The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2005-2009 Ariff Abdullah <ariff@FreeBSD.org>
    5  * Portions Copyright (c) Ryan Beasley <ryan.beasley@gmail.com> - GSoC 2006
    6  * Copyright (c) 1999 Cameron Grant <cg@FreeBSD.org>
    7  * All rights reserved.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  */
   30 
   31 #ifdef HAVE_KERNEL_OPTION_HEADERS
   32 #include "opt_snd.h"
   33 #endif
   34 
   35 #include <dev/sound/pcm/sound.h>
   36 
   37 #include "feeder_if.h"
   38 
   39 #define SND_USE_FXDIV
   40 #define SND_DECLARE_FXDIV
   41 #include "snd_fxdiv_gen.h"
   42 
   43 SND_DECLARE_FILE("$FreeBSD: stable/12/sys/dev/sound/pcm/buffer.c 326255 2017-11-27 14:52:40Z pfg $");
   44 
   45 struct snd_dbuf *
   46 sndbuf_create(device_t dev, char *drv, char *desc, struct pcm_channel *channel)
   47 {
   48         struct snd_dbuf *b;
   49 
   50         b = malloc(sizeof(*b), M_DEVBUF, M_WAITOK | M_ZERO);
   51         snprintf(b->name, SNDBUF_NAMELEN, "%s:%s", drv, desc);
   52         b->dev = dev;
   53         b->channel = channel;
   54 
   55         return b;
   56 }
   57 
   58 void
   59 sndbuf_destroy(struct snd_dbuf *b)
   60 {
   61         sndbuf_free(b);
   62         free(b, M_DEVBUF);
   63 }
   64 
   65 bus_addr_t
   66 sndbuf_getbufaddr(struct snd_dbuf *buf)
   67 {
   68         return (buf->buf_addr);
   69 }
   70 
   71 static void
   72 sndbuf_setmap(void *arg, bus_dma_segment_t *segs, int nseg, int error)
   73 {
   74         struct snd_dbuf *b = (struct snd_dbuf *)arg;
   75 
   76         if (snd_verbose > 3) {
   77                 device_printf(b->dev, "sndbuf_setmap %lx, %lx; ",
   78                     (u_long)segs[0].ds_addr, (u_long)segs[0].ds_len);
   79                 printf("%p -> %lx\n", b->buf, (u_long)segs[0].ds_addr);
   80         }
   81         if (error == 0)
   82                 b->buf_addr = segs[0].ds_addr;
   83         else
   84                 b->buf_addr = 0;
   85 }
   86 
   87 /*
   88  * Allocate memory for DMA buffer. If the device does not use DMA transfers,
   89  * the driver can call malloc(9) and sndbuf_setup() itself.
   90  */
   91 
   92 int
   93 sndbuf_alloc(struct snd_dbuf *b, bus_dma_tag_t dmatag, int dmaflags,
   94     unsigned int size)
   95 {
   96         int ret;
   97 
   98         b->dmatag = dmatag;
   99         b->dmaflags = dmaflags | BUS_DMA_NOWAIT | BUS_DMA_COHERENT;
  100         b->maxsize = size;
  101         b->bufsize = b->maxsize;
  102         b->buf_addr = 0;
  103         b->flags |= SNDBUF_F_MANAGED;
  104         if (bus_dmamem_alloc(b->dmatag, (void **)&b->buf, b->dmaflags,
  105             &b->dmamap)) {
  106                 sndbuf_free(b);
  107                 return (ENOMEM);
  108         }
  109         if (bus_dmamap_load(b->dmatag, b->dmamap, b->buf, b->maxsize,
  110             sndbuf_setmap, b, 0) != 0 || b->buf_addr == 0) {
  111                 sndbuf_free(b);
  112                 return (ENOMEM);
  113         }
  114 
  115         ret = sndbuf_resize(b, 2, b->maxsize / 2);
  116         if (ret != 0)
  117                 sndbuf_free(b);
  118 
  119         return (ret);
  120 }
  121 
  122 int
  123 sndbuf_setup(struct snd_dbuf *b, void *buf, unsigned int size)
  124 {
  125         b->flags &= ~SNDBUF_F_MANAGED;
  126         if (buf)
  127                 b->flags |= SNDBUF_F_MANAGED;
  128         b->buf = buf;
