Implement ALSA volume support

7 files changed, 719 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index 9f61eef..c7635dd 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ CFLAGS+=-g
 CFLAGS+=-std=gnu99
 CFLAGS+=-pedantic
 CFLAGS+=-DPREFIX=\"\"
-CFLAGS+=-I.
+CFLAGS+=-Iinclude
 LDFLAGS+=-lconfuse
 
 VERSION=$(shell git describe --tags --abbrev=0)
@@ -11,7 +11,7 @@ VERSION=$(shell git describe --tags --abbrev=0)
 ifeq ($(shell uname),Linux)
 CFLAGS+=-DLINUX
 CFLAGS+=-D_GNU_SOURCE
-LDFLAGS+=-liw
+LDFLAGS+=-liw -lasound
 endif
 
 ifeq ($(shell uname),GNU/kFreeBSD)
diff --git a/debian/control b/debian/control
index 4d6bde3..f6b9e7d 100644
--- a/debian/control
+++ b/debian/control
@@ -3,7 +3,7 @@ Section: utils
 Priority: extra
 Maintainer: Michael Stapelberg <michael@stapelberg.de>
 DM-Upload-Allowed: yes
-Build-Depends: debhelper (>= 5), libiw-dev [!kfreebsd-i386 !kfreebsd-amd64 !hurd-i386], libconfuse-dev, asciidoc, xmlto, libcap2-bin
+Build-Depends: debhelper (>= 5), libiw-dev [!kfreebsd-i386 !kfreebsd-amd64 !hurd-i386], libconfuse-dev, asciidoc, xmlto, libcap2-bin, libasound2-dev
 Standards-Version: 3.8.4
 Homepage: http://i3.zekjur.net/i3status
 
diff --git a/i3status.c b/i3status.c
index eabcd6c..e0139eb 100644
--- a/i3status.c
+++ b/i3status.c
@@ -151,6 +151,14 @@ int main(int argc, char *argv[]) {
                 CFG_END()
         };
 
+        cfg_opt_t volume_opts[] = {
+                CFG_STR("format", "♪: %volume", CFGF_NONE),
+                CFG_STR("device", "default", CFGF_NONE),
+                CFG_STR("mixer", "Master", CFGF_NONE),
+                CFG_INT("mixer_idx", 0, CFGF_NONE),
+                CFG_END()
+        };
+
         cfg_opt_t opts[] = {
                 CFG_STR_LIST("order", "{ipv6,\"run_watch DHCP\",\"wireless wlan0\",\"ethernet eth0\",\"battery 0\",\"cpu_temperature 0\",load,time}", CFGF_NONE),
                 CFG_SEC("general", general_opts, CFGF_NONE),
@@ -160,6 +168,7 @@ int main(int argc, char *argv[]) {
                 CFG_SEC("battery", battery_opts, CFGF_TITLE | CFGF_MULTI),
                 CFG_SEC("cpu_temperature", temp_opts, CFGF_TITLE | CFGF_MULTI),
                 CFG_SEC("disk", disk_opts, CFGF_TITLE | CFGF_MULTI),
+                CFG_SEC("volume", volume_opts, CFGF_TITLE | CFGF_MULTI),
                 CFG_SEC("ipv6", ipv6_opts, CFGF_NONE),
                 CFG_SEC("time", time_opts, CFGF_NONE),
                 CFG_SEC("ddate", ddate_opts, CFGF_NONE),
@@ -260,6 +269,12 @@ int main(int argc, char *argv[]) {
                         CASE_SEC("ddate")
                                 print_ddate(cfg_getstr(sec, "format"));
 
+                        CASE_SEC("volume")
+                                print_volume(cfg_getstr(sec, "format"),
+                                             cfg_getstr(sec, "device"),
+                                             cfg_getstr(sec, "mixer"),
+                                             cfg_getint(sec, "mixer_idx"));
+
                         CASE_SEC_TITLE("cpu_temperature")
                                 print_cpu_temperature_info(atoi(title), cfg_getstr(sec, "format"));
                 }
diff --git a/i3status.h b/include/i3status.h
index 512b4ad..a79be18 100644
--- a/i3status.h
+++ b/include/i3status.h
@@ -69,6 +69,7 @@ void print_run_watch(const char *title, const char *pidfile, const char *format)
 void print_cpu_temperature_info(int zone, const char *format);
 void print_eth_info(const char *interface, const char *format_up, const char *format_down);
 void print_load();
+void print_volume(const char *fmt, const char *device, const char *mixer, int mixer_idx);
 bool process_runs(const char *path);
 
