/* st_au_lib.c */
/*
 * Copyright (c) 2001 Bruce R. Montague <brucem@mail.cruzio.com>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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, WHETHERIN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THEPOSSIBILITY OF
 * SUCH DAMAGE.
 */
/*
 * A very elementary audio library, really just
 * a wrapper for open with standard ioctls.
 * A read buffer is allocated based on the read sample size.
 */

#include  <stdlib.h>
#include  <fcntl.h>
#include  <sys/soundcard.h>

void st_err( char *msg );

static int  au_dev;
static int  err;

static int  dsp_blk_size;
static int  bytes_per_sample;

static char *buf;

/*--------------------------------------------*/
void
open_au_dev( char *dev, int mode ) {
	int   tmp;

	/*--- Access driver. */
	au_dev = open( dev, mode, 0 );
	if( 0 > au_dev ) {
	    perror( "Cant access audio device!" );
	    st_err( "\n Cant access /dev/dsp\n" );
	}

	/*--- Get blocksize, alloc buffer.*/
	err = ioctl( au_dev, SNDCTL_DSP_GETBLKSIZE, &dsp_blk_size );
	if( 0 > err ) st_err( "\n Cant get /dev/dsp blocksize!\n" );

	/* printf( "\n dsp block size=%d.\n", dsp_blk_size ); */

	if( 
	    (32        > dsp_blk_size) ||
	    ((64*1024) < dsp_blk_size)
	) {
	    printf( "\n Bad dsp_blk_size=%d.\n", dsp_blk_size );
	    st_err( "Bad blk size" );
	}

	buf = (char *)malloc( dsp_blk_size ); 
	if( !buf ) st_err( "Cant malloc!" );

	/*--- Set bits in sample (16).*/
	bytes_per_sample = 2;

	tmp = 16;
	err = ioctl( au_dev, SNDCTL_DSP_SAMPLESIZE, &tmp );
	if( 0 > err ) {
	    perror( "SNDCTL_DSP_SAMPLESIZE ioctl error" );
	    st_err( "\n Cant set sample size!\n" );
	}

	/*--- Set stereo mode (mono is 0).*/
	tmp = 1;
	err = ioctl( au_dev, SNDCTL_DSP_STEREO, &tmp );
	if( 0 > err ) st_err( "\n Cant set stereo mode!\n" );

	/*--- Set sampling rate.*/
	/* tmp = 48000; */
	tmp = 22050;
	err = ioctl( au_dev, SNDCTL_DSP_SPEED, &tmp );
	if( 0 > err ) st_err( "\n Cant set speed!\n" );
}

/*--------------------------------------------*/
void
close_au_dev() {

	err = close( au_dev );
	if( err ) {
	    printf( "\n close err=%d \n", err );
	}

	if( buf ) free( buf );
}

/*--------------------------------------------*/
int
read_au_dev( char **buf_p ) {
	int  len;

	len = read( au_dev, buf, dsp_blk_size );
	if( 0 > len ) {
	    printf( "\n read len=%d.\n", len );
	    st_err( "read" );
	}

	*buf_p = buf;

	return( len ); 
}

/*--------------------------------------------*/
int  
write_au_dev( char *play_buf, int buf_len  ) {
	int  len;

	len = write( au_dev, play_buf, buf_len );
	if( 0 > len ) {
	    printf( "\n write len=%d.\n", len );
	    st_err( "write" );
	}

	return( len );
}

/*--------------------------------------------*/
void
st_err( char *msg ) {
	printf( "\n st error: <%s> \n", msg );
	exit(1);
}