2 * Copyright (C) 2012 Andre Noll <maan@tuebingen.mpg.de>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file alsa_mix.c The ALSA mixer plugin. */
10 #include <alsa/asoundlib.h>
18 /* The ALSA mixer handle */
20 /* Copy of the alsa device name, e.g. "hw:0". */
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(). */
28 static void alsa_mix_close(struct mixer_handle **handle)
30 struct mixer_handle *h;
36 PARA_INFO_LOG("closing mixer handle\n");
37 if (h->mixer) /* nec. */
38 snd_mixer_close(h->mixer);
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.
46 snd_config_update_free_global();
51 static int alsa_mix_open(const char *dev, struct mixer_handle **handle)
55 struct mixer_handle *h;
57 PARA_INFO_LOG("snd_mixer_{open,attach,register,load}\n");
59 h = para_calloc(sizeof(*h));
60 h->card = para_strdup(dev? dev : "hw:0");
61 ret = snd_mixer_open(&h->mixer, 0);
63 msg = make_message("snd_mixer_open() failed: %s",
67 ret = snd_mixer_attach(h->mixer, h->card);
69 msg = make_message("mixer attach error (%s): %s", h->card,
73 ret = snd_mixer_selem_register(h->mixer, NULL, NULL);
75 msg = make_message("mixer register error (%s): %s", h->card,
79 ret = snd_mixer_load(h->mixer);
81 msg = make_message("mixer load error (%s): %s", h->card,
89 PARA_NOTICE_LOG("%s\n", msg);
92 return -E_ALSA_MIX_OPEN;
95 static bool channel_has_playback(snd_mixer_selem_channel_id_t chn,
96 snd_mixer_elem_t *elem)
98 return snd_mixer_selem_has_playback_channel(elem, chn);
101 static char *alsa_mix_get_channels(struct mixer_handle *handle)
105 snd_mixer_selem_id_t *sid;
106 snd_mixer_elem_t *elem;
108 ret = snd_mixer_selem_id_malloc(&sid);
110 elem = snd_mixer_first_elem(handle->mixer);
111 for (; elem; elem = snd_mixer_elem_next(elem)) {
115 if (!channel_has_playback(0, elem))
117 if (!snd_mixer_selem_has_playback_volume(elem))
119 snd_mixer_selem_get_id(elem, sid);
120 name = snd_mixer_selem_id_get_name(sid);
121 list = make_message("%s%s%s",
127 snd_mixer_selem_id_free(sid);
131 static int alsa_mix_set_channel(struct mixer_handle *h,
132 const char *mixer_channel)
134 int ret, selem_id = 0;
135 snd_mixer_selem_id_t *sid;
138 mixer_channel = "Master";
139 ret = snd_mixer_selem_id_malloc(&sid);
141 snd_mixer_selem_id_set_index(sid, selem_id);
142 snd_mixer_selem_id_set_name(sid, mixer_channel);
143 h->elem = snd_mixer_find_selem(h->mixer, sid);
145 PARA_NOTICE_LOG("unable to find simple control '%s',%i\n",
146 snd_mixer_selem_id_get_name(sid),
147 snd_mixer_selem_id_get_index(sid));
148 ret = -E_BAD_CHANNEL;
151 ret = snd_mixer_selem_get_playback_volume_range(h->elem,
154 PARA_NOTICE_LOG("unable to get %s range (%s): %s\n",
155 mixer_channel, h->card, snd_strerror(ret));
156 ret = -E_ALSA_MIX_RANGE;
159 if (h->pmin >= h->pmax) {
160 PARA_NOTICE_LOG("alsa reported %s range %ld-%ld (%s)\n",
161 mixer_channel, h->pmin, h->pmax, h->card);
162 ret = -E_ALSA_MIX_RANGE;
167 snd_mixer_selem_id_free(sid);
171 static int alsa_mix_get(struct mixer_handle *h)
173 snd_mixer_selem_channel_id_t chn;
177 /* compute average over all channels */
178 for (chn = 0; chn <= SND_MIXER_SCHN_LAST; chn++) {
182 if (!channel_has_playback(chn, h->elem))
184 ret = snd_mixer_selem_get_playback_volume(h->elem, chn, &val);
186 PARA_NOTICE_LOG("unable to get value for channel %d (%s): %s\n",
187 (int)chn, h->card, snd_strerror(ret));
188 return -E_ALSA_MIX_GET_VAL;
190 /* update the rolling average */
191 avg = (val + n * avg) / (n + 1);
194 /* scale to 0..100 */
195 avg = 100 * (avg - h->pmin) / (h->pmax - h->pmin);
199 static int alsa_mix_set(struct mixer_handle *h, int val)
202 snd_mixer_selem_channel_id_t chn;
203 long scaled = val / 100.0 * (h->pmax - h->pmin) + h->pmin;
205 PARA_INFO_LOG("new value: %d\n", val);
206 for (chn = 0; chn <= SND_MIXER_SCHN_LAST; chn++) {
207 if (!channel_has_playback(chn, h->elem))
209 ret = snd_mixer_selem_set_playback_volume(h->elem, chn, scaled);
211 PARA_NOTICE_LOG("unable to set value for channel %d (%s): %s\n",
212 (int)chn, h->card, snd_strerror(ret));
213 return -E_ALSA_MIX_SET_VAL;
220 * The init function of the ALSA mixer.
222 * \param self The structure to initialize.
224 * \sa struct \ref mixer, \ref oss_mix_init().
226 void alsa_mix_init(struct mixer *self)
228 self->open = alsa_mix_open;
229 self->get_channels = alsa_mix_get_channels;
230 self->set_channel = alsa_mix_set_channel;
231 self->close = alsa_mix_close;
232 self->get = alsa_mix_get;
233 self->set = alsa_mix_set;