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Memory management for hands-off reader
[disorder] / lib / uaudio-alsa.c
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1/*
2 * This file is part of DisOrder.
3 * Copyright (C) 2009 Richard Kettlewell
4 *
5 * This program is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, either version 3 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 */
18/** @file lib/uaudio-alsa.c
19 * @brief Support for ALSA backend */
20#include "common.h"
21
22#if HAVE_ALSA_ASOUNDLIB_H
23
24#include <alsa/asoundlib.h>
25
26#include "mem.h"
27#include "log.h"
28#include "uaudio.h"
ba70caca 29#include "configuration.h"
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30
31/** @brief The current PCM handle */
32static snd_pcm_t *alsa_pcm;
33
34static const char *const alsa_options[] = {
35 "device",
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36 "mixer-control",
37 "mixer-channel",
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38 NULL
39};
40
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41/** @brief Mixer handle */
42snd_mixer_t *alsa_mixer_handle;
43
44/** @brief Mixer control */
45static snd_mixer_elem_t *alsa_mixer_elem;
46
47/** @brief Left channel */
48static snd_mixer_selem_channel_id_t alsa_mixer_left;
49
50/** @brief Right channel */
51static snd_mixer_selem_channel_id_t alsa_mixer_right;
52
53/** @brief Minimum level */
54static long alsa_mixer_min;
55
56/** @brief Maximum level */
57static long alsa_mixer_max;
58
4fd38868 59/** @brief Actually play sound via ALSA */
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60static size_t alsa_play(void *buffer, size_t samples, unsigned flags) {
61 /* If we're paused we just pretend. We rely on snd_pcm_writei() blocking so
62 * we have to fake up a sleep here. However it doesn't have to be all that
63 * accurate - in particular it's quite acceptable to greatly underestimate
64 * the required wait time. For 'lengthy' waits we do this by the blunt
65 * instrument of halving it. */
66 if(flags & UAUDIO_PAUSED) {
67 if(samples > 64)
68 samples /= 2;
69 const uint64_t ns = ((uint64_t)samples * 1000000000
70 / (uaudio_rate * uaudio_channels));
71 struct timespec ts[1];
72 ts->tv_sec = ns / 1000000000;
73 ts->tv_nsec = ns % 1000000000;
74 while(nanosleep(ts, ts) < 0 && errno == EINTR)
75 ;
76 return samples;
77 }
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78 int err;
79 /* ALSA wants 'frames', where frame = several concurrently played samples */
80 const snd_pcm_uframes_t frames = samples / uaudio_channels;
81
82 snd_pcm_sframes_t rc = snd_pcm_writei(alsa_pcm, buffer, frames);
83 if(rc < 0) {
84 switch(rc) {
85 case -EPIPE:
86 if((err = snd_pcm_prepare(alsa_pcm)))
c04511f6 87 disorder_fatal(0, "error calling snd_pcm_prepare: %d", err);
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88 return 0;
89 case -EAGAIN:
90 return 0;
91 default:
2e9ba080 92 disorder_fatal(0, "error calling snd_pcm_writei: %d", (int)rc);
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93 }
94 }
95 return rc * uaudio_channels;
96}
97
98/** @brief Open the ALSA sound device */
99static void alsa_open(void) {
b50cfb8a 100 const char *device = uaudio_get("device", "default");
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101 int err;
102
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103 if((err = snd_pcm_open(&alsa_pcm,
104 device,
105 SND_PCM_STREAM_PLAYBACK,
106 0)))
2e9ba080 107 disorder_fatal(0, "error from snd_pcm_open: %d", err);
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108 snd_pcm_hw_params_t *hwparams;
109 snd_pcm_hw_params_alloca(&hwparams);
110 if((err = snd_pcm_hw_params_any(alsa_pcm, hwparams)) < 0)
2e9ba080 111 disorder_fatal(0, "error from snd_pcm_hw_params_any: %d", err);
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112 if((err = snd_pcm_hw_params_set_access(alsa_pcm, hwparams,
113 SND_PCM_ACCESS_RW_INTERLEAVED)) < 0)
2e9ba080 114 disorder_fatal(0, "error from snd_pcm_hw_params_set_access: %d", err);
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115 int sample_format;
