buffer.c revision 170815
1/*- 2 * Copyright (c) 1999 Cameron Grant <cg@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <dev/sound/pcm/sound.h> 28 29#include "feeder_if.h" 30 31SND_DECLARE_FILE("$FreeBSD: head/sys/dev/sound/pcm/buffer.c 170815 2007-06-16 03:37:28Z ariff $"); 32 33struct snd_dbuf * 34sndbuf_create(device_t dev, char *drv, char *desc, struct pcm_channel *channel) 35{ 36 struct snd_dbuf *b; 37 38 b = malloc(sizeof(*b), M_DEVBUF, M_WAITOK | M_ZERO); 39 snprintf(b->name, SNDBUF_NAMELEN, "%s:%s", drv, desc); 40 b->dev = dev; 41 b->channel = channel; 42 43 return b; 44} 45 46void 47sndbuf_destroy(struct snd_dbuf *b) 48{ 49 sndbuf_free(b); 50 free(b, M_DEVBUF); 51} 52 53bus_addr_t 54sndbuf_getbufaddr(struct snd_dbuf *buf) 55{ 56 return (buf->buf_addr); 57} 58 59static void 60sndbuf_setmap(void *arg, bus_dma_segment_t *segs, int nseg, int error) 61{ 62 struct snd_dbuf *b = (struct snd_dbuf *)arg; 63 64 if (bootverbose) { 65 device_printf(b->dev, "sndbuf_setmap %lx, %lx; ", 66 (u_long)segs[0].ds_addr, (u_long)segs[0].ds_len); 67 printf("%p -> %lx\n", b->buf, (u_long)segs[0].ds_addr); 68 } 69 if (error == 0) 70 b->buf_addr = segs[0].ds_addr; 71 else 72 b->buf_addr = 0; 73} 74 75/* 76 * Allocate memory for DMA buffer. If the device does not use DMA transfers, 77 * the driver can call malloc(9) and sndbuf_setup() itself. 78 */ 79 80int 81sndbuf_alloc(struct snd_dbuf *b, bus_dma_tag_t dmatag, int dmaflags, 82 unsigned int size) 83{ 84 int ret; 85 86 b->dmatag = dmatag; 87 b->dmaflags = dmaflags | BUS_DMA_NOWAIT; 88 b->maxsize = size; 89 b->bufsize = b->maxsize; 90 b->buf_addr = 0; 91 b->flags |= SNDBUF_F_MANAGED; 92 if (bus_dmamem_alloc(b->dmatag, (void **)&b->buf, b->dmaflags, 93 &b->dmamap)) { 94 sndbuf_free(b); 95 return (ENOMEM); 96 } 97 if (bus_dmamap_load(b->dmatag, b->dmamap, b->buf, b->maxsize, 98 sndbuf_setmap, b, 0) != 0 || b->buf_addr == 0) { 99 sndbuf_free(b); 100 return (ENOMEM); 101 } 102 103 ret = sndbuf_resize(b, 2, b->maxsize / 2); 104 if (ret != 0) 105 sndbuf_free(b); 106 107 return (ret); 108} 109 110int 111sndbuf_setup(struct snd_dbuf *b, void *buf, unsigned int size) 112{ 113 b->flags &= ~SNDBUF_F_MANAGED; 114 if (buf) 115 b->flags |= SNDBUF_F_MANAGED; 116 b->buf = buf; 117 b->maxsize = size; 118 b->bufsize = b->maxsize; 119 return sndbuf_resize(b, 2, b->maxsize / 2); 120} 121 122void 123sndbuf_free(struct snd_dbuf *b) 124{ 125 if (b->tmpbuf) 126 free(b->tmpbuf, M_DEVBUF); 127 128 if (b->shadbuf) 129 free(b->shadbuf, M_DEVBUF); 130 131 if (b->buf) { 132 if (b->flags & SNDBUF_F_MANAGED) { 133 if (b->dmamap) 134 bus_dmamap_unload(b->dmatag, b->dmamap); 135 if (b->dmatag) 136 bus_dmamem_free(b->dmatag, b->buf, b->dmamap); 137 } else 138 free(b->buf, M_DEVBUF); 139 } 140 141 b->tmpbuf = NULL; 142 b->shadbuf = NULL; 143 b->buf = NULL; 144 b->sl = 0; 145 b->dmatag = NULL; 146 b->dmamap = NULL; 147} 148 149#define SNDBUF_CACHE_SHIFT 5 150 151int 152sndbuf_resize(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz) 153{ 154 unsigned int bufsize, allocsize; 155 u_int8_t *tmpbuf; 156 157 chn_lock(b->channel); 158 if (b->maxsize == 0) 159 goto out; 160 if (blkcnt == 0) 161 blkcnt = b->blkcnt; 162 if (blksz == 0) 163 blksz = b->blksz; 164 if (blkcnt < 2 || blksz < 16 || (blkcnt * blksz) > b->maxsize) { 165 chn_unlock(b->channel); 166 return EINVAL; 167 } 168 if (blkcnt == b->blkcnt && blksz == b->blksz) 169 goto out; 170 171 bufsize = blkcnt * blksz; 172 173 if (bufsize > b->allocsize || 174 bufsize < (b->allocsize >> SNDBUF_CACHE_SHIFT)) { 175 allocsize = round_page(bufsize); 176 chn_unlock(b->channel); 177 tmpbuf = malloc(allocsize, M_DEVBUF, M_WAITOK); 178 chn_lock(b->channel); 179 if (snd_verbose > 3) 180 printf("%s(): b=%p %p -> %p [%d -> %d : %d]\n", 181 __func__, b, b->tmpbuf, tmpbuf, 182 b->allocsize, allocsize, bufsize); 183 if (b->tmpbuf != NULL) 184 free(b->tmpbuf, M_DEVBUF); 185 b->tmpbuf = tmpbuf; 186 b->allocsize = allocsize; 187 } else if (snd_verbose > 3) 188 printf("%s(): b=%p %d [%d] NOCHANGE\n", 189 __func__, b, b->allocsize, b->bufsize); 190 191 b->blkcnt = blkcnt; 192 b->blksz = blksz; 193 b->bufsize = bufsize; 194 195 sndbuf_reset(b); 196out: 197 chn_unlock(b->channel); 198 return 0; 199} 200 201int 202sndbuf_remalloc(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz) 203{ 204 unsigned int bufsize, allocsize; 205 u_int8_t *buf, *tmpbuf, *shadbuf; 206 207 if (blkcnt < 2 || blksz < 16) 208 return EINVAL; 209 210 bufsize = blksz * blkcnt; 211 212 if (bufsize > b->allocsize || 213 bufsize < (b->allocsize >> SNDBUF_CACHE_SHIFT)) { 214 allocsize = round_page(bufsize); 215 chn_unlock(b->channel); 216 buf = malloc(allocsize, M_DEVBUF, M_WAITOK); 217 tmpbuf = malloc(allocsize, M_DEVBUF, M_WAITOK); 218 shadbuf = malloc(allocsize, M_DEVBUF, M_WAITOK); 219 chn_lock(b->channel); 220 if (b->buf != NULL) 221 free(b->buf, M_DEVBUF); 222 b->buf = buf; 223 if (b->tmpbuf != NULL) 224 free(b->tmpbuf, M_DEVBUF); 225 b->tmpbuf = tmpbuf; 226 if (b->shadbuf != NULL) 227 free(b->shadbuf, M_DEVBUF); 228 b->shadbuf = shadbuf; 229 if (snd_verbose > 3) 230 printf("%s(): b=%p %d -> %d [%d]\n", 231 __func__, b, b->allocsize, allocsize, bufsize); 232 b->allocsize = allocsize; 233 } else if (snd_verbose > 3) 234 printf("%s(): b=%p %d [%d] NOCHANGE\n", 235 __func__, b, b->allocsize, b->bufsize); 236 237 b->blkcnt = blkcnt; 238 b->blksz = blksz; 239 b->bufsize = bufsize; 240 b->maxsize = bufsize; 241 b->sl = bufsize; 242 243 sndbuf_reset(b); 244 245 return 0; 246} 247 248/** 249 * @brief Zero out space in buffer free area 250 * 251 * This function clears a chunk of @c length bytes in the buffer free area 252 * (i.e., where the next write will be placed). 