entity LED_DRIVER is
  port (D : in BIT_VECTOR (1 downto 0);
        S : out BIT_VECTOR(6 downto 0));
end LED_DRIVER;

architecture CONCURRENT of LED_DRIVER is
begin
  S <= "1111011" when D = "00" else
       "0001010" when D = "01" else
       "0110111" when D = "10" else
       "0011111";
end CONCURRENT;