1 // SPDX-License-Identifier: LGPL-2.0+
2 /*
3 * Route Plug-In
4 * Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
5 */
6
7 #include <linux/time.h>
8 #include <sound/core.h>
9 #include <sound/pcm.h>
10 #include "pcm_plugin.h"
11
zero_areas(struct snd_pcm_plugin_channel * dvp,int ndsts,snd_pcm_uframes_t frames,snd_pcm_format_t format)12 static void zero_areas(struct snd_pcm_plugin_channel *dvp, int ndsts,
13 snd_pcm_uframes_t frames, snd_pcm_format_t format)
14 {
15 int dst = 0;
16 for (; dst < ndsts; ++dst) {
17 if (dvp->wanted)
18 snd_pcm_area_silence(&dvp->area, 0, frames, format);
19 dvp->enabled = 0;
20 dvp++;
21 }
22 }
23
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)24 static inline void copy_area(const struct snd_pcm_plugin_channel *src_channel,
25 struct snd_pcm_plugin_channel *dst_channel,
26 snd_pcm_uframes_t frames, snd_pcm_format_t format)
27 {
28 dst_channel->enabled = 1;
29 snd_pcm_area_copy(&src_channel->area, 0, &dst_channel->area, 0, frames, format);
30 }
31
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)32 static snd_pcm_sframes_t route_transfer(struct snd_pcm_plugin *plugin,
33 const struct snd_pcm_plugin_channel *src_channels,
34 struct snd_pcm_plugin_channel *dst_channels,
35 snd_pcm_uframes_t frames)
36 {
37 int nsrcs, ndsts, dst;
38 struct snd_pcm_plugin_channel *dvp;
39 snd_pcm_format_t format;
40
41 if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
42 return -ENXIO;
43 if (frames == 0)
44 return 0;
45 if (frames > dst_channels[0].frames)
46 frames = dst_channels[0].frames;
47
48 nsrcs = plugin->src_format.channels;
49 ndsts = plugin->dst_format.channels;
50
51 format = plugin->dst_format.format;
52 dvp = dst_channels;
53 if (nsrcs <= 1) {
54 /* expand to all channels */
55 for (dst = 0; dst < ndsts; ++dst) {
56 copy_area(src_channels, dvp, frames, format);
57 dvp++;
58 }
59 return frames;
60 }
61
62 for (dst = 0; dst < ndsts && dst < nsrcs; ++dst) {
63 copy_area(src_channels, dvp, frames, format);
64 dvp++;
65 src_channels++;
66 }
67 if (dst < ndsts)
68 zero_areas(dvp, ndsts - dst, frames, format);
69 return frames;
70 }
71
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)72 int snd_pcm_plugin_build_route(struct snd_pcm_substream *plug,
73 struct snd_pcm_plugin_format *src_format,
74 struct snd_pcm_plugin_format *dst_format,
75 struct snd_pcm_plugin **r_plugin)
76 {
77 struct snd_pcm_plugin *plugin;
78 int err;
79
80 if (snd_BUG_ON(!r_plugin))
81 return -ENXIO;
82 *r_plugin = NULL;
83 if (snd_BUG_ON(src_format->rate != dst_format->rate))
84 return -ENXIO;
85 if (snd_BUG_ON(src_format->format != dst_format->format))
86 return -ENXIO;
87
88 err = snd_pcm_plugin_build(plug, "route conversion",
89 src_format, dst_format, 0, &plugin);
90 if (err < 0)
91 return err;
92
93 plugin->transfer = route_transfer;
94 *r_plugin = plugin;
95 return 0;
96 }
97