SameBoy/libretro/libretro.c

#include <stdio.h>
#include <stdbool.h>
#include <unistd.h>
#include <time.h>
#include <assert.h>
#include <signal.h>
#include <stdarg.h>

#ifndef WIIU
#define AUDIO_FREQUENCY 384000
#else
#define AUDIO_FREQUENCY 44100
#endif

#define FRAME_RATE (0x400000 / 70224.0)

#ifdef _WIN32
#include <direct.h>
#include <windows.h>
#define snprintf _snprintf
#endif

#include <Core/gb.h>
#include "libretro.h"

#ifdef _WIN32
static const char slash = '\\';
#else
static const char slash = '/';
#endif

#define VIDEO_WIDTH 160
#define VIDEO_HEIGHT 144
#define VIDEO_PIXELS (VIDEO_WIDTH * VIDEO_HEIGHT)

char battery_save_path[512];
char symbols_path[512];

enum model {
    MODEL_DMG,
    MODEL_CGB,
    MODEL_AGB,
    MODEL_AUTO
};

static enum model model = MODEL_AUTO;
static enum model auto_model = MODEL_CGB;

enum layout {
    LAYOUT_TOP_DOWN,
    LAYOUT_LEFT_RIGHT
};

static enum model model[2];
static uint32_t *frame_buf = NULL;
static struct retro_log_callback logging;
static retro_log_printf_t log_cb;

static retro_video_refresh_t video_cb;
static retro_audio_sample_batch_t audio_batch_cb;
static retro_input_poll_t input_poll_cb;
static retro_input_state_t input_state_cb;

static unsigned emulated_devices = 1;
static unsigned pre_init = 1;
static unsigned layout = 0;

signed short soundbuf[1024 * 2];

char retro_system_directory[4096];
char retro_save_directory[4096];
char retro_game_path[4096];

GB_gameboy_t gb[2];

extern const unsigned char dmg_boot[], cgb_boot[], agb_boot[];
extern const unsigned dmg_boot_length, cgb_boot_length, agb_boot_length;
bool vblank1_occurred = false, vblank2_occurred = false;

static void fallback_log(enum retro_log_level level, const char *fmt, ...)
{
    (void)level;
    va_list va;
    va_start(va, fmt);
    vfprintf(stderr, fmt, va);
    va_end(va);
}

static struct retro_rumble_interface rumble;

static void GB_update_keys_status(GB_gameboy_t *gb, unsigned port)
{

    input_poll_cb();
    
    GB_set_key_state(gb, GB_KEY_RIGHT,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_RIGHT));
    GB_set_key_state(gb, GB_KEY_LEFT, input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_LEFT));
    GB_set_key_state(gb, GB_KEY_UP,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_UP) );
    GB_set_key_state(gb, GB_KEY_DOWN,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_DOWN));
    GB_set_key_state(gb, GB_KEY_A,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_A) );
    GB_set_key_state(gb, GB_KEY_B,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_B) );
    GB_set_key_state(gb, GB_KEY_SELECT,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_SELECT));
    GB_set_key_state(gb, GB_KEY_START,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_START) );
    
    if (gb->rumble_state)
        rumble.set_rumble_state(port, RETRO_RUMBLE_STRONG, 65535);
    else
        rumble.set_rumble_state(port, RETRO_RUMBLE_STRONG, 0);
    
}


static void audio_callback(void *gb)
{
    size_t length = GB_apu_get_current_buffer_length(gb);

    while (length > sizeof(soundbuf) / 4)
    {
        GB_apu_copy_buffer(gb, (GB_sample_t *) soundbuf, 1024);
        audio_batch_cb(soundbuf, 1024);
        length -= 1024;
    }
    if (length) {
        GB_apu_copy_buffer(gb, (GB_sample_t *) soundbuf, length);
        audio_batch_cb(soundbuf, length);
    }
}

static void vblank1(GB_gameboy_t *gb)
{
    vblank1_occurred = true;
    GB_update_keys_status(gb, 0);
    audio_callback(gb);
}

