The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/dev/sound/pcm/buffer.c

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    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 
   31 SND_DECLARE_FILE("$FreeBSD: releng/7.4/sys/dev/sound/pcm/buffer.c 207880 2010-05-10 19:22:34Z jkim $");
   32 
   33 struct snd_dbuf *
   34 sndbuf_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 
   46 void
   47 sndbuf_destroy(struct snd_dbuf *b)
   48 {
   49         sndbuf_free(b);
   50         free(b, M_DEVBUF);
   51 }
   52 
   53 bus_addr_t
   54 sndbuf_getbufaddr(struct snd_dbuf *buf)
   55 {
   56         return (buf->buf_addr);
   57 }
   58 
   59 static void
   60 sndbuf_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 
   80 int
   81 sndbuf_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 
  110 int
  111 sndbuf_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 
  122 void
  123 sndbuf_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 
  151 int
  152 sndbuf_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);
  196 out:
  197         chn_unlock(b->channel);
  198         return 0;
  199 }
  200 
  201 int
  202 sndbuf_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  */
  257 void
  258 sndbuf_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  */
  286 void
  287 sndbuf_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  */
  304 void
  305 sndbuf_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 
  312 void
  313 sndbuf_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 
  327 u_int32_t
  328 sndbuf_getfmt(struct snd_dbuf *b)
  329 {
  330         return b->fmt;
  331 }
  332 
  333 int
  334 sndbuf_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 
  348 unsigned int
  349 sndbuf_getspd(struct snd_dbuf *b)
  350 {
  351         return b->spd;
  352 }
  353 
  354 void
  355 sndbuf_setspd(struct snd_dbuf *b, unsigned int spd)
  356 {
  357         b->spd = spd;
  358 }
  359 
  360 unsigned int
  361 sndbuf_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 
  368 unsigned int
  369 sndbuf_getblkcnt(struct snd_dbuf *b)
  370 {
  371         return b->blkcnt;
  372 }
  373 
  374 void
  375 sndbuf_setblkcnt(struct snd_dbuf *b, unsigned int blkcnt)
  376 {
  377         b->blkcnt = blkcnt;
  378 }
  379 
  380 unsigned int
  381 sndbuf_getblksz(struct snd_dbuf *b)
  382 {
  383         return b->blksz;
  384 }
  385 
  386 void
  387 sndbuf_setblksz(struct snd_dbuf *b, unsigned int blksz)
  388 {
  389         b->blksz = blksz;
  390 }
  391 
  392 unsigned int
  393 sndbuf_getbps(struct snd_dbuf *b)
  394 {
  395         return b->bps;
  396 }
  397 
  398 void *
  399 sndbuf_getbuf(struct snd_dbuf *b)
  400 {
  401         return b->buf;
  402 }
  403 
  404 void *
  405 sndbuf_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 
  412 unsigned int
  413 sndbuf_getsize(struct snd_dbuf *b)
  414 {
  415         return b->bufsize;
  416 }
  417 
  418 unsigned int
  419 sndbuf_getmaxsize(struct snd_dbuf *b)
  420 {
  421         return b->maxsize;
  422 }
  423 
  424 unsigned int
  425 sndbuf_getallocsize(struct snd_dbuf *b)
  426 {
  427         return b->allocsize;
  428 }
  429 
  430 unsigned int
  431 sndbuf_runsz(struct snd_dbuf *b)
  432 {
  433         return b->dl;
  434 }
  435 
  436 void
  437 sndbuf_setrun(struct snd_dbuf *b, int go)
  438 {
  439         b->dl = go? b->blksz : 0;
  440 }
  441 
  442 struct selinfo *
  443 sndbuf_getsel(struct snd_dbuf *b)
  444 {
  445         return &b->sel;
  446 }
  447 
  448 /************************************************************/
  449 unsigned int
  450 sndbuf_getxrun(struct snd_dbuf *b)
  451 {
  452         SNDBUF_LOCKASSERT(b);
  453 
  454         return b->xrun;
  455 }
  456 
  457 void
  458 sndbuf_setxrun(struct snd_dbuf *b, unsigned int xrun)
  459 {
  460         SNDBUF_LOCKASSERT(b);
  461 
  462         b->xrun = xrun;