  129         b->maxsize = size;
  130         b->bufsize = b->maxsize;
  131         return sndbuf_resize(b, 2, b->maxsize / 2);
  132 }
  133 
  134 void
  135 sndbuf_free(struct snd_dbuf *b)
  136 {
  137         if (b->tmpbuf)
  138                 free(b->tmpbuf, M_DEVBUF);
  139 
  140         if (b->shadbuf)
  141                 free(b->shadbuf, M_DEVBUF);
  142 
  143         if (b->buf) {
  144                 if (b->flags & SNDBUF_F_MANAGED) {
  145                         if (b->buf_addr)
  146                                 bus_dmamap_unload(b->dmatag, b->dmamap);
  147                         if (b->dmatag)
  148                                 bus_dmamem_free(b->dmatag, b->buf, b->dmamap);
  149                 } else
  150                         free(b->buf, M_DEVBUF);
  151         }
  152 
  153         b->tmpbuf = NULL;
  154         b->shadbuf = NULL;
  155         b->buf = NULL;
  156         b->sl = 0;
  157         b->dmatag = NULL;
  158         b->dmamap = NULL;
  159 }
  160 
  161 #define SNDBUF_CACHE_SHIFT      5
  162 
  163 int
  164 sndbuf_resize(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz)
  165 {
  166         unsigned int bufsize, allocsize;
  167         u_int8_t *tmpbuf;
  168 
  169         CHN_LOCK(b->channel);
  170         if (b->maxsize == 0)
  171                 goto out;
  172         if (blkcnt == 0)
  173                 blkcnt = b->blkcnt;
  174         if (blksz == 0)
  175                 blksz = b->blksz;
  176         if (blkcnt < 2 || blksz < 16 || (blkcnt * blksz) > b->maxsize) {
  177                 CHN_UNLOCK(b->channel);
  178                 return EINVAL;
  179         }
  180         if (blkcnt == b->blkcnt && blksz == b->blksz)
  181                 goto out;
  182 
  183         bufsize = blkcnt * blksz;
  184 
  185         if (bufsize > b->allocsize ||
  186             bufsize < (b->allocsize >> SNDBUF_CACHE_SHIFT)) {
  187                 allocsize = round_page(bufsize);
  188                 CHN_UNLOCK(b->channel);
  189                 tmpbuf = malloc(allocsize, M_DEVBUF, M_WAITOK);
  190                 CHN_LOCK(b->channel);
  191                 if (snd_verbose > 3)
  192                         printf("%s(): b=%p %p -> %p [%d -> %d : %d]\n",
  193                             __func__, b, b->tmpbuf, tmpbuf,
  194                             b->allocsize, allocsize, bufsize);
  195                 if (b->tmpbuf != NULL)
  196                         free(b->tmpbuf, M_DEVBUF);
  197                 b->tmpbuf = tmpbuf;
  198                 b->allocsize = allocsize;
  199         } else if (snd_verbose > 3)
  200                 printf("%s(): b=%p %d [%d] NOCHANGE\n",
  201                     __func__, b, b->allocsize, b->bufsize);
  202 
  203         b->blkcnt = blkcnt;
  204         b->blksz = blksz;
  205         b->bufsize = bufsize;
  206 
  207         sndbuf_reset(b);
  208 out:
  209         CHN_UNLOCK(b->channel);
  210         return 0;
  211 }
  212 
  213 int
  214 sndbuf_remalloc(struct snd_dbuf *b, unsigned int blkcnt, unsigned int blksz)
  215 {
  216         unsigned int bufsize, allocsize;
  217         u_int8_t *buf, *tmpbuf, *shadbuf;
  218 
  219         if (blkcnt < 2 || blksz < 16)
  220                 return EINVAL;
  221 
  222         bufsize = blksz * blkcnt;
  223 
  224         if (bufsize > b->allocsize ||
  225             bufsize < (b->allocsize >> SNDBUF_CACHE_SHIFT)) {