static void vblank2(GB_gameboy_t *gb)
{
    vblank2_occurred = true;
    GB_update_keys_status(gb, 1);
    //audio_callback(gb);
}

static uint8_t byte_to_send1 = 0xFF, byte_to_send2 = 0xFF;

static void serial_start1(GB_gameboy_t *gb, uint8_t byte_received)
{
    byte_to_send1 = byte_received;
}

static uint8_t serial_end1(GB_gameboy_t *gb)
{
    uint8_t ret = GB_serial_get_data(&gb[1]);
    GB_serial_set_data(&gb[1], byte_to_send1);
    return ret;
}

static void serial_start2(GB_gameboy_t *gb, uint8_t byte_received)
{
    byte_to_send2 = byte_received;
}

static uint8_t serial_end2(GB_gameboy_t *gb)
{
    uint8_t ret = GB_serial_get_data(&gb[0]);
    GB_serial_set_data(&gb[0], byte_to_send2);
    return ret;
}

static uint32_t rgb_encode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
{
    return r<<16|g<<8|b;
}

static retro_environment_t environ_cb;

static const struct retro_variable vars[] = {
    { "sameboy_link", "Link Cable (restart); disabled|enabled" },
    { "sameboy_link_layout", "Screen Layout; top-down|left-right" },
    { "sameboy_color_correction_mode", "Color Correction; off|correct curves|emulate hardware|preserve brightness" },
    { "sameboy_high_pass_filter_mode", "High Pass Filter; off|accurate|remove dc offset" },
    { "sameboy_model", "Emulated Model; Game Boy Color|Game Boy Advance|Game Boy" },
    { NULL }
};
static const struct retro_variable vars_link[] = {
    { "sameboy_link", "Link Cable; disabled|enabled" },
    { "sameboy_link_layout", "Screen Layout; top-down|left-right" },
    { "sameboy_model_1", "Emulated Model for GB #1; Game Boy Color|Game Boy Advance|Game Boy" },
    { "sameboy_model_2", "Emulated Model for GB #2; Game Boy Color|Game Boy Advance|Game Boy" },
    { "sameboy_color_correction_mode_1", "Color Correction for GB #1; off|correct curves|emulate hardware|preserve brightness" },
    { "sameboy_color_correction_mode_2", "Color Correction for GB #2; off|correct curves|emulate hardware|preserve brightness" },
    { "sameboy_high_pass_filter_mode_1", "High Pass Filter for GB #1; off|accurate|remove dc offset" },
    { "sameboy_high_pass_filter_mode_2", "High Pass Filter for GB #2; off|accurate|remove dc offset" },
    { NULL }
};

static void init_for_current_model(void)
{
    enum model effective_model = model;
    if (effective_model == MODEL_AUTO) {
        effective_model = auto_model;
    }

    for (i = 0; i < emulated_devices; i++)
    {
        if (GB_is_inited(&gb[i]))
            GB_switch_model_and_reset(&gb[i], effective_model[i] != MODEL_DMG);

        else
        {
            if (effective_model[i] == MODEL_DMG)
                GB_init(&gb[i]);
            else
                GB_init_cgb(&gb[i]);
        }
        const char *model_name = (const char *[]){"dmg", "cgb", "agb"}[model[i]];
        const unsigned char *boot_code = (const unsigned char *[]){dmg_boot, cgb_boot, agb_boot}[model[i]];
        unsigned boot_length = (unsigned []){dmg_boot_length, cgb_boot_length, agb_boot_length}[model[i]];
    
        char buf[256];
        snprintf(buf, sizeof(buf), "%s%c%s_boot.bin", retro_system_directory, slash, model_name);
        log_cb(RETRO_LOG_INFO, "Loading boot image: %s\n", buf);
        if (GB_load_boot_rom(&gb[i], buf))
            GB_load_boot_rom_from_buffer(&gb[i], boot_code, boot_length);
        GB_set_user_data(&gb[i], (void*)NULL);
        GB_set_pixels_output(&gb[i],(unsigned int*)(frame_buf + i * VIDEO_PIXELS));
        GB_set_rgb_encode_callback(&gb[i], rgb_encode);
        GB_set_sample_rate(&gb[i], AUDIO_FREQUENCY);
    }

