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 
zero_areas(struct snd_pcm_plugin_channel * dvp,int ndsts,snd_pcm_uframes_t frames,snd_pcm_format_t format)27 static 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 
copy_area(const struct snd_pcm_plugin_channel * src_channel,struct snd_pcm_plugin_channel * dst_channel,snd_pcm_uframes_t frames,snd_pcm_format_t format)39 static 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 
route_transfer(struct snd_pcm_plugin * plugin,const struct snd_pcm_plugin_channel * src_channels,struct snd_pcm_plugin_channel * dst_channels,snd_pcm_uframes_t frames)47 static 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 	if (frames > dst_channels[0].frames)
61 		frames = dst_channels[0].frames;
62 
63 	nsrcs = plugin->src_format.channels;
64 	ndsts = plugin->dst_format.channels;
65 
66 	format = plugin->dst_format.format;
67 	dvp = dst_channels;
68 	if (nsrcs <= 1) {
69 		/* expand to all channels */
70 		for (dst = 0; dst < ndsts; ++dst) {
71 			copy_area(src_channels, dvp, frames, format);
72 			dvp++;
73 		}
74 		return frames;
75 	}
76 
77 	for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {
78 		copy_area(src_channels, dvp, frames, format);
79 		dvp++;
80 		src_channels++;
81 	}
82 	if (dst < ndsts)
83 		zero_areas(dvp, ndsts - dst, frames, format);
84 	return frames;
85 }
86 
snd_pcm_plugin_build_route(struct snd_pcm_substream * plug,struct snd_pcm_plugin_format * src_format,struct snd_pcm_plugin_format * dst_format,struct snd_pcm_plugin ** r_plugin)87 int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,
88 			       struct snd_pcm_plugin_format *src_format,
89 			       struct snd_pcm_plugin_format *dst_format,
90 			       struct snd_pcm_plugin **r_plugin)
91 {
92 	struct snd_pcm_plugin *plugin;
93 	int err;
94 
95 	if (snd_BUG_ON(!r_plugin))
96 		return -ENXIO;
97 	*r_plugin = NULL;
98 	if (snd_BUG_ON(src_format->rate != dst_format->rate))
99 		return -ENXIO;
100 	if (snd_BUG_ON(src_format->format != dst_format->format))
101 		return -ENXIO;
102 
103 	err = snd_pcm_plugin_build(plug, "route conversion",
104 				   src_format, dst_format, 0, &plugin);
105 	if (err < 0)
106 		return err;
107 
108 	plugin->transfer = route_transfer;
109 	*r_plugin = plugin;
110 	return 0;
111 }
112