Implement ALSA volume support

1 files changed, 154 insertions, 0 deletions

diff --git a/src/print_volume.c b/src/print_volume.c
new file mode 100644
index 0000000..0eca0c0
--- /dev/null
+++ b/src/print_volume.c
@@ -0,0 +1,154 @@
+// vim:ts=8:expandtab
+#include <time.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#ifdef LINUX
+#include <alsa/asoundlib.h>
+#include <alloca.h>
+#endif
+
+#include "i3status.h"
+#include "queue.h"
+
+#ifdef LINUX
+struct mixer_hdl {
+	char *device;
+	char *mixer;
+	int mixer_idx;
+	snd_mixer_selem_id_t *sid;
+	snd_mixer_t *m;
+	snd_mixer_elem_t *elem;
+	long min;
+	long max;
+
+	TAILQ_ENTRY(mixer_hdl) handles;
+};
+
+TAILQ_HEAD(handles_head, mixer_hdl) cached = TAILQ_HEAD_INITIALIZER(cached);
+#endif
+
+static void free_hdl(struct mixer_hdl *hdl) {
+	free(hdl->device);
+	free(hdl->mixer);
+	free(hdl);
+}
+
+void print_volume(const char *fmt, const char *device, const char *mixer, int mixer_idx) {
+/* Printing volume only works with ALSA at the moment */
+#ifndef LINUX
+	return;
+#endif
+	/* Check if we already opened the mixer and get the handle
+	 * from cache if so */
+	bool found = false;
+	int err;
+	struct mixer_hdl *hdl;
+	TAILQ_FOREACH(hdl, &cached, handles) {
+		if (strcmp(hdl->device, device) != 0 ||
+		    strcmp(hdl->mixer, mixer) != 0 ||
+		    hdl->mixer_idx != mixer_idx)
+			continue;
+		found = true;
+		break;
+	}
+
+	if (!found) {
+		if ((hdl = calloc(sizeof(struct mixer_hdl), 1)) == NULL)
+			return;
+
+		if ((hdl->device = strdup(device)) == NULL) {
+			free(hdl);
+			return;
+		}
+
+		if ((hdl->mixer = strdup(mixer)) == NULL) {
+			free(hdl->device);
+			free(hdl);
+			return;
+		}
+
+		hdl->mixer_idx = mixer_idx;
+		snd_mixer_selem_id_malloc(&(hdl->sid));
+		if (hdl->sid == NULL) {
+			free_hdl(hdl);
+			return;
+		}
+
+		if ((err = snd_mixer_open(&(hdl->m), 0)) < 0) {
+			fprintf(stderr, "ALSA: Cannot open mixer: %s\n", snd_strerror(err));
+			free_hdl(hdl);
+			return;
+		}
+
+		/* Attach this mixer handle to the given device */
+		if ((err = snd_mixer_attach(hdl->m, device)) < 0) {
+			fprintf(stderr, "ALSA: Cannot attach mixer to device: %s\n", snd_strerror(err));
+			snd_mixer_close(hdl->m);
+			free_hdl(hdl);
+			return;
+		}
+
+		/* Register this mixer */
+		if ((err = snd_mixer_selem_register(hdl->m, NULL, NULL)) < 0) {
+			fprintf(stderr, "ALSA: snd_mixer_selem_register: %s\n", snd_strerror(err));
+			snd_mixer_close(hdl->m);
+			free_hdl(hdl);
+			return;
+		}
+
+		if ((err = snd_mixer_load(hdl->m)) < 0) {
+			fprintf(stderr, "ALSA: snd_mixer_load: %s\n", snd_strerror(err));
+			snd_mixer_close(hdl->m);
+			free_hdl(hdl);
+			return;
+		}
+
+		/* Find the given mixer */
+		snd_mixer_selem_id_set_index(hdl->sid, mixer_idx);
+		snd_mixer_selem_id_set_name(hdl->sid, mixer);
+		if (!(hdl->elem = snd_mixer_find_selem(hdl->m, hdl->sid))) {
+			fprintf(stderr, "ALSA: Cannot find mixer %s (index %i)\n",
+				snd_mixer_selem_id_get_name(hdl->sid), snd_mixer_selem_id_get_index(hdl->sid));
+			snd_mixer_close(hdl->m);
+			free_hdl(hdl);
+			return;
+		}
+
+		/* Get the volume range to convert the volume later */
+		snd_mixer_selem_get_playback_volume_range(hdl->elem, &(hdl->min), &(hdl->max));
+		TAILQ_INSERT_TAIL(&cached, hdl, handles);
+	}
+
+	long val;
+	snd_mixer_handle_events (hdl->m);
+	snd_mixer_selem_get_playback_volume (hdl->elem, 0, &val);
+	int avg;
+	if (hdl->max != 100) {
+		float avgf = ((float)val / hdl->max) * 100;
+		avg = (int)avgf;
+		avg = (avgf - avg < 0.5 ? avg : (avg+1));
+	} else avg = (int)val;
+
+	/* Check for mute */
+	if (snd_mixer_selem_has_playback_switch(hdl->elem)) {
+		int pbval;
+		if ((err = snd_mixer_selem_get_playback_switch(hdl->elem, 0, &pbval)) < 0)
+			fprintf (stderr, "ALSA: playback_switch: %s\n", snd_strerror(err));
+		if (!pbval)
+			avg = 0;
+	}
+
+	const char *walk = fmt;
+	for (; *walk != '\0'; walk++) {
+		if (*walk != '%') {
+			putchar(*walk);
+			continue;
+		}
+		if (BEGINS_WITH(walk+1, "volume")) {
+			printf("%d%%", avg);
+			walk += strlen("volume");
+		}
+	}
+}