rp + b->rl) % b->bufsize;
535 }
536 
537 u_int64_t
538 sndbuf_getblocks(struct snd_dbuf *b)
539 {
540 	SNDBUF_LOCKASSERT(b);
541 
542 	return b->total / b->blksz;
543 }
544 
545 u_int64_t
546 sndbuf_getprevblocks(struct snd_dbuf *b)
547 {
548 	SNDBUF_LOCKASSERT(b);
549 
550 	return b->prev_total / b->blksz;
551 }
552 
553 u_int64_t
554 sndbuf_gettotal(struct snd_dbuf *b)
555 {
556 	SNDBUF_LOCKASSERT(b);
557 
558 	return b->total;
559 }
560 
561 u_int64_t
562 sndbuf_getprevtotal(struct snd_dbuf *b)
563 {
564 	SNDBUF_LOCKASSERT(b);
565 
566 	return b->prev_total;
567 }
568 
569 void
570 sndbuf_updateprevtotal(struct snd_dbuf *b)
571 {
572 	SNDBUF_LOCKASSERT(b);
573 
574 	b->prev_total = b->total;
575 }
576 
577 unsigned int
578 sndbuf_xbytes(unsigned int v, struct snd_dbuf *from, struct snd_dbuf *to)
579 {
580 	if (from == NULL || to == NULL || v == 0)
581 		return 0;
582 
583 	return snd_xbytes(v, sndbuf_getalign(from) * sndbuf_getspd(from),
584 	    sndbuf_getalign(to) * sndbuf_getspd(to));
585 }
586 
587 u_int8_t
588 sndbuf_zerodata(u_int32_t fmt)
589 {
590 	if (fmt & (AFMT_SIGNED | AFMT_PASSTHROUGH))
591 		return (0x00);
592 	else if (fmt & AFMT_MU_LAW)
593 		return (0x7f);
594 	else if (fmt & AFMT_A_LAW)
595 		return (0x55);
596 	return (0x80);
597 }
598 
599 /************************************************************/
600 
601 /**
602  * @brief Acquire buffer space to extend ready area
603  *
604  * This function extends the ready area length by @c count bytes, and may
605  * optionally copy samples from another location stored in @c from.  The
606  * counter @c snd_dbuf::total is also incremented by @c count bytes.
607  *
608  * @param b	audio buffer
609  * @param from	sample source (optional)
610  * @param count	number of bytes to acquire
611  *
612  * @retval 0	Unconditional
613  */
614 int
615 sndbuf_acquire(struct snd_dbuf *b, u_int8_t *from, unsigned int count)
616 {
617 	int l;
618 
619 	KASSERT(count <= sndbuf_getfree(b), ("%s: count %d > free %d", __func__, count, sndbuf_getfree(b)));
620 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
621 	b->total += count;
622 	if (from != NULL) {
623 		while (count > 0) {
624 			l = min(count, sndbuf_getsize(b) - sndbuf_getfreeptr(b));
625 			bcopy(from, sndbuf_getbufofs(b, sndbuf_getfreeptr(b)), l);
626 			from += l;
627 			b->rl += l;
628 			count -= l;
629 		}
630 	} else
631 		b->rl += count;
632 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count));
633 
634 	return 0;
635 }
636 
637 /**
638  * @brief Dispose samples from channel buffer, increasing size of ready area
639  *
640  * This function discards samples from the supplied buffer by advancing the
641  * ready area start pointer and decrementing the ready area length.  If
642  * @c to is not NULL, then the discard samples will be copied to the location
643  * it points to.
