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#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 */
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