alsa_mix.c

   1 /*
   2  * Copyright (C) 2012-2014 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file alsa_mix.c The ALSA mixer plugin. */
   8
   9 #include <regex.h>
  10 #include <alsa/asoundlib.h>
  11
  12 #include "para.h"
  13 #include "error.h"
  14 #include "mix.h"
  15 #include "string.h"
  16
  17 struct mixer_handle {
  18         /* The ALSA mixer handle */
  19         snd_mixer_t *mixer;
  20         /* Copy of the alsa device name, e.g. "hw:0". */
  21         char *card;
  22         /* ALSA's representation of the given mixer channel. */
  23         snd_mixer_elem_t *elem;
  24         /* Set in ->set_channel(), used for ->get() and ->set(). */
  25         long pmin, pmax;
  26 };
  27
  28 static void alsa_mix_close(struct mixer_handle **handle)
  29 {
  30         struct mixer_handle *h;
  31
  32         if (!handle)
  33                 return;
  34         h = *handle;
  35         if (h) {
  36                 PARA_INFO_LOG("closing mixer handle\n");
  37                 if (h->mixer) /* nec. */
  38                         snd_mixer_close(h->mixer);
  39                 free(h->card);
  40                 free(h);
  41                 /*
  42                  * The global ALSA configuration is cached for next usage,
  43                  * which causes valgrind to report many memory leaks. Calling
  44                  * snd_config_update_free_global() frees the cache.
  45                  */
  46                 snd_config_update_free_global();
  47         }
  48         *handle = NULL;
  49 }
  50
  51 static int alsa_mix_open(const char *dev, struct mixer_handle **handle)
  52 {
  53         int ret;
  54         char *msg;
  55         struct mixer_handle *h;
  56
  57         PARA_INFO_LOG("snd_mixer_{open,attach,register,load}\n");
  58         *handle = NULL;
  59         h = para_calloc(sizeof(*h));
  60         h->card = para_strdup(dev? dev : "hw:0");
  61         ret = snd_mixer_open(&h->mixer, 0);
  62         if (ret < 0) {
  63                 msg = make_message("snd_mixer_open() failed: %s",
  64                         snd_strerror(ret));
  65                 goto fail;
  66         }
  67         ret = snd_mixer_attach(h->mixer, h->card);
  68         if (ret < 0) {
  69                 msg = make_message("mixer attach error (%s): %s", h->card,
  70                         snd_strerror(ret));
  71                 goto fail;
  72         }
  73         ret = snd_mixer_selem_register(h->mixer, NULL, NULL);
  74         if (ret < 0) {
  75                 msg = make_message("mixer register error (%s): %s", h->card,
  76                         snd_strerror(ret));
  77                 goto fail;
  78         }
  79         ret = snd_mixer_load(h->mixer);
  80         if (ret < 0) {
  81                 msg = make_message("mixer load error (%s): %s", h->card,
  82                         snd_strerror(ret));
  83                 goto fail;
  84         }
  85         /* success */
  86         *handle = h;
  87         return 1;
  88 fail:
  89         PARA_NOTICE_LOG("%s\n", msg);
  90         free(msg);
  91         alsa_mix_close(&h);
  92         return -E_ALSA_MIX_OPEN;
  93 }
  94
  95 static bool channel_has_playback(snd_mixer_selem_channel_id_t chn,
  96                 snd_mixer_elem_t *elem)
  97 {
  98         return snd_mixer_selem_has_playback_channel(elem, chn);
  99 }
 100
 101 static char *alsa_mix_get_channels(struct mixer_handle *handle)
 102 {
 103         char *list = NULL;
 104         snd_mixer_selem_id_t *sid;
 105         snd_mixer_elem_t *elem;
 106
 107         snd_mixer_selem_id_alloca(&sid);
 108         elem = snd_mixer_first_elem(handle->mixer);
 109         for (; elem; elem = snd_mixer_elem_next(elem)) {
 110                 char *tmp = list;
 111                 const char *name;
 112
 113                 if (!channel_has_playback(0, elem))
 114                         continue;
 115                 if (!snd_mixer_selem_has_playback_volume(elem))
 116                         continue;
 117                 snd_mixer_selem_get_id(elem, sid);
 118                 name = snd_mixer_selem_id_get_name(sid);
