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
  27 static 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
  39 static 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
  47 static 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
  87 int 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 }