    /* todo: attempt to make these more generic */
    GB_set_vblank_callback(&gb[0], (GB_vblank_callback_t) vblank1);
    if (emulated_devices == 2)
    {
        GB_set_vblank_callback(&gb[1], (GB_vblank_callback_t) vblank2);
        GB_set_serial_transfer_start_callback(&gb[0], serial_start1);
        GB_set_serial_transfer_end_callback(&gb[0], serial_end1);
        GB_set_serial_transfer_start_callback(&gb[1], serial_start2);
        GB_set_serial_transfer_end_callback(&gb[1], serial_end2);
    }

    struct retro_memory_descriptor descs[7];
    size_t size;
    uint16_t bank;


    /* todo: add netplay awareness for this so achievements can be granted on the respective client */
    i = 0;
    memset(descs, 0, sizeof(descs));

    descs[0].ptr   = GB_get_direct_access(&gb[i], GB_DIRECT_ACCESS_IE, &size, &bank);
    descs[0].start = 0xFFFF;
    descs[0].len   = 1;

    descs[1].ptr   = GB_get_direct_access(&gb[i], GB_DIRECT_ACCESS_HRAM, &size, &bank);
    descs[1].start = 0xFF80;
    descs[1].len   = 0x0080;

    descs[2].ptr   = GB_get_direct_access(&gb[i], GB_DIRECT_ACCESS_RAM, &size, &bank);
    descs[2].start = 0xC000;
    descs[2].len   = 0x2000;

    descs[3].ptr   = GB_get_direct_access(&gb[i], GB_DIRECT_ACCESS_CART_RAM, &size, &bank);
    descs[3].start = 0xA000;
    descs[3].len   = 0x2000;

    descs[4].ptr   = GB_get_direct_access(&gb[i], GB_DIRECT_ACCESS_VRAM, &size, &bank);
    descs[4].start = 0x8000;
    descs[4].len   = 0x2000;

    descs[5].ptr   = GB_get_direct_access(&gb[i], GB_DIRECT_ACCESS_ROM, &size, &bank);
    descs[5].start = 0x0000;
    descs[5].len   = 0x4000;
    descs[5].flags = RETRO_MEMDESC_CONST;

    descs[6].ptr   = GB_get_direct_access(&gb[i], GB_DIRECT_ACCESS_OAM, &size, &bank);
    descs[6].start = 0xFE00;
    descs[6].len   = 0x00A0;

    struct retro_memory_map mmaps;
    mmaps.descriptors = descs;
    mmaps.num_descriptors = sizeof(descs) / sizeof(descs[0]);
    environ_cb(RETRO_ENVIRONMENT_SET_MEMORY_MAPS, &mmaps);
}

static void check_variables(bool link)
{
    struct retro_variable var = {0};

    if (!link)
    {
        var.key = "sameboy_color_correction_mode";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value && GB_is_cgb(&gb[0]))
        {
            if (strcmp(var.value, "off") == 0)
                GB_set_color_correction_mode(&gb[0], GB_COLOR_CORRECTION_DISABLED);
            else if (strcmp(var.value, "correct curves") == 0)
                GB_set_color_correction_mode(&gb[0], GB_COLOR_CORRECTION_CORRECT_CURVES);
            else if (strcmp(var.value, "emulate hardware") == 0)
                GB_set_color_correction_mode(&gb[0], GB_COLOR_CORRECTION_EMULATE_HARDWARE);
            else if (strcmp(var.value, "preserve brightness") == 0)
                GB_set_color_correction_mode(&gb[0], GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS);
        }
        
