bsnes/Core/gb.h

#ifndef gb_h
#define gb_h
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <time.h>
#include "apu.h"
#include "save_struct.h"


#define GB_STRUCT_VERSION 8

enum {
    GB_REGISTER_AF,
    GB_REGISTER_BC,
    GB_REGISTER_DE,
    GB_REGISTER_HL,
    GB_REGISTER_SP,
    GB_REGISTERS_16_BIT /* Count */
};

/* Todo: Actually use these! */
enum {
    GB_CARRY_FLAG = 16,
    GB_HALF_CARRY_FLAG = 32,
    GB_SUBSTRACT_FLAG = 64,
    GB_ZERO_FLAG = 128,
};

enum {
    /* Joypad and Serial */
    GB_IO_JOYP       = 0x00, // Joypad (R/W)
    GB_IO_SB         = 0x01, // Serial transfer data (R/W)
    GB_IO_SC         = 0x02, // Serial Transfer Control (R/W)

    /* Missing */

    /* Timers */
    GB_IO_DIV        = 0x04, // Divider Register (R/W)
    GB_IO_TIMA       = 0x05, // Timer counter (R/W)
    GB_IO_TMA        = 0x06, // Timer Modulo (R/W)
    GB_IO_TAC        = 0x07, // Timer Control (R/W)

    /* Missing */

    GB_IO_IF         = 0x0f, // Interrupt Flag (R/W)

    /* Sound */
    GB_IO_NR10       = 0x10, // Channel 1 Sweep register (R/W)
    GB_IO_NR11       = 0x11, // Channel 1 Sound length/Wave pattern duty (R/W)
    GB_IO_NR12       = 0x12, // Channel 1 Volume Envelope (R/W)
    GB_IO_NR13       = 0x13, // Channel 1 Frequency lo (Write Only)
    GB_IO_NR14       = 0x14, // Channel 1 Frequency hi (R/W)
    GB_IO_NR21       = 0x16, // Channel 2 Sound Length/Wave Pattern Duty (R/W)
    GB_IO_NR22       = 0x17, // Channel 2 Volume Envelope (R/W)
    GB_IO_NR23       = 0x18, // Channel 2 Frequency lo data (W)
    GB_IO_NR24       = 0x19, // Channel 2 Frequency hi data (R/W)
    GB_IO_NR30       = 0x1a, // Channel 3 Sound on/off (R/W)
    GB_IO_NR31       = 0x1b, // Channel 3 Sound Length
    GB_IO_NR32       = 0x1c, // Channel 3 Select output level (R/W)
    GB_IO_NR33       = 0x1d, // Channel 3 Frequency's lower data (W)
    GB_IO_NR34       = 0x1e, // Channel 3 Frequency's higher data (R/W)

    /* Missing */

    GB_IO_NR41       = 0x20, // Channel 4 Sound Length (R/W)
    GB_IO_NR42       = 0x21, // Channel 4 Volume Envelope (R/W)
    GB_IO_NR43       = 0x22, // Channel 4 Polynomial Counter (R/W)
    GB_IO_NR44       = 0x23, // Channel 4 Counter/consecutive, Inital (R/W)
    GB_IO_NR50       = 0x24, // Channel control / ON-OFF / Volume (R/W)
    GB_IO_NR51       = 0x25, // Selection of Sound output terminal (R/W)
    GB_IO_NR52       = 0x26, // Sound on/off

    /* Missing */

    GB_IO_WAV_START  = 0x30, // Wave pattern start
    GB_IO_WAV_END    = 0x3f, // Wave pattern end

    /* Graphics */
    GB_IO_LCDC       = 0x40, // LCD Control (R/W)
    GB_IO_STAT       = 0x41, // LCDC Status (R/W)
    GB_IO_SCY        = 0x42, // Scroll Y (R/W)
    GB_IO_SCX        = 0x43, // Scroll X (R/W)
    GB_IO_LY         = 0x44, // LCDC Y-Coordinate (R)
    GB_IO_LYC        = 0x45, // LY Compare (R/W)
    GB_IO_DMA        = 0x46, // DMA Transfer and Start Address (W)
    GB_IO_BGP        = 0x47, // BG Palette Data (R/W) - Non CGB Mode Only
    GB_IO_OBP0       = 0x48, // Object Palette 0 Data (R/W) - Non CGB Mode Only
    GB_IO_OBP1       = 0x49, // Object Palette 1 Data (R/W) - Non CGB Mode Only
    GB_IO_WY         = 0x4a, // Window Y Position (R/W)
    GB_IO_WX         = 0x4b, // Window X Position minus 7 (R/W)
    // Has some undocumented compatibility flags written at boot.
    // Unfortunately it is not readable or writable after boot has finished, so research of this
    // register is quite limited. The value written to this register, however, can be controlled
    // in some cases.
    GB_IO_DMG_EMULATION = 0x4c,