  226                 allocsize = round_page(bufsize);
  227                 CHN_UNLOCK(b->channel);
  228                 buf = malloc(allocsize, M_DEVBUF, M_WAITOK);
  229                 tmpbuf = malloc(allocsize, M_DEVBUF, M_WAITOK);
  230                 shadbuf = malloc(allocsize, M_DEVBUF, M_WAITOK);
  231                 CHN_LOCK(b->channel);
  232                 if (b->buf != NULL)
  233                         free(b->buf, M_DEVBUF);
  234                 b->buf = buf;
  235                 if (b->tmpbuf != NULL)
  236                         free(b->tmpbuf, M_DEVBUF);
  237                 b->tmpbuf = tmpbuf;
  238                 if (b->shadbuf != NULL)
  239                         free(b->shadbuf, M_DEVBUF);
  240                 b->shadbuf = shadbuf;
  241                 if (snd_verbose > 3)
  242                         printf("%s(): b=%p %d -> %d [%d]\n",
  243                             __func__, b, b->allocsize, allocsize, bufsize);
  244                 b->allocsize = allocsize;
  245         } else if (snd_verbose > 3)
  246                 printf("%s(): b=%p %d [%d] NOCHANGE\n",
  247                     __func__, b, b->allocsize, b->bufsize);
  248 
  249         b->blkcnt = blkcnt;
  250         b->blksz = blksz;
  251         b->bufsize = bufsize;
  252         b->maxsize = bufsize;
  253         b->sl = bufsize;
  254 
  255         sndbuf_reset(b);
  256 
  257         return 0;
  258 }
  259 
  260 /**
  261  * @brief Zero out space in buffer free area
  262  *
  263  * This function clears a chunk of @c length bytes in the buffer free area
  264  * (i.e., where the next write will be placed).
  265  *
  266  * @param b             buffer context
  267  * @param length        number of bytes to blank
  268  */
  269 void
  270 sndbuf_clear(struct snd_dbuf *b, unsigned int length)
  271 {
  272         int i;
  273         u_char data, *p;
  274 
  275         if (length == 0)
  276                 return;
  277         if (length > b->bufsize)
  278                 length = b->bufsize;
  279 
  280         data = sndbuf_zerodata(b->fmt);
  281 
  282         i = sndbuf_getfreeptr(b);
  283         p = sndbuf_getbuf(b);
  284         while (length > 0) {
  285                 p[i] = data;
  286                 length--;
  287                 i++;
  288                 if (i >= b->bufsize)
  289                         i = 0;
  290         }
  291 }
  292 
  293 /**
  294  * @brief Zap buffer contents, resetting "ready area" fields
  295  *
  296  * @param b     buffer context
  297  */
  298 void
  299 sndbuf_fillsilence(struct snd_dbuf *b)
  300 {
  301         if (b->bufsize > 0)
  302                 memset(sndbuf_getbuf(b), sndbuf_zerodata(b->fmt), b->bufsize);
  303         b->rp = 0;
  304         b->rl = b->bufsize;
  305 }
  306 
  307 void
  308 sndbuf_fillsilence_rl(struct snd_dbuf *b, u_int rl)
  309 {
  310         if (b->bufsize > 0)
  311                 memset(sndbuf_getbuf(b), sndbuf_zerodata(b->fmt), b->bufsize);
  312         b->rp = 0;
  313         b->rl = min(b->bufsize, rl);
  314 }
  315 
  316 /**
  317  * @brief Reset buffer w/o flushing statistics
  318  *
  319  * This function just zeroes out buffer contents and sets the "ready length"
  320  * to zero.  This was originally to facilitate minimal playback interruption
  321  * (i.e., dropped samples) in SNDCTL_DSP_SILENCE/SKIP ioctls.