 /* socket file descriptor for general purposes */
diff --git a/include/queue.h b/include/queue.h
new file mode 100644
index 0000000..75bb957
--- /dev/null
+++ b/include/queue.h
@@ -0,0 +1,527 @@
+/*	$OpenBSD: queue.h,v 1.1 2007/10/26 03:14:08 niallo Exp $	*/
+/*	$NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $	*/
+
+/*
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)queue.h	8.5 (Berkeley) 8/20/94
+ */
+
+#ifndef	_SYS_QUEUE_H_
+#define	_SYS_QUEUE_H_
+
+/*
+ * This file defines five types of data structures: singly-linked lists,
+ * lists, simple queues, tail queues, and circular queues.
+ *
+ *
+ * A singly-linked list is headed by a single forward pointer. The elements
+ * are singly linked for minimum space and pointer manipulation overhead at
+ * the expense of O(n) removal for arbitrary elements. New elements can be
+ * added to the list after an existing element or at the head of the list.
+ * Elements being removed from the head of the list should use the explicit
+ * macro for this purpose for optimum efficiency. A singly-linked list may
+ * only be traversed in the forward direction.  Singly-linked lists are ideal
+ * for applications with large datasets and few or no removals or for
+ * implementing a LIFO queue.
+ *
+ * A list is headed by a single forward pointer (or an array of forward
+ * pointers for a hash table header). The elements are doubly linked
+ * so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may only be traversed in the forward direction.
+ *
+ * A simple queue is headed by a pair of pointers, one the head of the
+ * list and the other to the tail of the list. The elements are singly
+ * linked to save space, so elements can only be removed from the
+ * head of the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the
+ * list. A simple queue may only be traversed in the forward direction.
+ *
+ * A tail queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
+ *
+ * A circle queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the list.
+ * A circle queue may be traversed in either direction, but has a more
+ * complex end of list detection.
+ *
+ * For details on the use of these macros, see the queue(3) manual page.
+ */
+
+#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
+#define _Q_INVALIDATE(a) (a) = ((void *)-1)
+#else
+#define _Q_INVALIDATE(a)
+#endif
+
+/*
+ * Singly-linked List definitions.
+ */
+#define SLIST_HEAD(name, type)						\
+struct name {								\
+	struct type *slh_first;	/* first element */			\
+}
+
+#define	SLIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define SLIST_ENTRY(type)						\
+struct {								\
+	struct type *sle_next;	/* next element */			\
+}
+
+/*
+ * Singly-linked List access methods.
+ */
+#define	SLIST_FIRST(head)	((head)->slh_first)
+#define	SLIST_END(head)		NULL
+#define	SLIST_EMPTY(head)	(SLIST_FIRST(head) == SLIST_END(head))
+#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
+
+#define	SLIST_FOREACH(var, head, field)					\
+	for((var) = SLIST_FIRST(head);					\
+	    (var) != SLIST_END(head);					\
+	    (var) = SLIST_NEXT(var, field))
+
+#define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
+	for ((varp) = &SLIST_FIRST((head));				\
+	    ((var) = *(varp)) != SLIST_END(head);			\
+	    (varp) = &SLIST_NEXT((var), field))
+
+/*
+ * Singly-linked List functions.
+ */
+#define	SLIST_INIT(head) {						\
+	SLIST_FIRST(head) = SLIST_END(head);				\
+}
+
+#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
+	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
+	(slistelm)->field.sle_next = (elm);				\
+} while (0)
+
+#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
+	(elm)->field.sle_next = (head)->slh_first;			\
+	(head)->slh_first = (elm);					\
+} while (0)
+
+#define	SLIST_REMOVE_NEXT(head, elm, field) do {			\
+	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;	\
+} while (0)
+
+#define	SLIST_REMOVE_HEAD(head, field) do {				\
+	(head)->slh_first = (head)->slh_first->field.sle_next;		\
+} while (0)
+
+#define SLIST_REMOVE(head, elm, type, field) do {			\
+	if ((head)->slh_first == (elm)) {				\
+		SLIST_REMOVE_HEAD((head), field);			\
