-- LED matrix is 8 by 16 wide with 2 colors.
-- This signal is sent to the LED matrix to be displayed.
signal maze: DISPLAY := (   -- Left is red; right green
"0000000000000000" & "0000000000000001",
"0000000000000000" & "0000000000000000",
"0000000000000000" & "0000000000000000",
"0000000000000000" & "0000000000000000",
"0000000000000000" & "0000000000000000",
"0000000000000000" & "0000000000000000",
"0000000000000000" & "0000000000000000",
"0000000000000000" & "0000000000000000"
);

-- Access a position in the map
signal x: INTEGER := 0; -- 0 to 15 (width)
signal y: INTEGER := 7; -- 0 to 7 (height)

-- Random direction (up, down, left, right)
signal random: STD_LOGIC_VECTOR(1 downto 0); -- 0 to 3

-- SNIP...
-- In the architecture:
make_maze: process(clk)
begin
    if falling_edge(clk) then
        -- Choose a random direction to walk in (up, down, left, right)
        case random is
            when "00" =>
                x <= x + 1;
            when "01" =>
                y <= y + 1;
            when "10" =>
                x <= x - 1;
            when "11" =>
                y <= y - 1;
            when others => null;
        end case
        -- Light up that position in the maze
        maze(y)(x) <= '1';
        maze(y)(x + 16) <= '1';
    end if;
end process;