253 * 254 * @param b buffer context 255 * @param length number of bytes to blank 256 */ 257void 258sndbuf_clear(struct snd_dbuf *b, unsigned int length) 259{ 260 int i; 261 u_char data, *p; 262 263 if (length == 0) 264 return; 265 if (length > b->bufsize) 266 length = b->bufsize; 267 268 data = sndbuf_zerodata(b->fmt); 269 270 i = sndbuf_getfreeptr(b); 271 p = sndbuf_getbuf(b); 272 while (length > 0) { 273 p[i] = data; 274 length--; 275 i++; 276 if (i >= b->bufsize) 277 i = 0; 278 } 279} 280 281/** 282 * @brief Zap buffer contents, resetting "ready area" fields 283 * 284 * @param b buffer context 285 */ 286void 287sndbuf_fillsilence(struct snd_dbuf *b) 288{ 289 if (b->bufsize > 0) 290 memset(sndbuf_getbuf(b), sndbuf_zerodata(b->fmt), b->bufsize); 291 b->rp = 0; 292 b->rl = b->bufsize; 293} 294 295/** 296 * @brief Reset buffer w/o flushing statistics 297 * 298 * This function just zeroes out buffer contents and sets the "ready length" 299 * to zero. This was originally to facilitate minimal playback interruption 300 * (i.e., dropped samples) in SNDCTL_DSP_SILENCE/SKIP ioctls. 301 * 302 * @param b buffer context 303 */ 304void 305sndbuf_softreset(struct snd_dbuf *b) 306{ 307 b->rl = 0; 308 if (b->buf && b->bufsize > 0) 309 sndbuf_clear(b, b->bufsize); 310} 311 312void 313sndbuf_reset(struct snd_dbuf *b) 314{ 315 b->hp = 0; 316 b->rp = 0; 317 b->rl = 0; 318 b->dl = 0; 319 b->prev_total = 0; 320 b->total = 0; 321 b->xrun = 0; 322 if (b->buf && b->bufsize > 0) 323 sndbuf_clear(b, b->bufsize); 324 sndbuf_clearshadow(b); 325} 326 327u_int32_t 328sndbuf_getfmt(struct snd_dbuf *b) 329{ 330 return b->fmt; 331} 332 333int 334sndbuf_setfmt(struct snd_dbuf *b, u_int32_t fmt) 335{ 336 b->fmt = fmt; 337 b->bps = 1; 338 b->bps <<= (b->fmt & AFMT_STEREO)? 1 : 0; 339 if (b->fmt & AFMT_16BIT) 340 b->bps <<= 1; 341 else if (b->fmt & AFMT_24BIT) 342 b->bps *= 3; 343 else if (b->fmt & AFMT_32BIT) 344 b->bps <<= 2; 345 return 0; 346} 347 348unsigned int 349sndbuf_getspd(struct snd_dbuf *b) 350{ 351 return b->spd; 352} 353 354void 355sndbuf_setspd(struct snd_dbuf *b, unsigned int spd) 356{ 357 b->spd = spd; 358} 359 360unsigned int 361sndbuf_getalign(struct snd_dbuf *b) 362{ 363 static int align[] = {0, 1, 1, 2, 2, 2, 2, 3}; 364 365 return align[b->bps - 1]; 366} 367 368unsigned int 369sndbuf_getblkcnt(struct snd_dbuf *b) 370{ 371 return b->blkcnt; 372} 373 374void 375sndbuf_setblkcnt(struct snd_dbuf *b, unsigned int blkcnt) 376{ 377 b->blkcnt = blkcnt; 378} 379 380unsigned int 381sndbuf_getblksz(struct snd_dbuf *b) 382{ 383 return b->blksz; 384} 385 386void 387sndbuf_setblksz(struct snd_dbuf *b, unsigned int blksz) 388{ 389 b->blksz = blksz; 390} 391 392unsigned int 393sndbuf_getbps(struct snd_dbuf *b) 394{ 395 return b->bps; 396} 397 398void * 399sndbuf_getbuf(struct snd_dbuf *b) 400{ 401 return b->buf; 402} 403 404void * 405sndbuf_getbufofs(struct snd_dbuf *b, unsigned