LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL;USE IEEE.STD_LOGIC_UNSIGNED.ALL;ENTITY DECOUNTER16 ISPORT( CLK:IN STD_LOGIC; RST:IN STD_LOGIC; EN :IN STD_LOGIC; CNT_VAL:OUT STD_LOGIC_VECTOR(3 DOWNTO 0); END ENTITY DECOUNTER16; ARCHITECTURE ONE OF DECOUNTER16 IS BEGIN PROCESS(CLK,RST,EN) VARIABLE Q:STD_LOGIC_VECTOR(3 DOWNTO 0); BEGIN IF RST=1THEN Q:=1111; ELSIF CLKEVENT AND CLK=1THEN IF EN=1THEN Q:=Q-1; ELSE Q:=0000; END IF; END IF; CNT_VAL=Q; END PROCESS; END ONE;