116 if(uaudio_bits == 16)
117 sample_format = uaudio_signed ? SND_PCM_FORMAT_S16 : SND_PCM_FORMAT_U16;
118 else
119 sample_format = uaudio_signed ? SND_PCM_FORMAT_S8 : SND_PCM_FORMAT_U8;
120 if((err = snd_pcm_hw_params_set_format(alsa_pcm, hwparams,
121 sample_format)) < 0)
2e9ba080 122 disorder_fatal(0, "error from snd_pcm_hw_params_set_format (%d): %d",
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123 sample_format, err);
124 unsigned rate = uaudio_rate;
125 if((err = snd_pcm_hw_params_set_rate_near(alsa_pcm, hwparams, &rate, 0)) < 0)
2e9ba080 126 disorder_fatal(0, "error from snd_pcm_hw_params_set_rate_near (%d): %d",
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127 rate, err);
128 if((err = snd_pcm_hw_params_set_channels(alsa_pcm, hwparams,
129 uaudio_channels)) < 0)
2e9ba080 130 disorder_fatal(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
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131 uaudio_channels, err);
132 if((err = snd_pcm_hw_params(alsa_pcm, hwparams)) < 0)
2e9ba080 133 disorder_fatal(0, "error calling snd_pcm_hw_params: %d", err);
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134
135}
136
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137static void alsa_start(uaudio_callback *callback,
138 void *userdata) {
139 if(uaudio_channels != 1 && uaudio_channels != 2)
2e9ba080 140 disorder_fatal(0, "asked for %d channels but only support 1 or 2",
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141 uaudio_channels);
142 if(uaudio_bits != 8 && uaudio_bits != 16)
2e9ba080 143 disorder_fatal(0, "asked for %d bits/channel but only support 8 or 16",
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144 uaudio_bits);
145 alsa_open();
146 uaudio_thread_start(callback, userdata, alsa_play,
147 32 / uaudio_sample_size,
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148 4096 / uaudio_sample_size,
149 0);
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150}
151
152static void alsa_stop(void) {
153 uaudio_thread_stop();
154 snd_pcm_close(alsa_pcm);
155 alsa_pcm = 0;
156}
157
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158/** @brief Convert a level to a percentage */
159static int to_percent(long n) {
160 return (n - alsa_mixer_min) * 100 / (alsa_mixer_max - alsa_mixer_min);
161}
162
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163/** @brief Convert a percentage to a level */
164static int from_percent(int n) {
165 return alsa_mixer_min + n * (alsa_mixer_max - alsa_mixer_min) / 100;
166}
167
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168static void alsa_open_mixer(void) {
169 int err;
170 snd_mixer_selem_id_t *id;
171 const char *device = uaudio_get("device", "default");
172 const char *mixer = uaudio_get("mixer-control", "0");
173 const char *channel = uaudio_get("mixer-channel", "PCM");
174
175 snd_mixer_selem_id_alloca(&id);
176 if((err = snd_mixer_open(&alsa_mixer_handle, 0)))
2e9ba080 177 disorder_fatal(0, "snd_mixer_open: %s", snd_strerror(err));
42f738c2 178 if((err = snd_mixer_attach(alsa_mixer_handle, device)))
2e9ba080 179 disorder_fatal(0, "snd_mixer_attach %s: %s", device, snd_strerror(err));
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180 if((err = snd_mixer_selem_register(alsa_mixer_handle,
181 0/*options*/, 0/*classp*/)))
2e9ba080 182 disorder_fatal(0, "snd_mixer_selem_register %s: %s",
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183 device, snd_strerror(err));
184 if((err = snd_mixer_load(alsa_mixer_handle)))
2e9ba080 185 disorder_fatal(0, "snd_mixer_load %s: %s", device, snd_strerror(err));
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186 snd_mixer_selem_id_set_name(id, channel);
187 snd_mixer_selem_id_set_index(id, atoi(mixer));
188 if(!(alsa_mixer_elem = snd_mixer_find_selem(alsa_mixer_handle, id)))
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189 disorder_fatal(0, "device '%s' mixer control '%s,%s' does not exist",
190 device, channel, mixer);
b50cfb8a 191 if(!snd_mixer_selem_has_playback_volume(alsa_mixer_elem))
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192 disorder_fatal(0,