int ofs) 406{ 407 KASSERT(ofs < b->bufsize, ("%s: ofs invalid %d", __func__, ofs)); 408 409 return b->buf + ofs; 410} 411 412unsigned int 413sndbuf_getsize(struct snd_dbuf *b) 414{ 415 return b->bufsize; 416} 417 418unsigned int 419sndbuf_getmaxsize(struct snd_dbuf *b) 420{ 421 return b->maxsize; 422} 423 424unsigned int 425sndbuf_getallocsize(struct snd_dbuf *b) 426{ 427 return b->allocsize; 428} 429 430unsigned int 431sndbuf_runsz(struct snd_dbuf *b) 432{ 433 return b->dl; 434} 435 436void 437sndbuf_setrun(struct snd_dbuf *b, int go) 438{ 439 b->dl = go? b->blksz : 0; 440} 441 442struct selinfo * 443sndbuf_getsel(struct snd_dbuf *b) 444{ 445 return &b->sel; 446} 447 448/************************************************************/ 449unsigned int 450sndbuf_getxrun(struct snd_dbuf *b) 451{ 452 SNDBUF_LOCKASSERT(b); 453 454 return b->xrun; 455} 456 457void 458sndbuf_setxrun(struct snd_dbuf *b, unsigned int xrun) 459{ 460 SNDBUF_LOCKASSERT(b); 461 462 b->xrun = xrun; 463} 464 465unsigned int 466sndbuf_gethwptr(struct snd_dbuf *b) 467{ 468 SNDBUF_LOCKASSERT(b); 469 470 return b->hp; 471} 472 473void 474sndbuf_sethwptr(struct snd_dbuf *b, unsigned int ptr) 475{ 476 SNDBUF_LOCKASSERT(b); 477 478 b->hp = ptr; 479} 480 481unsigned int 482sndbuf_getready(struct snd_dbuf *b) 483{ 484 SNDBUF_LOCKASSERT(b); 485 KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl)); 486 487 return b->rl; 488} 489 490unsigned int 491sndbuf_getreadyptr(struct snd_dbuf *b) 492{ 493 SNDBUF_LOCKASSERT(b); 494 KASSERT((b->rp >= 0) && (b->rp <= b->bufsize), ("%s: b->rp invalid %d", __func__, b->rp)); 495 496 return b->rp; 497} 498 499unsigned int 500sndbuf_getfree(struct snd_dbuf *b) 501{ 502 SNDBUF_LOCKASSERT(b); 503 KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl)); 504 505 return b->bufsize - b->rl; 506} 507 508unsigned int 509sndbuf_getfreeptr(struct snd_dbuf *b) 510{ 511 SNDBUF_LOCKASSERT(b); 512 KASSERT((b->rp >= 0) && (b->rp <= b->bufsize), ("%s: b->rp invalid %d", __func__, b->rp)); 513 KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl)); 514 515 return (b->rp + b->rl) % b->bufsize; 516} 517 518unsigned int 519sndbuf_getblocks(struct snd_dbuf *b) 520{ 521 SNDBUF_LOCKASSERT(b); 522 523 return b->total / b->blksz; 524} 525 526unsigned int 527sndbuf_getprevblocks(struct snd_dbuf *b) 528{ 529 SNDBUF_LOCKASSERT(b); 530 531 return b->prev_total / b->blksz; 532} 533 534unsigned int 535sndbuf_gettotal(struct snd_dbuf *b) 536{ 537 SNDBUF_LOCKASSERT(b); 538 539 return b->total; 540} 541 542void 543sndbuf_updateprevtotal(struct snd_dbuf *b) 544{ 545 SNDBUF_LOCKASSERT(b); 546 547 b->prev_total = b->total; 548} 549 550unsigned int 551snd_xbytes(unsigned int v, unsigned int from, unsigned int to) 552{ 553 unsigned int w, x, y; 554 555 if (from == to) 556 return v; 557 558 if (from == 0 || to == 0 || v == 0) 559 return 0; 