SameBoy/Core/gb.c

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <stdarg.h>
#ifndef _WIN32
#include <sys/select.h>
#include <unistd.h>
#endif
#include "random.h"
#include "gb.h"


#ifdef DISABLE_REWIND
#define GB_rewind_free(...)
#define GB_rewind_push(...)
#endif


static inline uint32_t state_magic(void)
{
    if (sizeof(bool) == 1) return 'SAME';
    return 'S4ME';
}

void GB_attributed_logv(GB_gameboy_t *gb, GB_log_attributes attributes, const char *fmt, va_list args)
{
    char *string = NULL;
    vasprintf(&string, fmt, args);
    if (string) {
        if (gb->log_callback) {
            gb->log_callback(gb, string, attributes);
        }
        else {
            /* Todo: Add ANSI escape sequences for attributed text */
            printf("%s", string);
        }
    }
    free(string);
}

void GB_attributed_log(GB_gameboy_t *gb, GB_log_attributes attributes, const char *fmt, ...)
{
    va_list args;
    va_start(args, fmt);
    GB_attributed_logv(gb, attributes, fmt, args);
    va_end(args);
}

void GB_log(GB_gameboy_t *gb, const char *fmt, ...)
{
    va_list args;
    va_start(args, fmt);
    GB_attributed_logv(gb, 0, fmt, args);
    va_end(args);
}

#ifndef DISABLE_DEBUGGER
static char *default_input_callback(GB_gameboy_t *gb)
{
    char *expression = NULL;
    size_t size = 0;

    if (getline(&expression, &size, stdin) == -1) {
        /* The user doesn't have STDIN or used ^D. We make sure the program keeps running. */
        GB_set_async_input_callback(gb, NULL); /* Disable async input */
        return strdup("c");
    }

    if (!expression) {
        return strdup("");
    }

    size_t length = strlen(expression);
    if (expression[length - 1] == '\n') {
        expression[length - 1] = 0;
    }
    return expression;
}

static char *default_async_input_callback(GB_gameboy_t *gb)
{
#ifndef _WIN32
    fd_set set;
    FD_ZERO(&set);
    FD_SET(STDIN_FILENO, &set);
    struct timeval time = {0,};
    if (select(1, &set, NULL, NULL, &time) == 1) {
        if (feof(stdin)) {
            GB_set_async_input_callback(gb, NULL); /* Disable async input */
            return NULL;
        }
        return default_input_callback(gb);
    }
#endif
    return NULL;
}
#endif

void GB_init(GB_gameboy_t *gb, GB_model_t model)
{
    memset(gb, 0, sizeof(*gb));
    gb->model = model;
    if (GB_is_cgb(gb)) {
        gb->ram = malloc(gb->ram_size = 0x1000 * 8);
        gb->vram = malloc(gb->vram_size = 0x2000 * 2);
    }
    else {
        gb->ram = malloc(gb->ram_size = 0x2000);
        gb->vram = malloc(gb->vram_size = 0x2000);
    }

#ifndef DISABLE_DEBUGGER
    gb->input_callback = default_input_callback;
    gb->async_input_callback = default_async_input_callback;
#endif
    gb->cartridge_type = &GB_cart_defs[0]; // Default cartridge type
    gb->clock_multiplier = 1.0;
    
    if (model & GB_MODEL_NO_SFC_BIT) {
        /* Disable time syncing. Timing should be done by the SFC emulator. */
        gb->turbo = true;
    }
    
    GB_reset(gb);
}

GB_model_t GB_get_model(GB_gameboy_t *gb)
{
    return gb->model;
}

void GB_free(GB_gameboy_t *gb)
{
    gb->magic = 0;
    if (gb->ram) {
        free(gb->ram);
    }
    if (gb->vram) {
        free(gb->vram);
    }
    if (gb->mbc_ram) {
        free(gb->mbc_ram);
    }
    if (gb->rom) {
        free(gb->rom);
    }
    if (gb->breakpoints) {
        free(gb->breakpoints);
    }
    if (gb->sgb) {
        free(gb->sgb);
    }
    if (gb->nontrivial_jump_state) {
        free(gb->nontrivial_jump_state);
    }
#ifndef DISABLE_DEBUGGER
    GB_debugger_clear_symbols(gb);
#endif
    GB_rewind_free(gb);
    memset(gb, 0, sizeof(*gb));
}

int GB_load_boot_rom(GB_gameboy_t *gb, const char *path)
{
    FILE *f = fopen(path, "rb");
    if (!f) {
        GB_log(gb, "Could not open boot ROM: %s.\n", strerror(errno));
        return errno;
    }
    fread(gb->boot_rom, sizeof(gb->boot_rom), 1, f);
    fclose(f);
    return 0;
}

void GB_load_boot_rom_from_buffer(GB_gameboy_t *gb, const unsigned char *buffer, size_t size)
{
    if (size > sizeof(gb->boot_rom)) {
        size = sizeof(gb->boot_rom);
    }
    memset(gb->boot_rom, 0xFF, sizeof(gb->boot_rom));
    memcpy(gb->boot_rom, buffer, size);
}

