LXR linux/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
  28static 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
  40static 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
  48static 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        if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
  58                return -ENXIO;
  59        if (frames == 0)
  60                return 0;
  61
  62        nsrcs = plugin->src_format.channels;
  63        ndsts = plugin->dst_format.channels;
  64
  65        format = plugin->dst_format.format;
  66        dvp = dst_channels;
  67        if (nsrcs <= 1) {
  68                /* expand to all channels */
  69                for (dst = 0; dst < ndsts; ++dst) {
  70                        copy_area(src_channels, dvp, frames, format);
  71                        dvp++;
  72                }
  73                return frames;
  74        }
  75
  76        for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {
  77                copy_area(src_channels, dvp, frames, format);
  78                dvp++;
  79                src_channels++;
  80        }
  81        if (dst < ndsts)
  82                zero_areas(dvp, ndsts - dst, frames, format);
  83        return frames;
  84}
  85
  86int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,
  87                               struct snd_pcm_plugin_format *src_format,
  88                               struct snd_pcm_plugin_format *dst_format,
  89                               struct snd_pcm_plugin **r_plugin)
  90{
  91        struct snd_pcm_plugin *plugin;
  92        int err;
  93
  94        if (snd_BUG_ON(!r_plugin))
  95                return -ENXIO;
  96        *r_plugin = NULL;
  97        if (snd_BUG_ON(src_format->rate != dst_format->rate))
  98                return -ENXIO;
  99        if (snd_BUG_ON(src_format->format != dst_format->format))
 100                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