//-------------------------------------------------------------------
//	makeA440.cpp
//
//	Creates a .wav file for a sine-wave of frequency 440 HZ for
//	a duration of one second stereo at a sample-rate of 32-kHz,
//	suitable for playback on the Logitech Z305 stereo speakers.  
//
//	programmer: ALLAN CRUSE
//	written on: 28 SEP 2011
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for lseek() 
#include <math.h>	// for sin()

#define SAMPLE_RATE	32000
#define PI		3.14158625

typedef	struct	{short	L, R; } Sample;

const int	size_Sample = sizeof( Sample );
Sample		sample[ SAMPLE_RATE ];


int main( int argc, char **argv )
{
	//-------------------------------------------------
	// initialize the PCM data in the 'sample[]' array 
	//-------------------------------------------------	

	double	pitch = 440.0;
	double	volume = 20000.0;
	double	inc = pitch * ((2.0 * PI) / (double)SAMPLE_RATE ); 

	for (int i = 0; i < SAMPLE_RATE; i++)
		{
		double	x = i * inc;
		double	y = sin( x );
		Sample	s;
		s.L = y * volume;
		s.R = y * volume;
		sample[ i ] = s;
		}

	//-----------------------------------------
	// setup the .wav file's audio parameters
	//----------------------------------------- 

	short	formatTag = 1;
	short	nChannels = 2;
	int	samplesPerSec = SAMPLE_RATE; 
	int	avBytesPerSec = samplesPerSec * size_Sample;
	short	blockAlignmnt = size_Sample; 
	short	bitsPerSample = 8 * blockAlignmnt; 

	int	dataChunkSize = SAMPLE_RATE * size_Sample; 
	int	fmt_ChunkSize = 16;
	int	riffChunkSize = 4 + (8 + fmt_ChunkSize) + (8 + dataChunkSize);

	//-----------------------------------
	// write the PCM data in a .wav file
	//-----------------------------------	

	// open the wav-file for writing
	char	wavname[] = "a440.wav";
	int	wav = open( wavname, O_CREAT | O_RDWR | O_TRUNC, 0666 );
	if ( wav < 0 ) { perror( wavname ); exit(1); }

	// output the RIFF chunk 
	write( wav, "RIFF", 4 );
	write( wav, &riffChunkSize, 4 );
	write( wav, "WAVE", 4 );

	// output the FORMAT chunk
	write( wav, "fmt ", 4 );
	write( wav, &fmt_ChunkSize, 4 );
	write( wav, &formatTag, 2 );
	write( wav, &nChannels, 2 );
	write( wav, &samplesPerSec, 4 );
	write( wav, &avBytesPerSec, 4 );
	write( wav, &blockAlignmnt, 2 );
	write( wav, &bitsPerSample, 2 );

	// write the DATA chunk
	write( wav, "data", 4 );
	write( wav, &dataChunkSize, 4 );
	char	*wp = (char*)&sample[0]; 
	int	bytes_to_file = lseek( wav, 0L, SEEK_CUR );
	int	bytes_to_save = dataChunkSize; 
	while ( bytes_to_save > 0 )
		{
		int	wbytes = write( wav, wp, bytes_to_save );
		if ( wbytes < 0 ) break;
		bytes_to_save -= wbytes;
		bytes_to_file += wbytes;
		wp += wbytes;
		}
	close( wav );

	printf( "Written %d bytes to \'%s\' \n", bytes_to_file, wavname );

	//display_UHCI_registers();
	printf( "\nDONE\n\n" );
}