        var.key = "sameboy_high_pass_filter_mode";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
        {
            if (strcmp(var.value, "off") == 0)
                GB_set_highpass_filter_mode(&gb[0], GB_HIGHPASS_OFF);
            else if (strcmp(var.value, "accurate") == 0)
                GB_set_highpass_filter_mode(&gb[0], GB_HIGHPASS_ACCURATE);
            else if (strcmp(var.value, "remove dc offset") == 0)
                GB_set_highpass_filter_mode(&gb[0], GB_HIGHPASS_REMOVE_DC_OFFSET);
        }
        
        var.key = "sameboy_model";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
        {
            enum model new_model = model[0];
            if (strcmp(var.value, "Game Boy") == 0)
                new_model = MODEL_DMG;
            else if (strcmp(var.value, "Game Boy Color") == 0)
                new_model = MODEL_CGB;
            else if (strcmp(var.value, "Game Boy Advance") == 0)
                new_model = MODEL_AGB;
            else if (strcmp(var.value, "Auto") == 0)
                new_model = MODEL_AUTO;
            if (GB_is_inited(&gb[0]) && new_model != model[0]) {
                model[0] = new_model;
                init_for_current_model();
            }
        }
    }
    else
    {
        var.key = "sameboy_color_correction_mode_1";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value && GB_is_cgb(&gb[0]))
        {
            if (strcmp(var.value, "off") == 0)
                GB_set_color_correction_mode(&gb[0], GB_COLOR_CORRECTION_DISABLED);
            else if (strcmp(var.value, "correct curves") == 0)
                GB_set_color_correction_mode(&gb[0], GB_COLOR_CORRECTION_CORRECT_CURVES);
            else if (strcmp(var.value, "emulate hardware") == 0)
                GB_set_color_correction_mode(&gb[0], GB_COLOR_CORRECTION_EMULATE_HARDWARE);
            else if (strcmp(var.value, "preserve brightness") == 0)
                GB_set_color_correction_mode(&gb[0], GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS);
        }

        var.key = "sameboy_color_correction_mode_2";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value && GB_is_cgb(&gb[1]))
        {
            if (strcmp(var.value, "off") == 0)
                GB_set_color_correction_mode(&gb[1], GB_COLOR_CORRECTION_DISABLED);
            else if (strcmp(var.value, "correct curves") == 0)
                GB_set_color_correction_mode(&gb[1], GB_COLOR_CORRECTION_CORRECT_CURVES);
            else if (strcmp(var.value, "emulate hardware") == 0)
                GB_set_color_correction_mode(&gb[1], GB_COLOR_CORRECTION_EMULATE_HARDWARE);
            else if (strcmp(var.value, "preserve brightness") == 0)
                GB_set_color_correction_mode(&gb[1], GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS);
        }

        var.key = "sameboy_high_pass_filter_mode_1";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
        {
            if (strcmp(var.value, "off") == 0)
                GB_set_highpass_filter_mode(&gb[0], GB_HIGHPASS_OFF);
            else if (strcmp(var.value, "accurate") == 0)
                GB_set_highpass_filter_mode(&gb[0], GB_HIGHPASS_ACCURATE);
            else if (strcmp(var.value, "remove dc offset") == 0)
                GB_set_highpass_filter_mode(&gb[0], GB_HIGHPASS_REMOVE_DC_OFFSET);
        }

        var.key = "sameboy_high_pass_filter_mode_2";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
        {
            if (strcmp(var.value, "off") == 0)
                GB_set_highpass_filter_mode(&gb[1], GB_HIGHPASS_OFF);
            else if (strcmp(var.value, "accurate") == 0)
                GB_set_highpass_filter_mode(&gb[1], GB_HIGHPASS_ACCURATE);
            else if (strcmp(var.value, "remove dc offset") == 0)
                GB_set_highpass_filter_mode(&gb[1], GB_HIGHPASS_REMOVE_DC_OFFSET);
        }

