ENCODER

 library ieee;

use ieee.std_logic_1164.all;

entity encoder is

port(y:in std_logic_vector(3 downto 0); a,b : out std_logic);

end encoder;

architecture a_encoder of encoder is

begin

process(y)

begin

case yis

when "1000" => a<='0';b<='0';

when "0100" => a<='0';b<='1';

when "0010" => a<='1';b<='0';

when "0001" => a<='1';b<='1';

when others => null;

end case;

end process;

end a_encoder;