Root/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

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