        var.key = "sameboy_model_1";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
        {
            enum model new_model = model[0];
            if (strcmp(var.value, "Game Boy") == 0)
                new_model = MODEL_DMG;
            else if (strcmp(var.value, "Game Boy Color") == 0)
                new_model = MODEL_CGB;
            else if (strcmp(var.value, "Game Boy Advance") == 0)
                new_model = MODEL_AGB;
            if (GB_is_inited(&gb[0]) && new_model != model[0]) {
                model[0] = new_model;
                init_for_current_model();
            }
        }

        var.key = "sameboy_model_2";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
        {
            enum model new_model = model[0];
            if (strcmp(var.value, "Game Boy") == 0)
                new_model = MODEL_DMG;
            else if (strcmp(var.value, "Game Boy Color") == 0)
                new_model = MODEL_CGB;
            else if (strcmp(var.value, "Game Boy Advance") == 0)
                new_model = MODEL_AGB;
            if (GB_is_inited(&gb[1]) && new_model != model[0]) {
                model[0] = new_model;
                init_for_current_model();
            }
        }

    }

    var.key = "sameboy_link";
    var.value = NULL;
    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
    {
        int old_emulated_devices = emulated_devices;
        if (strcmp(var.value, "enabled") == 0)
            emulated_devices = 2;
        else
            emulated_devices = 1;
        if (pre_init == 0 && emulated_devices != old_emulated_devices)
            emulated_devices = old_emulated_devices;
    }

    var.key = "sameboy_link_layout";
    var.value = NULL;
    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
    {
        if (strcmp(var.value, "top-down") == 0)
            layout = LAYOUT_TOP_DOWN;
        else
            layout = LAYOUT_LEFT_RIGHT;
    }
}

void retro_init(void)
{
    frame_buf = (uint32_t*)malloc(2 * VIDEO_PIXELS * sizeof(uint32_t));
    const char *dir = NULL;
    
    if (environ_cb(RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY, &dir) && dir)
        snprintf(retro_system_directory, sizeof(retro_system_directory), "%s", dir);
    else
        snprintf(retro_system_directory, sizeof(retro_system_directory), "%s", ".");
    
    if (environ_cb(RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY, &dir) && dir)
        snprintf(retro_save_directory, sizeof(retro_save_directory), "%s", dir);
    else
        snprintf(retro_save_directory, sizeof(retro_save_directory), "%s", ".");

    environ_cb(RETRO_ENVIRONMENT_SET_VARIABLES, emulated_devices == 2 ? (void *)vars_link : (void *)vars);
    check_variables(emulated_devices == 2 ? true : false);
    environ_cb(RETRO_ENVIRONMENT_SET_VARIABLES, emulated_devices == 2 ? (void *)vars_link : (void *)vars);
}

void retro_deinit(void)
{
    free(frame_buf);
    frame_buf = NULL;
}

unsigned retro_api_version(void)
{
    return RETRO_API_VERSION;
}

void retro_set_controller_port_device(unsigned port, unsigned device)
{
    log_cb(RETRO_LOG_INFO, "Plugging device %u into port %u.\n", device, port);
}

void retro_get_system_info(struct retro_system_info *info)
{
    memset(info, 0, sizeof(*info));
    info->library_name     = "SameBoy";
#ifdef GIT_VERSION
    info->library_version  = SAMEBOY_CORE_VERSION GIT_VERSION;
#else
    info->library_version  = SAMEBOY_CORE_VERSION;
#endif
    info->need_fullpath    = true;
    info->valid_extensions = "gb|gbc";
}

void retro_get_system_av_info(struct retro_system_av_info *info)
{
    struct retro_game_geometry geom = { VIDEO_WIDTH, VIDEO_HEIGHT * 2, VIDEO_WIDTH, VIDEO_HEIGHT * 2 ,160.0 / 288.0 };
    struct retro_system_timing timing = { FRAME_RATE, AUDIO_FREQUENCY };
    
    info->geometry = geom;
    info->timing   = timing;
    
