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io.c
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1 /*
2  * PCM I/O Plug-In Interface
3  * Copyright (c) 1999 by Jaroslav Kysela <[email protected]>
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 <sound/pcm_params.h>
26 #include "pcm_plugin.h"
27 
28 #define pcm_write(plug,buf,count) snd_pcm_oss_write3(plug,buf,count,1)
29 #define pcm_writev(plug,vec,count) snd_pcm_oss_writev3(plug,vec,count,1)
30 #define pcm_read(plug,buf,count) snd_pcm_oss_read3(plug,buf,count,1)
31 #define pcm_readv(plug,vec,count) snd_pcm_oss_readv3(plug,vec,count,1)
32 
33 /*
34  * Basic io plugin
35  */
36 
37 static snd_pcm_sframes_t io_playback_transfer(struct snd_pcm_plugin *plugin,
38  const struct snd_pcm_plugin_channel *src_channels,
39  struct snd_pcm_plugin_channel *dst_channels,
40  snd_pcm_uframes_t frames)
41 {
42  if (snd_BUG_ON(!plugin))
43  return -ENXIO;
44  if (snd_BUG_ON(!src_channels))
45  return -ENXIO;
46  if (plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED) {
47  return pcm_write(plugin->plug, src_channels->area.addr, frames);
48  } else {
49  int channel, channels = plugin->dst_format.channels;
50  void **bufs = (void**)plugin->extra_data;
51  if (snd_BUG_ON(!bufs))
52  return -ENXIO;
53  for (channel = 0; channel < channels; channel++) {
54  if (src_channels[channel].enabled)
55  bufs[channel] = src_channels[channel].area.addr;
56  else
57  bufs[channel] = NULL;
58  }
59  return pcm_writev(plugin->plug, bufs, frames);
60  }
61 }
62 
63 static snd_pcm_sframes_t io_capture_transfer(struct snd_pcm_plugin *plugin,
64  const struct snd_pcm_plugin_channel *src_channels,
65  struct snd_pcm_plugin_channel *dst_channels,
66  snd_pcm_uframes_t frames)
67 {
68  if (snd_BUG_ON(!plugin))
69  return -ENXIO;
70  if (snd_BUG_ON(!dst_channels))
71  return -ENXIO;
72  if (plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED) {
73  return pcm_read(plugin->plug, dst_channels->area.addr, frames);
74  } else {
75  int channel, channels = plugin->dst_format.channels;
76  void **bufs = (void**)plugin->extra_data;
77  if (snd_BUG_ON(!bufs))
78  return -ENXIO;
79  for (channel = 0; channel < channels; channel++) {
80  if (dst_channels[channel].enabled)
81  bufs[channel] = dst_channels[channel].area.addr;
82  else
83  bufs[channel] = NULL;
84  }
85  return pcm_readv(plugin->plug, bufs, frames);
86  }
87  return 0;
88 }
89 
90 static snd_pcm_sframes_t io_src_channels(struct snd_pcm_plugin *plugin,
91  snd_pcm_uframes_t frames,
92  struct snd_pcm_plugin_channel **channels)
93 {
94  int err;
95  unsigned int channel;
96  struct snd_pcm_plugin_channel *v;
97  err = snd_pcm_plugin_client_channels(plugin, frames, &v);
98  if (err < 0)
99  return err;
100  *channels = v;
101  if (plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED) {
102  for (channel = 0; channel < plugin->src_format.channels; ++channel, ++v)
103  v->wanted = 1;
104  }
105  return frames;
106 }
107 
109  struct snd_pcm_hw_params *params,
110  struct snd_pcm_plugin **r_plugin)
111 {
112  int err;
113  struct snd_pcm_plugin_format format;
114  struct snd_pcm_plugin *plugin;
115 
116  if (snd_BUG_ON(!r_plugin))
117  return -ENXIO;
118  *r_plugin = NULL;
119  if (snd_BUG_ON(!plug || !params))
120  return -ENXIO;
121  format.format = params_format(params);
122  format.rate = params_rate(params);
123  format.channels = params_channels(params);
124  err = snd_pcm_plugin_build(plug, "I/O io",
125  &format, &format,
126  sizeof(void *) * format.channels,
127  &plugin);
128  if (err < 0)
129  return err;
130  plugin->access = params_access(params);
131  if (snd_pcm_plug_stream(plug) == SNDRV_PCM_STREAM_PLAYBACK) {
132  plugin->transfer = io_playback_transfer;
133  if (plugin->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED)
134  plugin->client_channels = io_src_channels;
135  } else {
136  plugin->transfer = io_capture_transfer;
137  }
138 
139  *r_plugin = plugin;
140  return 0;
141 }