LXR linux/sound/core/oss/route.c

   1/*
   2 *  Route Plug-In
   3 *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
   4 *
   5 *
   6 *   This library is free software; you can redistribute it and/or modify
   7 *   it under the terms of the GNU Library General Public License as
   8 *   published by the Free Software Foundation; either version 2 of
   9 *   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 of
  13 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 *   GNU Library General Public License for more details.
  15 *
  16 *   You should have received a copy of the GNU Library General Public
  17 *   License along with this library; if not, write to the Free Software
  18 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19 *
  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
  61        nsrcs = plugin->src_format.channels;
  62        ndsts = plugin->dst_format.channels;
  63
  64        format = plugin->dst_format.format;
  65        dvp = dst_channels;
  66        if (nsrcs <= 1) {
  67                /* expand to all channels */
  68                for (dst = 0; dst < ndsts; ++dst) {
  69                        copy_area(src_channels, dvp, frames, format);
  70                        dvp++;
  71                }
  72                return frames;
  73        }
  74
  75        for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {
  76                copy_area(src_channels, dvp, frames, format);
  77                dvp++;
  78                src_channels++;
  79        }
  80        if (dst < ndsts)
  81                zero_areas(dvp, ndsts - dst, frames, format);
  82        return frames;
  83}
  84
  85int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,
  86                               struct snd_pcm_plugin_format *src_format,
  87                               struct snd_pcm_plugin_format *dst_format,
  88                               struct snd_pcm_plugin **r_plugin)
  89{
  90        struct snd_pcm_plugin *plugin;
  91        int err;
  92
  93        if (snd_BUG_ON(!r_plugin))
  94                return -ENXIO;
  95        *r_plugin = NULL;
  96        if (snd_BUG_ON(src_format->rate != dst_format->rate))
  97                return -ENXIO;
  98        if (snd_BUG_ON(src_format->format != dst_format->format))
  99                return -ENXIO;
 100
 101        err = snd_pcm_plugin_build(plug, "route conversion",
 102                                   src_format, dst_format, 0, &plugin);
 103        if (err < 0)
 104                return err;
 105
 106        plugin->transfer = route_transfer;
 107        *r_plugin = plugin;
 108        return 0;
 109}
 110