alsa-lib/src/mixer/mixer.c

/*
 *  Mixer Interface - main file
 *  Copyright (c) 1998 by Jaroslav Kysela <perex@jcu.cz>
 *
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library 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 Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include "asoundlib.h"

#define SND_FILE_MIXER		"/dev/snd/mixerC%iD%i"
#define SND_MIXER_VERSION_MAX	SND_PROTOCOL_VERSION( 1, 1, 0 )

typedef struct {
	int card;
	int device;
	int fd;
} snd_mixer_t;

int snd_mixer_open(void **handle, int card, int device)
{
	int fd, ver;
	char filename[32];
	snd_mixer_t *mixer;

	*handle = NULL;

	if (card < 0 || card >= SND_CARDS)
		return -EINVAL;
	sprintf(filename, SND_FILE_MIXER, card, device);
	if ((fd = open(filename, O_RDWR)) < 0) {
		snd_card_load(card);	
		if ((fd = open(filename, O_RDWR)) < 0) 
			return -errno;
	}
	if (ioctl(fd, SND_MIXER_IOCTL_PVERSION, &ver) < 0) {
		close(fd);
		return -errno;
	}
	if (SND_PROTOCOL_UNCOMPATIBLE(ver, SND_MIXER_VERSION_MAX)) {
		close(fd);
		return -SND_ERROR_UNCOMPATIBLE_VERSION;
	}
	mixer = (snd_mixer_t *) calloc(1, sizeof(snd_mixer_t));
	if (mixer == NULL) {
		close(fd);
		return -ENOMEM;
	}
	mixer->card = card;
	mixer->device = device;
	mixer->fd = fd;
	*handle = mixer;
	return 0;
}

int snd_mixer_close(void *handle)
{
	snd_mixer_t *mixer;
	int res;

	mixer = (snd_mixer_t *) handle;
	if (!mixer)
		return -EINVAL;
	res = close(mixer->fd) < 0 ? -errno : 0;
	free(mixer);
	return res;
}

int snd_mixer_file_descriptor(void *handle)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer)
		return -EINVAL;
	return mixer->fd;
}

int snd_mixer_channels(void *handle)
{
	snd_mixer_t *mixer;
	int result;

	mixer = (snd_mixer_t *) handle;
	if (!mixer)
		return -EINVAL;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNELS, &result) < 0)
		return -errno;
	return result;
}

int snd_mixer_info(void *handle, snd_mixer_info_t * info)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !info)
		return -EINVAL;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_INFO, info) < 0)
		return -errno;
	return 0;
}

int snd_mixer_exact_mode(void *handle, int enable)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer)
		return -EINVAL;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_EXACT, &enable) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel(void *handle, const char *channel_id)
{
	snd_mixer_t *mixer;
	snd_mixer_channel_info_t info;
	int idx, channels, err;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !channel_id)
		return -EINVAL;
	/* bellow implementation isn't optimized for speed */
	/* info about channels should be cached in the snd_mixer_t structure */
	if ((channels = snd_mixer_channels(handle)) < 0)
		return channels;
	for (idx = 0; idx < channels; idx++) {
		if ((err = snd_mixer_channel_info(handle, idx, &info)) < 0)
			return err;
		if (!strncmp(channel_id, info.name, sizeof(info.name)))
			return idx;
	}
	return -EINVAL;
}

int snd_mixer_channel_info(void *handle, int channel, snd_mixer_channel_info_t * info)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !info || channel < 0)
		return -EINVAL;
	info->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_INFO, info) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel_output_info(void *handle, int channel, snd_mixer_channel_direction_info_t * info)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !info || channel < 0)
		return -EINVAL;
	info->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_OINFO, info) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel_input_info(void *handle, int channel, snd_mixer_channel_direction_info_t * info)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !info || channel < 0)
		return -EINVAL;
	info->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_IINFO, info) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel_read(void *handle, int channel, snd_mixer_channel_t * data)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !data || channel < 0)
		return -EINVAL;
	bzero(data, sizeof(snd_mixer_channel_t));
	data->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_READ, data) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel_write(void *handle, int channel, snd_mixer_channel_t * data)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !data)
		return -EINVAL;
	data->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_WRITE, data) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel_output_read(void *handle, int channel, snd_mixer_channel_direction_t * data)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !data || channel < 0)
		return -EINVAL;
	bzero(data, sizeof(snd_mixer_channel_t));
	data->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_OREAD, data) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel_output_write(void *handle, int channel, snd_mixer_channel_direction_t * data)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !data || channel < 0)
		return -EINVAL;
	data->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_OWRITE, data) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel_input_read(void *handle, int channel, snd_mixer_channel_direction_t * data)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !data || channel < 0)
		return -EINVAL;
	bzero(data, sizeof(snd_mixer_channel_t));
	data->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_IREAD, data) < 0)
		return -errno;
	return 0;
}

int snd_mixer_channel_input_write(void *handle, int channel, snd_mixer_channel_direction_t * data)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !data || channel < 0)
		return -EINVAL;
	data->channel = channel;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_CHANNEL_IWRITE, data) < 0)
		return -errno;
	return 0;
}

int snd_mixer_switch_list(void *handle, snd_switch_list_t * list)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !list)
		return -EINVAL;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_SWITCH_LIST, &list) < 0)
		return -errno;
	return 0;
}

int snd_mixer_switch_read(void *handle, snd_switch_t * sw)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !sw || sw->name[0] == '\0')
		return -EINVAL;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_SWITCH_READ, sw) < 0)
		return -errno;
	return 0;
}

int snd_mixer_switch_write(void *handle, snd_switch_t * sw)
{
	snd_mixer_t *mixer;

	mixer = (snd_mixer_t *) handle;
	if (!mixer || !sw || sw->name[0] == '\0')
		return -EINVAL;
	if (ioctl(mixer->fd, SND_MIXER_IOCTL_SWITCH_WRITE, sw) < 0)
		return -errno;
	return 0;
}

int snd_mixer_read(void *handle, snd_mixer_callbacks_t * callbacks)
{
	snd_mixer_t *mixer;
	int idx, result, count;
	unsigned int cmd, tmp;
	unsigned char buffer[64];

	mixer = (snd_mixer_t *) handle;
	if (!mixer)
		return -EINVAL;
	count = 0;
	while ((result = read(mixer->fd, &buffer, sizeof(buffer))) > 0) {
		if (result & 7)
			return -EIO;
		if (!callbacks)
			continue;
		for (idx = 0; idx < result; idx += 8) {
			cmd = *(unsigned int *) &buffer[idx];
			tmp = *(unsigned int *) &buffer[idx + 4];
			if (cmd == SND_MIXER_CHANGED && 
			    callbacks->channel_was_changed) {
				callbacks->channel_was_changed(callbacks->private_data, (int) tmp);
			}
			if (cmd == SND_MIXER_OUTPUT_CHANGED && 
			    callbacks->output_channel_was_changed) {
				callbacks->output_channel_was_changed(callbacks->private_data, (int) tmp);
			}
			if (cmd == SND_MIXER_INPUT_CHANGED && 
			    callbacks->input_channel_was_changed) {
				callbacks->input_channel_was_changed(callbacks->private_data, (int) tmp);
			}
			if (cmd == SND_MIXER_SWITCH_CHANGED && 
			    callbacks->switch_was_changed) {
				callbacks->switch_was_changed(callbacks->private_data, (int) tmp);
			}
		}
		count += result >> 3;	/* return only number of changes */
	}
	return result >= 0 ? count : -errno;
}