    /* General CGB features */
    GB_IO_KEY1       = 0x4d, // CGB Mode Only - Prepare Speed Switch

    /* Missing */

    GB_IO_VBK        = 0x4f, // CGB Mode Only - VRAM Bank
    GB_IO_BIOS       = 0x50, // Write to disable the BIOS mapping

    /* CGB DMA */
    GB_IO_HDMA1      = 0x51, // CGB Mode Only - New DMA Source, High
    GB_IO_HDMA2      = 0x52, // CGB Mode Only - New DMA Source, Low
    GB_IO_HDMA3      = 0x53, // CGB Mode Only - New DMA Destination, High
    GB_IO_HDMA4      = 0x54, // CGB Mode Only - New DMA Destination, Low
    GB_IO_HDMA5      = 0x55, // CGB Mode Only - New DMA Length/Mode/Start

    /* IR */
    GB_IO_RP         = 0x56, // CGB Mode Only - Infrared Communications Port

    /* Missing */

    /* CGB Paletts */
    GB_IO_BGPI       = 0x68, // CGB Mode Only - Background Palette Index
    GB_IO_BGPD       = 0x69, // CGB Mode Only - Background Palette Data
    GB_IO_OBPI       = 0x6a, // CGB Mode Only - Sprite Palette Index
    GB_IO_OBPD       = 0x6b, // CGB Mode Only - Sprite Palette Data

    // 1 is written for DMG ROMs on a CGB. Does not appear to have an effect.
    GB_IO_DMG_EMULATION_INDICATION   = 0x6c, // (FEh) Bit 0 (Read/Write)

    /* Missing */

    GB_IO_SVBK       = 0x70, // CGB Mode Only - WRAM Bank
    GB_IO_UNKNOWN2   = 0x72, // (00h) - Bit 0-7 (Read/Write)
    GB_IO_UNKNOWN3   = 0x73, // (00h) - Bit 0-7 (Read/Write)
    GB_IO_UNKNOWN4   = 0x74, // (00h) - Bit 0-7 (Read/Write) - CGB Mode Only
    GB_IO_UNKNOWN5   = 0x75, // (8Fh) - Bit 4-6 (Read/Write)
    GB_IO_PCM_12     = 0x76, // Channels 1 and 2 amplitudes
    GB_IO_PCM_34     = 0x77, // Channels 3 and 4 amplitudes
    GB_IO_UNKNOWN8   = 0x7F, // Unknown, write only
};

#define LCDC_PERIOD 70224
#define CPU_FREQUENCY 0x400000
#define DIV_CYCLES (0x100)
#define FRAME_LENGTH 16742706 // in nanoseconds

typedef enum {
    GB_LOG_BOLD = 1,
    GB_LOG_DASHED_UNDERLINE = 2,
    GB_LOG_UNDERLINE = 4,
    GB_LOG_UNDERLINE_MASK =  GB_LOG_DASHED_UNDERLINE | GB_LOG_UNDERLINE
} gb_log_attributes;

struct GB_gameboy_s;
typedef struct GB_gameboy_s GB_gameboy_t;
typedef void (*GB_vblank_callback_t)(GB_gameboy_t *gb);
typedef void (*GB_log_callback_t)(GB_gameboy_t *gb, const char *string, gb_log_attributes attributes);
typedef char *(*GB_input_callback_t)(GB_gameboy_t *gb);
typedef uint32_t (*GB_rgb_encode_callback_t)(GB_gameboy_t *gb, unsigned char r, unsigned char g, unsigned char b);

typedef struct {
    enum {
        NO_MBC,
        MBC1,
        MBC2,
        MBC3,
        MBC4, // Does this exist???
        MBC5,
    } mbc_type;
    bool has_ram;
    bool has_battery;
    bool has_rtc;
    bool has_rumble;
} GB_cartridge_t;

/* When state saving, each section is dumped independently of other sections.
   This allows adding data to the end of the section without worrying about future compatibility.
   Some other changes might be "safe" as well. */

typedef struct GB_gameboy_s {
    GB_SECTION(header,
        uintptr_t magic; // States are currently platform dependent
        int version; // and version dependent
    );

    GB_SECTION(core_state,
        /* Registers */
        unsigned short pc;
        unsigned short registers[GB_REGISTERS_16_BIT];
        bool ime;
        unsigned char interrupt_enable;
        unsigned char cgb_ram_bank;

        /* CPU and General Hardware Flags*/
        bool cgb_mode;
        bool is_cgb;
        bool cgb_double_speed;
        bool halted;
        bool stopped;
        bool bios_finished;
    );

    /* HDMA */
    GB_SECTION(hdma,
        bool hdma_on;
        bool hdma_on_hblank;
        unsigned char hdma_steps_left;
        unsigned short hdma_cycles;
        unsigned short hdma_current_src, hdma_current_dest;
    );
    
