112 lines · c
1/*2 * Route Plug-In3 * Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>4 *5 *6 * This library is free software; you can redistribute it and/or modify7 * it under the terms of the GNU Library General Public License as8 * published by the Free Software Foundation; either version 2 of9 * the License, or (at your option) any later version.10 *11 * This program is distributed in the hope that it will be useful,12 * but WITHOUT ANY WARRANTY; without even the implied warranty of13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the14 * GNU Library General Public License for more details.15 *16 * You should have received a copy of the GNU Library General Public17 * License along with this library; if not, write to the Free Software18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA19 *20 */21 22#include <linux/time.h>23#include <sound/core.h>24#include <sound/pcm.h>25#include "pcm_plugin.h"26 27static void zero_areas(struct snd_pcm_plugin_channel *dvp, int ndsts,28 snd_pcm_uframes_t frames, snd_pcm_format_t format)29{30 int dst = 0;31 for (; dst < ndsts; ++dst) {32 if (dvp->wanted)33 snd_pcm_area_silence(&dvp->area, 0, frames, format);34 dvp->enabled = 0;35 dvp++;36 }37}38 39static inline void copy_area(const struct snd_pcm_plugin_channel *src_channel,40 struct snd_pcm_plugin_channel *dst_channel,41 snd_pcm_uframes_t frames, snd_pcm_format_t format)42{43 dst_channel->enabled = 1;44 snd_pcm_area_copy(&src_channel->area, 0, &dst_channel->area, 0, frames, format);45}46 47static snd_pcm_sframes_t route_transfer(struct snd_pcm_plugin *plugin,48 const struct snd_pcm_plugin_channel *src_channels,49 struct snd_pcm_plugin_channel *dst_channels,50 snd_pcm_uframes_t frames)51{52 int nsrcs, ndsts, dst;53 struct snd_pcm_plugin_channel *dvp;54 snd_pcm_format_t format;55 56 if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))57 return -ENXIO;58 if (frames == 0)59 return 0;60 if (frames > dst_channels[0].frames)61 frames = dst_channels[0].frames;62 63 nsrcs = plugin->src_format.channels;64 ndsts = plugin->dst_format.channels;65 66 format = plugin->dst_format.format;67 dvp = dst_channels;68 if (nsrcs <= 1) {69 /* expand to all channels */70 for (dst = 0; dst < ndsts; ++dst) {71 copy_area(src_channels, dvp, frames, format);72 dvp++;73 }74 return frames;75 }76 77 for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {78 copy_area(src_channels, dvp, frames, format);79 dvp++;80 src_channels++;81 }82 if (dst < ndsts)83 zero_areas(dvp, ndsts - dst, frames, format);84 return frames;85}86 87int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,88 struct snd_pcm_plugin_format *src_format,89 struct snd_pcm_plugin_format *dst_format,90 struct snd_pcm_plugin **r_plugin)91{92 struct snd_pcm_plugin *plugin;93 int err;94 95 if (snd_BUG_ON(!r_plugin))96 return -ENXIO;97 *r_plugin = NULL;98 if (snd_BUG_ON(src_format->rate != dst_format->rate))99 return -ENXIO;100 if (snd_BUG_ON(src_format->format != dst_format->format))101 return -ENXIO;102 103 err = snd_pcm_plugin_build(plug, "route conversion",104 src_format, dst_format, 0, &plugin);105 if (err < 0)106 return err;107 108 plugin->transfer = route_transfer;109 *r_plugin = plugin;110 return 0;111}112