+	} else {							\
+		struct type *curelm = (head)->slh_first;		\
+									\
+		while (curelm->field.sle_next != (elm))			\
+			curelm = curelm->field.sle_next;		\
+		curelm->field.sle_next =				\
+		    curelm->field.sle_next->field.sle_next;		\
+		_Q_INVALIDATE((elm)->field.sle_next);			\
+	}								\
+} while (0)
+
+/*
+ * List definitions.
+ */
+#define LIST_HEAD(name, type)						\
+struct name {								\
+	struct type *lh_first;	/* first element */			\
+}
+
+#define LIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define LIST_ENTRY(type)						\
+struct {								\
+	struct type *le_next;	/* next element */			\
+	struct type **le_prev;	/* address of previous next element */	\
+}
+
+/*
+ * List access methods
+ */
+#define	LIST_FIRST(head)		((head)->lh_first)
+#define	LIST_END(head)			NULL
+#define	LIST_EMPTY(head)		(LIST_FIRST(head) == LIST_END(head))
+#define	LIST_NEXT(elm, field)		((elm)->field.le_next)
+
+#define LIST_FOREACH(var, head, field)					\
+	for((var) = LIST_FIRST(head);					\
+	    (var)!= LIST_END(head);					\
+	    (var) = LIST_NEXT(var, field))
+
+/*
+ * List functions.
+ */
+#define	LIST_INIT(head) do {						\
+	LIST_FIRST(head) = LIST_END(head);				\
+} while (0)
+
+#define LIST_INSERT_AFTER(listelm, elm, field) do {			\
+	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
+		(listelm)->field.le_next->field.le_prev =		\
+		    &(elm)->field.le_next;				\
+	(listelm)->field.le_next = (elm);				\
+	(elm)->field.le_prev = &(listelm)->field.le_next;		\
+} while (0)
+
+#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.le_prev = (listelm)->field.le_prev;		\
+	(elm)->field.le_next = (listelm);				\
+	*(listelm)->field.le_prev = (elm);				\
+	(listelm)->field.le_prev = &(elm)->field.le_next;		\
+} while (0)
+
+#define LIST_INSERT_HEAD(head, elm, field) do {				\
+	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
+		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
+	(head)->lh_first = (elm);					\
+	(elm)->field.le_prev = &(head)->lh_first;			\
+} while (0)
+
+#define LIST_REMOVE(elm, field) do {					\
+	if ((elm)->field.le_next != NULL)				\
+		(elm)->field.le_next->field.le_prev =			\
+		    (elm)->field.le_prev;				\
+	*(elm)->field.le_prev = (elm)->field.le_next;			\
+	_Q_INVALIDATE((elm)->field.le_prev);				\
+	_Q_INVALIDATE((elm)->field.le_next);				\
+} while (0)
+
+#define LIST_REPLACE(elm, elm2, field) do {				\
+	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)	\
+		(elm2)->field.le_next->field.le_prev =			\
+		    &(elm2)->field.le_next;				\
+	(elm2)->field.le_prev = (elm)->field.le_prev;			\
+	*(elm2)->field.le_prev = (elm2);				\
+	_Q_INVALIDATE((elm)->field.le_prev);				\
+	_Q_INVALIDATE((elm)->field.le_next);				\
+} while (0)
+
+/*
+ * Simple queue definitions.
+ */
+#define SIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqh_first;	/* first element */			\
+	struct type **sqh_last;	/* addr of last next element */		\
+}
+
+#define SIMPLEQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).sqh_first }
+
+#define SIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqe_next;	/* next element */			\
+}
+
+/*
+ * Simple queue access methods.
+ */
+#define	SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
+#define	SIMPLEQ_END(head)	    NULL
+#define	SIMPLEQ_EMPTY(head)	    (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
+#define	SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
+
+#define SIMPLEQ_FOREACH(var, head, field)				\
+	for((var) = SIMPLEQ_FIRST(head);				\
+	    (var) != SIMPLEQ_END(head);					\
+	    (var) = SIMPLEQ_NEXT(var, field))
+
+/*
+ * Simple queue functions.
+ */
+#define	SIMPLEQ_INIT(head) do {						\
+	(head)->sqh_first = NULL;					\
+	(head)->sqh_last = &(head)->sqh_first;				\
+} while (0)
+
+#define SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(head)->sqh_first = (elm);					\
+} while (0)
+
+#define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqe_next = NULL;					\
+	*(head)->sqh_last = (elm);					\
+	(head)->sqh_last = &(elm)->field.sqe_next;			\
+} while (0)
+
+#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(listelm)->field.sqe_next = (elm);				\
