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

static unsigned int FREQUENCY = 8192;

static double (*waveForm)( double angle );

enum {
    BYTES_PER_SAMPLE = 2
};

enum {
    MAX_SAMPLE = (~(~0 << (8*BYTES_PER_SAMPLE-1)))
};

static double
squareWave( double angle )
{
    double waveNumber;
    double proportion;

    proportion = modf( angle / ( 2.0 * M_PI ), &waveNumber );

    if ( proportion < 0.5 ) {
	return 1.0;
    } else {
	return -1.0;
    }
}

static double
triangleWave( double angle )
{
    double waveNumber;
    double proportion;

    proportion = modf( angle / ( 2.0 * M_PI ), &waveNumber );

    if ( proportion < 0.5 ) {
	return 1.0 - 4.0 * proportion;
    } else {
	return 4.0 * proportion - 3.0;
    }
}

static double
sawtoothWave( double angle )
{
    double waveNumber;
    double proportion;

    proportion = modf( angle / ( 2.0 * M_PI ), &waveNumber );

    return 2.0 * proportion - 1.0;
}

static double
toothsawWave( double angle )
{
    double waveNumber;
    double proportion;

    proportion = modf( angle / ( 2.0 * M_PI ), &waveNumber );

    return 1.0 - 2.0 * proportion;
}

static double (*waveForm)( double angle );

static double
getSample( unsigned int sampleNumber, double hz )
{
    return (*waveForm)( sampleNumber * hz * 2.0 * M_PI / (double)FREQUENCY );
}

static double
getValue( FILE* fp )
{
    int input;
    int hi;
    int lo;

    hi = fgetc( stdin );
    lo = fgetc( stdin );

    if ( hi == EOF || lo == EOF ) {
	return 0.0;
    }

    input = ( hi << 8 ) | ( lo << 0 );

    if ( ( input & ( 1 << ( BYTES_PER_SAMPLE * 8 - 1 ) ) ) != 0  ) {
	input |= ~( 0xFFFF );
    }

    return (double)input / (double)MAX_SAMPLE;
}

static int
getOutputValue( double val, double gamma )
{
    if ( val < 0.0 ) {
	return 0;
    } else if ( val >= 255.0 ) {
	return 255;
    } else {
	return (int)( 255.0 * pow( val / 255.0, gamma ) );
    }
}

int
main( int argc, const char* argv[] )
{
    unsigned int help = 0;
    double linesPerSecond = 64.0;
    unsigned int width = 32;
    double minHz = 128.0;
    double maxHz = 4096.0;
    unsigned int stereo = 0;
    double logMinHz;
    double logMaxHz;
    double* hzTable;
    double  gamma = 0.44;
    unsigned int ii;
    unsigned int yy = 0;
    double* outBuf;

    for ( ii=1; ii < argc; ++ii ) {
	if ( !strcmp( argv[ ii ], "-lps" ) ) {
	    linesPerSecond = strtod( argv[ ++ii ], 0 );
	} else if ( !strcmp( argv[ ii ], "-width" ) ) {
	    width = strtol( argv[ ++ii ], 0, 0 );
	} else if ( !strcmp( argv[ ii ], "-gamma" ) ) {
	    gamma = strtod( argv[ ++ii ], 0 );
	} else if ( !strcmp( argv[ ii ], "-minHz" ) ) {
	    minHz = strtod( argv[ ++ii ], 0 );
	} else if ( !strcmp( argv[ ii ], "-maxHz" ) ) {
	    maxHz = strtod( argv[ ++ii ], 0 );
	} else if ( !strcmp( argv[ ii ], "-freq" ) ) {
	    FREQUENCY = strtol( argv[ ++ii ], 0, 0 );
	} else if ( !strcmp( argv[ ii ], "-stereo" ) ) {
	    stereo = 1;
	} else if ( !strcmp( argv[ ii ], "-wave" ) ) {
	    ++ii;
	    if ( !strcmp( argv[ ii ], "sine" ) ) {
		waveForm = sin;
	    } else if ( !strcmp( argv[ ii ], "square" ) ) {
		waveForm = squareWave;
	    } else if ( !strcmp( argv[ ii ], "triangle" ) ) {
		waveForm = triangleWave;
	    } else if ( !strcmp( argv[ ii ], "sawtooth" ) ) {
		waveForm = sawtoothWave;
	    } else if ( !strcmp( argv[ ii ], "toothsaw" ) ) {
		waveForm = toothsawWave;
	    } else {
		fprintf( stderr, "Unknown waveform: %s\n", argv[ii] );
		help = 1;
	    }
	} else {
	    help = 1;
	}
    }