560 561 x = from; 562 y = to; 563 while (y != 0) { 564 w = x % y; 565 x = y; 566 y = w; 567 } 568 from /= x; 569 to /= x; 570 571 return (unsigned int)(((u_int64_t)v * to) / from); 572} 573 574unsigned int 575sndbuf_xbytes(unsigned int v, struct snd_dbuf *from, struct snd_dbuf *to) 576{ 577 if (from == NULL || to == NULL || v == 0) 578 return 0; 579 580 return snd_xbytes(v, sndbuf_getbps(from) * sndbuf_getspd(from), 581 sndbuf_getbps(to) * sndbuf_getspd(to)); 582} 583 584u_int8_t 585sndbuf_zerodata(u_int32_t fmt) 586{ 587 if (fmt & AFMT_SIGNED) 588 return (0x00); 589 else if (fmt & AFMT_MU_LAW) 590 return (0x7f); 591 else if (fmt & AFMT_A_LAW) 592 return (0x55); 593 return (0x80); 594} 595 596/************************************************************/ 597 598/** 599 * @brief Acquire buffer space to extend ready area 600 * 601 * This function extends the ready area length by @c count bytes, and may 602 * optionally copy samples from another location stored in @c from. The 603 * counter @c snd_dbuf::total is also incremented by @c count bytes. 604 * 605 * @param b audio buffer 606 * @param from sample source (optional) 607 * @param count number of bytes to acquire 608 * 609 * @retval 0 Unconditional 610 */ 611int 612sndbuf_acquire(struct snd_dbuf *b, u_int8_t *from, unsigned int count) 613{ 614 int l; 615 616 KASSERT(count <= sndbuf_getfree(b), ("%s: count %d > free %d", __func__, count, sndbuf_getfree(b))); 617 KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl)); 618 b->total += count; 619 if (from != NULL) { 620 while (count > 0) { 621 l = min(count, sndbuf_getsize(b) - sndbuf_getfreeptr(b)); 622 bcopy(from, sndbuf_getbufofs(b, sndbuf_getfreeptr(b)), l); 623 from += l; 624 b->rl += l; 625 count -= l; 626 } 627 } else 628 b->rl += count; 629 KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count)); 630 631 return 0; 632} 633 634/** 635 * @brief Dispose samples from channel buffer, increasing size of ready area 636 * 637 * This function discards samples from the supplied buffer by advancing the 638 * ready area start pointer and decrementing the ready area length. If 639 * @c to is not NULL, then the discard samples will be copied to the location 640 * it points to. 641 * 642 * @param b PCM channel sound buffer 643 * @param to destination buffer (optional) 644 * @param count number of bytes to discard 645 * 646 * @returns 0 unconditionally 647 */ 648int 649sndbuf_dispose(struct snd_dbuf *b, u_int8_t *to, unsigned int count) 650{ 651 int l; 652 653 KASSERT(count <= sndbuf_getready(b), ("%s: count %d > ready %d", __func__, count, sndbuf_getready(b))); 654 KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl)); 655 if (to != NULL) { 656 while (count > 0) { 657 l = min(count, sndbuf_getsize(b) - sndbuf_getreadyptr(b)); 658 bcopy(sndbuf_getbufofs(b, sndbuf_getreadyptr(b)), to, l); 659 to += l; 