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/*
* Copyright (C) 2016 Anton Khirnov <anton@khirnov.net>
*
* mixnotify is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* mixnotify is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with mixnotify. If not, see <http://www.gnu.org/licenses/>.
*/
#include <alsa/asoundlib.h>
#include <stdio.h>
#include <string.h>
typedef struct MixerPrivate {
snd_mixer_elem_t *elem;
} MixerPrivate;
static int elem_callback(snd_mixer_elem_t *elem, unsigned int mask)
{
MixerPrivate *s = snd_mixer_elem_get_callback_private(elem);
long val, min, max;
int ret;
if (!(mask & SND_CTL_EVENT_MASK_VALUE))
return 0;
ret = snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_UNKNOWN, &val);
if (ret < 0) {
fprintf(stderr, "Error getting element volume: %d (%s)\n");
return ret;
}
ret = snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
if (ret < 0) {
fprintf(stderr, "Error getting element volume range: %d (%s)\n",
ret, snd_strerror(ret));
return ret;
}
fprintf(stdout, "%ld %ld %ld\n", val, min, max);
fflush(stdout);
return 0;
}
int main(int argc, const char **argv)
{
static const char *ctl_name = "default";
static const char *elem_name = "Master";
MixerPrivate priv = { NULL };
snd_mixer_t *mixer = NULL;
snd_mixer_elem_t *elem;
int ret;
if (argc > 1)
ctl_name = argv[1];
if (argc > 2)
elem_name = argv[2];
fprintf(stderr, "Using CTL: %s\n", ctl_name);
fprintf(stderr, "Using mixer element: %s\n", elem_name);
ret = snd_mixer_open(&mixer, 0);
if (ret < 0) {
fprintf(stderr, "Error opening a new mixer: %d (%s)\n",
ret, snd_strerror(ret));
return -1;
}
ret = snd_mixer_attach(mixer, ctl_name);
if (ret < 0) {
fprintf(stderr, "Error attachng a HCTL '%s' to the mixer: %d (%s)\n",
ctl_name, ret, snd_strerror(ret));
ret = -1;
goto fail;
}
ret = snd_mixer_selem_register(mixer, NULL, NULL);
if (ret < 0) {
fprintf(stderr, "Error registering simple element class: %d (%s)\n",
ctl_name, ret, snd_strerror(ret));
ret = -1;
goto fail;
}
ret = snd_mixer_load(mixer);
if (ret < 0) {
fprintf(stderr, "Error loading mixer elements: %d (%s)\n",
ret, snd_strerror(ret));
ret = -1;
goto fail;
}
for (elem = snd_mixer_first_elem(mixer); elem; elem = snd_mixer_elem_next(elem)) {
snd_mixer_elem_type_t type = snd_mixer_elem_get_type(elem);
if (type == SND_MIXER_ELEM_SIMPLE &&
!strcmp(snd_mixer_selem_get_name(elem), elem_name))
break;
}
if (!elem) {
fprintf(stderr, "Mixer element '%s' not found\n", elem_name);
ret = -1;
goto fail;
}
snd_mixer_elem_set_callback_private(elem, &priv);
snd_mixer_elem_set_callback(elem, elem_callback);
while (!(ret = snd_mixer_wait(mixer, -1))) {
ret = snd_mixer_handle_events(mixer);
if (ret < 0) {
fprintf(stderr, "Error handling events: %d (%s)\n",
ret, snd_strerror(ret));
ret = -1;
goto fail;
}
}
if (ret < 0) {
fprintf(stderr, "Error waiting for mixer events: %d (%s)\n",
ret, snd_strerror(ret));
ret = -1;
goto fail;
}
fail:
snd_mixer_close(mixer);
return ret;
}
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