sound/core/oss/copy.c

   1 /*
   2  *  Linear conversion 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 snd_pcm_sframes_t copy_transfer(struct snd_pcm_plugin *plugin,
  28                              const struct snd_pcm_plugin_channel *src_channels,
  29                              struct snd_pcm_plugin_channel *dst_channels,
  30                              snd_pcm_uframes_t frames)
  31 {
  32         unsigned int channel;
  33         unsigned int nchannels;
  34
  35         snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
  36         if (frames == 0)
  37                 return 0;
  38         nchannels = plugin->src_format.channels;
  39         for (channel = 0; channel < nchannels; channel++) {
  40                 snd_assert(src_channels->area.first % 8 == 0 &&
  41                            src_channels->area.step % 8 == 0,
  42                            return -ENXIO);
  43                 snd_assert(dst_channels->area.first % 8 == 0 &&
  44                            dst_channels->area.step % 8 == 0,
  45                            return -ENXIO);
  46                 if (!src_channels->enabled) {
  47                         if (dst_channels->wanted)
  48                                 snd_pcm_area_silence(&dst_channels->area, 0, frames, plugin->dst_format.format);
  49                         dst_channels->enabled = 0;
  50                         continue;
  51                 }
  52                 dst_channels->enabled = 1;
  53                 snd_pcm_area_copy(&src_channels->area, 0, &dst_channels->area, 0, frames, plugin->src_format.format);
  54                 src_channels++;
  55                 dst_channels++;
  56         }
  57         return frames;
  58 }
  59
  60 int snd_pcm_plugin_build_copy(struct snd_pcm_substream *plug,
  61                               struct snd_pcm_plugin_format *src_format,
  62                               struct snd_pcm_plugin_format *dst_format,
  63                               struct snd_pcm_plugin **r_plugin)
  64 {
  65         int err;
  66         struct snd_pcm_plugin *plugin;
  67         int width;
  68
  69         snd_assert(r_plugin != NULL, return -ENXIO);
  70         *r_plugin = NULL;
  71
  72         snd_assert(src_format->format == dst_format->format, return -ENXIO);
  73         snd_assert(src_format->rate == dst_format->rate, return -ENXIO);
  74         snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
  75
  76         width = snd_pcm_format_physical_width(src_format->format);
  77         snd_assert(width > 0, return -ENXIO);
  78
  79         err = snd_pcm_plugin_build(plug, "copy", src_format, dst_format,
  80                                    0, &plugin);
  81         if (err < 0)
  82                 return err;
  83         plugin->transfer = copy_transfer;
  84         *r_plugin = plugin;
  85         return 0;
  86 }