2 * This file is part of DisOrder.
3 * Copyright (C) 2009 Richard Kettlewell
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.
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.
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/>.
18 /** @file lib/uaudio-alsa.c
19 * @brief Support for ALSA backend */
22 #if HAVE_ALSA_ASOUNDLIB_H
24 #include <alsa/asoundlib.h>
29 #include "configuration.h"
31 /** @brief The current PCM handle */
32 static snd_pcm_t
*alsa_pcm
;
34 static const char *const alsa_options
[] = {
41 /** @brief Mixer handle */
42 snd_mixer_t
*alsa_mixer_handle
;
44 /** @brief Mixer control */
45 static snd_mixer_elem_t
*alsa_mixer_elem
;
47 /** @brief Left channel */
48 static snd_mixer_selem_channel_id_t alsa_mixer_left
;
50 /** @brief Right channel */
51 static snd_mixer_selem_channel_id_t alsa_mixer_right
;
53 /** @brief Minimum level */
54 static long alsa_mixer_min
;
56 /** @brief Maximum level */
57 static long alsa_mixer_max
;
59 /** @brief Actually play sound via ALSA */
60 static size_t alsa_play(void *buffer
, size_t samples
) {
62 /* ALSA wants 'frames', where frame = several concurrently played samples */
63 const snd_pcm_uframes_t frames
= samples
/ uaudio_channels
;
65 snd_pcm_sframes_t rc
= snd_pcm_writei(alsa_pcm
, buffer
, frames
);
69 if((err
= snd_pcm_prepare(alsa_pcm
)))
70 fatal(0, "error calling snd_pcm_prepare: %d", err
);
75 fatal(0, "error calling snd_pcm_writei: %d", (int)rc
);
78 return rc
* uaudio_channels
;
81 /** @brief Open the ALSA sound device */
82 static void alsa_open(void) {
83 const char *device
= uaudio_get("device", "default");
86 if((err
= snd_pcm_open(&alsa_pcm
,
88 SND_PCM_STREAM_PLAYBACK
,
90 fatal(0, "error from snd_pcm_open: %d", err
);
91 snd_pcm_hw_params_t
*hwparams
;
92 snd_pcm_hw_params_alloca(&hwparams
);
93 if((err
= snd_pcm_hw_params_any(alsa_pcm
, hwparams
)) < 0)
94 fatal(0, "error from snd_pcm_hw_params_any: %d", err
);
95 if((err
= snd_pcm_hw_params_set_access(alsa_pcm
, hwparams
,
96 SND_PCM_ACCESS_RW_INTERLEAVED
)) < 0)
97 fatal(0, "error from snd_pcm_hw_params_set_access: %d", err
);
100 sample_format
= uaudio_signed ? SND_PCM_FORMAT_S16
: SND_PCM_FORMAT_U16
;
102 sample_format
= uaudio_signed ? SND_PCM_FORMAT_S8
: SND_PCM_FORMAT_U8
;
103 if((err
= snd_pcm_hw_params_set_format(alsa_pcm
, hwparams
,
105 fatal(0, "error from snd_pcm_hw_params_set_format (%d): %d",
107 unsigned rate
= uaudio_rate
;
108 if((err
= snd_pcm_hw_params_set_rate_near(alsa_pcm
, hwparams
, &rate
, 0)) < 0)
109 fatal(0, "error from snd_pcm_hw_params_set_rate_near (%d): %d",
111 if((err
= snd_pcm_hw_params_set_channels(alsa_pcm
, hwparams
,
112 uaudio_channels
)) < 0)
113 fatal(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
114 uaudio_channels
, err
);
115 if((err
= snd_pcm_hw_params(alsa_pcm
, hwparams
)) < 0)
116 fatal(0, "error calling snd_pcm_hw_params: %d", err
);
120 static void alsa_activate(void) {
121 uaudio_thread_activate();
124 static void alsa_deactivate(void) {
125 uaudio_thread_deactivate();
128 static void alsa_start(uaudio_callback
*callback
,
130 if(uaudio_channels
!= 1 && uaudio_channels
!= 2)
131 fatal(0, "asked for %d channels but only support 1 or 2",
133 if(uaudio_bits
!= 8 && uaudio_bits
!= 16)
134 fatal(0, "asked for %d bits/channel but only support 8 or 16",
137 uaudio_thread_start(callback
, userdata
, alsa_play
,
138 32 / uaudio_sample_size
,
139 4096 / uaudio_sample_size
);
142 static void alsa_stop(void) {
143 uaudio_thread_stop();
144 snd_pcm_close(alsa_pcm
);
148 /** @brief Convert a level to a percentage */
149 static int to_percent(long n
) {
150 return (n
- alsa_mixer_min
) * 100 / (alsa_mixer_max
- alsa_mixer_min
);
153 /** @brief Convert a percentage to a level */
154 static int from_percent(int n
) {
155 return alsa_mixer_min
+ n
* (alsa_mixer_max
- alsa_mixer_min
) / 100;
158 static void alsa_open_mixer(void) {
