define INPUT = 0xbffe;
define SCREEN = 0xbfff;
define SPAWN_X = 1;
define SPAWN_Y = 1;
define CASE_SIZE = 42;

global player_turn = 0;

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

draw_x(x, y, selected)
{
	local current_x = 0;
	local current_y;
	loop
	{
		if (current_x == CASE_SIZE)
			return;
		current_y = 0;
		loop
		{
			if (current_y == CASE_SIZE)
				break;
			if (current_x == current_y | current_x == CASE_SIZE - current_y)
				draw_pixel(x + current_x, y + current_y, 0xffff);
			else
				draw_pixel(x + current_x, y + current_y, 0x1111 * (selected + 2));
			current_y++;
		}
		current_x++;
	}
}

draw_o(x, y, selected)
{
	local current_x = 0;
	local current_y;
	loop
	{
		if (current_x == CASE_SIZE)
			return;
		current_y = 0;
		loop
		{
			if (current_y == CASE_SIZE)
				break;
			if (current_x == 2 | current_y == 2 | current_x == CASE_SIZE - 2 | current_y == CASE_SIZE - 2)
				draw_pixel(x + current_x, y + current_y, 0xffff);
			else
				draw_pixel(x + current_x, y + current_y, 0x1111 * (selected + 2));
			current_y++;
		}
		current_x++;
	}
}

draw_blank(x, y, selected)
{
	local current_x = 0;
	local current_y;
	loop
	{
		if (current_x == CASE_SIZE)
			return;
		current_y = 0;
		loop
		{
			if (current_y == CASE_SIZE)
				break;
			draw_pixel(x + current_x, y + current_y, 0x1111 * (selected + 2));
			current_y++;
		}
		current_x++;
	}
}

draw_case(x, y, content, selected)
{
	if (content == 'x')
		draw_x(x, y, selected);
	else if (content == 'o')
		draw_o(x, y, selected);
	else
		draw_blank(x, y, selected);
}

draw_map(map, cursor_x, cursor_y)
{
	local x = 0;
	local y;

	loop
	{
		if (x == 3)
			return;
		y = 0;
		loop
		{
			if (y == 3)
				break;
			draw_case(x * CASE_SIZE + x, y * CASE_SIZE + y, [map + x * 3 + y], cursor_x == x & cursor_y == y);
			y++;
		}
		x++;
	}
}

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

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;
	input_space = (input & 0x1) != 0;
}

cursor_update(cursor_x_ptr, cursor_y_ptr)
{
	if (input_up)
		[cursor_y_ptr] = ([cursor_y_ptr] - 1) % 3; 
	if (input_down)
		[cursor_y_ptr] = ([cursor_y_ptr] + 1) % 3; 
	if (input_left)
		[cursor_x_ptr] = ([cursor_x_ptr] - 1) % 3; 
	if (input_right)
		[cursor_x_ptr] = ([cursor_x_ptr] + 1) % 3; 
}

map_update(map, cursor_x, cursor_y)
{
	if (input_space == 0)
		return;
	if (player_turn)
		[map + cursor_x * 3 + cursor_y] = 'x';
	else
		[map + cursor_x * 3 + cursor_y] = 'o';
	player_turn = player_turn == 0;
}

main()
{
	local cursor_x, cursor_y;
	local map = {'b', 'b', 'b','b', 'b', 'b', 'b', 'b', 'b'};
	
	cursor_x = SPAWN_X;
	cursor_y = SPAWN_Y;
	
	loop
	{
		slp;
		slp;
		slp;
		draw_map(map, cursor_x, cursor_y);
		input_update();
		cursor_update(&cursor_x, &cursor_y);
		map_update(map, cursor_x, cursor_y);
	}
}