int GB_load_rom(GB_gameboy_t *gb, const char *path)
{
    FILE *f = fopen(path, "rb");
    if (!f) {
        GB_log(gb, "Could not open ROM: %s.\n", strerror(errno));
        return errno;
    }
    fseek(f, 0, SEEK_END);
    gb->rom_size = (ftell(f) + 0x3FFF) & ~0x3FFF; /* Round to bank */
    /* And then round to a power of two */
    while (gb->rom_size & (gb->rom_size - 1)) {
        /* I promise this works. */
        gb->rom_size |= gb->rom_size >> 1;
        gb->rom_size++;
    }
    fseek(f, 0, SEEK_SET);
    if (gb->rom) {
        free(gb->rom);
    }
    gb->rom = malloc(gb->rom_size);
    memset(gb->rom, 0xFF, gb->rom_size); /* Pad with 0xFFs */
    fread(gb->rom, 1, gb->rom_size, f);
    fclose(f);
    GB_configure_cart(gb);

    return 0;
}

void GB_load_rom_from_buffer(GB_gameboy_t *gb, const uint8_t *buffer, size_t size)
{
    gb->rom_size = (size + 0x3fff) & ~0x3fff;
    while (gb->rom_size & (gb->rom_size - 1)) {
        gb->rom_size |= gb->rom_size >> 1;
        gb->rom_size++;
    }
    if (gb->rom) {
        free(gb->rom);
    }
    gb->rom = malloc(gb->rom_size);
    memset(gb->rom, 0xff, gb->rom_size);
    memcpy(gb->rom, buffer, size);
    GB_configure_cart(gb);
}

typedef struct {
    uint8_t seconds;
    uint8_t padding1[3];
    uint8_t minutes;
    uint8_t padding2[3];
    uint8_t hours;
    uint8_t padding3[3];
    uint8_t days;
    uint8_t padding4[3];
    uint8_t high;
    uint8_t padding5[3];
} GB_vba_rtc_time_t;

typedef union {
    struct __attribute__((packed)) {
        GB_rtc_time_t rtc_real;
        time_t last_rtc_second; /* Platform specific endianess and size */
    } sameboy_legacy;
    struct {
        /* Used by VBA versions with 32-bit timestamp*/
        GB_vba_rtc_time_t rtc_real, rtc_latched;
        uint32_t last_rtc_second; /* Always little endian */
    } vba32;
    struct {
        /* Used by BGB and VBA versions with 64-bit timestamp*/
        GB_vba_rtc_time_t rtc_real, rtc_latched;
        uint64_t last_rtc_second; /* Always little endian */
    } vba64;
} GB_rtc_save_t;

int GB_save_battery_size(GB_gameboy_t *gb)
{
    if (!gb->cartridge_type->has_battery) return 0; // Nothing to save.
    if (gb->mbc_ram_size == 0 && !gb->cartridge_type->has_rtc) return 0; /* Claims to have battery, but has no RAM or RTC */

    GB_rtc_save_t rtc_save_size;
    return gb->mbc_ram_size + (gb->cartridge_type->has_rtc ? sizeof(rtc_save_size.vba64) : 0);
}

int GB_save_battery_to_buffer(GB_gameboy_t *gb, uint8_t *buffer, size_t size)
{
    if (!gb->cartridge_type->has_battery) return 0; // Nothing to save.
    if (gb->mbc_ram_size == 0 && !gb->cartridge_type->has_rtc) return 0; /* Claims to have battery, but has no RAM or RTC */

    if (size < GB_save_battery_size(gb)) return EIO;

    memcpy(buffer, gb->mbc_ram, gb->mbc_ram_size);

    if (gb->cartridge_type->has_rtc) {
        GB_rtc_save_t rtc_save = {{{{0,}},},};
        rtc_save.vba64.rtc_real.seconds = gb->rtc_real.seconds;
        rtc_save.vba64.rtc_real.minutes = gb->rtc_real.minutes;
        rtc_save.vba64.rtc_real.hours = gb->rtc_real.hours;
        rtc_save.vba64.rtc_real.days = gb->rtc_real.days;
        rtc_save.vba64.rtc_real.high = gb->rtc_real.high;
        rtc_save.vba64.rtc_latched.seconds = gb->rtc_latched.seconds;
        rtc_save.vba64.rtc_latched.minutes = gb->rtc_latched.minutes;
        rtc_save.vba64.rtc_latched.hours = gb->rtc_latched.hours;
        rtc_save.vba64.rtc_latched.days = gb->rtc_latched.days;
        rtc_save.vba64.rtc_latched.high = gb->rtc_latched.high;
#ifdef GB_BIG_ENDIAN
        rtc_save.vba64.last_rtc_second = __builtin_bswap64(gb->last_rtc_second);
#else
        rtc_save.vba64.last_rtc_second = gb->last_rtc_second;
#endif
        memcpy(buffer + gb->mbc_ram_size, &rtc_save.vba64, sizeof(rtc_save.vba64));
    }

    errno = 0;
    return errno;
}

int GB_save_battery(GB_gameboy_t *gb, const char *path)
{
    if (!gb->cartridge_type->has_battery) return 0; // Nothing to save.
    if (gb->mbc_ram_size == 0 && !gb->cartridge_type->has_rtc) return 0; /* Claims to have battery, but has no RAM or RTC */
    FILE *f = fopen(path, "wb");
    if (!f) {
        GB_log(gb, "Could not open battery save: %s.\n", strerror(errno));
        return errno;
    }