}

void retro_set_environment(retro_environment_t cb)
{
    environ_cb = cb;
    
    if (cb(RETRO_ENVIRONMENT_GET_LOG_INTERFACE, &logging))
        log_cb = logging.log;
    else
        log_cb = fallback_log;
    
    static const struct retro_controller_description controllers[] = {
        { "Nintendo Gameboy", RETRO_DEVICE_SUBCLASS(RETRO_DEVICE_JOYPAD, 0) },
    };
    
    static const struct retro_controller_info ports[] = {
        { controllers, 1 },
        { NULL, 0 },
    };
    cb(RETRO_ENVIRONMENT_SET_CONTROLLER_INFO, (void*)ports);
}

void retro_set_audio_sample(retro_audio_sample_t cb)
{
}

void retro_set_audio_sample_batch(retro_audio_sample_batch_t cb)
{
    audio_batch_cb = cb;
}

void retro_set_input_poll(retro_input_poll_t cb)
{
    input_poll_cb = cb;
}

void retro_set_input_state(retro_input_state_t cb)
{
    input_state_cb = cb;
}

void retro_set_video_refresh(retro_video_refresh_t cb)
{
    video_cb = cb;
}

void retro_reset(void)
{
    for (int i = 0; i < emulated_devices; i++)
       GB_reset(&gb[i]);

}

void retro_run(void)
{
    bool updated = false;
    pre_init = 0;
    
    if (!frame_buf)
        return;

    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE, &updated) && updated)
        check_variables(emulated_devices == 2 ? true : false);

    vblank1_occurred = vblank2_occurred = false;
    signed delta = 0;
    if (emulated_devices == 2)
    {
    while (!vblank1_occurred || !vblank2_occurred) {
            if (delta >= 0) {
                delta -= GB_run(&gb[0]);
            }
            else {
                delta += GB_run(&gb[1]);
            }
        }
    }
    else
        GB_run_frame(&gb[0]);

    video_cb(frame_buf, VIDEO_WIDTH, VIDEO_HEIGHT * 2, VIDEO_WIDTH * sizeof(uint32_t));
}

bool retro_load_game(const struct retro_game_info *info)
{
    struct retro_input_descriptor desc[] = {
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_LEFT,  "Left" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_UP,    "Up" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_DOWN,  "Down" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_RIGHT, "Right" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_B, "B" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_A, "A" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_SELECT, "Select" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_START, "Start" },
        { 0 },
    };

    environ_cb(RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS, desc);

    enum retro_pixel_format fmt = RETRO_PIXEL_FORMAT_XRGB8888;
    if (!environ_cb(RETRO_ENVIRONMENT_SET_PIXEL_FORMAT, &fmt))
    {
        log_cb(RETRO_LOG_INFO, "XRGB8888 is not supported.\n");
        return false;
    }

    snprintf(retro_game_path, sizeof(retro_game_path), "%s", info->path);

    auto_model = (info->path[strlen(info->path) - 1] & ~0x20) == 'C' ? MODEL_CGB : MODEL_DMG;
    init_for_current_model();

    for (int i = 0; i < emulated_devices; i++)
    {
        if (GB_load_rom(&gb[i],info->path))
        {
            log_cb(RETRO_LOG_INFO, "Failed to load ROM\n");
            return false;
        }
    }

    bool yes = true;
    environ_cb(RETRO_ENVIRONMENT_SET_SUPPORT_ACHIEVEMENTS, &yes);

    if (environ_cb(RETRO_ENVIRONMENT_GET_RUMBLE_INTERFACE, &rumble))
        log_cb(RETRO_LOG_INFO, "Rumble environment supported.\n");
    else
        log_cb(RETRO_LOG_INFO, "Rumble environment not supported.\n");

    static const struct retro_variable vars[] = {
        { "sameboy_color_correction_mode", "Color Correction; off|correct curves|emulate hardware|preserve brightness" },
        { "sameboy_high_pass_filter_mode", "High Pass Filter; off|accurate|remove dc offset" },
        { "sameboy_model", "Emulated Model; Auto|Game Boy|Game Boy Color|Game Boy Advance" },
        { "sameboy_link", "Link Cable; disabled|enabled" },
        { "sameboy_link_layout", "Screen Layout; top-down|left-right" },
        { NULL }
    };

