#include <math.h>
#include "instruments.h"
#include "noise.h"

static inline double sine_wave(int step, double period);
static inline double square_wave(int step, double period);
static inline double sawtooth_wave(int step, double period);
static inline double triangle_wave(int step, double period);
static inline double exp_envelope(int step, double dur);

#define INSTRUMENT(name, dur) struct instrument_t name = {inst_##name, (dur)}

static double inst_sine(struct voice_t* v)
{
	return sine_wave(v->step, v->period) * exp_envelope(v->step, v->dur);
}
INSTRUMENT(sine, 1.25);

static double inst_sine_fifths(struct voice_t* v)
{
	return (sine_wave(v->step, v->period) + sine_wave(v->step * pow(2, 7.0 /
			12), v->period)) / 2 * exp_envelope(v->step, v->dur);
}
INSTRUMENT(sine_fifths, 1.25);

static double inst_thunk(struct voice_t* v)
{
	return (sin(cos(2 * M_PI * v->step / v->period) * v->period / (v->step +
			1) * 16) + 1) / 2;
}
INSTRUMENT(thunk, 1.25);

static double inst_square(struct voice_t* v)
{
	return square_wave(v->step, v->period) * exp_envelope(v->step, v->dur);
}
INSTRUMENT(square, 1.25);

static double inst_sawtooth(struct voice_t* v)
{
	return sawtooth_wave(v->step, v->period) * exp_envelope(v->step,
			v->dur);
}
INSTRUMENT(sawtooth, 1.25);

static double inst_tri(struct voice_t* v)
{
	return triangle_wave(v->step, v->period) * exp_envelope(v->step,
			v->dur);
}
INSTRUMENT(tri, 1.25);

static double inst_saw_square(struct voice_t* v)
{
	return (sawtooth_wave(v->step, v->period) + square_wave(v->step,
			v->period)) / 2 * exp_envelope(v->step, v->dur);
}
INSTRUMENT(saw_square, 1);

static double inst_triangle_sines(struct voice_t* v)
{
	return (sine_wave(v->step, v->period) + sine_wave(v->step * 8 / 3,
			v->period) + triangle_wave(v->step, v->period)) / 3 *
			exp_envelope(v->step, v->dur);
}
INSTRUMENT(triangle_sines, 1);

static double inst_weird(struct voice_t* v)
{
	return (sine_wave(v->step, v->period) * (1 - sine_wave(v->step * 8 / 3,
			v->period)) + 2) / 3;
}
INSTRUMENT(weird, 1);

/* Some basic functions used by instruments */
static inline double sine_wave(int step, double period)
{
	return (sin(2 * M_PI * step / period) + 1) / 2;
}

static inline double square_wave(int step, double period)
{
	return step % (int)period > period / 2 ? 1 : 0;
}

static inline double sawtooth_wave(int step, double period)
{
	return (double)(step % (int)period) / period;
}

static inline double triangle_wave(int step, double period)
{
	return (step % (int)period > period / 2 ? 1 - (double)(step % 
			(int)period / 2) / (period / 2) : (double)(step %
			(int)period / 2) / (period / 2)) * 2;
}

static inline double exp_envelope(int step, double dur)
{
	//return 1;
	//return exp(-step / dur);
	return 1 - step / dur;
}