  463 }
  464 
  465 unsigned int
  466 sndbuf_gethwptr(struct snd_dbuf *b)
  467 {
  468         SNDBUF_LOCKASSERT(b);
  469 
  470         return b->hp;
  471 }
  472 
  473 void
  474 sndbuf_sethwptr(struct snd_dbuf *b, unsigned int ptr)
  475 {
  476         SNDBUF_LOCKASSERT(b);
  477 
  478         b->hp = ptr;
  479 }
  480 
  481 unsigned int
  482 sndbuf_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 
  490 unsigned int
  491 sndbuf_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 
  499 unsigned int
  500 sndbuf_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 
  508 unsigned int
  509 sndbuf_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 
  518 unsigned int
  519 sndbuf_getblocks(struct snd_dbuf *b)
  520 {
  521         SNDBUF_LOCKASSERT(b);
  522 
  523         return b->total / b->blksz;
  524 }
  525 
  526 unsigned int
  527 sndbuf_getprevblocks(struct snd_dbuf *b)
  528 {
  529         SNDBUF_LOCKASSERT(b);
  530 
  531         return b->prev_total / b->blksz;
  532 }
  533 
  534 unsigned int
  535 sndbuf_gettotal(struct snd_dbuf *b)
  536 {
  537         SNDBUF_LOCKASSERT(b);
  538 
  539         return b->total;
  540 }
  541 
  542 void
  543 sndbuf_updateprevtotal(struct snd_dbuf *b)
  544 {
  545         SNDBUF_LOCKASSERT(b);
  546 
  547         b->prev_total = b->total;
  548 }
  549 
  550 unsigned int
  551 sndbuf_xbytes(unsigned int v, struct snd_dbuf *from, struct snd_dbuf *to)
  552 {
  553         if (from == NULL || to == NULL || v == 0)
  554                 return 0;
  555 
  556         return snd_xbytes(v, sndbuf_getbps(from) * sndbuf_getspd(from),
  557             sndbuf_getbps(to) * sndbuf_getspd(to));
  558 }
  559 
  560 u_int8_t
  561 sndbuf_zerodata(u_int32_t fmt)
  562 {
  563         if (fmt & AFMT_SIGNED)
  564                 return (0x00);
  565         else if (fmt & AFMT_MU_LAW)
  566                 return (0x7f);
  567         else if (fmt & AFMT_A_LAW)
  568                 return (0x55);
  569         return (0x80);
  570 }
  571 
  572 /************************************************************/
  573 
  574 /**
  575  * @brief Acquire buffer space to extend ready area
  576  *
  577  * This function extends the ready area length by @c count bytes, and may
  578  * optionally copy samples from another location stored in @c from.  The
  579  * counter @c snd_dbuf::total is also incremented by @c count bytes.
  580  *
  581  * @param b     audio buffer
  582  * @param from  sample source (optional)
  583  * @param count number of bytes to acquire
  584  *
  585  * @retval 0    Unconditional
  586  */
  587 int
  588 sndbuf_acquire(struct snd_dbuf *b, u_int8_t *from, unsigned int count)
  589 {
  590         int l;
  591 
  592         KASSERT(count <= sndbuf_getfree(b), ("%s: count %d > free %d", __func__, count, sndbuf_getfree(b)));
  593         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
  594         b->total += count;
  595         if (from != NULL) {
  596                 while (count > 0) {
  597                         l = min(count, sndbuf_getsize(b) - sndbuf_getfreeptr(b));
  598                         bcopy(from, sndbuf_getbufofs(b, sndbuf_getfreeptr(b)), l);
  599                         from += l;
  600                         b->rl += l;
  601                         count -= l;
  602                 }
  603         } else
  604                 b->rl += count;
  605         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count));
  606 
  607         return 0;
  608 }
  609 
  610 /**
  611  * @brief Dispose samples from channel buffer, increasing size of ready area
  612  *
  613  * This function discards samples from the supplied buffer by advancing the
  614  * ready area start pointer and decrementing the ready area length.  If 
  615  * @c to is not NULL, then the discard samples will be copied to the location
  616  * it points to.