 119                 list = make_message("%s%s%s",
 120                         list? list : "",
 121                         list? ", " : "",
 122                         name);
 123                 free(tmp);
 124         }
 125         return list;
 126 }
 127
 128 static int alsa_mix_set_channel(struct mixer_handle *h,
 129                 const char *mixer_channel)
 130 {
 131         int ret, selem_id = 0;
 132         snd_mixer_selem_id_t *sid;
 133
 134         if (!mixer_channel)
 135                 mixer_channel = "Master";
 136         snd_mixer_selem_id_alloca(&sid);
 137         snd_mixer_selem_id_set_index(sid, selem_id);
 138         snd_mixer_selem_id_set_name(sid, mixer_channel);
 139         h->elem = snd_mixer_find_selem(h->mixer, sid);
 140         if (!h->elem) {
 141                 PARA_NOTICE_LOG("unable to find simple control '%s',%i\n",
 142                         snd_mixer_selem_id_get_name(sid),
 143                         snd_mixer_selem_id_get_index(sid));
 144                 return -E_BAD_CHANNEL;
 145         }
 146         ret = snd_mixer_selem_get_playback_volume_range(h->elem,
 147                 &h->pmin, &h->pmax);
 148         if (ret < 0) {
 149                 PARA_NOTICE_LOG("unable to get %s range (%s): %s\n",
 150                         mixer_channel, h->card, snd_strerror(ret));
 151                 return -E_ALSA_MIX_RANGE;
 152         }
 153         if (h->pmin >= h->pmax) {
 154                 PARA_NOTICE_LOG("alsa reported %s range %ld-%ld (%s)\n",
 155                         mixer_channel, h->pmin, h->pmax, h->card);
 156                 return -E_ALSA_MIX_RANGE;
 157         }
 158         return 1;
 159 }
 160
 161 static int alsa_mix_get(struct mixer_handle *h)
 162 {
 163         snd_mixer_selem_channel_id_t chn;
 164         int n = 0;
 165         float avg = 0;
 166
 167         /* compute average over all channels */
 168         for (chn = 0; chn <= SND_MIXER_SCHN_LAST; chn++) {
 169                 long val;
 170                 int ret;
 171
 172                 if (!channel_has_playback(chn, h->elem))
 173                         continue;
 174                 ret = snd_mixer_selem_get_playback_volume(h->elem, chn, &val);
 175                 if (ret < 0) {
 176                         PARA_NOTICE_LOG("unable to get value for channel %d (%s): %s\n",
 177                                 (int)chn, h->card, snd_strerror(ret));
 178                         return -E_ALSA_MIX_GET_VAL;
 179                 }
 180                 /* update the rolling average */
 181                 avg = (val + n * avg) / (n + 1);
 182                 n++;
 183         }
 184         /* scale to 0..100 */
 185         avg = 100 * (avg - h->pmin) / (h->pmax - h->pmin);
 186         return avg;
 187 }
 188
 189 static int alsa_mix_set(struct mixer_handle *h, int val)
 190 {
 191         int ret;
 192         snd_mixer_selem_channel_id_t chn;
 193         long scaled = val / 100.0 * (h->pmax - h->pmin) + h->pmin;
 194
 195         PARA_INFO_LOG("new value: %d\n", val);
 196         for (chn = 0; chn <= SND_MIXER_SCHN_LAST; chn++) {
 197                 if (!channel_has_playback(chn, h->elem))
 198                         continue;
 199                 ret = snd_mixer_selem_set_playback_volume(h->elem, chn, scaled);
 200                 if (ret < 0) {
 201                         PARA_NOTICE_LOG("unable to set value for channel %d (%s): %s\n",
 202                                 (int)chn, h->card, snd_strerror(ret));
 203                         return -E_ALSA_MIX_SET_VAL;
 204                 }
 205         }
 206         return 1;
 207 }
 208
 209 /**
 210  * The init function of the ALSA mixer.
 211  *
 212  * \param self The structure to initialize.
 213  *
 214  * \sa struct \ref mixer, \ref oss_mix_init().
 215  */
 216 void alsa_mix_init(struct mixer *self)
 217 {
 218         self->open = alsa_mix_open;
 219         self->get_channels = alsa_mix_get_channels;
 220         self->set_channel = alsa_mix_set_channel;
 221         self->close = alsa_mix_close;
 222         self->get = alsa_mix_get;
 223         self->set = alsa_mix_set;
 224 }