    if (fwrite(gb->mbc_ram, 1, gb->mbc_ram_size, f) != gb->mbc_ram_size) {
        fclose(f);
        return EIO;
    }
    if (gb->cartridge_type->has_rtc) {
        GB_rtc_save_t rtc_save = {{{{0,}},},};
        rtc_save.vba64.rtc_real.seconds = gb->rtc_real.seconds;
        rtc_save.vba64.rtc_real.minutes = gb->rtc_real.minutes;
        rtc_save.vba64.rtc_real.hours = gb->rtc_real.hours;
        rtc_save.vba64.rtc_real.days = gb->rtc_real.days;
        rtc_save.vba64.rtc_real.high = gb->rtc_real.high;
        rtc_save.vba64.rtc_latched.seconds = gb->rtc_latched.seconds;
        rtc_save.vba64.rtc_latched.minutes = gb->rtc_latched.minutes;
        rtc_save.vba64.rtc_latched.hours = gb->rtc_latched.hours;
        rtc_save.vba64.rtc_latched.days = gb->rtc_latched.days;
        rtc_save.vba64.rtc_latched.high = gb->rtc_latched.high;
#ifdef GB_BIG_ENDIAN
        rtc_save.vba64.last_rtc_second = __builtin_bswap64(gb->last_rtc_second);
#else
        rtc_save.vba64.last_rtc_second = gb->last_rtc_second;
#endif
        if (fwrite(&rtc_save.vba64, 1, sizeof(rtc_save.vba64), f) != sizeof(rtc_save.vba64)) {
            fclose(f);
            return EIO;
        }

    }

    errno = 0;
    fclose(f);
    return errno;
}

void GB_load_battery_from_buffer(GB_gameboy_t *gb, const uint8_t *buffer, size_t size)
{
    memcpy(gb->mbc_ram, buffer, MIN(gb->mbc_ram_size, size));
    if (size <= gb->mbc_ram_size) {
        goto reset_rtc;
    }

    GB_rtc_save_t rtc_save;
    memcpy(&rtc_save, buffer + gb->mbc_ram_size, MIN(sizeof(rtc_save), size));
    switch (size - gb->mbc_ram_size) {
        case sizeof(rtc_save.sameboy_legacy):
            memcpy(&gb->rtc_real, &rtc_save.sameboy_legacy.rtc_real, sizeof(gb->rtc_real));
            memcpy(&gb->rtc_latched, &rtc_save.sameboy_legacy.rtc_real, sizeof(gb->rtc_real));
            gb->last_rtc_second = rtc_save.sameboy_legacy.last_rtc_second;
            break;
            
        case sizeof(rtc_save.vba32):
            gb->rtc_real.seconds = rtc_save.vba32.rtc_real.seconds;
            gb->rtc_real.minutes = rtc_save.vba32.rtc_real.minutes;
            gb->rtc_real.hours = rtc_save.vba32.rtc_real.hours;
            gb->rtc_real.days = rtc_save.vba32.rtc_real.days;
            gb->rtc_real.high = rtc_save.vba32.rtc_real.high;
            gb->rtc_latched.seconds = rtc_save.vba32.rtc_latched.seconds;
            gb->rtc_latched.minutes = rtc_save.vba32.rtc_latched.minutes;
            gb->rtc_latched.hours = rtc_save.vba32.rtc_latched.hours;
            gb->rtc_latched.days = rtc_save.vba32.rtc_latched.days;
            gb->rtc_latched.high = rtc_save.vba32.rtc_latched.high;
#ifdef GB_BIG_ENDIAN
            gb->last_rtc_second = __builtin_bswap32(rtc_save.vba32.last_rtc_second);
#else
            gb->last_rtc_second = rtc_save.vba32.last_rtc_second;
#endif
            break;
            
        case sizeof(rtc_save.vba64):
            gb->rtc_real.seconds = rtc_save.vba64.rtc_real.seconds;
            gb->rtc_real.minutes = rtc_save.vba64.rtc_real.minutes;
            gb->rtc_real.hours = rtc_save.vba64.rtc_real.hours;
            gb->rtc_real.days = rtc_save.vba64.rtc_real.days;
            gb->rtc_real.high = rtc_save.vba64.rtc_real.high;
            gb->rtc_latched.seconds = rtc_save.vba64.rtc_latched.seconds;
            gb->rtc_latched.minutes = rtc_save.vba64.rtc_latched.minutes;
            gb->rtc_latched.hours = rtc_save.vba64.rtc_latched.hours;
            gb->rtc_latched.days = rtc_save.vba64.rtc_latched.days;
            gb->rtc_latched.high = rtc_save.vba64.rtc_latched.high;
#ifdef GB_BIG_ENDIAN
            gb->last_rtc_second = __builtin_bswap64(rtc_save.vba64.last_rtc_second);
#else
            gb->last_rtc_second = rtc_save.vba64.last_rtc_second;
#endif
            break;
            
        default:
            goto reset_rtc;
    }
    if (gb->last_rtc_second > time(NULL)) {
        /* We must reset RTC here, or it will not advance. */
        goto reset_rtc;
    }

    if (gb->last_rtc_second < 852076800) { /* 1/1/97. There weren't any RTC games that time,
                                            so if the value we read is lower it means it wasn't
                                            really RTC data. */
        goto reset_rtc;
    }
    goto exit;
reset_rtc:
    gb->last_rtc_second = time(NULL);
    gb->rtc_real.high |= 0x80; /* This gives the game a hint that the clock should be reset. */
exit:
    return;
}