  322  *
  323  * @param b     buffer context
  324  */
  325 void
  326 sndbuf_softreset(struct snd_dbuf *b)
  327 {
  328         b->rl = 0;
  329         if (b->buf && b->bufsize > 0)
  330                 sndbuf_clear(b, b->bufsize);
  331 }
  332 
  333 void
  334 sndbuf_reset(struct snd_dbuf *b)
  335 {
  336         b->hp = 0;
  337         b->rp = 0;
  338         b->rl = 0;
  339         b->dl = 0;
  340         b->prev_total = 0;
  341         b->total = 0;
  342         b->xrun = 0;
  343         if (b->buf && b->bufsize > 0)
  344                 sndbuf_clear(b, b->bufsize);
  345         sndbuf_clearshadow(b);
  346 }
  347 
  348 u_int32_t
  349 sndbuf_getfmt(struct snd_dbuf *b)
  350 {
  351         return b->fmt;
  352 }
  353 
  354 int
  355 sndbuf_setfmt(struct snd_dbuf *b, u_int32_t fmt)
  356 {
  357         b->fmt = fmt;
  358         b->bps = AFMT_BPS(b->fmt);
  359         b->align = AFMT_ALIGN(b->fmt);
  360 #if 0
  361         b->bps = AFMT_CHANNEL(b->fmt);
  362         if (b->fmt & AFMT_16BIT)
  363                 b->bps <<= 1;
  364         else if (b->fmt & AFMT_24BIT)
  365                 b->bps *= 3;
  366         else if (b->fmt & AFMT_32BIT)
  367                 b->bps <<= 2;
  368 #endif
  369         return 0;
  370 }
  371 
  372 unsigned int
  373 sndbuf_getspd(struct snd_dbuf *b)
  374 {
  375         return b->spd;
  376 }
  377 
  378 void
  379 sndbuf_setspd(struct snd_dbuf *b, unsigned int spd)
  380 {
  381         b->spd = spd;
  382 }
  383 
  384 unsigned int
  385 sndbuf_getalign(struct snd_dbuf *b)
  386 {
  387         return (b->align);
  388 }
  389 
  390 unsigned int
  391 sndbuf_getblkcnt(struct snd_dbuf *b)
  392 {
  393         return b->blkcnt;
  394 }
  395 
  396 void
  397 sndbuf_setblkcnt(struct snd_dbuf *b, unsigned int blkcnt)
  398 {
  399         b->blkcnt = blkcnt;
  400 }
  401 
  402 unsigned int
  403 sndbuf_getblksz(struct snd_dbuf *b)
  404 {
  405         return b->blksz;
  406 }
  407 
  408 void
  409 sndbuf_setblksz(struct snd_dbuf *b, unsigned int blksz)
  410 {
  411         b->blksz = blksz;
  412 }
  413 
  414 unsigned int
  415 sndbuf_getbps(struct snd_dbuf *b)
  416 {
  417         return b->bps;
  418 }
  419 
  420 void *
  421 sndbuf_getbuf(struct snd_dbuf *b)
  422 {
  423         return b->buf;
  424 }
  425 
  426 void *
  427 sndbuf_getbufofs(struct snd_dbuf *b, unsigned int ofs)
  428 {
  429         KASSERT(ofs < b->bufsize, ("%s: ofs invalid %d", __func__, ofs));
  430 
  431         return b->buf + ofs;
  432 }
  433 
  434 unsigned int
  435 sndbuf_getsize(struct snd_dbuf *b)
  436 {
  437         return b->bufsize;
  438 }
  439 
  440 unsigned int
  441 sndbuf_getmaxsize(struct snd_dbuf *b)
  442 {
  443         return b->maxsize;
  444 }
  445 
  446 unsigned int
  447 sndbuf_getallocsize(struct snd_dbuf *b)
  448 {
  449         return b->allocsize;
  450 }
  451 
  452 unsigned int
  453 sndbuf_runsz(struct snd_dbuf *b)
  454 {
  455         return b->dl;
  456 }
  457 
  458 void
  459 sndbuf_setrun(struct snd_dbuf *b, int go)
  460 {
  461         b->dl = go? b->blksz : 0;
  462 }
  463 
  464 struct selinfo *
  465 sndbuf_getsel(struct snd_dbuf *b)
  466 {
  467         return &b->sel;
  468 }
  469 
  470 /************************************************************/
  471 unsigned int
  472 sndbuf_getxrun(struct snd_dbuf *b)
  473 {
  474         SNDBUF_LOCKASSERT(b);
  475 
  476         return b->xrun;
  477 }
  478 
