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Sourcecode: alsa-driver version File versions

pcm_timer.c

/*
 *  Digital Audio (PCM) abstract layer
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <linux/time.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/timer.h>

/*
 *  Timer functions
 */

/* Greatest common divisor */
static unsigned long gcd(unsigned long a, unsigned long b)
{
      unsigned long r;
      if (a < b) {
            r = a;
            a = b;
            b = r;
      }
      while ((r = a % b) != 0) {
            a = b;
            b = r;
      }
      return b;
}

void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)
{
      unsigned long rate, mult, fsize, l, post;
      struct snd_pcm_runtime *runtime = substream->runtime;
      
        mult = 1000000000;
      rate = runtime->rate;
      if (snd_BUG_ON(!rate))
            return;
      l = gcd(mult, rate);
      mult /= l;
      rate /= l;
      fsize = runtime->period_size;
      if (snd_BUG_ON(!fsize))
            return;
      l = gcd(rate, fsize);
      rate /= l;
      fsize /= l;
      post = 1;
      while ((mult * fsize) / fsize != mult) {
            mult /= 2;
            post *= 2;
      }
      if (rate == 0) {
            snd_printk(KERN_ERR "pcm timer resolution out of range (rate = %u, period_size = %lu)\n", runtime->rate, runtime->period_size);
            runtime->timer_resolution = -1;
            return;
      }
      runtime->timer_resolution = (mult * fsize / rate) * post;
}

static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)
{
      struct snd_pcm_substream *substream;
      
      substream = timer->private_data;
      return substream->runtime ? substream->runtime->timer_resolution : 0;
}

static int snd_pcm_timer_start(struct snd_timer * timer)
{
      struct snd_pcm_substream *substream;
      
      substream = snd_timer_chip(timer);
      substream->timer_running = 1;
      return 0;
}

static int snd_pcm_timer_stop(struct snd_timer * timer)
{
      struct snd_pcm_substream *substream;
      
      substream = snd_timer_chip(timer);
      substream->timer_running = 0;
      return 0;
}

static struct snd_timer_hardware snd_pcm_timer =
{
      .flags =    SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,
      .resolution =     0,
      .ticks =    1,
      .c_resolution =   snd_pcm_timer_resolution,
      .start =    snd_pcm_timer_start,
      .stop =           snd_pcm_timer_stop,
};

/*
 *  Init functions
 */

static void snd_pcm_timer_free(struct snd_timer *timer)
{
      struct snd_pcm_substream *substream = timer->private_data;
      substream->timer = NULL;
}

void snd_pcm_timer_init(struct snd_pcm_substream *substream)
{
      struct snd_timer_id tid;
      struct snd_timer *timer;
      
      tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
      tid.dev_class = SNDRV_TIMER_CLASS_PCM;
      tid.card = substream->pcm->card->number;
      tid.device = substream->pcm->device;
      tid.subdevice = (substream->number << 1) | (substream->stream & 1);
      if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)
            return;
      sprintf(timer->name, "PCM %s %i-%i-%i",
                  substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
                        "capture" : "playback",
                  tid.card, tid.device, tid.subdevice);
      timer->hw = snd_pcm_timer;
      if (snd_device_register(timer->card, timer) < 0) {
            snd_device_free(timer->card, timer);
            return;
      }
      timer->private_data = substream;
      timer->private_free = snd_pcm_timer_free;
      substream->timer = timer;
}

void snd_pcm_timer_done(struct snd_pcm_substream *substream)
{
      if (substream->timer) {
            snd_device_free(substream->pcm->card, substream->timer);
            substream->timer = NULL;
      }
}

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