/* Loading will silently stop if the format is incomplete */
void GB_load_battery(GB_gameboy_t *gb, const char *path)
{
    FILE *f = fopen(path, "rb");
    if (!f) {
        return;
    }

    if (fread(gb->mbc_ram, 1, gb->mbc_ram_size, f) != gb->mbc_ram_size) {
        goto reset_rtc;
    }

    GB_rtc_save_t rtc_save;
    switch (fread(&rtc_save, 1, sizeof(rtc_save), f)) {
        case sizeof(rtc_save.sameboy_legacy):
            memcpy(&gb->rtc_real, &rtc_save.sameboy_legacy.rtc_real, sizeof(gb->rtc_real));
            memcpy(&gb->rtc_latched, &rtc_save.sameboy_legacy.rtc_real, sizeof(gb->rtc_real));
            gb->last_rtc_second = rtc_save.sameboy_legacy.last_rtc_second;
            break;
            
        case sizeof(rtc_save.vba32):
            gb->rtc_real.seconds = rtc_save.vba32.rtc_real.seconds;
            gb->rtc_real.minutes = rtc_save.vba32.rtc_real.minutes;
            gb->rtc_real.hours = rtc_save.vba32.rtc_real.hours;
            gb->rtc_real.days = rtc_save.vba32.rtc_real.days;
            gb->rtc_real.high = rtc_save.vba32.rtc_real.high;
            gb->rtc_latched.seconds = rtc_save.vba32.rtc_latched.seconds;
            gb->rtc_latched.minutes = rtc_save.vba32.rtc_latched.minutes;
            gb->rtc_latched.hours = rtc_save.vba32.rtc_latched.hours;
            gb->rtc_latched.days = rtc_save.vba32.rtc_latched.days;
            gb->rtc_latched.high = rtc_save.vba32.rtc_latched.high;
#ifdef GB_BIG_ENDIAN
            gb->last_rtc_second = __builtin_bswap32(rtc_save.vba32.last_rtc_second);
#else
            gb->last_rtc_second = rtc_save.vba32.last_rtc_second;
#endif
            break;
            
        case sizeof(rtc_save.vba64):
            gb->rtc_real.seconds = rtc_save.vba64.rtc_real.seconds;
            gb->rtc_real.minutes = rtc_save.vba64.rtc_real.minutes;
            gb->rtc_real.hours = rtc_save.vba64.rtc_real.hours;
            gb->rtc_real.days = rtc_save.vba64.rtc_real.days;
            gb->rtc_real.high = rtc_save.vba64.rtc_real.high;
            gb->rtc_latched.seconds = rtc_save.vba64.rtc_latched.seconds;
            gb->rtc_latched.minutes = rtc_save.vba64.rtc_latched.minutes;
            gb->rtc_latched.hours = rtc_save.vba64.rtc_latched.hours;
            gb->rtc_latched.days = rtc_save.vba64.rtc_latched.days;
            gb->rtc_latched.high = rtc_save.vba64.rtc_latched.high;
#ifdef GB_BIG_ENDIAN
            gb->last_rtc_second = __builtin_bswap64(rtc_save.vba64.last_rtc_second);
#else
            gb->last_rtc_second = rtc_save.vba64.last_rtc_second;
#endif
            break;
            
        default:
            goto reset_rtc;
    }
    if (gb->last_rtc_second > time(NULL)) {
        /* We must reset RTC here, or it will not advance. */
        goto reset_rtc;
    }

    if (gb->last_rtc_second < 852076800) { /* 1/1/97. There weren't any RTC games that time,
                                            so if the value we read is lower it means it wasn't
                                            really RTC data. */
        goto reset_rtc;
    }
    goto exit;
reset_rtc:
    gb->last_rtc_second = time(NULL);
    gb->rtc_real.high |= 0x80; /* This gives the game a hint that the clock should be reset. */
exit:
    fclose(f);
    return;
}

uint8_t GB_run(GB_gameboy_t *gb)
{
    gb->vblank_just_occured = false;

    if (gb->sgb && gb->sgb->intro_animation < 140) {
        /* On the SGB, the GB is halted after finishing the boot ROM.
           Then, after the boot animation is almost done, it's reset.
           Since the SGB HLE does not perform any header validity checks,
           we just halt the CPU (with hacky code) until the correct time.
           This ensures the Nintendo logo doesn't flash on screen, and
           the game does "run in background" while the animation is playing. */
        GB_display_run(gb, 228);
        gb->cycles_since_last_sync += 228;
        return 228;
    }
    