193 "device '%s' mixer control '%s,%s' has no playback volume",
194 device, channel, mixer);
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195 if(snd_mixer_selem_is_playback_mono(alsa_mixer_elem)) {
196 alsa_mixer_left = alsa_mixer_right = SND_MIXER_SCHN_MONO;
197 } else {
198 alsa_mixer_left = SND_MIXER_SCHN_FRONT_LEFT;
199 alsa_mixer_right = SND_MIXER_SCHN_FRONT_RIGHT;
200 }
201 if(!snd_mixer_selem_has_playback_channel(alsa_mixer_elem,
202 alsa_mixer_left)
203 || !snd_mixer_selem_has_playback_channel(alsa_mixer_elem,
204 alsa_mixer_right))
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205 disorder_fatal(0, "device '%s' mixer control '%s,%s' lacks required playback channels",
206 device, channel, mixer);
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207 snd_mixer_selem_get_playback_volume_range(alsa_mixer_elem,
208 &alsa_mixer_min, &alsa_mixer_max);
209
210}
211
212static void alsa_close_mixer(void) {
213 /* TODO alsa_mixer_elem */
214 if(alsa_mixer_handle)
215 snd_mixer_close(alsa_mixer_handle);
216}
217
218static void alsa_get_volume(int *left, int *right) {
219 long l, r;
220 int err;
221
222 if((err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
223 alsa_mixer_left, &l))
224 || (err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
225 alsa_mixer_right, &r)))
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226 disorder_fatal(0, "snd_mixer_selem_get_playback_volume: %s",
227 snd_strerror(err));
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228 *left = to_percent(l);
229 *right = to_percent(r);
230}
231
232static void alsa_set_volume(int *left, int *right) {
233 long l, r;
234 int err;
235
236 /* Set the volume */
237 if(alsa_mixer_left == alsa_mixer_right) {
238 /* Mono output - just use the loudest */
239 if((err = snd_mixer_selem_set_playback_volume
240 (alsa_mixer_elem, alsa_mixer_left,
241 from_percent(*left > *right ? *left : *right))))
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242 disorder_fatal(0, "snd_mixer_selem_set_playback_volume: %s",
243 snd_strerror(err));
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244 } else {
245 /* Stereo output */
246 if((err = snd_mixer_selem_set_playback_volume
247 (alsa_mixer_elem, alsa_mixer_left, from_percent(*left)))
248 || (err = snd_mixer_selem_set_playback_volume
249 (alsa_mixer_elem, alsa_mixer_right, from_percent(*right))))
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250 disorder_fatal(0, "snd_mixer_selem_set_playback_volume: %s",
251 snd_strerror(err));
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252 }
253 /* Read it back to see what we ended up at */
254 if((err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
255 alsa_mixer_left, &l))
256 || (err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
257 alsa_mixer_right, &r)))
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258 disorder_fatal(0, "snd_mixer_selem_get_playback_volume: %s",
259 snd_strerror(err));
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260 *left = to_percent(l);
261 *right = to_percent(r);
262}
263
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264static void alsa_configure(void) {
265 uaudio_set("device", config->device);
266 uaudio_set("mixer-control", config->mixer);
267 uaudio_set("mixer-channel", config->channel);
268}
269
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270const struct uaudio uaudio_alsa = {
271 .name = "alsa",
272 .options = alsa_options,
273 .start = alsa_start,
274 .stop = alsa_stop,
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275 .activate = uaudio_thread_activate,
276 .deactivate = uaudio_thread_deactivate,
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277 .open_mixer = alsa_open_mixer,
278 .close_mixer = alsa_close_mixer,
279 .get_volume = alsa_get_volume,
280 .set_volume = alsa_set_volume,
ba70caca 281 .configure = alsa_configure
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282};
283
284#endif
285
286/*
287Local Variables:
288c-basic-offset:2
289comment-column:40
290fill-column:79
291indent-tabs-mode:nil
292End:
293*/