root/sound/core/pcm_timer.c

DEFINITIONS

1. gcd
2. snd_pcm_timer_resolution_change
3. snd_pcm_timer_resolution
4. snd_pcm_timer_start
5. snd_pcm_timer_stop
6. snd_pcm_timer_free
7. snd_pcm_timer_init
8. snd_pcm_timer_done

/*
 *  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)
{
        unsigned long flags;
        struct snd_pcm_substream *substream;
        
        substream = snd_timer_chip(timer);
        spin_lock_irqsave(&substream->timer_lock, flags);
        substream->timer_running = 1;
        spin_unlock_irqrestore(&substream->timer_lock, flags);
        return 0;
}

static int snd_pcm_timer_stop(struct snd_timer * timer)
{
        unsigned long flags;
        struct snd_pcm_substream *substream;
        
        substream = snd_timer_chip(timer);
        spin_lock_irqsave(&substream->timer_lock, flags);
        substream->timer_running = 0;
        spin_unlock_irqrestore(&substream->timer_lock, flags);
        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;
        }
}