mirror of https://gitee.com/openkylin/linux.git
108 lines
3.1 KiB
C
108 lines
3.1 KiB
C
/*
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* Route Plug-In
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* Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
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*
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Library General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (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 Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; 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 <sound/driver.h>
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#include <linux/slab.h>
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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 "pcm_plugin.h"
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static void zero_areas(struct snd_pcm_plugin_channel *dvp, int ndsts,
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snd_pcm_uframes_t frames, int format)
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{
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int dst = 0;
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for (; dst < ndsts; ++dst) {
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if (dvp->wanted)
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snd_pcm_area_silence(&dvp->area, 0, frames, format);
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dvp->enabled = 0;
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dvp++;
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}
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}
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static inline void copy_area(const struct snd_pcm_plugin_channel *src_channel,
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struct snd_pcm_plugin_channel *dst_channel,
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snd_pcm_uframes_t frames, int format)
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{
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dst_channel->enabled = 1;
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snd_pcm_area_copy(&src_channel->area, 0, &dst_channel->area, 0, frames, format);
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}
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static snd_pcm_sframes_t route_transfer(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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snd_pcm_uframes_t frames)
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{
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int nsrcs, ndsts, dst;
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struct snd_pcm_plugin_channel *dvp;
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int format;
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snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
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if (frames == 0)
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return 0;
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nsrcs = plugin->src_format.channels;
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ndsts = plugin->dst_format.channels;
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format = plugin->dst_format.format;
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dvp = dst_channels;
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if (nsrcs <= 1) {
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/* expand to all channels */
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for (dst = 0; dst < ndsts; ++dst) {
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copy_area(src_channels, dvp, frames, format);
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dvp++;
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}
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return frames;
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}
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for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {
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copy_area(src_channels, dvp, frames, format);
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dvp++;
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src_channels++;
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}
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if (dst < ndsts)
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zero_areas(dvp, ndsts - dst, frames, format);
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return frames;
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}
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int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,
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struct snd_pcm_plugin_format *src_format,
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struct snd_pcm_plugin_format *dst_format,
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struct snd_pcm_plugin **r_plugin)
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{
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struct snd_pcm_plugin *plugin;
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int err;
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snd_assert(r_plugin != NULL, return -ENXIO);
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*r_plugin = NULL;
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snd_assert(src_format->rate == dst_format->rate, return -ENXIO);
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snd_assert(src_format->format == dst_format->format, return -ENXIO);
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err = snd_pcm_plugin_build(plug, "route conversion",
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src_format, dst_format, 0, &plugin);
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if (err < 0)
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return err;
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plugin->transfer = route_transfer;
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*r_plugin = plugin;
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return 0;
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}
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