Subversion Repositories v6502

library IEEE;

use IEEE.std_logic_1164.all;  -- defines std_logic types

use IEEE.STD_LOGIC_unsigned.all;

use IEEE.STD_LOGIC_arith.all;

-- 8 bit three-way multiplexer

entity data_mux is

  port(    s:  in STD_LOGIC_VECTOR(3 downto 0);

           a:  in STD_LOGIC_VECTOR(7 downto 0);

           b:  in STD_LOGIC_VECTOR(7 downto 0);

           c:  in STD_LOGIC_VECTOR(7 downto 0);

           d:  in STD_LOGIC_VECTOR(7 downto 0);

           y: out STD_LOGIC_VECTOR(7 downto 0)

      );

end data_mux;

architecture comb of data_mux is

begin

  process(s,a,b,c,d)

  begin

    case s is

      when "1110"  => y <= a;

      when "1101"  => y <= b;

      when "1011"  => y <= c;

      when "0111"  => y <= d;

      when others  => y <= a;

    end case;

  end process;

end comb;