define INPUT = 0xbffe;
define SCREEN = 0xbfff;

main() {
	loop {
		slp;
		erase();
		update();
		draw();
	}
}


update() {
	input_update();
	=> player_update();
}


erase() => player_erase();


draw() => player_draw();


global input_left;
global input_right;
global input_up;
global input_down;

input_update() {
	local input = [INPUT];
	input_up = (input & 0x10) != 0;
	input_down = (input & 0x20) != 0;
	input_left = (input & 0x40) != 0;
	input_right = (input & 0x80) != 0;
}


global player_x = 64;
global player_y = 64;

player_update() {
	player_x = player_x + input_right - input_left;
	player_y = player_y + input_down - input_up;
}


player_erase() => pset(player_x, player_y, 0x1111);


player_draw() => pset(player_x, player_y, 0xffff);


pset(x, y, c) {
	[SCREEN + (x & 127) + (y & 127) * 128] = c;
}