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commit 655fa298091591c3d21f2c47c3615b52c2f2a192
parent 449890cd3657c607f2546cb6299e640a7ab74352
Author: wifiextender <router@archlinux.info>
Date:   Fri, 22 Jul 2016 00:10:05 +0200

New helper function

Diffstat:
M
dwm.suckless.org/dwmstatus/index.md
 | 
1
+
A
dwm.suckless.org/dwmstatus/volume.c
 | 
100
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 101 insertions(+), 0 deletions(-)
diff --git a/dwm.suckless.org/dwmstatus/index.md b/dwm.suckless.org/dwmstatus/index.md
@@ -35,6 +35,7 @@ Helper functions
 If you have simple C functions for gathering system information, please
 add them here as file or as code example.
 
+* [Basic ALSA Volume API example with error checks and handling](volume.c)
 * [Support for ACPI battery status Linux](new-acpi-battery.c)
 * [Reading out a temperature from /sys](dwmstatus-temperature.c)
 * [Reading up-, and downspeeds of all network interfaces from /proc/net](dwmstatus-netusage.c)
diff --git a/dwm.suckless.org/dwmstatus/volume.c b/dwm.suckless.org/dwmstatus/volume.c
@@ -0,0 +1,100 @@
+/*
+ Copyright 07/20/2016 Aaron Caffrey https://github.com/wifiextender
+
+ This program 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 2 of the License, or
+ (at your option) any later version.
+
+ This program 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 this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ MA 02110-1301, USA.
+
+ Compile with:
+  gcc -Wall -Wextra -O2 volume.c -o test -lasound
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <alsa/asoundlib.h>
+
+#define ALSA_ERR "Error: alsa failed"
+
+void exit_with_err(const char *);
+void get_sound(void);
+
+int main(void) {
+  get_sound();
+  return EXIT_SUCCESS;
+}
+
+void
+exit_with_err(const char *str1) {
+  printf("%s\n", str1);
+  exit(EXIT_FAILURE);
+}
+
+void
+get_sound(void) {
+  snd_mixer_t *handle = NULL;
+  snd_mixer_elem_t *elem = NULL;
+  snd_mixer_selem_id_t *s_elem = NULL;
+  long int vol, max, min;
+
+  if (0 < (snd_mixer_open(&handle, 0))) {
+    exit_with_err(ALSA_ERR);
+  }
+
+  if (0 < (snd_mixer_attach(handle, "default"))) {
+    goto error;
+  }
+
+  if (0 < (snd_mixer_selem_register(handle, NULL, NULL))) {
+    goto error;
+  }
+
+  if (0 < (snd_mixer_load(handle))) {
+    goto error;
+  }
+
+  snd_mixer_selem_id_malloc(&s_elem);
+  if (NULL == s_elem) {
+    goto error;
+  }
+
+  snd_mixer_selem_id_set_name(s_elem, "Master");
+  if (NULL == (elem = snd_mixer_find_selem(handle, s_elem))) {
+    goto error;
+  }
+
+  /* Use `set' to change the current volume value */
+  if (0 < (snd_mixer_selem_get_playback_volume(elem, 0, &vol))) {
+    goto error;
+  }
+  snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
+
+  snd_mixer_selem_id_free(s_elem);
+  snd_mixer_close(handle);
+
+  printf("%s %ld%%\n", "Volume set to", (vol * 100) / max);
+  return;
+
+/* stay cheesy no matter what */
+error:
+  if (NULL != s_elem) {
+    snd_mixer_selem_id_free(s_elem);
+    s_elem = NULL;
+  }
+  if (NULL != handle) {
+    snd_mixer_close(handle);
+    handle = NULL;
+  }
+  exit_with_err(ALSA_ERR);
+}