From 368d2c052594644d8a7e673c38277592a3ef7673 Mon Sep 17 00:00:00 2001
From: Mike Gerow <gerow@mgerow.com>
Date: Sun, 17 May 2015 20:30:06 -0700
Subject: [PATCH] Add a command line utility for interacting with /dev/mixer

---
 userspace/extra/mixerctl.c | 123 +++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 userspace/extra/mixerctl.c

diff --git a/userspace/extra/mixerctl.c b/userspace/extra/mixerctl.c
new file mode 100644
index 00000000..83efd379
--- /dev/null
+++ b/userspace/extra/mixerctl.c
@@ -0,0 +1,123 @@
+/* vim: tabstop=4 shiftwidth=4 noexpandtab
+ * This file is part of ToaruOS and is released under the terms
+ * of the NCSA / University of Illinois License - see LICENSE.md
+ * Copyright (C) 2015 Mike Gerow
+ */
+
+#include <fcntl.h>
+#include <lib/sound.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+static const char usage[] =
+"Usage  %s [-d device_id] -l\n"
+"       %s [-d device_id] [-k knob_id] -r\n"
+"       %s [-d device_id] [-k knob_id] -w knob_value\n"
+"       %s -h\n"
+"    -d: Device id to address. Defaults to the main sound device.\n"
+"    -l: List the knobs on a device.\n"
+"    -k: Knob id to address. Defaults to the device's master knob.\n"
+"    -r: Perform a read on the given device's knob. Defaults to the device's\n"
+"        master knob.\n"
+"    -w: Perform a write on the given device's knob. The value should be a\n"
+"        float from 0.0 to 1.0.\n"
+"    -h: Print this help message and exit.\n";
+
+int main(int argc, char * argv[]) {
+	uint32_t device_id = SND_DEVICE_MAIN;
+	uint32_t knob_id   = SND_KNOB_MASTER;
+	uint8_t list_flag = 0;
+	uint8_t read_flag  = 0;
+	uint8_t write_flag = 0;
+	double write_value = 0.0;
+
+	int c;
+
+	while ((c = getopt(argc, argv, "d:lk:rw:h")) != -1) {
+		switch (c) {
+			case 'd':
+				device_id = atol(optarg);
+				break;
+			case 'l':
+				list_flag = 1;
+				break;
+			case 'k':
+				knob_id = atol(optarg);
+				break;
+			case 'r':
+				read_flag = 1;
+				break;
+			case 'w':
+				write_flag = 1;
+				write_value = atof(optarg);
+				if (write_value < 0.0 || write_value > 1.0) {
+					fprintf(stderr, "argument -w value must be between 0.0 and 1.0\n");
+					exit(EXIT_FAILURE);
+				}
+				break;
+			case 'h':
+				fprintf(stdout, usage, argv[0], argv[0], argv[0], argv[0]);
+				exit(EXIT_SUCCESS);
+			default:
+				fprintf(stderr, usage, argv[0], argv[0], argv[0], argv[0]);
+				exit(EXIT_FAILURE);
+		}
+	}
+
+	int mixer = open("/dev/mixer", O_RDONLY);
+	if (mixer < 1) {
+		perror("open");
+		exit(EXIT_FAILURE);
+	}
+
+	if (list_flag) {
+		snd_knob_list_t list = {0};
+		list.device = device_id;
+		if (ioctl(mixer, SND_MIXER_GET_KNOBS, &list) < 0) {
+			perror("ioctl");
+			exit(EXIT_FAILURE);
+		}
+		for (uint32_t i = 0; i < list.num; i++) {
+			snd_knob_info_t info = {0};
+			info.device = device_id;
+			info.id = list.ids[i];
+			if (ioctl(mixer, SND_MIXER_GET_KNOB_INFO, &info) < 0) {
+				perror("ioctl");
+				exit(EXIT_FAILURE);
+			}
+			fprintf(stdout, "%d: %s\n", info.id, info.name);
+		}
+
+		exit(EXIT_SUCCESS);
+	}
+
+	if (read_flag) {
+		snd_knob_value_t value = {0};
+		value.device = device_id;
+		value.id = knob_id;
+		if (ioctl(mixer, SND_MIXER_READ_KNOB, &value) < 0) {
+			perror("ioctl");
+			exit(EXIT_FAILURE);
+		}
+		double double_val = (double)value.val / SND_KNOB_MAX_VALUE;
+		fprintf(stdout, "%f\n", double_val);
+		exit(EXIT_FAILURE);
+	}
+
+	if (write_flag) {
+		snd_knob_value_t value = {0};
+		value.device = device_id;
+		value.id = knob_id;
+		value.val = (uint32_t)(write_value * SND_KNOB_MAX_VALUE);
+		if (ioctl(mixer, SND_MIXER_WRITE_KNOB, &value) < 0) {
+			perror("ioctl");
+			exit(EXIT_FAILURE);
+		}
+		exit(EXIT_SUCCESS);
+	}
+
+	fprintf(stderr, "No operation specified.\n");
+	exit(EXIT_FAILURE);
+}