pcm_timer.c

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/*
 *  Digital Audio (PCM) abstract layer
 *  Copyright (c) by Jaroslav Kysela <[email protected]>
 *
 *
 *   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 <linux/gcd.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/timer.h>

/*
 *  Timer functions
 */

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;
    }
}