    GB_debugger_run(gb);
    gb->cycles_since_run = 0;
    GB_cpu_run(gb);
    if (gb->vblank_just_occured) {
        GB_rtc_run(gb);
        GB_debugger_handle_async_commands(gb);
        GB_rewind_push(gb);
    }
    return gb->cycles_since_run;
}

uint64_t GB_run_frame(GB_gameboy_t *gb)
{
    /* Configure turbo temporarily, the user wants to handle FPS capping manually. */
    bool old_turbo = gb->turbo;
    bool old_dont_skip = gb->turbo_dont_skip;
    gb->turbo = true;
    gb->turbo_dont_skip = true;
    
    gb->cycles_since_last_sync = 0;
    while (true) {
        GB_run(gb);
        if (gb->vblank_just_occured) {
            break;
        }
    }
    gb->turbo = old_turbo;
    gb->turbo_dont_skip = old_dont_skip;
    return gb->cycles_since_last_sync * 1000000000LL / 2 / GB_get_clock_rate(gb); /* / 2 because we use 8MHz units */
}

void GB_set_pixels_output(GB_gameboy_t *gb, uint32_t *output)
{
    gb->screen = output;
}

void GB_set_vblank_callback(GB_gameboy_t *gb, GB_vblank_callback_t callback)
{
    gb->vblank_callback = callback;
}

void GB_set_log_callback(GB_gameboy_t *gb, GB_log_callback_t callback)
{
    gb->log_callback = callback;
}

void GB_set_input_callback(GB_gameboy_t *gb, GB_input_callback_t callback)
{
#ifndef DISABLE_DEBUGGER
    if (gb->input_callback == default_input_callback) {
        gb->async_input_callback = NULL;
    }
    gb->input_callback = callback;
#endif
}

void GB_set_async_input_callback(GB_gameboy_t *gb, GB_input_callback_t callback)
{
#ifndef DISABLE_DEBUGGER
    gb->async_input_callback = callback;
#endif
}


void GB_set_rgb_encode_callback(GB_gameboy_t *gb, GB_rgb_encode_callback_t callback)
{
    if (!gb->rgb_encode_callback && !GB_is_cgb(gb)) {
        gb->sprite_palettes_rgb[4] = gb->sprite_palettes_rgb[0] = gb->background_palettes_rgb[0] =
        callback(gb, 0xFF, 0xFF, 0xFF);
        gb->sprite_palettes_rgb[5] = gb->sprite_palettes_rgb[1] = gb->background_palettes_rgb[1] =
        callback(gb, 0xAA, 0xAA, 0xAA);
        gb->sprite_palettes_rgb[6] = gb->sprite_palettes_rgb[2] = gb->background_palettes_rgb[2] =
        callback(gb, 0x55, 0x55, 0x55);
        gb->sprite_palettes_rgb[7] = gb->sprite_palettes_rgb[3] = gb->background_palettes_rgb[3] =
        callback(gb, 0, 0, 0);
    }

    gb->rgb_encode_callback = callback;
    
    for (unsigned i = 0; i < 32; i++) {
        GB_palette_changed(gb, true, i * 2);
        GB_palette_changed(gb, false, i * 2);
    }
}

void GB_set_infrared_callback(GB_gameboy_t *gb, GB_infrared_callback_t callback)
{
    gb->infrared_callback = callback;
}

void GB_set_infrared_input(GB_gameboy_t *gb, bool state)
{
    gb->infrared_input = state;
    gb->cycles_since_input_ir_change = 0;
    gb->ir_queue_length = 0;
}

void GB_queue_infrared_input(GB_gameboy_t *gb, bool state, long cycles_after_previous_change)
{
    if (gb->ir_queue_length == GB_MAX_IR_QUEUE) {
        GB_log(gb, "IR Queue is full\n");
        return;
    }
    gb->ir_queue[gb->ir_queue_length++] = (GB_ir_queue_item_t){state, cycles_after_previous_change};
}

void GB_set_rumble_callback(GB_gameboy_t *gb, GB_rumble_callback_t callback)
{
    gb->rumble_callback = callback;
}

void GB_set_serial_transfer_bit_start_callback(GB_gameboy_t *gb, GB_serial_transfer_bit_start_callback_t callback)
{
    gb->serial_transfer_bit_start_callback = callback;
}

void GB_set_serial_transfer_bit_end_callback(GB_gameboy_t *gb, GB_serial_transfer_bit_end_callback_t callback)
{
    gb->serial_transfer_bit_end_callback = callback;
}

bool GB_serial_get_data_bit(GB_gameboy_t *gb)
{
    if (gb->io_registers[GB_IO_SC] & 1) {
        /* Internal Clock */
        GB_log(gb, "Serial read request while using internal clock. \n");
        return 0xFF;
    }
    return gb->io_registers[GB_IO_SB] & 0x80;
}
void GB_serial_set_data_bit(GB_gameboy_t *gb, bool data)
{
    if (gb->io_registers[GB_IO_SC] & 1) {
        /* Internal Clock */
        GB_log(gb, "Serial write request while using internal clock. \n");
        return;
    }
    gb->io_registers[GB_IO_SB] <<= 1;
    gb->io_registers[GB_IO_SB] |= data;
    gb->serial_count++;
    if (gb->serial_count == 8) {
        gb->io_registers[GB_IO_IF] |= 8;
        gb->serial_count = 0;
    }
}

void GB_disconnect_serial(GB_gameboy_t *gb)
{
    gb->serial_transfer_bit_start_callback = NULL;
    gb->serial_transfer_bit_end_callback = NULL;
    
