dec2to4.vhd

来自「一本很好的关于学习VHDL的书,Fundamentals of Digital 」· VHDL 代码 · 共 21 行

LIBRARY ieee ;
USE ieee.std_logic_1164.all ;

ENTITY dec2to4 IS
	PORT (	w	: IN 	STD_LOGIC_VECTOR(1 DOWNTO 0) ;
			En 	: IN 	STD_LOGIC ;
			y 	: OUT 	STD_LOGIC_VECTOR(0 TO 3) ) ;
END dec2to4 ;

ARCHITECTURE Behavior OF dec2to4 IS
	SIGNAL Enw : STD_LOGIC_VECTOR(2 DOWNTO 0) ;
BEGIN
	Enw <= En & w ;
	WITH Enw SELECT
		y <= 	"1000" WHEN "100",
				"0100" WHEN "101",
				"0010" WHEN "110",
				"0001" WHEN "111",
				"0000" WHEN OTHERS ;
END Behavior ;