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 <sound/driver.h>
  23
  24 #ifdef CONFIG_SND_PCM_OSS_PLUGINS
  25
  26 #include <linux/slab.h>
  27 #include <linux/time.h>
  28 #include <sound/core.h>
  29 #include <sound/pcm.h>
  30 #include "pcm_plugin.h"
  31
  32 static void zero_areas(struct snd_pcm_plugin_channel *dvp, int ndsts,
  33                        snd_pcm_uframes_t frames, int format)
  34 {
  35         int dst = 0;
  36         for (; dst < ndsts; ++dst) {
  37                 if (dvp->wanted)
  38                         snd_pcm_area_silence(&dvp->area, 0, frames, format);
  39                 dvp->enabled = 0;
  40                 dvp++;
  41         }
  42 }
  43
  44 static inline void copy_area(const struct snd_pcm_plugin_channel *src_channel,
  45                              struct snd_pcm_plugin_channel *dst_channel,
  46                              snd_pcm_uframes_t frames, int format)
  47 {
  48         dst_channel->enabled = 1;
  49         snd_pcm_area_copy(&src_channel->area, 0, &dst_channel->area, 0, frames, format);
  50 }
  51
  52 static snd_pcm_sframes_t route_transfer(struct snd_pcm_plugin *plugin,
  53                                         const struct snd_pcm_plugin_channel *src_channels,
  54                                         struct snd_pcm_plugin_channel *dst_channels,
  55                                         snd_pcm_uframes_t frames)
  56 {
  57         int nsrcs, ndsts, dst;
  58         struct snd_pcm_plugin_channel *dvp;
  59         int format;
  60
  61         snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
  62         if (frames == 0)
  63                 return 0;
  64
  65         nsrcs = plugin->src_format.channels;
  66         ndsts = plugin->dst_format.channels;
  67
  68         format = plugin->dst_format.format;
  69         dvp = dst_channels;
  70         if (nsrcs <= 1) {
  71                 /* expand to all channels */
  72                 for (dst = 0; dst < ndsts; ++dst) {
  73                         copy_area(src_channels, dvp, frames, format);
  74                         dvp++;
  75                 }
  76                 return frames;
  77         }
  78
  79         for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {
  80                 copy_area(src_channels, dvp, frames, format);
  81                 dvp++;
  82                 src_channels++;
  83         }
  84         if (dst < ndsts)
  85                 zero_areas(dvp, ndsts - dst, frames, format);
  86         return frames;
  87 }
  88
  89 int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,
  90                                struct snd_pcm_plugin_format *src_format,
  91                                struct snd_pcm_plugin_format *dst_format,
  92                                struct snd_pcm_plugin **r_plugin)
  93 {
  94         struct snd_pcm_plugin *plugin;
  95         int err;
  96
  97         snd_assert(r_plugin != NULL, return -ENXIO);
  98         *r_plugin = NULL;
  99         snd_assert(src_format->rate == dst_format->rate, return -ENXIO);
 100         snd_assert(src_format->format == dst_format->format, return -ENXIO);
 101
 102         err = snd_pcm_plugin_build(plug, "route conversion",
 103                                    src_format, dst_format, 0, &plugin);
 104         if (err < 0)
 105                 return err;
 106
 107         plugin->transfer = route_transfer;
 108         *r_plugin = plugin;
 109         return 0;
 110 }
 111
 112 #endif