mux52.vhd

假设某个十字路口是由一条主干道和一条次干道汇合而成

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY MUX52 IS
   PORT( A1,A2,A3,A4,A5:IN STD_LOGIC_VECTOR(7 DOWNTO 0);
         MQ,BQ:OUT STD_LOGIC_VECTOR(7 DOWNTO 0));
END MUX52;
 ARCHITECTURE ONE OF MUX52  IS 
  BEGIN
PROCESS(A1,A2,A3,A4,A5)
  VARIABLE M,B:STD_LOGIC_VECTOR(7 DOWNTO 0);
BEGIN
   IF      A4>0  THEN  M:=A4 ;B:=A5;
    ELSIF  A5>0  THEN  M:=A1 ;B:=A5;
    ELSIF  A2>0  THEN  M:=A3; B:=A2;
    ELSIF  A3>0  THEN  M:=A3; B:=A1;
  END IF;
  MQ<=M;BQ<=B;
 END PROCESS;
END  ARCHITECTURE  ONE;