decoder3_8.vhd

在quartus开发环境下

library ieee;
use ieee.std_logic_1164.all;
entity decoder3_8 is
port(a:in std_logic_vector(2 downto 0);
     g1,g2,g3:in std_logic;
     y:out std_logic_vector(7 downto 0));
end;
architecture one of decoder3_8 is
begin
process(a,g1,g2,g3)
begin
	if g1='0' then y<="11111111";
	elsif g2='1' or g3='1' then Y<="11111111";
	else
	case a is
		when "000"=>y<="11111110";
		when "001"=>y<="11111101";
		when "010"=>y<="11111011";
		when "011"=>y<="11110111";
		when "100"=>y<="11101111";
		when "101"=>y<="11011111";
		when "110"=>y<="10111111";
		when "111"=>y<="01111111";
		when others=>y<="11111111";
	end case;
	end if;
end process;
end;