func4.vhd

<数字逻辑与VHDL设计>代码 作者：STEPHEN BROWN

LIBRARY ieee ;
USE ieee.std_logic_1164.all ;

ENTITY func4 IS 
	PORT ( 	x1, x2, x3, x4  	: IN 	STD_LOGIC ; 
			f 					: OUT	STD_LOGIC ) ; 
END func4 ; 

ARCHITECTURE LogicFunc OF func4 IS 
BEGIN   
	f <= 	(NOT x1 AND NOT x2 AND x3 AND NOT x4) OR 
			(NOT x1 AND NOT x2 AND x3 AND x4) OR 
			(x1 AND NOT x2 AND NOT x3 AND x4) OR 
			(x1 AND NOT x2 AND x3 AND NOT x4) OR
			(x1 AND NOT x2 AND x3 AND x4) OR
			(x1 AND x2 AND NOT x3 AND x4) ;
END LogicFunc ;