  479 void
  480 sndbuf_setxrun(struct snd_dbuf *b, unsigned int xrun)
  481 {
  482         SNDBUF_LOCKASSERT(b);
  483 
  484         b->xrun = xrun;
  485 }
  486 
  487 unsigned int
  488 sndbuf_gethwptr(struct snd_dbuf *b)
  489 {
  490         SNDBUF_LOCKASSERT(b);
  491 
  492         return b->hp;
  493 }
  494 
  495 void
  496 sndbuf_sethwptr(struct snd_dbuf *b, unsigned int ptr)
  497 {
  498         SNDBUF_LOCKASSERT(b);
  499 
  500         b->hp = ptr;
  501 }
  502 
  503 unsigned int
  504 sndbuf_getready(struct snd_dbuf *b)
  505 {
  506         SNDBUF_LOCKASSERT(b);
  507         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
  508 
  509         return b->rl;
  510 }
  511 
  512 unsigned int
  513 sndbuf_getreadyptr(struct snd_dbuf *b)
  514 {
  515         SNDBUF_LOCKASSERT(b);
  516         KASSERT((b->rp >= 0) && (b->rp <= b->bufsize), ("%s: b->rp invalid %d", __func__, b->rp));
  517 
  518         return b->rp;
  519 }
  520 
  521 unsigned int
  522 sndbuf_getfree(struct snd_dbuf *b)
  523 {
  524         SNDBUF_LOCKASSERT(b);
  525         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
  526 
  527         return b->bufsize - b->rl;
  528 }
  529 
  530 unsigned int
  531 sndbuf_getfreeptr(struct snd_dbuf *b)
  532 {
  533         SNDBUF_LOCKASSERT(b);
  534         KASSERT((b->rp >= 0) && (b->rp <= b->bufsize), ("%s: b->rp invalid %d", __func__, b->rp));
  535         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
  536 
  537         return (b->rp + b->rl) % b->bufsize;
  538 }
  539 
  540 u_int64_t
  541 sndbuf_getblocks(struct snd_dbuf *b)
  542 {
  543         SNDBUF_LOCKASSERT(b);
  544 
  545         return b->total / b->blksz;
  546 }
  547 
  548 u_int64_t
  549 sndbuf_getprevblocks(struct snd_dbuf *b)
  550 {
  551         SNDBUF_LOCKASSERT(b);
  552 
  553         return b->prev_total / b->blksz;
  554 }
  555 
  556 u_int64_t
  557 sndbuf_gettotal(struct snd_dbuf *b)
  558 {
  559         SNDBUF_LOCKASSERT(b);
  560 
  561         return b->total;
  562 }
  563 
  564 u_int64_t
  565 sndbuf_getprevtotal(struct snd_dbuf *b)
  566 {
  567         SNDBUF_LOCKASSERT(b);
  568 
  569         return b->prev_total;
  570 }
  571 
  572 void
  573 sndbuf_updateprevtotal(struct snd_dbuf *b)
  574 {
  575         SNDBUF_LOCKASSERT(b);
  576 
  577         b->prev_total = b->total;
  578 }
  579 
  580 unsigned int
  581 sndbuf_xbytes(unsigned int v, struct snd_dbuf *from, struct snd_dbuf *to)
  582 {
  583         if (from == NULL || to == NULL || v == 0)
  584                 return 0;
  585 
  586         return snd_xbytes(v, sndbuf_getalign(from) * sndbuf_getspd(from),
  587             sndbuf_getalign(to) * sndbuf_getspd(to));
  588 }
  589 
  590 u_int8_t
  591 sndbuf_zerodata(u_int32_t fmt)
  592 {
  593         if (fmt & (AFMT_SIGNED | AFMT_PASSTHROUGH))
  594                 return (0x00);
  595         else if (fmt & AFMT_MU_LAW)
  596                 return (0x7f);
  597         else if (fmt & AFMT_A_LAW)
  598                 return (0x55);
  599         return (0x80);
  600 }
  601 
  602 /************************************************************/
  603 
  604 /**
  605  * @brief Acquire buffer space to extend ready area
  606  *
  607  * This function extends the ready area length by @c count bytes, and may
  608  * optionally copy samples from another location stored in @c from.  The
  609  * counter @c snd_dbuf::total is also incremented by @c count bytes.
