#ifndef apu_h
#define apu_h
#include <stdbool.h>
#include <stdint.h>
#include "gb_struct_def.h"


#ifdef GB_INTERNAL
/* Divides nicely and never overflows with 4 channels */
#define MAX_CH_AMP 0x1E00
#define CH_STEP (MAX_CH_AMP/0xF)
#endif

/* Lengths are in either DIV ticks (256Hz, triggered by the DIV register) or
   APU ticks (2MHz, triggered by an internal APU clock)*/

typedef struct
{
    int16_t left;
    int16_t right;
} GB_sample_t;

typedef struct
{
    double left;
    double right;
} GB_double_sample_t;

enum GB_CHANNELS {
    GB_SQUARE_1,
    GB_SQUARE_2,
    GB_WAVE,
    GB_NOISE,
    GB_N_CHANNELS
};

typedef struct
{
    bool global_enable;
    uint8_t left_volume;
    uint8_t right_volume;
    
    uint8_t samples[GB_N_CHANNELS];
    bool left_enabled[GB_N_CHANNELS];
    bool right_enabled[GB_N_CHANNELS];
    bool is_active[GB_N_CHANNELS];
    
    struct {
        bool enable; // NR30
        uint8_t pulse_length; // Reloaded from NR31 (xorred), in DIV ticks
        uint8_t shift; // NR32
        uint16_t sample_length; // NR33, NR34, in APU ticks
        bool length_enabled; // NR34
        
        uint16_t sample_countdown; // in APU ticks
        uint8_t current_sample_index;
        uint8_t current_sample; // Current sample before shifting.
        
        int8_t wave_form[32];
        bool wave_form_just_read;
    } wave_channel;
} GB_apu_t;

void GB_set_sample_rate(GB_gameboy_t *gb, unsigned int sample_rate);
void GB_apu_copy_buffer(GB_gameboy_t *gb, GB_sample_t *dest, unsigned int count);
unsigned GB_apu_get_current_buffer_length(GB_gameboy_t *gb);

#ifdef GB_INTERNAL
void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value);
uint8_t GB_apu_read(GB_gameboy_t *gb, uint8_t reg);
void GB_apu_div_event(GB_gameboy_t *gb);
void GB_apu_init(GB_gameboy_t *gb);
void GB_apu_run(GB_gameboy_t *gb, uint8_t cycles);
#endif

#endif /* apu_h */