linux/sound/core/pcm_timer.c
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   1/*
   2 *  Digital Audio (PCM) abstract layer
   3 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   4 *
   5 *
   6 *   This program is free software; you can redistribute it and/or modify
   7 *   it under the terms of the GNU General Public License as published by
   8 *   the Free Software Foundation; either version 2 of the License, or
   9 *   (at your option) any later version.
  10 *
  11 *   This program is distributed in the hope that it will be useful,
  12 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 *   GNU General Public License for more details.
  15 *
  16 *   You should have received a copy of the GNU General Public License
  17 *   along with this program; if not, write to the Free Software
  18 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19 *
  20 */
  21
  22#include <linux/time.h>
  23#include <linux/gcd.h>
  24#include <sound/core.h>
  25#include <sound/pcm.h>
  26#include <sound/timer.h>
  27
  28/*
  29 *  Timer functions
  30 */
  31
  32void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)
  33{
  34        unsigned long rate, mult, fsize, l, post;
  35        struct snd_pcm_runtime *runtime = substream->runtime;
  36        
  37        mult = 1000000000;
  38        rate = runtime->rate;
  39        if (snd_BUG_ON(!rate))
  40                return;
  41        l = gcd(mult, rate);
  42        mult /= l;
  43        rate /= l;
  44        fsize = runtime->period_size;
  45        if (snd_BUG_ON(!fsize))
  46                return;
  47        l = gcd(rate, fsize);
  48        rate /= l;
  49        fsize /= l;
  50        post = 1;
  51        while ((mult * fsize) / fsize != mult) {
  52                mult /= 2;
  53                post *= 2;
  54        }
  55        if (rate == 0) {
  56                snd_printk(KERN_ERR "pcm timer resolution out of range (rate = %u, period_size = %lu)\n", runtime->rate, runtime->period_size);
  57                runtime->timer_resolution = -1;
  58                return;
  59        }
  60        runtime->timer_resolution = (mult * fsize / rate) * post;
  61}
  62
  63static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)
  64{
  65        struct snd_pcm_substream *substream;
  66        
  67        substream = timer->private_data;
  68        return substream->runtime ? substream->runtime->timer_resolution : 0;
  69}
  70
  71static int snd_pcm_timer_start(struct snd_timer * timer)
  72{
  73        struct snd_pcm_substream *substream;
  74        
  75        substream = snd_timer_chip(timer);
  76        substream->timer_running = 1;
  77        return 0;
  78}
  79
  80static int snd_pcm_timer_stop(struct snd_timer * timer)
  81{
  82        struct snd_pcm_substream *substream;
  83        
  84        substream = snd_timer_chip(timer);
  85        substream->timer_running = 0;
  86        return 0;
  87}
  88
  89static struct snd_timer_hardware snd_pcm_timer =
  90{
  91        .flags =        SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,
  92        .resolution =   0,
  93        .ticks =        1,
  94        .c_resolution = snd_pcm_timer_resolution,
  95        .start =        snd_pcm_timer_start,
  96        .stop =         snd_pcm_timer_stop,
  97};
  98
  99/*
 100 *  Init functions
 101 */
 102
 103static void snd_pcm_timer_free(struct snd_timer *timer)
 104{
 105        struct snd_pcm_substream *substream = timer->private_data;
 106        substream->timer = NULL;
 107}
 108
 109void snd_pcm_timer_init(struct snd_pcm_substream *substream)
 110{
 111        struct snd_timer_id tid;
 112        struct snd_timer *timer;
 113        
 114        tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
 115        tid.dev_class = SNDRV_TIMER_CLASS_PCM;
 116        tid.card = substream->pcm->card->number;
 117        tid.device = substream->pcm->device;
 118        tid.subdevice = (substream->number << 1) | (substream->stream & 1);
 119        if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)
 120                return;
 121        sprintf(timer->name, "PCM %s %i-%i-%i",
 122                        substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
 123                                "capture" : "playback",
 124                        tid.card, tid.device, tid.subdevice);
 125        timer->hw = snd_pcm_timer;
 126        if (snd_device_register(timer->card, timer) < 0) {
 127                snd_device_free(timer->card, timer);
 128                return;
 129        }
 130        timer->private_data = substream;
 131        timer->private_free = snd_pcm_timer_free;
 132        substream->timer = timer;
 133}
 134
 135void snd_pcm_timer_done(struct snd_pcm_substream *substream)
 136{
 137        if (substream->timer) {
 138                snd_device_free(substream->pcm->card, substream->timer);
 139                substream->timer = NULL;
 140        }
 141}
 142
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