  610  *
  611  * @param b     audio buffer
  612  * @param from  sample source (optional)
  613  * @param count number of bytes to acquire
  614  *
  615  * @retval 0    Unconditional
  616  */
  617 int
  618 sndbuf_acquire(struct snd_dbuf *b, u_int8_t *from, unsigned int count)
  619 {
  620         int l;
  621 
  622         KASSERT(count <= sndbuf_getfree(b), ("%s: count %d > free %d", __func__, count, sndbuf_getfree(b)));
  623         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
  624         b->total += count;
  625         if (from != NULL) {
  626                 while (count > 0) {
  627                         l = min(count, sndbuf_getsize(b) - sndbuf_getfreeptr(b));
  628                         bcopy(from, sndbuf_getbufofs(b, sndbuf_getfreeptr(b)), l);
  629                         from += l;
  630                         b->rl += l;
  631                         count -= l;
  632                 }
  633         } else
  634                 b->rl += count;
  635         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count));
  636 
  637         return 0;
  638 }
  639 
  640 /**
  641  * @brief Dispose samples from channel buffer, increasing size of ready area
  642  *
  643  * This function discards samples from the supplied buffer by advancing the
  644  * ready area start pointer and decrementing the ready area length.  If 
  645  * @c to is not NULL, then the discard samples will be copied to the location
  646  * it points to.
  647  *
  648  * @param b     PCM channel sound buffer
  649  * @param to    destination buffer (optional)
  650  * @param count number of bytes to discard
  651  *
  652  * @returns 0 unconditionally
  653  */
  654 int
  655 sndbuf_dispose(struct snd_dbuf *b, u_int8_t *to, unsigned int count)
  656 {
  657         int l;
  658 
  659         KASSERT(count <= sndbuf_getready(b), ("%s: count %d > ready %d", __func__, count, sndbuf_getready(b)));
  660         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d", __func__, b->rl));
  661         if (to != NULL) {
  662                 while (count > 0) {
  663                         l = min(count, sndbuf_getsize(b) - sndbuf_getreadyptr(b));
  664                         bcopy(sndbuf_getbufofs(b, sndbuf_getreadyptr(b)), to, l);
  665                         to += l;
  666                         b->rl -= l;
  667                         b->rp = (b->rp + l) % b->bufsize;
  668                         count -= l;
  669                 }
  670         } else {
  671                 b->rl -= count;
  672                 b->rp = (b->rp + count) % b->bufsize;
  673         }
  674         KASSERT((b->rl >= 0) && (b->rl <= b->bufsize), ("%s: b->rl invalid %d, count %d", __func__, b->rl, count));
  675 
  676         return 0;
  677 }
  678 
  679 #ifdef SND_DIAGNOSTIC
  680 static uint32_t snd_feeder_maxfeed = 0;
  681 SYSCTL_UINT(_hw_snd, OID_AUTO, feeder_maxfeed, CTLFLAG_RD,
  682     &snd_feeder_maxfeed, 0, "maximum feeder count request");
  683 
  684 static uint32_t snd_feeder_maxcycle = 0;
  685 SYSCTL_UINT(_hw_snd, OID_AUTO, feeder_maxcycle, CTLFLAG_RD,
  686     &snd_feeder_maxcycle, 0, "maximum feeder cycle");
  687 #endif
  688 
  689 /* count is number of bytes we want added to destination buffer */
  690 int
  691 sndbuf_feed(struct snd_dbuf *from, struct snd_dbuf *to, struct pcm_channel *channel, struct pcm_feeder *feeder, unsigned int count)
  692 {
  693         unsigned int cnt, maxfeed;
  694 #ifdef SND_DIAGNOSTIC
  695         unsigned int cycle;
  696 
