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/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  * $FreeBSD: src/sys/dev/sound/pcm/feeder_volume.c,v 1.2.2.1 2005/12/30 19:55:54 netchild Exp $
   27  *
   28  * feeder_volume, a long 'Lost Technology' rather than a new feature.
   29  */
   30 
   31 #include <dev/sound/pcm/sound.h>
   32 #include "feeder_if.h"
   33 
   34 SND_DECLARE_FILE("$DragonFly: src/sys/dev/sound/pcm/feeder_volume.c,v 1.1 2007/01/04 21:47:03 corecode Exp $");
   35 
   36 static int
   37 feed_volume_s16(struct pcm_feeder *f, struct pcm_channel *c, uint8_t *b,
   38                 uint32_t count, void *source)
   39 {
   40         int i, j, k, vol[2];
   41         int16_t *buf;
   42 
   43         k = FEEDER_FEED(f->source, c, b, count & ~1, source);
   44         if (k < 2) {
   45 #if 0
   46                 device_printf(c->dev, "%s: Not enough data (Got: %d bytes)\n",
   47                                 __func__, k);
   48 #endif
   49                 return 0;
   50         }
   51 #if 0
   52         if (k & 1)
   53                 device_printf(c->dev, "%s: Bytes not 16bit aligned.\n", __func__);
   54 #endif
   55         k &= ~1;
   56         i = k >> 1;
   57         buf = (int16_t *)b;
   58         vol[0] = c->volume & 0x7f;
   59         vol[1] = (c->volume >> 8) & 0x7f;
   60         while (i > 0) {
   61                 i--;
   62                 j = (vol[i & 1] * buf[i]) / 100;
   63                 if (j > 32767)
   64                         j = 32767;
   65                 if (j < -32768)
   66                         j = -32768;
   67                 buf[i] = j;
   68         }
   69         return k;
   70 }
   71 
   72 static struct pcm_feederdesc feeder_volume_s16_desc[] = {
   73         {FEEDER_VOLUME, AFMT_S16_LE|AFMT_STEREO, AFMT_S16_LE|AFMT_STEREO, 0},
   74         {0, 0, 0, 0},
   75 };
   76 static kobj_method_t feeder_volume_s16_methods[] = {
   77         KOBJMETHOD(feeder_feed, feed_volume_s16),
   78         KOBJMETHOD_END
   79 };
   80 FEEDER_DECLARE(feeder_volume_s16, 2, NULL);

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