libretro.c

#include "libretro.h"
#include "gb.h"

GameBoy* gb;

static retro_environment_t environ_cb;
static retro_video_refresh_t video_cb;
static retro_audio_sample_t audio_cb;
static retro_input_poll_t input_poll_cb;
static retro_input_state_t input_state_cb;

void retro_set_environment(retro_environment_t cb) {
    static enum retro_pixel_format format = RETRO_PIXEL_FORMAT_XRGB8888;
    cb(RETRO_ENVIRONMENT_SET_PIXEL_FORMAT, &format);

    environ_cb = cb;
}

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

void retro_set_audio_sample(retro_audio_sample_t cb) { audio_cb = cb; }

void retro_set_audio_sample_batch(retro_audio_sample_batch_t 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_init(void) {}

void retro_deinit(void) {}

unsigned retro_api_version(void) { return RETRO_API_VERSION; }

void retro_get_system_info(struct retro_system_info* info) {
    info->library_name = "Rondo";
    info->library_version = "dev";
    info->valid_extensions = "gb";
    info->need_fullpath = false;
    info->block_extract = false;
}

void retro_get_system_av_info(struct retro_system_av_info* info) {
    info->geometry.base_width = SCREEN_WIDTH;
    info->geometry.base_height = SCREEN_HEIGHT;
    info->geometry.max_width = SCREEN_WIDTH;
    info->geometry.max_height = SCREEN_HEIGHT;
    info->geometry.aspect_ratio = 0; // Interpreted as base_width/base_height

    info->timing.fps = FRAME_RATE;
    info->timing.sample_rate = 1048576.0; // Placeholder
}

void retro_set_controller_port_device(unsigned port, unsigned device) {}

void retro_reset(void) {}

static void update_input() {
    input_poll_cb();

    static const unsigned buttons[8] = {
        RETRO_DEVICE_ID_JOYPAD_RIGHT,  RETRO_DEVICE_ID_JOYPAD_LEFT,
        RETRO_DEVICE_ID_JOYPAD_UP,     RETRO_DEVICE_ID_JOYPAD_DOWN,
        RETRO_DEVICE_ID_JOYPAD_A,      RETRO_DEVICE_ID_JOYPAD_B,
        RETRO_DEVICE_ID_JOYPAD_SELECT, RETRO_DEVICE_ID_JOYPAD_START};
    u8 input = 0;
    for (size_t i = 0; i < 8; i++) {
        if (input_state_cb(0, RETRO_DEVICE_JOYPAD, 0, buttons[i])) {
            input |= (1 << i);
        }
    }

    // We need to invert the input since gameboy treats 0 as pressed and 1 as
    // not pressed
    gb->input = ~input;
}

void retro_run(void) {
    update_input();
    run_frame(gb);

    video_cb(gb->fbuf, SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_WIDTH * sizeof(u32));
}

size_t retro_serialize_size(void) { return 0; }

bool retro_serialize(void* data, size_t size) { return false; }

bool retro_unserialize(const void* data, size_t size) { return false; }

void retro_cheat_reset(void) {}

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

bool retro_load_game(const struct retro_game_info* game) {
    static const struct retro_controller_description controller = {
        "Game Boy", RETRO_DEVICE_JOYPAD};
    static const struct retro_controller_info ports[] = {{&controller, 1}, {0}};
    // libretro.h says we should call this in retro_load_game
    environ_cb(RETRO_ENVIRONMENT_SET_CONTROLLER_INFO, ports);

    gb = make_gb(game->data, game->size);
    if (!gb) {
        return false;
    }

    return true;
}

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

void retro_unload_game(void) {
    destroy_gb(gb);
    gb = NULL;
}

unsigned retro_get_region(void) { return 0; }

void* retro_get_memory_data(unsigned id) { return NULL; }

size_t retro_get_memory_size(unsigned id) { return 0; }

// Used in apu.c
void play_sample(s16 l, s16 r) { audio_cb(l, r); }