+} while (0)
+
+#define SIMPLEQ_REMOVE_HEAD(head, field) do {			\
+	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
+		(head)->sqh_last = &(head)->sqh_first;			\
+} while (0)
+
+/*
+ * Tail queue definitions.
+ */
+#define TAILQ_HEAD(name, type)						\
+struct name {								\
+	struct type *tqh_first;	/* first element */			\
+	struct type **tqh_last;	/* addr of last next element */		\
+}
+
+#define TAILQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).tqh_first }
+
+#define TAILQ_ENTRY(type)						\
+struct {								\
+	struct type *tqe_next;	/* next element */			\
+	struct type **tqe_prev;	/* address of previous next element */	\
+}
+
+/*
+ * tail queue access methods
+ */
+#define	TAILQ_FIRST(head)		((head)->tqh_first)
+#define	TAILQ_END(head)			NULL
+#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
+#define TAILQ_LAST(head, headname)					\
+	(*(((struct headname *)((head)->tqh_last))->tqh_last))
+/* XXX */
+#define TAILQ_PREV(elm, headname, field)				\
+	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+#define	TAILQ_EMPTY(head)						\
+	(TAILQ_FIRST(head) == TAILQ_END(head))
+
+#define TAILQ_FOREACH(var, head, field)					\
+	for((var) = TAILQ_FIRST(head);					\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_NEXT(var, field))
+
+#define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
+	for((var) = TAILQ_LAST(head, headname);				\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_PREV(var, headname, field))
+
+/*
+ * Tail queue functions.
+ */
+#define	TAILQ_INIT(head) do {						\
+	(head)->tqh_first = NULL;					\
+	(head)->tqh_last = &(head)->tqh_first;				\
+} while (0)
+
+#define TAILQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
+		(head)->tqh_first->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(head)->tqh_first = (elm);					\
+	(elm)->field.tqe_prev = &(head)->tqh_first;			\
+} while (0)
+
+#define TAILQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.tqe_next = NULL;					\
+	(elm)->field.tqe_prev = (head)->tqh_last;			\
+	*(head)->tqh_last = (elm);					\
+	(head)->tqh_last = &(elm)->field.tqe_next;			\
+} while (0)
+
+#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
+		(elm)->field.tqe_next->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(listelm)->field.tqe_next = (elm);				\
+	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
+} while (0)
+
+#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
+	(elm)->field.tqe_next = (listelm);				\
+	*(listelm)->field.tqe_prev = (elm);				\
+	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
+} while (0)
+
+#define TAILQ_REMOVE(head, elm, field) do {				\
+	if (((elm)->field.tqe_next) != NULL)				\
+		(elm)->field.tqe_next->field.tqe_prev =			\
+		    (elm)->field.tqe_prev;				\
+	else								\
+		(head)->tqh_last = (elm)->field.tqe_prev;		\
+	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
+	_Q_INVALIDATE((elm)->field.tqe_prev);				\
+	_Q_INVALIDATE((elm)->field.tqe_next);				\
+} while (0)
+
+#define TAILQ_REPLACE(head, elm, elm2, field) do {			\
+	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)	\
+		(elm2)->field.tqe_next->field.tqe_prev =		\
+		    &(elm2)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm2)->field.tqe_next;		\
+	(elm2)->field.tqe_prev = (elm)->field.tqe_prev;			\
+	*(elm2)->field.tqe_prev = (elm2);				\
+	_Q_INVALIDATE((elm)->field.tqe_prev);				\
+	_Q_INVALIDATE((elm)->field.tqe_next);				\
+} while (0)
+
+/*
+ * Circular queue definitions.
+ */
+#define CIRCLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *cqh_first;		/* first element */		\
+	struct type *cqh_last;		/* last element */		\
+}
+
+#define CIRCLEQ_HEAD_INITIALIZER(head)					\
+	{ CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
+
+#define CIRCLEQ_ENTRY(type)						\
+struct {								\
+	struct type *cqe_next;		/* next element */		\
+	struct type *cqe_prev;		/* previous element */		\
+}
+
+/*
+ * Circular queue access methods
+ */
+#define	CIRCLEQ_FIRST(head)		((head)->cqh_first)
+#define	CIRCLEQ_LAST(head)		((head)->cqh_last)
+#define	CIRCLEQ_END(head)		((void *)(head))