    /* Reset any internally-emulated device. Currently, only the printer. */
    memset(&gb->printer, 0, sizeof(gb->printer));
}

bool GB_is_inited(GB_gameboy_t *gb)
{
    return gb->magic == state_magic();
}

bool GB_is_cgb(GB_gameboy_t *gb)
{
    return (gb->model & GB_MODEL_FAMILY_MASK) == GB_MODEL_CGB_FAMILY;
}

bool GB_is_sgb(GB_gameboy_t *gb)
{
    return (gb->model & ~GB_MODEL_PAL_BIT & ~GB_MODEL_NO_SFC_BIT) == GB_MODEL_SGB || (gb->model & ~GB_MODEL_NO_SFC_BIT) == GB_MODEL_SGB2;
}

bool GB_is_hle_sgb(GB_gameboy_t *gb)
{
    return (gb->model & ~GB_MODEL_PAL_BIT) == GB_MODEL_SGB || gb->model == GB_MODEL_SGB2;
}

void GB_set_turbo_mode(GB_gameboy_t *gb, bool on, bool no_frame_skip)
{
    gb->turbo = on;
    gb->turbo_dont_skip = no_frame_skip;
}

void GB_set_rendering_disabled(GB_gameboy_t *gb, bool disabled)
{
    gb->disable_rendering = disabled;
}

void *GB_get_user_data(GB_gameboy_t *gb)
{
    return gb->user_data;
}

void GB_set_user_data(GB_gameboy_t *gb, void *data)
{
    gb->user_data = data;
}

static void reset_ram(GB_gameboy_t *gb)
{
    switch (gb->model) {
        case GB_MODEL_CGB_E:
        case GB_MODEL_AGB: /* Unverified */
            for (unsigned i = 0; i < gb->ram_size; i++) {
                gb->ram[i] = GB_random();
            }
            break;
            
        case GB_MODEL_DMG_B:
        case GB_MODEL_SGB_NTSC: /* Unverified*/
        case GB_MODEL_SGB_PAL: /* Unverified */
        case GB_MODEL_SGB_NTSC_NO_SFC: /* Unverified */
        case GB_MODEL_SGB_PAL_NO_SFC: /* Unverified */
            for (unsigned i = 0; i < gb->ram_size; i++) {
                gb->ram[i] = GB_random();
                if (i & 0x100) {
                    gb->ram[i] &= GB_random();
                }
                else {
                    gb->ram[i] |= GB_random();
                }
            }
            break;
            
        case GB_MODEL_SGB2:
        case GB_MODEL_SGB2_NO_SFC:
            for (unsigned i = 0; i < gb->ram_size; i++) {
                gb->ram[i] = 0x55;
                gb->ram[i] ^= GB_random() & GB_random() & GB_random();
            }
            break;
        
        case GB_MODEL_CGB_C:
            for (unsigned i = 0; i < gb->ram_size; i++) {
                if ((i & 0x808) == 0x800 || (i & 0x808) == 0x008) {
                    gb->ram[i] = 0;
                }
                else {
                    gb->ram[i] = GB_random() | GB_random() | GB_random() | GB_random();
                }
            }
            break;
    }
    
    /* HRAM */
    switch (gb->model) {
        case GB_MODEL_CGB_C:
        // case GB_MODEL_CGB_D:
        case GB_MODEL_CGB_E:
        case GB_MODEL_AGB:
            for (unsigned i = 0; i < sizeof(gb->hram); i++) {
                gb->hram[i] = GB_random();
            }
            break;
            
        case GB_MODEL_DMG_B:
        case GB_MODEL_SGB_NTSC: /* Unverified*/
        case GB_MODEL_SGB_PAL: /* Unverified */
        case GB_MODEL_SGB_NTSC_NO_SFC: /* Unverified */
        case GB_MODEL_SGB_PAL_NO_SFC: /* Unverified */
        case GB_MODEL_SGB2:
        case GB_MODEL_SGB2_NO_SFC:
            for (unsigned i = 0; i < sizeof(gb->hram); i++) {
                if (i & 1) {
                    gb->hram[i] = GB_random() | GB_random() | GB_random();
                }
                else {
                    gb->hram[i] = GB_random() & GB_random() & GB_random();
                }
            }
            break;
    }
    
    /* OAM */
    switch (gb->model) {
        case GB_MODEL_CGB_C:
        case GB_MODEL_CGB_E:
        case GB_MODEL_AGB:
            /* Zero'd out by boot ROM anyway*/
            break;
            
        case GB_MODEL_DMG_B:
        case GB_MODEL_SGB_NTSC: /* Unverified */
        case GB_MODEL_SGB_PAL: /* Unverified */
        case GB_MODEL_SGB_NTSC_NO_SFC: /* Unverified */
        case GB_MODEL_SGB_PAL_NO_SFC: /* Unverified */
        case GB_MODEL_SGB2:
        case GB_MODEL_SGB2_NO_SFC:
            for (unsigned i = 0; i < 8; i++) {
                if (i & 2) {
                    gb->oam[i] = GB_random() & GB_random() & GB_random();
                }
                else {
                    gb->oam[i] = GB_random() | GB_random() | GB_random();
                }
            }
            for (unsigned i = 8; i < sizeof(gb->oam); i++) {
                gb->oam[i] = gb->oam[i - 8];
            }
            break;
    }
    