    if ( FREQUENCY == 0 || linesPerSecond < 0.0000001 || width == 0 ) {
	fprintf( stderr, "Bad parameters\n" );
	help = 1;
    }

    if ( help ) {
	fprintf( stderr, "Usage: %s\n", argv[0] );
	fprintf( stderr, "\t[-lps linesPerSecond]\n" );
	fprintf( stderr, "\t[-width width]\n" );
	fprintf( stderr, "\t[-gamma gamma]\n" );
	fprintf( stderr, "\t[-minHz minimumFrequency]\n" );
	fprintf( stderr, "\t[-maxHz maximumFrequency]\n" );
	fprintf( stderr, "\t[-freq outputSamplesPerSecond]\n" );
	fprintf( stderr, "\t[-stereo]\n" );
	fprintf( stderr,
		"\t[-wave sine | triangle | square | sawtooth | toothsaw ]\n"
	    );
	fprintf( stderr, "\t[-help]\n" );
	return __LINE__;
    }

    if ( minHz < 1.0 ) {
	minHz = 1.0;
    }

    if ( maxHz < 1.0 ) {
	maxHz = 1.0;
    }

    hzTable = (double*)malloc( width * sizeof( double ) );

    if ( hzTable == 0 ) {
	fprintf( stderr, "Couldn't get hzTable memory\n" );
	return __LINE__;
    }

    logMinHz = log( minHz );
    logMaxHz = log( maxHz );

    for ( ii=0; ii < width; ++ii ) {
	double horz = (double) ii / (double)width;
	double logHz = logMinHz + horz * ( logMaxHz - logMinHz );

	hzTable[ ii ] = exp( logHz );
    }

    if ( waveForm == 0 ) {
	waveForm = sin;
    }

    outBuf = (double*)malloc( width * sizeof( double ) );
    if ( outBuf == 0 ) {
	fprintf( stderr, "Couldn't get outBuf memory\n" );
	return __LINE__;
    }

    fprintf( stdout, "%d # %s\n", width, argv[0] );

    while ( !feof( stdin ) ) {
	static unsigned int lastRow = 0;
	static unsigned int lastYY = 0;
	double vert = ( (double) yy * linesPerSecond ) / (double)FREQUENCY;
	double realRow;
	double proportion;
	double value;
	int row;

	proportion = modf( vert, &realRow );
	row = (int)( realRow + 1.5 );

	if ( row != lastRow ) {
	    if ( yy > lastYY ) {
		double scale = 255.0 / (double)( yy - lastYY );

		for ( ii=0; ii < width; ++ii ) {
		    int output = getOutputValue( outBuf[ ii ] * scale, gamma );

		    if ( output < 0 ) {
			output = -output;
			output = 0;
		    }

		    if ( output > 255 ) {
			output = 255;
		    }

		    fputc( output, stdout );
		}
	    }

	    for ( ii=0; ii < width; ++ii ) {
		outBuf[ ii ] = 0.0;
	    }

	    lastRow = row;
	    lastYY = yy;
	}

	if ( stereo ) {
	    value = getValue( stdin ) + getValue( stdin );
	} else {
	    value = getValue( stdin );
	}

	for ( ii=0; ii < width; ++ii ) {
	    outBuf[ ii ] += value * getSample( yy, hzTable[ ii ] );
	}

	++yy;
    }

    return 0;
}