#ifndef APU_H
#define APU_H

#include <stdint.h>

struct pulse {
	/* $4000/$4004 */
	uint8_t duty : 2;
	uint8_t envelope : 1;
	uint8_t const_vol : 1;
	uint8_t envelope_vol : 4;
	/* $4001/$4005 */
	uint8_t sweep_enable : 1;
	uint8_t sweep_period : 3;
	uint8_t sweep_negative : 1;
	uint8_t sweep_shift_count : 3;
	/* $4002/$4006 */
	uint8_t timer_low;
	/* $4003/$4007 */
	uint8_t length_counter_load : 5;
	uint8_t timer_high : 3;
};

struct triangle {
	/* $4008 */
	uint8_t counter_disable : 1;
	uint8_t counter_reload : 7;
	/* $400A */
	uint8_t timer_low;
	/* $400B */
	uint8_t counter_load : 5;
	uint8_t timer_high : 3;
};

struct noise {
	/* $400C */
	uint8_t padding1 : 2;
	uint8_t loop_envelope : 1;
	uint8_t constant_volume : 1;
	uint8_t envelope_volume : 4;
	/* $400E */
	uint8_t loop_noise : 1;
	uint8_t padding2 : 3;
	uint8_t noise_period : 4;
	/* $400F */
	uint8_t length_counter_load : 5;
	uint8_t padding3 : 3;
};

struct dmc {
	/* $4010 */
	uint8_t irq_enable : 1;
	uint8_t loop : 1;
	uint8_t padding1 : 2;
	uint8_t frequency : 4;
	/* $4011 */
	uint8_t padding2 : 1;
	uint8_t load_counter : 7;
	/* $4012 */
	uint8_t sample_addr;
	/* $4013 */
	uint8_t sample_length;
};

struct apu {
	/* $4000-$4013 (write) */
	struct pulse pulse1;
	struct pulse pulse2;
	struct triangle triangle;
	struct noise noise;
	struct dmc dmc;
	/* $4015 (write) */
	struct control {
		uint8_t padding : 3;
		uint8_t dmc_enable : 1;
		uint8_t noise_enable : 1;
		uint8_t triangle_enable : 1;
		uint8_t pulse2_enable : 1;
		uint8_t pulse1_enable : 1;
	} control;
	/* $4015 (read) */
	struct status {
		uint8_t dmc_int : 1;
		uint8_t frame_int : 1;
		uint8_t padding : 1;
		uint8_t dmc_active : 1;
		uint8_t lc_noise : 1;
		uint8_t lc_triangle : 1;
		uint8_t lc_pulse2 : 1;
		uint8_t lc_pulse1 : 1;
	} status;
	/* $4017 (write) */
	struct frame_counter {
		uint8_t mode : 1;
		uint8_t irq_inhibit : 1;
		uint8_t padding : 6;
	} frame_counter;
};
extern struct apu apu;

void apu_tick(void);
uint8_t apu_read(uint16_t addr);
void apu_write(uint16_t addr, uint8_t byte);

#endif /* APU_H */