xref: /openbmc/linux/sound/core/oss/copy.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 <sound/driver.h>
23 
24 #ifdef CONFIG_SND_PCM_OSS_PLUGINS
25 
26 #include <linux/time.h>
27 #include <sound/core.h>
28 #include <sound/pcm.h>
29 #include "pcm_plugin.h"
30 
31 static snd_pcm_sframes_t copy_transfer(struct snd_pcm_plugin *plugin,
32 			     const struct snd_pcm_plugin_channel *src_channels,
33 			     struct snd_pcm_plugin_channel *dst_channels,
34 			     snd_pcm_uframes_t frames)
35 {
36 	unsigned int channel;
37 	unsigned int nchannels;
38 
39 	snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
40 	if (frames == 0)
41 		return 0;
42 	nchannels = plugin->src_format.channels;
43 	for (channel = 0; channel < nchannels; channel++) {
44 		snd_assert(src_channels->area.first % 8 == 0 &&
45 			   src_channels->area.step % 8 == 0,
46 			   return -ENXIO);
47 		snd_assert(dst_channels->area.first % 8 == 0 &&
48 			   dst_channels->area.step % 8 == 0,
49 			   return -ENXIO);
50 		if (!src_channels->enabled) {
51 			if (dst_channels->wanted)
52 				snd_pcm_area_silence(&dst_channels->area, 0, frames, plugin->dst_format.format);
53 			dst_channels->enabled = 0;
54 			continue;
55 		}
56 		dst_channels->enabled = 1;
57 		snd_pcm_area_copy(&src_channels->area, 0, &dst_channels->area, 0, frames, plugin->src_format.format);
58 		src_channels++;
59 		dst_channels++;
60 	}
61 	return frames;
62 }
63 
64 int snd_pcm_plugin_build_copy(struct snd_pcm_substream *plug,
65 			      struct snd_pcm_plugin_format *src_format,
66 			      struct snd_pcm_plugin_format *dst_format,
67 			      struct snd_pcm_plugin **r_plugin)
68 {
69 	int err;
70 	struct snd_pcm_plugin *plugin;
71 	int width;
72 
73 	snd_assert(r_plugin != NULL, return -ENXIO);
74 	*r_plugin = NULL;
75 
76 	snd_assert(src_format->format == dst_format->format, return -ENXIO);
77 	snd_assert(src_format->rate == dst_format->rate, return -ENXIO);
78 	snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
79 
80 	width = snd_pcm_format_physical_width(src_format->format);
81 	snd_assert(width > 0, return -ENXIO);
82 
83 	err = snd_pcm_plugin_build(plug, "copy", src_format, dst_format,
84 				   0, &plugin);
85 	if (err < 0)
86 		return err;
87 	plugin->transfer = copy_transfer;
88 	*r_plugin = plugin;
89 	return 0;
90 }
91 
92 #endif
93