+#define	CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
+#define	CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
+#define	CIRCLEQ_EMPTY(head)						\
+	(CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
+
+#define CIRCLEQ_FOREACH(var, head, field)				\
+	for((var) = CIRCLEQ_FIRST(head);				\
+	    (var) != CIRCLEQ_END(head);					\
+	    (var) = CIRCLEQ_NEXT(var, field))
+
+#define CIRCLEQ_FOREACH_REVERSE(var, head, field)			\
+	for((var) = CIRCLEQ_LAST(head);					\
+	    (var) != CIRCLEQ_END(head);					\
+	    (var) = CIRCLEQ_PREV(var, field))
+
+/*
+ * Circular queue functions.
+ */
+#define	CIRCLEQ_INIT(head) do {						\
+	(head)->cqh_first = CIRCLEQ_END(head);				\
+	(head)->cqh_last = CIRCLEQ_END(head);				\
+} while (0)
+
+#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
+	(elm)->field.cqe_prev = (listelm);				\
+	if ((listelm)->field.cqe_next == CIRCLEQ_END(head))		\
+		(head)->cqh_last = (elm);				\
+	else								\
+		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
+	(listelm)->field.cqe_next = (elm);				\
+} while (0)
+
+#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {		\
+	(elm)->field.cqe_next = (listelm);				\
+	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
+	if ((listelm)->field.cqe_prev == CIRCLEQ_END(head))		\
+		(head)->cqh_first = (elm);				\
+	else								\
+		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
+	(listelm)->field.cqe_prev = (elm);				\
+} while (0)
+
+#define CIRCLEQ_INSERT_HEAD(head, elm, field) do {			\
+	(elm)->field.cqe_next = (head)->cqh_first;			\
+	(elm)->field.cqe_prev = CIRCLEQ_END(head);			\
+	if ((head)->cqh_last == CIRCLEQ_END(head))			\
+		(head)->cqh_last = (elm);				\
+	else								\
+		(head)->cqh_first->field.cqe_prev = (elm);		\
+	(head)->cqh_first = (elm);					\
+} while (0)
+
+#define CIRCLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.cqe_next = CIRCLEQ_END(head);			\
+	(elm)->field.cqe_prev = (head)->cqh_last;			\
+	if ((head)->cqh_first == CIRCLEQ_END(head))			\
+		(head)->cqh_first = (elm);				\
+	else								\
+		(head)->cqh_last->field.cqe_next = (elm);		\
+	(head)->cqh_last = (elm);					\
+} while (0)
+
+#define	CIRCLEQ_REMOVE(head, elm, field) do {				\
+	if ((elm)->field.cqe_next == CIRCLEQ_END(head))			\
+		(head)->cqh_last = (elm)->field.cqe_prev;		\
+	else								\
+		(elm)->field.cqe_next->field.cqe_prev =			\
+		    (elm)->field.cqe_prev;				\
+	if ((elm)->field.cqe_prev == CIRCLEQ_END(head))			\
+		(head)->cqh_first = (elm)->field.cqe_next;		\
+	else								\
+		(elm)->field.cqe_prev->field.cqe_next =			\
+		    (elm)->field.cqe_next;				\
+	_Q_INVALIDATE((elm)->field.cqe_prev);				\
+	_Q_INVALIDATE((elm)->field.cqe_next);				\
+} while (0)
+
+#define CIRCLEQ_REPLACE(head, elm, elm2, field) do {			\
+	if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==		\
+	    CIRCLEQ_END(head))						\
+		(head)->cqh_last = (elm2);				\
+	else								\
+		(elm2)->field.cqe_next->field.cqe_prev = (elm2);	\
+	if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==		\
+	    CIRCLEQ_END(head))						\
+		(head)->cqh_first = (elm2);				\
+	else								\
+		(elm2)->field.cqe_prev->field.cqe_next = (elm2);	\
+	_Q_INVALIDATE((elm)->field.cqe_prev);				\
+	_Q_INVALIDATE((elm)->field.cqe_next);				\
+} while (0)
+
+#endif	/* !_SYS_QUEUE_H_ */
diff --git a/man/i3status.man b/man/i3status.man
index 18cfb19..0274cca 100644
--- a/man/i3status.man
+++ b/man/i3status.man
@@ -220,6 +220,25 @@ details on the format string.
 
 *Example format*: +%{%a, %b %d%}, %Y%N - %H+
 
+=== Volume
+
+Outputs the volume of the specified mixer on the specified device. Works only
+on Linux because it uses ALSA.
+
+*Example order*: +volume master+
+
+*Example format*: +♪: %volume+
+
+*Example configuration*:
+-------------------------------------------------------------
+volume master {
+	format = "♪: %volume"
+	device = "default"
+	mixer = "Master"
+	mixer_idx = 0
+}
+-------------------------------------------------------------
+
 == Using i3status with dzen2
 
 After installing dzen2, you can directly use it with i3status:
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");
+		}
+	}
+}