    /* Wave RAM */
    switch (gb->model) {
        case GB_MODEL_CGB_C:
        case GB_MODEL_CGB_E:
        case GB_MODEL_AGB:
            /* Initialized by CGB-A and newer, 0s in CGB-0*/
            break;
            
        case GB_MODEL_DMG_B:
        case GB_MODEL_SGB_NTSC: /* Unverified*/
        case GB_MODEL_SGB_PAL: /* Unverified */
        case GB_MODEL_SGB_NTSC_NO_SFC: /* Unverified */
        case GB_MODEL_SGB_PAL_NO_SFC: /* Unverified */
        case GB_MODEL_SGB2:
        case GB_MODEL_SGB2_NO_SFC: {
            uint8_t temp;
            for (unsigned i = 0; i < GB_IO_WAV_END - GB_IO_WAV_START; i++) {
                if (i & 1) {
                    temp = GB_random() & GB_random() & GB_random();
                }
                else {
                    temp = GB_random() | GB_random() | GB_random();
                }
                gb->apu.wave_channel.wave_form[i * 2]     = temp >> 4;
                gb->apu.wave_channel.wave_form[i * 2 + 1] = temp & 0xF;
                gb->io_registers[GB_IO_WAV_START + i] = temp;

            }
            break;
        }
    }
    
    for (unsigned i = 0; i < sizeof(gb->extra_oam); i++) {
        gb->extra_oam[i] = GB_random();
    }
    
    if (GB_is_cgb(gb)) {
        for (unsigned i = 0; i < 64; i++) {
            gb->background_palettes_data[i] = GB_random(); /* Doesn't really matter as the boot ROM overrides it anyway*/
            gb->sprite_palettes_data[i] = GB_random();
        }
        for (unsigned i = 0; i < 32; i++) {
            GB_palette_changed(gb, true, i * 2);
            GB_palette_changed(gb, false, i * 2);
        }
    }
}

void GB_reset(GB_gameboy_t *gb)
{
    uint32_t mbc_ram_size = gb->mbc_ram_size;
    GB_model_t model = gb->model;
    memset(gb, 0, (size_t)GB_GET_SECTION((GB_gameboy_t *) 0, unsaved));
    gb->model = model;
    gb->version = GB_STRUCT_VERSION;
    
    gb->mbc_rom_bank = 1;
    gb->last_rtc_second = time(NULL);
    gb->cgb_ram_bank = 1;
    gb->io_registers[GB_IO_JOYP] = 0xCF;
    gb->mbc_ram_size = mbc_ram_size;
    if (GB_is_cgb(gb)) {
        gb->ram_size = 0x1000 * 8;
        gb->vram_size = 0x2000 * 2;
        memset(gb->vram, 0, gb->vram_size);
        gb->cgb_mode = true;
    }
    else {
        gb->ram_size = 0x2000;
        gb->vram_size = 0x2000;
        memset(gb->vram, 0, gb->vram_size);
        
        if (gb->rgb_encode_callback) {
            gb->sprite_palettes_rgb[4] = gb->sprite_palettes_rgb[0] = gb->background_palettes_rgb[0] =
                gb->rgb_encode_callback(gb, 0xFF, 0xFF, 0xFF);
            gb->sprite_palettes_rgb[5] = gb->sprite_palettes_rgb[1] = gb->background_palettes_rgb[1] =
                gb->rgb_encode_callback(gb, 0xAA, 0xAA, 0xAA);
            gb->sprite_palettes_rgb[6] = gb->sprite_palettes_rgb[2] = gb->background_palettes_rgb[2] =
                gb->rgb_encode_callback(gb, 0x55, 0x55, 0x55);
            gb->sprite_palettes_rgb[7] = gb->sprite_palettes_rgb[3] = gb->background_palettes_rgb[3] =
                gb->rgb_encode_callback(gb, 0, 0, 0);
        }
    }
    reset_ram(gb);
    
    /* The serial interrupt always occur on the 0xF7th cycle of every 0x100 cycle since boot. */
    gb->serial_cycles = 0x100-0xF7;
    gb->io_registers[GB_IO_SC] = 0x7E;
    
    /* These are not deterministic, but 00 (CGB) and FF (DMG) are the most common initial values by far */
    gb->io_registers[GB_IO_DMA] = gb->io_registers[GB_IO_OBP0] = gb->io_registers[GB_IO_OBP1] = GB_is_cgb(gb)? 0x00 : 0xFF;
    
    gb->accessed_oam_row = -1;
    
    
    if (GB_is_hle_sgb(gb)) {
        if (!gb->sgb) {
            gb->sgb = malloc(sizeof(*gb->sgb));
        }
        memset(gb->sgb, 0, sizeof(*gb->sgb));
        memset(gb->sgb_intro_jingle_phases, 0, sizeof(gb->sgb_intro_jingle_phases));
        gb->sgb_intro_sweep_phase = 0;
        gb->sgb_intro_sweep_previous_sample = 0;
        gb->sgb->intro_animation = -10;
        
        gb->sgb->player_count = 1;
        GB_sgb_load_default_data(gb);

    }
    else {
        if (gb->sgb) {
            free(gb->sgb);
            gb->sgb = NULL;
        }
    }
    
    /* Todo: Ugly, fixme, see comment in the timer state machine */
    gb->div_state = 3;

