LXR linux/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
  27static 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        if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
  36                return -ENXIO;
  37        if (frames == 0)
  38                return 0;
  39        nchannels = plugin->src_format.channels;
  40        for (channel = 0; channel < nchannels; channel++) {
  41                if (snd_BUG_ON(src_channels->area.first % 8 ||
  42                               src_channels->area.step % 8))
  43                        return -ENXIO;
  44                if (snd_BUG_ON(dst_channels->area.first % 8 ||
  45                               dst_channels->area.step % 8))
  46                        return -ENXIO;
  47                if (!src_channels->enabled) {
  48                        if (dst_channels->wanted)
  49                                snd_pcm_area_silence(&dst_channels->area, 0, frames, plugin->dst_format.format);
  50                        dst_channels->enabled = 0;
  51                        continue;
  52                }
  53                dst_channels->enabled = 1;
  54                snd_pcm_area_copy(&src_channels->area, 0, &dst_channels->area, 0, frames, plugin->src_format.format);
  55                src_channels++;
  56                dst_channels++;
  57        }
  58        return frames;
  59}
  60
  61int snd_pcm_plugin_build_copy(struct snd_pcm_substream *plug,
  62                              struct snd_pcm_plugin_format *src_format,
  63                              struct snd_pcm_plugin_format *dst_format,
  64                              struct snd_pcm_plugin **r_plugin)
  65{
  66        int err;
  67        struct snd_pcm_plugin *plugin;
  68        int width;
  69
  70        if (snd_BUG_ON(!r_plugin))
  71                return -ENXIO;
  72        *r_plugin = NULL;
  73
  74        if (snd_BUG_ON(src_format->format != dst_format->format))
  75                return -ENXIO;
  76        if (snd_BUG_ON(src_format->rate != dst_format->rate))
  77                return -ENXIO;
  78        if (snd_BUG_ON(src_format->channels != dst_format->channels))
  79                return -ENXIO;
  80
  81        width = snd_pcm_format_physical_width(src_format->format);
  82        if (snd_BUG_ON(width <= 0))
  83                return -ENXIO;
  84
  85        err = snd_pcm_plugin_build(plug, "copy", src_format, dst_format,
  86                                   0, &plugin);
  87        if (err < 0)
  88                return err;
  89        plugin->transfer = copy_transfer;
  90        *r_plugin = plugin;
  91        return 0;
  92}
  93