/*
 *  makeaiff.c
 *  compute a sound
 *  write the int output to an aiff file
 *
 *  Created by Christopher Dobrian on Tue Jan 19 2004.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define	SAMPLE_RATE	(44100.0)
#define NCHANS  2
#define BYTES_PER_SAMPLE	2
#define	BUFSIZE	256
#define	OUTPUT_FILENAME	"toneoutput.aif"
#define MAXAMP	32000
#define FREQUENCY   (440.)
#define	DURATION	(1.0)
#define TWOPI		(6.283185307179586)

typedef int errormsg;

errormsg	openfilew( FILE *fp );
errormsg	aiffheader( FILE *fp, unsigned long nsamples );
errormsg	writestereodata( FILE *fp, unsigned long nsamples );

errormsg	openfilew( FILE *fp ){
	errormsg	err;
	
	fp = fopen( OUTPUT_FILENAME, "w" );
	if (fp == NULL) {
		fprintf( stderr, "Can't open file.\n" );
		err = -1;
	}
	else {
		err = 0;
	}
	
	return err;
}

errormsg	aiffheader( FILE *fp, unsigned long nsamples ){

	/* 
	 * This code for writing header information for an aiff
	 * is adapted from example source code provided in the web article
	 * "Audio Interchange File Format: Creating aiff Audio Formatted files"
	 * written by Paul Bourke, 1996, available on the web at
	 * http://astronomy.swin.edu.au/~pbourke/dataformats/aiff/
	 */
	 
	errormsg	err = 0;
	unsigned long   ndatabytes, totalsize;
	
	ndatabytes = NCHANS * BYTES_PER_SAMPLE * nsamples;

	/* Write the Form chunk */
	fprintf( fp, "FORM" );
	totalsize = 4 + 8 + 18 + 8 + 8 + ndatabytes;
	// "aiff", Common Chunk, Data Chunk Header, Block and Offset, Data
	putc( (totalsize & 0xFF000000) >> 24, fp );
	putc( (totalsize & 0x00FF0000) >> 16, fp );
	putc( (totalsize & 0x0000FF00) >> 8, fp );
	putc( (totalsize & 0x000000FF), fp );
	fprintf( fp, "AIFF" );
	
	/* Write the Common chunk */
	fprintf( fp, "COMM" );
	putc( 0, fp ); // 4 bytes telling the size of this common chunk (always 18)
	putc( 0, fp );
	putc( 0, fp );
	putc( 18, fp );
	putc( 0, fp ); // 2 bytes telling the number of audio channels
	putc( NCHANS, fp );
	putc( (nsamples & 0xFF000000) >> 24, fp );   // 4 bytes telling how many samples
	putc( (nsamples & 0x00FF0000) >> 16, fp );
	putc( (nsamples & 0x0000FF00) >> 8, fp );
	putc( (nsamples & 0x000000FF), fp );
	putc( 0, fp ); // 2 bytes telling how many bits per sample
	putc( 16, fp );
	putc( 0x40, fp ); // 10-byte SANE "extended" number telling the sampling rate (44100)
	putc( 0x0E, fp );
	putc( 0xAC, fp );
	putc( 0x44, fp );
	putc( 0, fp );
	putc( 0, fp );
	putc( 0, fp );
	putc( 0, fp );
	putc( 0, fp );
	putc( 0, fp );

	/* Write the sound data chunk header */
	fprintf( fp , "SSND" );
	putc( (ndatabytes+8 & 0xff000000) >> 24, fp ); // 4 bytes telling data size (plus block and offset)
	putc( (ndatabytes+8 & 0x00ff0000) >> 16, fp );
	putc( (ndatabytes+8 & 0x0000ff00) >> 8, fp );
	putc( (ndatabytes+8 & 0x000000ff), fp );
	putc( 0, fp ); // 4 bytes telling offset
	putc( 0, fp );
	putc( 0, fp );
	putc( 0, fp );
	putc( 0, fp ); // 4 bytes telling block
	putc( 0, fp );
	putc( 0, fp );
	putc( 0, fp );
	
	return err;
}

errormsg	writestereodata( FILE *fp, unsigned long nsamples ){
	errormsg	err = 0;
	float amplitude = MAXAMP;
    float frequency = FREQUENCY;
    float phase = 0.;
    unsigned long n; // the current sample number
    float twopiFoverR = TWOPI*frequency/SAMPLE_RATE;
    short int y; // current sample value
	
    for( n = 0 ; n < nsamples ; n++ )
    {
		y = (short int)amplitude*sin(twopiFoverR*n+phase);
		putc( ((y >> 8) & 0xFF), fp ); // left channel sample
		putc( (y & 0xFF), fp );
		putc( ((y >> 8) & 0xFF), fp ); // right channel sample
		putc( (y & 0xFF), fp );
    }
	
	return err;
}

int main(void) {
	FILE	*fp;
	errormsg	err;
	unsigned long   nsamples;
	
	nsamples = (unsigned long)DURATION*SAMPLE_RATE;
	
	fp = fopen( OUTPUT_FILENAME, "w" );
	if (fp == NULL) {
		fprintf( stderr, "Can't open file.\n" );
		err = -1;
	}
	else {
		err = 0;
	}
	if (err) goto error;
	err = aiffheader( fp, nsamples );
	if (err) goto error;
	err = writestereodata( fp, nsamples );
	if (err) goto error;
	fclose( fp );
	
	return 0;
	
	error:
		fprintf( stderr, "Error printing to file. Exiting.\n" );
		return -1;
}