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/slab.h>
  23 #include <linux/time.h>
  24 #include <sound/core.h>
  25 #include <sound/pcm.h>
  26 #include "pcm_plugin.h"
  27
  28 static void zero_areas(struct snd_pcm_plugin_channel *dvp, int ndsts,
  29                        snd_pcm_uframes_t frames, int format)
  30 {
  31         int dst = 0;
  32         for (; dst < ndsts; ++dst) {
  33                 if (dvp->wanted)
  34                         snd_pcm_area_silence(&dvp->area, 0, frames, format);
  35                 dvp->enabled = 0;
  36                 dvp++;
  37         }
  38 }
  39
  40 static inline void copy_area(const struct snd_pcm_plugin_channel *src_channel,
  41                              struct snd_pcm_plugin_channel *dst_channel,
  42                              snd_pcm_uframes_t frames, int format)
  43 {
  44         dst_channel->enabled = 1;
  45         snd_pcm_area_copy(&src_channel->area, 0, &dst_channel->area, 0, frames, format);
  46 }
  47
  48 static snd_pcm_sframes_t route_transfer(struct snd_pcm_plugin *plugin,
  49                                         const struct snd_pcm_plugin_channel *src_channels,
  50                                         struct snd_pcm_plugin_channel *dst_channels,
  51                                         snd_pcm_uframes_t frames)
  52 {
  53         int nsrcs, ndsts, dst;
  54         struct snd_pcm_plugin_channel *dvp;
  55         int format;
  56
  57         snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, 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
  85 int 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         snd_assert(r_plugin != NULL, return -ENXIO);
  94         *r_plugin = NULL;
  95         snd_assert(src_format->rate == dst_format->rate, return -ENXIO);
  96         snd_assert(src_format->format == dst_format->format, return -ENXIO);
  97
  98         err = snd_pcm_plugin_build(plug, "route conversion",
  99                                    src_format, dst_format, 0, &plugin);
 100         if (err < 0)
 101                 return err;
 102
 103         plugin->transfer = route_transfer;
 104         *r_plugin = plugin;
 105         return 0;
 106 }