660 b->rl -= l; 661 b->rp = (b->rp + l) % b->bufsize; 662 count -= l; 663 } 664 } else { 665 b->rl -= count; 666 b->rp = (b->rp + count) % b->bufsize; 667 } 668 KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count)); 669 670 return 0; 671} 672 673/* count is number of bytes we want added to destination buffer */ 674int 675sndbuf_feed(struct snd_dbuf *from, struct snd_dbuf *to, struct pcm_channel *channel, struct pcm_feeder *feeder, unsigned int count) 676{ 677 unsigned int cnt; 678 679 KASSERT(count > 0, ("can't feed 0 bytes")); 680 681 if (sndbuf_getfree(to) < count) 682 return EINVAL; 683 684 do { 685 cnt = FEEDER_FEED(feeder, channel, to->tmpbuf, count, from); 686 if (cnt) { 687 sndbuf_acquire(to, to->tmpbuf, cnt); 688 count -= cnt; 689 } 690 } while (count && cnt); 691 692 return 0; 693} 694 695/************************************************************/ 696 697void 698sndbuf_dump(struct snd_dbuf *b, char *s, u_int32_t what) 699{ 700 printf("%s: [", s); 701 if (what & 0x01) 702 printf(" bufsize: %d, maxsize: %d", b->bufsize, b->maxsize); 703 if (what & 0x02) 704 printf(" dl: %d, rp: %d, rl: %d, hp: %d", b->dl, b->rp, b->rl, b->hp); 705 if (what & 0x04) 706 printf(" total: %d, prev_total: %d, xrun: %d", b->total, b->prev_total, b->xrun); 707 if (what & 0x08) 708 printf(" fmt: 0x%x, spd: %d", b->fmt, b->spd); 709 if (what & 0x10) 710 printf(" blksz: %d, blkcnt: %d, flags: 0x%x", b->blksz, b->blkcnt, b->flags); 711 printf(" ]\n"); 712} 713 714/************************************************************/ 715u_int32_t 716sndbuf_getflags(struct snd_dbuf *b) 717{ 718 return b->flags; 719} 720 721void 722sndbuf_setflags(struct snd_dbuf *b, u_int32_t flags, int on) 723{ 724 b->flags &= ~flags; 725 if (on) 726 b->flags |= flags; 727} 728 729/** 730 * @brief Clear the shadow buffer by filling with samples equal to zero. 731 * 732 * @param b buffer to clear 733 */ 734void 735sndbuf_clearshadow(struct snd_dbuf *b) 736{ 737 KASSERT(b != NULL, ("b is a null pointer")); 738 KASSERT(b->sl >= 0, ("illegal shadow length")); 739 740 if ((b->shadbuf != NULL) && (b->sl > 0)) 741 memset(b->shadbuf, sndbuf_zerodata(b->fmt), b->sl); 742} 743 744#ifdef OSSV4_EXPERIMENT 745/** 746 * @brief Return peak value from samples in buffer ready area. 747 * 748 * Peak ranges from 0-32767. If channel is monaural, most significant 16 749 * bits will be zero. For now, only expects to work with 1-2 channel 750 * buffers. 751 * 752 * @note Currently only operates with linear PCM formats. 753 * 754 * @param b buffer to analyze 755 * @param lpeak pointer to store left peak value 756 * @param rpeak pointer to store right peak value 757 */ 758void 759sndbuf_getpeaks(struct snd_dbuf *b, int *lp, int *rp) 760{ 761 u_int32_t lpeak, rpeak; 762 763 lpeak = 0; 764 rpeak = 0; 765 766 /** 767 * @todo fill this in later 768 */ 769} 770#endif 771