tone-generator/tone.hpp

#pragma once

#include <inttypes.h>
#include <avr/pgmspace.h>
#include "util.hpp"

extern const PROGMEM int8_t TONE_LOOKUP[4][256];

struct Tone {

	enum Type {
		tt_sine     = 0,
		tt_saw      = 1,
		tt_square   = 2,
		tt_triangle = 3,
	};

	uint32_t phase;
	uint16_t frequency;
	uint8_t amplitude;
	Type mode;


	inline bool active() const AW_IN {
		return amplitude > 0;
	}

	inline void update(uint32_t t) AW_IN {
		phase += t * frequency;
	}

	inline int get() const AW_IN {
		int8_t v = pgm_read_byte_near(&TONE_LOOKUP[mode][(uint8_t)(phase >> 12)]);
		return (int)v * amplitude;
	}
};