160 snd_mixer_selem_id_t
*id
;
161 const char *device
= uaudio_get("device", "default");
162 const char *mixer
= uaudio_get("mixer-control", "0");
163 const char *channel
= uaudio_get("mixer-channel", "PCM");
165 snd_mixer_selem_id_alloca(&id
);
166 if((err
= snd_mixer_open(&alsa_mixer_handle
, 0)))
167 fatal(0, "snd_mixer_open: %s", snd_strerror(err
));
168 if((err
= snd_mixer_attach(alsa_mixer_handle
, device
)))
169 fatal(0, "snd_mixer_attach %s: %s", device
, snd_strerror(err
));
170 if((err
= snd_mixer_selem_register(alsa_mixer_handle
,
171 0/*options*/, 0/*classp*/)))
172 fatal(0, "snd_mixer_selem_register %s: %s",
173 device
, snd_strerror(err
));
174 if((err
= snd_mixer_load(alsa_mixer_handle
)))
175 fatal(0, "snd_mixer_load %s: %s", device
, snd_strerror(err
));
176 snd_mixer_selem_id_set_name(id
, channel
);
177 snd_mixer_selem_id_set_index(id
, atoi(mixer
));
178 if(!(alsa_mixer_elem
= snd_mixer_find_selem(alsa_mixer_handle
, id
)))
179 fatal(0, "device '%s' mixer control '%s,%s' does not exist",
180 device
, channel
, mixer
);
181 if(!snd_mixer_selem_has_playback_volume(alsa_mixer_elem
))
182 fatal(0, "device '%s' mixer control '%s,%s' has no playback volume",
183 device
, channel
, mixer
);
184 if(snd_mixer_selem_is_playback_mono(alsa_mixer_elem
)) {
185 alsa_mixer_left
= alsa_mixer_right
= SND_MIXER_SCHN_MONO
;
187 alsa_mixer_left
= SND_MIXER_SCHN_FRONT_LEFT
;
188 alsa_mixer_right
= SND_MIXER_SCHN_FRONT_RIGHT
;
190 if(!snd_mixer_selem_has_playback_channel(alsa_mixer_elem
,
192 || !snd_mixer_selem_has_playback_channel(alsa_mixer_elem
,
194 fatal(0, "device '%s' mixer control '%s,%s' lacks required playback channels",
195 device
, channel
, mixer
);
196 snd_mixer_selem_get_playback_volume_range(alsa_mixer_elem
,
197 &alsa_mixer_min
, &alsa_mixer_max
);
201 static void alsa_close_mixer(void) {
202 /* TODO alsa_mixer_elem */
203 if(alsa_mixer_handle
)
204 snd_mixer_close(alsa_mixer_handle
);
207 static void alsa_get_volume(int *left
, int *right
) {
211 if((err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
212 alsa_mixer_left
, &l
))
213 || (err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
214 alsa_mixer_right
, &r
)))
215 fatal(0, "snd_mixer_selem_get_playback_volume: %s", snd_strerror(err
));
216 *left
= to_percent(l
);
217 *right
= to_percent(r
);
220 static void alsa_set_volume(int *left
, int *right
) {
225 if(alsa_mixer_left
== alsa_mixer_right
) {
226 /* Mono output - just use the loudest */
227 if((err
= snd_mixer_selem_set_playback_volume
228 (alsa_mixer_elem
, alsa_mixer_left
,
229 from_percent(*left
> *right ?
*left
: *right
))))
230 fatal(0, "snd_mixer_selem_set_playback_volume: %s", snd_strerror(err
));
233 if((err
= snd_mixer_selem_set_playback_volume
234 (alsa_mixer_elem
, alsa_mixer_left
, from_percent(*left
)))
235 || (err
= snd_mixer_selem_set_playback_volume
236 (alsa_mixer_elem
, alsa_mixer_right
, from_percent(*right
))))
237 fatal(0, "snd_mixer_selem_set_playback_volume: %s", snd_strerror(err
));
239 /* Read it back to see what we ended up at */
240 if((err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
241 alsa_mixer_left
, &l
))
242 || (err
= snd_mixer_selem_get_playback_volume(alsa_mixer_elem
,
243 alsa_mixer_right
, &r
)))
244 fatal(0, "snd_mixer_selem_get_playback_volume: %s", snd_strerror(err
));
245 *left
= to_percent(l
);
246 *right
= to_percent(r
);
249 static void alsa_configure(void) {
250 uaudio_set("device", config
->device
);
251 uaudio_set("mixer-control", config
->mixer
);
252 uaudio_set("mixer-channel", config
->channel
);
255 const struct uaudio uaudio_alsa
= {
257 .options
= alsa_options
,
260 .activate
= alsa_activate
,
261 .deactivate
= alsa_deactivate
,
262 .open_mixer
= alsa_open_mixer
,
263 .close_mixer
= alsa_close_mixer
,
264 .get_volume
= alsa_get_volume
,
265 .set_volume
= alsa_set_volume
,
266 .configure
= alsa_configure