    /* MBC */
    GB_SECTION(mbc,
        unsigned short mbc_rom_bank;
        unsigned char mbc_ram_bank;
        size_t mbc_ram_size;
        bool mbc_ram_enable;
        bool mbc_ram_banking;
    );


    /* HRAM and HW Registers */
    GB_SECTION(hram,
        unsigned char hram[0xFFFF - 0xFF80];
        unsigned char io_registers[0x80];
    );

    /* Timing */
    GB_SECTION(timing,
        signed long last_vblank;
        unsigned long display_cycles;
        unsigned long div_cycles;
        unsigned long tima_cycles;
        unsigned long dma_cycles;
        double apu_cycles;
    );

    /* APU */
    GB_SECTION(apu,
        GB_apu_t apu;
    );

    /* RTC */
    GB_SECTION(rtc,
        union {
            struct {
                unsigned char rtc_seconds;
                unsigned char rtc_minutes;
                unsigned char rtc_hours;
                unsigned char rtc_days;
                unsigned char rtc_high;
            };
            unsigned char rtc_data[5];
        };
        time_t last_rtc_second;
    );

    /* Video Display */
    GB_SECTION(video,
        unsigned long vram_size; // Different between CGB and DMG
        unsigned char cgb_vram_bank;
        unsigned char oam[0xA0];
        unsigned char background_palletes_data[0x40];
        unsigned char sprite_palletes_data[0x40];
        uint32_t background_palletes_rgb[0x20];
        uint32_t sprite_palletes_rgb[0x20];
        GB_PADDING(bool, ly144_bug_oam);
        GB_PADDING(bool, ly144_bug_hblank);
        signed short previous_lcdc_x;
        unsigned char padding;
        bool effective_window_enabled;
        unsigned char effective_window_y;
        bool stat_interrupt_line;
        unsigned char effective_scx;
    );

    /* Unsaved data. This includes all pointers, as well as everything that shouldn't be on a save state */

    /* ROM */
    unsigned char *rom;
    size_t rom_size;
    const GB_cartridge_t *cartridge_type;

    /* Various RAMs */
    unsigned char *ram;
    unsigned char *vram;
    unsigned char *mbc_ram;

    /* I/O */
    uint32_t *screen;
    GB_sample_t *audio_buffer;
    bool keys[8];

    /* Audio Specific */
    unsigned int buffer_size;
    unsigned int sample_rate;
    unsigned int audio_position;
    bool audio_stream_started; // detects first copy request to minimize lag
    volatile bool audio_copy_in_progress;

    /* Callbacks */
    void *user_data;
    GB_log_callback_t log_callback;
    GB_input_callback_t input_callback;
    GB_rgb_encode_callback_t rgb_encode_callback;
    GB_vblank_callback_t vblank_callback;

    /* Debugger */
    int debug_call_depth;
    bool debug_fin_command, debug_next_command;
    unsigned short n_breakpoints;
    unsigned short *breakpoints;
    bool stack_leak_detection;
    unsigned short sp_for_call_depth[0x200]; /* Should be much more than enough */
    unsigned short addr_for_call_depth[0x200];
    bool debug_stopped;

    /* Misc */
    bool turbo;
    unsigned long ram_size; // Different between CGB and DMG
    unsigned char bios[0x900];

} GB_gameboy_t;

#ifndef __printflike
/* Missing from Linux headers. */
#define __printflike(fmtarg, firstvararg) \
__attribute__((__format__ (__printf__, fmtarg, firstvararg)))
#endif

void gb_init(GB_gameboy_t *gb);
void gb_init_cgb(GB_gameboy_t *gb);
void gb_free(GB_gameboy_t *gb);
int gb_load_bios(GB_gameboy_t *gb, const char *path);
int gb_load_rom(GB_gameboy_t *gb, const char *path);
int gb_save_battery(GB_gameboy_t *gb, const char *path);
void gb_load_battery(GB_gameboy_t *gb, const char *path);
int gb_save_state(GB_gameboy_t *gb, const char *path);
int gb_load_state(GB_gameboy_t *gb, const char *path);
void gb_run(GB_gameboy_t *gb);
void gb_set_pixels_output(GB_gameboy_t *gb, uint32_t *output);
void gb_set_vblank_callback(GB_gameboy_t *gb, GB_vblank_callback_t callback);
void gb_set_log_callback(GB_gameboy_t *gb, GB_log_callback_t callback);
void gb_log(GB_gameboy_t *gb, const char *fmt, ...) __printflike(2, 3);
void gb_attributed_log(GB_gameboy_t *gb, gb_log_attributes attributes, const char *fmt, ...) __printflike(3, 4);
void gb_set_input_callback(GB_gameboy_t *gb, GB_input_callback_t callback);
void gb_set_sample_rate(GB_gameboy_t *gb, unsigned int sample_rate);
void gb_set_rgb_encode_callback(GB_gameboy_t *gb, GB_rgb_encode_callback_t callback);

#endif /* gb_h */