feeder_volume.c

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    1 /*-
    2  * Copyright (c) 2005 Ariff Abdullah <ariff@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  * feeder_volume, a long 'Lost Technology' rather than a new feature.
   27  */
   28 
   29 #include <dev/sound/pcm/sound.h>
   30 #include "feeder_if.h"
   31 
   32 SND_DECLARE_FILE("$FreeBSD: releng/6.4/sys/dev/sound/pcm/feeder_volume.c 153901 2005-12-30 19:55:55Z netchild $");
   33 
   34 static int
   35 feed_volume_s16(struct pcm_feeder *f, struct pcm_channel *c, uint8_t *b,
   36                 uint32_t count, void *source)
   37 {
   38         int i, j, k, vol[2];
   39         int16_t *buf;
   40 
   41         k = FEEDER_FEED(f->source, c, b, count & ~1, source);
   42         if (k < 2) {
   43 #if 0
   44                 device_printf(c->dev, "%s: Not enough data (Got: %d bytes)\n",
   45                                 __func__, k);
   46 #endif
   47                 return 0;
   48         }
   49 #if 0
   50         if (k & 1)
   51                 device_printf(c->dev, "%s: Bytes not 16bit aligned.\n", __func__);
   52 #endif
   53         k &= ~1;
   54         i = k >> 1;
   55         buf = (int16_t *)b;
   56         vol[0] = c->volume & 0x7f;
   57         vol[1] = (c->volume >> 8) & 0x7f;
   58         while (i > 0) {
   59                 i--;
   60                 j = (vol[i & 1] * buf[i]) / 100;
   61                 if (j > 32767)
   62                         j = 32767;
   63                 if (j < -32768)
   64                         j = -32768;
   65                 buf[i] = j;
   66         }
   67         return k;
   68 }
   69 
   70 static struct pcm_feederdesc feeder_volume_s16_desc[] = {
   71         {FEEDER_VOLUME, AFMT_S16_LE|AFMT_STEREO, AFMT_S16_LE|AFMT_STEREO, 0},
   72         {0, 0, 0, 0},
   73 };
   74 static kobj_method_t feeder_volume_s16_methods[] = {
   75         KOBJMETHOD(feeder_feed, feed_volume_s16),
   76         {0, 0}
   77 };
   78 FEEDER_DECLARE(feeder_volume_s16, 2, NULL);

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FreeBSD/Linux Kernel Cross Reference sys/dev/sound/pcm/feeder_volume.c

FreeBSD/Linux Kernel Cross Reference
sys/dev/sound/pcm/feeder_volume.c