    environ_cb(RETRO_ENVIRONMENT_SET_VARIABLES, emulated_devices == 2 ? (void *)vars_link : (void *)vars);
    check_variables(emulated_devices == 2 ? true : false);
    return true;
}

void retro_unload_game(void)
{
    for (int i = 0; i < emulated_devices; i++)
        GB_free(&gb[i]);
}

unsigned retro_get_region(void)
{
    return RETRO_REGION_NTSC;
}

bool retro_load_game_special(unsigned type, const struct retro_game_info *info, size_t num)
{
    return false;
}

size_t retro_serialize_size(void)
{
    return 2 * GB_get_save_state_size(&gb[0]);
}

bool retro_serialize(void *data, size_t size)
{
    if (pre_init == 1)
        return false;

    void* save_data[2];
    for (int i = 0; i < emulated_devices; i++)
    {
        save_data[i] = (uint8_t*)malloc(size * sizeof(uint8_t) / emulated_devices);
        GB_save_state_to_buffer(&gb[i], (uint8_t*) save_data[i]);
        memcpy(data + (size * i / emulated_devices), save_data[i], size / emulated_devices);
        free(save_data[i]);
    }

    if (data)
        return true;
    else
        return false;
}

bool retro_unserialize(const void *data, size_t size)
{
    void* save_data[2];
    int ret;

    for (int i = 0; i < emulated_devices; i++)
    {
        save_data[i] = (uint8_t*)malloc(size * sizeof(uint8_t)/ emulated_devices);
        memcpy (save_data[i], data + (size * i / emulated_devices), size / emulated_devices);
        ret = GB_load_state_from_buffer(&gb[i], save_data[i], size / emulated_devices);
        free(save_data[i]);

        if (ret != 0)
            return false;
    }

    return true;

}

void *retro_get_memory_data(unsigned type)
{
    void* data;
    switch(type)
    {
        case RETRO_MEMORY_SYSTEM_RAM:
            data = gb[0].ram;
            break;
        case RETRO_MEMORY_SAVE_RAM:
            if (gb[0].cartridge_type->has_battery && gb[0].mbc_ram_size != 0)
            {
                data = gb[0].mbc_ram;
                /* let's copy the save to gb[1] so it can save independently */
                //memcpy(gb[1].mbc_ram, gb[0].mbc_ram, gb[0].mbc_ram_size);
            }
            else
                data = NULL;
            break;
        case RETRO_MEMORY_VIDEO_RAM:
            data = gb[0].vram;
            break;
        case RETRO_MEMORY_RTC:
            if(gb[0].cartridge_type->has_battery)
                data = &gb[0].rtc_real;
            else
                data = NULL;
            break;
        default:
            data = NULL;
    }
    return data;
}

size_t retro_get_memory_size(unsigned type)
{
    size_t size;
    switch(type)
    {
        case RETRO_MEMORY_SYSTEM_RAM:
            size = gb[0].ram_size;
            break;
        case RETRO_MEMORY_SAVE_RAM:
            if (gb[0].cartridge_type->has_battery && gb[0].mbc_ram_size != 0)
                size = gb[0].mbc_ram_size;
            else
                size = 0;
            break;
        case RETRO_MEMORY_VIDEO_RAM:
            size = gb[0].vram_size;
            break;
        case RETRO_MEMORY_RTC:
            if(gb[0].cartridge_type->has_battery)
                size = sizeof (gb[0].rtc_real);
            else
                size =  0;
            break;
        default:
            size = 0;
            break;
    }
    
    return size;
}

void retro_cheat_reset(void)
{}

void retro_cheat_set(unsigned index, bool enabled, const char *code)
{
    (void)index;
    (void)enabled;
    (void)code;
}