mdw@git.distorted.org.uk Git - disorder/blob - lib/uaudio-alsa.c

   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"
  29 #include "configuration.h"
  30
  31 /** @brief The current PCM handle */
  32 static snd_pcm_t *alsa_pcm;
  33
  34 static const char *const alsa_options[] = {
  35   "device",
  36   "mixer-control",
  37   "mixer-channel",
  38   NULL
  39 };
  40
  41 /** @brief Mixer handle */
  42 snd_mixer_t *alsa_mixer_handle;
  43
  44 /** @brief Mixer control */
  45 static snd_mixer_elem_t *alsa_mixer_elem;
  46
  47 /** @brief Left channel */
  48 static snd_mixer_selem_channel_id_t alsa_mixer_left;
  49
  50 /** @brief Right channel */
  51 static snd_mixer_selem_channel_id_t alsa_mixer_right;
  52
  53 /** @brief Minimum level */
  54 static long alsa_mixer_min;
  55
  56 /** @brief Maximum level */
  57 static long alsa_mixer_max;
  58
  59 /** @brief Actually play sound via ALSA */
  60 static size_t alsa_play(void *buffer, size_t samples) {
  61   int err;
  62   /* ALSA wants 'frames', where frame = several concurrently played samples */
  63   const snd_pcm_uframes_t frames = samples / uaudio_channels;
  64
  65   snd_pcm_sframes_t rc = snd_pcm_writei(alsa_pcm, buffer, frames);
  66   if(rc < 0) {
  67     switch(rc) {
  68     case -EPIPE:
  69       if((err = snd_pcm_prepare(alsa_pcm)))
  70         fatal(0, "error calling snd_pcm_prepare: %d", err);
  71       return 0;
  72     case -EAGAIN:
  73       return 0;
  74     default:
  75       fatal(0, "error calling snd_pcm_writei: %d", (int)rc);
  76     }
  77   }
  78   return rc * uaudio_channels;
  79 }
  80
  81 /** @brief Open the ALSA sound device */
  82 static void alsa_open(void) {
  83   const char *device = uaudio_get("device", "default");
  84   int err;
  85
  86   if((err = snd_pcm_open(&alsa_pcm,
  87                          device,
  88                          SND_PCM_STREAM_PLAYBACK,
  89                          0)))
  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);
  98   int sample_format;
  99   if(uaudio_bits == 16)
 100     sample_format = uaudio_signed ? SND_PCM_FORMAT_S16 : SND_PCM_FORMAT_U16;
 101   else
 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,
 104                                          sample_format)) < 0)
 105     fatal(0, "error from snd_pcm_hw_params_set_format (%d): %d",
 106           sample_format, err);
 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",
 110           rate, err);
 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);
 117
 118 }
 119
 120 static void alsa_activate(void) {
 121   uaudio_thread_activate();
 122 }
 123
 124 static void alsa_deactivate(void) {
 125   uaudio_thread_deactivate();
 126 }
 127
 128 static void alsa_start(uaudio_callback *callback,
 129                       void *userdata) {
 130   if(uaudio_channels != 1 && uaudio_channels != 2)
 131     fatal(0, "asked for %d channels but only support 1 or 2",
 132           uaudio_channels);
 133   if(uaudio_bits != 8 && uaudio_bits != 16)
 134     fatal(0, "asked for %d bits/channel but only support 8 or 16",
 135           uaudio_bits);
 136   alsa_open();
 137   uaudio_thread_start(callback, userdata, alsa_play,
 138                       32 / uaudio_sample_size,
 139                       4096 / uaudio_sample_size,
 140                       0);
 141 }
 142
 143 static void alsa_stop(void) {
 144   uaudio_thread_stop();
 145   snd_pcm_close(alsa_pcm);
 146   alsa_pcm = 0;
 147 }
 148
 149 /** @brief Convert a level to a percentage */
 150 static int to_percent(long n) {
 151   return (n - alsa_mixer_min) * 100 / (alsa_mixer_max - alsa_mixer_min);
 152 }
 153
 154 /** @brief Convert a percentage to a level */
 155 static int from_percent(int n) {
 156   return alsa_mixer_min + n * (alsa_mixer_max - alsa_mixer_min) / 100;
 157 }
 158
 159 static void alsa_open_mixer(void) {
 160   int err;
 161   snd_mixer_selem_id_t *id;
 162   const char *device = uaudio_get("device", "default");
 163   const char *mixer = uaudio_get("mixer-control", "0");
 164   const char *channel = uaudio_get("mixer-channel", "PCM");
 165
 166   snd_mixer_selem_id_alloca(&id);
 167   if((err = snd_mixer_open(&alsa_mixer_handle, 0)))
 168     fatal(0, "snd_mixer_open: %s", snd_strerror(err));
 169   if((err = snd_mixer_attach(alsa_mixer_handle, device)))
 170     fatal(0, "snd_mixer_attach %s: %s", device, snd_strerror(err));
 171   if((err = snd_mixer_selem_register(alsa_mixer_handle,
