161 строка
4.1 KiB
C
161 строка
4.1 KiB
C
/*
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* Digital Audio (PCM) abstract layer
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* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <linux/time.h>
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#include <sound/core.h>
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#include <sound/pcm.h>
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#include <sound/timer.h>
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/*
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* Timer functions
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*/
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/* Greatest common divisor */
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static unsigned long gcd(unsigned long a, unsigned long b)
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{
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unsigned long r;
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if (a < b) {
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r = a;
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a = b;
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b = r;
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}
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while ((r = a % b) != 0) {
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a = b;
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b = r;
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}
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return b;
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}
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void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)
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{
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unsigned long rate, mult, fsize, l, post;
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struct snd_pcm_runtime *runtime = substream->runtime;
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mult = 1000000000;
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rate = runtime->rate;
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snd_assert(rate != 0, return);
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l = gcd(mult, rate);
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mult /= l;
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rate /= l;
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fsize = runtime->period_size;
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snd_assert(fsize != 0, return);
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l = gcd(rate, fsize);
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rate /= l;
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fsize /= l;
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post = 1;
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while ((mult * fsize) / fsize != mult) {
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mult /= 2;
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post *= 2;
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}
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if (rate == 0) {
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snd_printk(KERN_ERR "pcm timer resolution out of range (rate = %u, period_size = %lu)\n", runtime->rate, runtime->period_size);
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runtime->timer_resolution = -1;
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return;
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}
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runtime->timer_resolution = (mult * fsize / rate) * post;
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}
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static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)
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{
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struct snd_pcm_substream *substream;
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substream = timer->private_data;
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return substream->runtime ? substream->runtime->timer_resolution : 0;
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}
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static int snd_pcm_timer_start(struct snd_timer * timer)
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{
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unsigned long flags;
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struct snd_pcm_substream *substream;
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substream = snd_timer_chip(timer);
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spin_lock_irqsave(&substream->timer_lock, flags);
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substream->timer_running = 1;
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spin_unlock_irqrestore(&substream->timer_lock, flags);
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return 0;
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}
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static int snd_pcm_timer_stop(struct snd_timer * timer)
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{
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unsigned long flags;
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struct snd_pcm_substream *substream;
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substream = snd_timer_chip(timer);
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spin_lock_irqsave(&substream->timer_lock, flags);
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substream->timer_running = 0;
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spin_unlock_irqrestore(&substream->timer_lock, flags);
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return 0;
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}
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static struct snd_timer_hardware snd_pcm_timer =
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{
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.flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,
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.resolution = 0,
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.ticks = 1,
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.c_resolution = snd_pcm_timer_resolution,
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.start = snd_pcm_timer_start,
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.stop = snd_pcm_timer_stop,
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};
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/*
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* Init functions
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*/
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static void snd_pcm_timer_free(struct snd_timer *timer)
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{
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struct snd_pcm_substream *substream = timer->private_data;
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substream->timer = NULL;
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}
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void snd_pcm_timer_init(struct snd_pcm_substream *substream)
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{
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struct snd_timer_id tid;
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struct snd_timer *timer;
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tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
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tid.dev_class = SNDRV_TIMER_CLASS_PCM;
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tid.card = substream->pcm->card->number;
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tid.device = substream->pcm->device;
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tid.subdevice = (substream->number << 1) | (substream->stream & 1);
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if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)
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return;
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sprintf(timer->name, "PCM %s %i-%i-%i",
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substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
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"capture" : "playback",
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tid.card, tid.device, tid.subdevice);
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timer->hw = snd_pcm_timer;
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if (snd_device_register(timer->card, timer) < 0) {
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snd_device_free(timer->card, timer);
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return;
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}
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timer->private_data = substream;
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timer->private_free = snd_pcm_timer_free;
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substream->timer = timer;
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}
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void snd_pcm_timer_done(struct snd_pcm_substream *substream)
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{
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if (substream->timer) {
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snd_device_free(substream->pcm->card, substream->timer);
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substream->timer = NULL;
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}
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}
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