Root/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
27static 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
39static 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
47static 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
61    nsrcs = plugin->src_format.channels;
62    ndsts = plugin->dst_format.channels;
63
64    format = plugin->dst_format.format;
65    dvp = dst_channels;
66    if (nsrcs <= 1) {
67        /* expand to all channels */
68        for (dst = 0; dst < ndsts; ++dst) {
69            copy_area(src_channels, dvp, frames, format);
70            dvp++;
71        }
72        return frames;
73    }
74
75    for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {
76        copy_area(src_channels, dvp, frames, format);
77        dvp++;
78        src_channels++;
79    }
80    if (dst < ndsts)
81        zero_areas(dvp, ndsts - dst, frames, format);
82    return frames;
83}
84
85int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,
86                   struct snd_pcm_plugin_format *src_format,
87                   struct snd_pcm_plugin_format *dst_format,
88                   struct snd_pcm_plugin **r_plugin)
89{
90    struct snd_pcm_plugin *plugin;
91    int err;
92
93    if (snd_BUG_ON(!r_plugin))
94        return -ENXIO;
95    *r_plugin = NULL;
96    if (snd_BUG_ON(src_format->rate != dst_format->rate))
97        return -ENXIO;
98    if (snd_BUG_ON(src_format->format != dst_format->format))
99        return -ENXIO;
100
101    err = snd_pcm_plugin_build(plug, "route conversion",
102                   src_format, dst_format, 0, &plugin);
103    if (err < 0)
104        return err;
105
106    plugin->transfer = route_transfer;
107    *r_plugin = plugin;
108    return 0;
109}
110

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