    GB_apu_update_cycles_per_sample(gb);
    
    if (gb->nontrivial_jump_state) {
        free(gb->nontrivial_jump_state);
        gb->nontrivial_jump_state = NULL;
    }
    
    gb->magic = state_magic();
}

void GB_switch_model_and_reset(GB_gameboy_t *gb, GB_model_t model)
{
    gb->model = model;
    if (GB_is_cgb(gb)) {
        gb->ram = realloc(gb->ram, gb->ram_size = 0x1000 * 8);
        gb->vram = realloc(gb->vram, gb->vram_size = 0x2000 * 2);
    }
    else {
        gb->ram = realloc(gb->ram, gb->ram_size = 0x2000);
        gb->vram = realloc(gb->vram, gb->vram_size = 0x2000);
    }
    GB_rewind_free(gb);
    GB_reset(gb);
}

void *GB_get_direct_access(GB_gameboy_t *gb, GB_direct_access_t access, size_t *size, uint16_t *bank)
{
    /* Set size and bank to dummy pointers if not set */
    size_t dummy_size;
    uint16_t dummy_bank;
    if (!size) {
        size = &dummy_size;
    }
    
    if (!bank) {
        bank = &dummy_bank;
    }
    
    
    switch (access) {
        case GB_DIRECT_ACCESS_ROM:
            *size = gb->rom_size;
            *bank = gb->mbc_rom_bank;
            return gb->rom;
        case GB_DIRECT_ACCESS_RAM:
            *size = gb->ram_size;
            *bank = gb->cgb_ram_bank;
            return gb->ram;
        case GB_DIRECT_ACCESS_CART_RAM:
            *size = gb->mbc_ram_size;
            *bank = gb->mbc_ram_bank;
            return gb->mbc_ram;
        case GB_DIRECT_ACCESS_VRAM:
            *size = gb->vram_size;
            *bank = gb->cgb_vram_bank;
            return gb->vram;
        case GB_DIRECT_ACCESS_HRAM:
            *size = sizeof(gb->hram);
            *bank = 0;
            return &gb->hram;
        case GB_DIRECT_ACCESS_IO:
            *size = sizeof(gb->io_registers);
            *bank = 0;
            return &gb->io_registers;
        case GB_DIRECT_ACCESS_BOOTROM:
            *size = GB_is_cgb(gb)? sizeof(gb->boot_rom) : 0x100;
            *bank = 0;
            return &gb->boot_rom;
        case GB_DIRECT_ACCESS_OAM:
            *size = sizeof(gb->oam);
            *bank = 0;
            return &gb->oam;
        case GB_DIRECT_ACCESS_BGP:
            *size = sizeof(gb->background_palettes_data);
            *bank = 0;
            return &gb->background_palettes_data;
        case GB_DIRECT_ACCESS_OBP:
            *size = sizeof(gb->sprite_palettes_data);
            *bank = 0;
            return &gb->sprite_palettes_data;
        case GB_DIRECT_ACCESS_IE:
            *size = sizeof(gb->interrupt_enable);
            *bank = 0;
            return &gb->interrupt_enable;
        default:
            *size = 0;
            *bank = 0;
            return NULL;
    }
}

void GB_set_clock_multiplier(GB_gameboy_t *gb, double multiplier)
{
    gb->clock_multiplier = multiplier;
    GB_apu_update_cycles_per_sample(gb);
}

uint32_t GB_get_clock_rate(GB_gameboy_t *gb)
{
    if (gb->model & GB_MODEL_PAL_BIT) {
        return SGB_PAL_FREQUENCY * gb->clock_multiplier;
    }
    if ((gb->model & ~GB_MODEL_NO_SFC_BIT) == GB_MODEL_SGB) {
        return SGB_NTSC_FREQUENCY * gb->clock_multiplier;
    }
    return CPU_FREQUENCY * gb->clock_multiplier;
}

unsigned GB_get_screen_width(GB_gameboy_t *gb)
{
    return GB_is_hle_sgb(gb)? 256 : 160;
}

unsigned GB_get_screen_height(GB_gameboy_t *gb)
{
    return GB_is_hle_sgb(gb)? 224 : 144;
}

unsigned GB_get_player_count(GB_gameboy_t *gb)
{
    return GB_is_hle_sgb(gb)? gb->sgb->player_count : 1;
}

void GB_set_update_input_hint_callback(GB_gameboy_t *gb, GB_update_input_hint_callback_t callback)
{
    gb->update_input_hint_callback = callback;
}

double GB_get_usual_frame_rate(GB_gameboy_t *gb)
{
    return GB_get_clock_rate(gb) / (double)LCDC_PERIOD;
}

void GB_set_joyp_write_callback(GB_gameboy_t *gb, GB_joyp_write_callback_t callback)
{
    gb->joyp_write_callback = callback;
}

void GB_set_icd_pixel_callback(GB_gameboy_t *gb, GB_icd_pixel_callback_t callback)
{
    gb->icd_pixel_callback = callback;
}

void GB_set_icd_hreset_callback(GB_gameboy_t *gb, GB_icd_hreset_callback_t callback)
{
    gb->icd_hreset_callback = callback;
}


void GB_set_icd_vreset_callback(GB_gameboy_t *gb, GB_icd_vreset_callback_t callback)
{
    gb->icd_vreset_callback = callback;
}