3 to 8 DECODER (Behavioral)

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_arith.ALL;

use IEEE.STD_LOGIC_signed.ALL;

entity decoder3to8 is

    Port ( e : in  STD_LOGIC;

           s : in  STD_LOGIC_VECTOR (2 downto 0);

           y : out  STD_LOGIC_VECTOR (7 downto 0));

end decoder3to8;

architecture Behavioral of decoder3to8 is

begin

process (e,s)

begin

if e='0' then y<="00000000";

else case s is

when "000"=> y(0)<='1';y(1)<='0';y(2)<='0';y(3)<='0';y(4)<='0';y(5)<='0';y(6)<='0';y(7)<='0';

when "001"=> y(1)<='1';y(2)<='0';y(3)<='0';y(4)<='0';y(5)<='0';y(6)<='0';y(7)<='0';y(0)<='0';

when "010"=> y(2)<='1';y(3)<='0';y(4)<='0';y(5)<='0';y(6)<='0';y(7)<='0';y(0)<='0';y(1)<='0';

when "011"=> y(3)<='1';y(4)<='0';y(5)<='0';y(6)<='0';y(7)<='0';y(0)<='0';y(1)<='0';y(2)<='0';

when "100"=> y(4)<='1';y(5)<='0';y(6)<='0';y(7)<='0';y(0)<='0';y(1)<='0';y(2)<='0';y(3)<='0';

when "101"=> y(5)<='1';y(6)<='0';y(7)<='0';y(0)<='0';y(1)<='0';y(2)<='0';y(3)<='0';y(4)<='0';

when "110"=> y(6)<='1';y(7)<='0';y(0)<='0';y(1)<='0';y(2)<='0';y(3)<='0';y(4)<='0';y(5)<='0';

when others=> y(7)<='1';y(0)<='0';y(1)<='0';y(2)<='0';y(3)<='0';y(4)<='0';y(5)<='0';y(6)<='0';

end case;

end if;

end process;

end Behavioral;