import "msx";

bank rom1 @ 0x4000 : [constdata; 0x4000];
bank rom2 @ 0x8000 : [constdata; 0x4000];
bank ram @ 0xE000 : [vardata; 0x2000];

in ram {
    struct Word {
        low : u8,
        high : u8,
    }

    struct Enemy {
        hp : Word
    }

    var enemy_data : [Enemy; 32];
}

in rom1 {
    namespace header {
        const id = "AB";
        const init_handler = main;
        const statement_handler = 0u16;
        const expansion_handler = 0u16;
        const basic_start = 0u16;
        const padding = [0u8; 6];
    }

    #[fallthrough] func main() {
        interrupt = false;

        io_write(msx.io.ppi.primary_slot, a = 0b11_01_01_00);
        msx.ppi.secondary_slot = a = 0b11_11_11_11;

        // Init VDP.
        c = msx.io.vdp.control;
        hl = &vdp_init_data as u16;
        b = vdp_init_data.len;
        do { io_write_inc_repeat(c, hl, b); } while !zero;

        {
            var enemy_ptr : *Enemy in ix;
            enemy_ptr.hp.low = 1;
            enemy_ptr.hp.high = 1;

            bc = sizeof(Enemy);
            <>:enemy_ptr += bc;
        }

        // Clear VRAM.
        io_write(msx.io.vdp.control, a = <:0x0000);
        io_write(msx.io.vdp.control, a = >:0x0000 | msx.io.vdp.CONTROL_ACCESS_VRAM_WRITE);
        bc = 0x4000;
        do {
            io_write(msx.io.vdp.data, a = 0);
            bc--;
            a = b | c;
        } while !zero;

        // Load background colormap.
        io_write(msx.io.vdp.control, a = <:0x2000);
        io_write(msx.io.vdp.control, a = >:0x2000 | msx.io.vdp.CONTROL_ACCESS_VRAM_WRITE);
        bc = 0x1800;
        do {
            io_write(msx.io.vdp.data, a = (msx.vdp.color.WHITE << 4) | msx.vdp.color.LIGHT_BLUE);
            bc--;
            a = b | c;
        } while !zero;

        // Load background tileset.
        io_write(msx.io.vdp.control, a = <:0x0000);
        io_write(msx.io.vdp.control, a = >:0x0000 | msx.io.vdp.CONTROL_ACCESS_VRAM_WRITE);
        hl = &bkg_tileset as u16;
        bc = sizeof(typeof(bkg_tileset));
        do {
            io_write(msx.io.vdp.data, a = *(hl as *u8));
            hl++;
            bc--;
            a = b | c;
        } while !zero;

        io_write(msx.io.vdp.control, a = <:0x0800);
        io_write(msx.io.vdp.control, a = >:0x0800 | msx.io.vdp.CONTROL_ACCESS_VRAM_WRITE);
        hl = &bkg_tileset as u16;
        bc = sizeof(typeof(bkg_tileset));
        do {
            io_write(msx.io.vdp.data, a = *(hl as *u8));
            hl++;
            bc--;
            a = b | c;
        } while !zero;

        io_write(msx.io.vdp.control, a = <:0x1000);
        io_write(msx.io.vdp.control, a = >:0x1000 | msx.io.vdp.CONTROL_ACCESS_VRAM_WRITE);
        hl = &bkg_tileset as u16;
        bc = sizeof(typeof(bkg_tileset));
        do {
            io_write(msx.io.vdp.data, a = *(hl as *u8));
            hl++;
            bc--;
            a = b | c;
        } while !zero;

        // Write text to nametable.
        io_write(msx.io.vdp.control, a = <:0x190A);
        io_write(msx.io.vdp.control, a = >:0x190A | msx.io.vdp.CONTROL_ACCESS_VRAM_WRITE);
        hl = &message as u16;
        bc = message.len;
        do {
            io_write(msx.io.vdp.data, a = *(hl as *u8));
            hl++;
            bc--;
            a = b | c;
        } while !zero;

        // Turn screen on
        io_write(msx.io.vdp.control, a = msx.vdp.MODE_CONTROL_1_ENABLE);
        io_write(msx.io.vdp.control, a = msx.vdp.mode_control_1 | msx.io.vdp.CONTROL_ACCESS_REGISTER);

        interrupt = true;

        while true {
            halt();
        }
    }

    const vdp_init_data : [u8] = [
        msx.vdp.MODE_CONTROL_0_M4, msx.vdp.mode_control_0 | msx.io.vdp.CONTROL_ACCESS_REGISTER,
        0, msx.vdp.mode_control_1 | msx.io.vdp.CONTROL_ACCESS_REGISTER,
        0x1800 >> msx.vdp.NAMETABLE_ADDRESS_SHIFT, msx.vdp.nametable_address | msx.io.vdp.CONTROL_ACCESS_REGISTER,
        0x2000 >> msx.vdp.COLORTABLE_ADDRESS_SHIFT, msx.vdp.colortable_address | msx.io.vdp.CONTROL_ACCESS_REGISTER,
        0x0000 >> msx.vdp.TILE_PATTERN_ADDRESS_SHIFT, msx.vdp.tile_pattern_address | msx.io.vdp.CONTROL_ACCESS_REGISTER,
        0x1B00 >> msx.vdp.SPRITE_ATTRIBUTE_ADDRESS_SHIFT, msx.vdp.sprite_attribute_address | msx.io.vdp.CONTROL_ACCESS_REGISTER,
        0x3800 >> msx.vdp.SPRITE_PATTERN_ADDRESS_SHIFT, msx.vdp.sprite_pattern_address | msx.io.vdp.CONTROL_ACCESS_REGISTER,
        msx.vdp.color.BLACK, msx.vdp.overscan_color | msx.io.vdp.CONTROL_ACCESS_REGISTER,
    ];

    const message = "HELLO  WORLD";
}

in rom2 {
    const bkg_tileset = embed "hello_tiles.chr";
}