  697         if (count > snd_feeder_maxfeed)
  698                 snd_feeder_maxfeed = count;
  699 
  700         cycle = 0;
  701 #endif
  702 
  703         KASSERT(count > 0, ("can't feed 0 bytes"));
  704 
  705         if (sndbuf_getfree(to) < count)
  706                 return (EINVAL);
  707 
  708         maxfeed = SND_FXROUND(SND_FXDIV_MAX, sndbuf_getalign(to));
  709 
  710         do {
  711                 cnt = FEEDER_FEED(feeder, channel, to->tmpbuf,
  712                     min(count, maxfeed), from);
  713                 if (cnt == 0)
  714                         break;
  715                 sndbuf_acquire(to, to->tmpbuf, cnt);
  716                 count -= cnt;
  717 #ifdef SND_DIAGNOSTIC
  718                 cycle++;
  719 #endif
  720         } while (count != 0);
  721 
  722 #ifdef SND_DIAGNOSTIC
  723         if (cycle > snd_feeder_maxcycle)
  724                 snd_feeder_maxcycle = cycle;
  725 #endif
  726 
  727         return (0);
  728 }
  729 
  730 /************************************************************/
  731 
  732 void
  733 sndbuf_dump(struct snd_dbuf *b, char *s, u_int32_t what)
  734 {
  735         printf("%s: [", s);
  736         if (what & 0x01)
  737                 printf(" bufsize: %d, maxsize: %d", b->bufsize, b->maxsize);
  738         if (what & 0x02)
  739                 printf(" dl: %d, rp: %d, rl: %d, hp: %d", b->dl, b->rp, b->rl, b->hp);
  740         if (what & 0x04)
  741                 printf(" total: %ju, prev_total: %ju, xrun: %d", (uintmax_t)b->total, (uintmax_t)b->prev_total, b->xrun);
  742         if (what & 0x08)
  743                 printf(" fmt: 0x%x, spd: %d", b->fmt, b->spd);
  744         if (what & 0x10)
  745                 printf(" blksz: %d, blkcnt: %d, flags: 0x%x", b->blksz, b->blkcnt, b->flags);
  746         printf(" ]\n");
  747 }
  748 
  749 /************************************************************/
  750 u_int32_t
  751 sndbuf_getflags(struct snd_dbuf *b)
  752 {
  753         return b->flags;
  754 }
  755 
  756 void
  757 sndbuf_setflags(struct snd_dbuf *b, u_int32_t flags, int on)
  758 {
  759         b->flags &= ~flags;
  760         if (on)
  761                 b->flags |= flags;
  762 }
  763 
  764 /**
  765  * @brief Clear the shadow buffer by filling with samples equal to zero.
  766  *
  767  * @param b buffer to clear
  768  */
  769 void
  770 sndbuf_clearshadow(struct snd_dbuf *b)
  771 {
  772         KASSERT(b != NULL, ("b is a null pointer"));
  773         KASSERT(b->sl >= 0, ("illegal shadow length"));
  774 
  775         if ((b->shadbuf != NULL) && (b->sl > 0))
  776                 memset(b->shadbuf, sndbuf_zerodata(b->fmt), b->sl);
  777 }
  778 
  779 #ifdef OSSV4_EXPERIMENT
  780 /**
  781  * @brief Return peak value from samples in buffer ready area.
  782  *
  783  * Peak ranges from 0-32767.  If channel is monaural, most significant 16
  784  * bits will be zero.  For now, only expects to work with 1-2 channel
  785  * buffers.
  786  *
  787  * @note  Currently only operates with linear PCM formats.
  788  *
  789  * @param b buffer to analyze
  790  * @param lpeak pointer to store left peak value
  791  * @param rpeak pointer to store right peak value
  792  */
  793 void
  794 sndbuf_getpeaks(struct snd_dbuf *b, int *lp, int *rp)
  795 {
  796         u_int32_t lpeak, rpeak;
  797 
  798         lpeak = 0;
  799         rpeak = 0;
  800 
  801         /**
  802          * @todo fill this in later
  803          */
  804 }
  805 #endif

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