644  *
645  * @param b	PCM channel sound buffer
646  * @param to	destination buffer (optional)
647  * @param count	number of bytes to discard
648  *
649  * @returns 0 unconditionally
650  */
651 int
652 sndbuf_dispose(struct snd_dbuf *b, u_int8_t *to, unsigned int count)
653 {
654 	int l;
655 
656 	KASSERT(count <= sndbuf_getready(b), ("%s: count %d > ready %d", __func__, count, sndbuf_getready(b)));
657 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
658 	if (to != NULL) {
659 		while (count > 0) {
660 			l = min(count, sndbuf_getsize(b) - sndbuf_getreadyptr(b));
661 			bcopy(sndbuf_getbufofs(b, sndbuf_getreadyptr(b)), to, l);
662 			to += l;
663 			b->rl -= l;
664 			b->rp = (b->rp + l) % b->bufsize;
665 			count -= l;
666 		}
667 	} else {
668 		b->rl -= count;
669 		b->rp = (b->rp + count) % b->bufsize;
670 	}
671 	KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count));
672 
673 	return 0;
674 }
675 
676 #ifdef SND_DIAGNOSTIC
677 static uint32_t snd_feeder_maxfeed = 0;
678 SYSCTL_UINT(_hw_snd, OID_AUTO, feeder_maxfeed, CTLFLAG_RD,
679     &snd_feeder_maxfeed, 0, "maximum feeder count request");
680 
681 static uint32_t snd_feeder_maxcycle = 0;
682 SYSCTL_UINT(_hw_snd, OID_AUTO, feeder_maxcycle, CTLFLAG_RD,
683     &snd_feeder_maxcycle, 0, "maximum feeder cycle");
684 #endif
685 
686 /* count is number of bytes we want added to destination buffer */
687 int
688 sndbuf_feed(struct snd_dbuf *from, struct snd_dbuf *to, struct pcm_channel *channel, struct pcm_feeder *feeder, unsigned int count)
689 {
690 	unsigned int cnt, maxfeed;
691 #ifdef SND_DIAGNOSTIC
692 	unsigned int cycle;
693 
694 	if (count > snd_feeder_maxfeed)
695 		snd_feeder_maxfeed = count;
696 
697 	cycle = 0;
698 #endif
699 
700 	KASSERT(count > 0, ("can't feed 0 bytes"));
701 
702 	if (sndbuf_getfree(to) < count)
703 		return (EINVAL);
704 
705 	maxfeed = SND_FXROUND(SND_FXDIV_MAX, sndbuf_getalign(to));
706 
707 	do {
708 		cnt = FEEDER_FEED(feeder, channel, to->tmpbuf,
709 		    min(count, maxfeed), from);
710 		if (cnt == 0)
711 			break;
712 		sndbuf_acquire(to, to->tmpbuf, cnt);
713 		count -= cnt;
714 #ifdef SND_DIAGNOSTIC
715 		cycle++;
716 #endif
717 	} while (count != 0);
718 
719 #ifdef SND_DIAGNOSTIC
720 	if (cycle > snd_feeder_maxcycle)
721 		snd_feeder_maxcycle = cycle;
722 #endif
723 
724 	return (0);
725 }
726 
727 /************************************************************/
728 
729 void
730 sndbuf_dump(struct snd_dbuf *b, char *s, u_int32_t what)
731 {
732 	printf("%s: [", s);
733 	if (what & 0x01)
734 		printf(" bufsize: %d, maxsize: %d", b->bufsize, b->maxsize);
735 	if (what & 0x02)
736 		printf(" dl: %d, rp: %d, rl: %d, hp: %d", b->dl, b->rp, b->rl, b->hp);
737 	if (what & 0x04)
738 		printf(" total: %ju, prev_total: %ju, xrun: %d", (uintmax_t)b->total, (uintmax_t)b->prev_total, b->xrun);
739    	if (what & 0x08)
740 		printf(" fmt: 0x%x, spd: %d", b->fmt, b->spd);
741 	if (what & 0x10)
742 		printf(" blksz: %d, blkcnt: %d, flags: 0x%x", b->blksz, b->blkcnt, b->flags);
743 	printf(" ]\n");
744 }
745 
746 /************************************************************/
747 u_int32_t
748 sndbuf_getflags(struct snd_dbuf *b)
749 {
750 	return b->flags;
751 }
752 
753 void
754 sndbuf_setflags(struct snd_dbuf *b, u_int32_t flags, int on)
755 {
756 	b->flags &= ~flags;
757 	if (on)
758 		b->flags |= flags;
759 }
760 
761 /**
762  * @brief Clear the shadow buffer by filling with samples equal to zero.
763  *
764  * @param b buffer to clear
765  */
766 void
767 sndbuf_clearshadow(struct snd_dbuf *b)
768 {
769 	KASSERT(b != NULL, ("b is a null pointer"));
770 	KASSERT(b->sl >= 0, ("illegal shadow length"));
771 
772 	if ((b->shadbuf != NULL) && (b->sl > 0))
773 		memset(b->shadbuf, sndbuf_zerodata(b->fmt), b->sl);
774 }
775 
776 #ifdef OSSV4_EXPERIMENT
777 /**
778  * @brief Return peak value from samples in buffer ready area.
779  *
780  * Peak ranges from 0-32767.  If channel is monaural, most significant 16
781  * bits will be zero.  For now, only expects to work with 1-2 channel
782  * buffers.
783  *
784  * @note  Currently only operates with linear PCM formats.
785  *
786  * @param b buffer to analyze
787  * @param lpeak pointer to store left peak value
788  * @param rpeak pointer to store right peak value
789  */
790 void
791 sndbuf_getpeaks(struct snd_dbuf *b, int *lp, int *rp)
792 {
793 	u_int32_t lpeak, rpeak;
794 
795 	lpeak = 0;
796 	rpeak = 0;
797 
798 	/**
799 	 * @todo fill this in later
800 	 */
801 }
802 #endif
803