 172                                      0/*options*/, 0/*classp*/)))
 173     fatal(0, "snd_mixer_selem_register %s: %s",
 174           device, snd_strerror(err));
 175   if((err = snd_mixer_load(alsa_mixer_handle)))
 176     fatal(0, "snd_mixer_load %s: %s", device, snd_strerror(err));
 177   snd_mixer_selem_id_set_name(id, channel);
 178   snd_mixer_selem_id_set_index(id, atoi(mixer));
 179   if(!(alsa_mixer_elem = snd_mixer_find_selem(alsa_mixer_handle, id)))
 180     fatal(0, "device '%s' mixer control '%s,%s' does not exist",
 181           device, channel, mixer);
 182   if(!snd_mixer_selem_has_playback_volume(alsa_mixer_elem))
 183     fatal(0, "device '%s' mixer control '%s,%s' has no playback volume",
 184           device, channel, mixer);
 185   if(snd_mixer_selem_is_playback_mono(alsa_mixer_elem)) {
 186     alsa_mixer_left = alsa_mixer_right = SND_MIXER_SCHN_MONO;
 187   } else {
 188     alsa_mixer_left = SND_MIXER_SCHN_FRONT_LEFT;
 189     alsa_mixer_right = SND_MIXER_SCHN_FRONT_RIGHT;
 190   }
 191   if(!snd_mixer_selem_has_playback_channel(alsa_mixer_elem,
 192                                            alsa_mixer_left)
 193      || !snd_mixer_selem_has_playback_channel(alsa_mixer_elem,
 194                                               alsa_mixer_right))
 195     fatal(0, "device '%s' mixer control '%s,%s' lacks required playback channels",
 196           device, channel, mixer);
 197   snd_mixer_selem_get_playback_volume_range(alsa_mixer_elem,
 198                                             &alsa_mixer_min, &alsa_mixer_max);
 199
 200 }
 201
 202 static void alsa_close_mixer(void) {
 203   /* TODO alsa_mixer_elem */
 204   if(alsa_mixer_handle)
 205     snd_mixer_close(alsa_mixer_handle);
 206 }
 207
 208 static void alsa_get_volume(int *left, int *right) {
 209   long l, r;
 210   int err;
 211
 212   if((err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
 213                                                 alsa_mixer_left, &l))
 214      || (err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
 215                                                    alsa_mixer_right, &r)))
 216     fatal(0, "snd_mixer_selem_get_playback_volume: %s", snd_strerror(err));
 217   *left = to_percent(l);
 218   *right = to_percent(r);
 219 }
 220
 221 static void alsa_set_volume(int *left, int *right) {
 222   long l, r;
 223   int err;
 224
 225   /* Set the volume */
 226   if(alsa_mixer_left == alsa_mixer_right) {
 227     /* Mono output - just use the loudest */
 228     if((err = snd_mixer_selem_set_playback_volume
 229         (alsa_mixer_elem, alsa_mixer_left,
 230          from_percent(*left > *right ? *left : *right))))
 231       fatal(0, "snd_mixer_selem_set_playback_volume: %s", snd_strerror(err));
 232   } else {
 233     /* Stereo output */
 234     if((err = snd_mixer_selem_set_playback_volume
 235         (alsa_mixer_elem, alsa_mixer_left, from_percent(*left)))
 236        || (err = snd_mixer_selem_set_playback_volume
 237            (alsa_mixer_elem, alsa_mixer_right, from_percent(*right))))
 238       fatal(0, "snd_mixer_selem_set_playback_volume: %s", snd_strerror(err));
 239   }
 240   /* Read it back to see what we ended up at */
 241   if((err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
 242                                                 alsa_mixer_left, &l))
 243      || (err = snd_mixer_selem_get_playback_volume(alsa_mixer_elem,
 244                                                    alsa_mixer_right, &r)))
 245     fatal(0, "snd_mixer_selem_get_playback_volume: %s", snd_strerror(err));
 246   *left = to_percent(l);
 247   *right = to_percent(r);
 248 }
 249
 250 static void alsa_configure(void) {
 251   uaudio_set("device", config->device);
 252   uaudio_set("mixer-control", config->mixer);
 253   uaudio_set("mixer-channel", config->channel);
 254 }
 255
 256 const struct uaudio uaudio_alsa = {
 257   .name = "alsa",
 258   .options = alsa_options,
 259   .start = alsa_start,
 260   .stop = alsa_stop,
 261   .activate = alsa_activate,
 262   .deactivate = alsa_deactivate,
 263   .open_mixer = alsa_open_mixer,
 264   .close_mixer = alsa_close_mixer,
 265   .get_volume = alsa_get_volume,
 266   .set_volume = alsa_set_volume,
 267   .configure = alsa_configure
 268 };
 269
 270 #endif
 271
 272 /*
 273 Local Variables:
 274 c-basic-offset:2
 275 comment-column:40
 276 fill-column:79
 277 indent-tabs-mode:nil
 278 End:
 279 */