  617  *
  618  * @param b     PCM channel sound buffer
  619  * @param to    destination buffer (optional)
  620  * @param count number of bytes to discard
  621  *
  622  * @returns 0 unconditionally
  623  */
  624 int
  625 sndbuf_dispose(struct snd_dbuf *b, u_int8_t *to, unsigned int count)
  626 {
  627         int l;
  628 
  629         KASSERT(count <= sndbuf_getready(b), ("%s: count %d > ready %d", __func__, count, sndbuf_getready(b)));
  630         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
  631         if (to != NULL) {
  632                 while (count > 0) {
  633                         l = min(count, sndbuf_getsize(b) - sndbuf_getreadyptr(b));
  634                         bcopy(sndbuf_getbufofs(b, sndbuf_getreadyptr(b)), to, l);
  635                         to += l;
  636                         b->rl -= l;
  637                         b->rp = (b->rp + l) % b->bufsize;
  638                         count -= l;
  639                 }
  640         } else {
  641                 b->rl -= count;
  642                 b->rp = (b->rp + count) % b->bufsize;
  643         }
  644         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count));
  645 
  646         return 0;
  647 }
  648 
  649 /* count is number of bytes we want added to destination buffer */
  650 int
  651 sndbuf_feed(struct snd_dbuf *from, struct snd_dbuf *to, struct pcm_channel *channel, struct pcm_feeder *feeder, unsigned int count)
  652 {
  653         unsigned int cnt;
  654 
  655         KASSERT(count > 0, ("can't feed 0 bytes"));
  656 
  657         if (sndbuf_getfree(to) < count)
  658                 return EINVAL;
  659 
  660         do {
  661                 cnt = FEEDER_FEED(feeder, channel, to->tmpbuf, count, from);
  662                 if (cnt) {
  663                         sndbuf_acquire(to, to->tmpbuf, cnt);
  664                         count -= cnt;
  665                 }
  666         } while (count && cnt);
  667 
  668         return 0;
  669 }
  670 
  671 /************************************************************/
  672 
  673 void
  674 sndbuf_dump(struct snd_dbuf *b, char *s, u_int32_t what)
  675 {
  676         printf("%s: [", s);
  677         if (what & 0x01)
  678                 printf(" bufsize: %d, maxsize: %d", b->bufsize, b->maxsize);
  679         if (what & 0x02)
  680                 printf(" dl: %d, rp: %d, rl: %d, hp: %d", b->dl, b->rp, b->rl, b->hp);
  681         if (what & 0x04)
  682                 printf(" total: %d, prev_total: %d, xrun: %d", b->total, b->prev_total, b->xrun);
  683         if (what & 0x08)
  684                 printf(" fmt: 0x%x, spd: %d", b->fmt, b->spd);
  685         if (what & 0x10)
  686                 printf(" blksz: %d, blkcnt: %d, flags: 0x%x", b->blksz, b->blkcnt, b->flags);
  687         printf(" ]\n");
  688 }
  689 
  690 /************************************************************/
  691 u_int32_t
  692 sndbuf_getflags(struct snd_dbuf *b)
  693 {
  694         return b->flags;
  695 }
  696 
  697 void
  698 sndbuf_setflags(struct snd_dbuf *b, u_int32_t flags, int on)
  699 {
  700         b->flags &= ~flags;
  701         if (on)
  702                 b->flags |= flags;
  703 }
  704 
  705 /**
  706  * @brief Clear the shadow buffer by filling with samples equal to zero.
  707  *
  708  * @param b buffer to clear
  709  */
  710 void
  711 sndbuf_clearshadow(struct snd_dbuf *b)
  712 {
  713         KASSERT(b != NULL, ("b is a null pointer"));
  714         KASSERT(b->sl >= 0, ("illegal shadow length"));
  715 
  716         if ((b->shadbuf != NULL) && (b->sl > 0))
  717                 memset(b->shadbuf, sndbuf_zerodata(b->fmt), b->sl);
  718 }
  719 
  720 #ifdef OSSV4_EXPERIMENT
  721 /**
  722  * @brief Return peak value from samples in buffer ready area.
  723  *
  724  * Peak ranges from 0-32767.  If channel is monaural, most significant 16
  725  * bits will be zero.  For now, only expects to work with 1-2 channel
  726  * buffers.
  727  *
  728  * @note  Currently only operates with linear PCM formats.
  729  *
  730  * @param b buffer to analyze
  731  * @param lpeak pointer to store left peak value
  732  * @param rpeak pointer to store right peak value
  733  */
  734 void
  735 sndbuf_getpeaks(struct snd_dbuf *b, int *lp, int *rp)
  736 {
  737         u_int32_t lpeak, rpeak;
  738 
  739         lpeak = 0;
  740         rpeak = 0;
  741 
  742         /**
  743          * @todo fill this in later
  744          */
  745 }
  746 #endif

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