4 BIT BINARY UP / DOWN COUNTER (Behavioral)

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use ieee.std_logic_unsigned.all;

Entity UP_COUNTER is

port(clr,clk,pr,m:in std_logic;Q:inout std_logic_vector(3 downto 0));

end UP_COUNTER;

Architecture behavioral of UP_COUNTER is

begin

process( clr,clk,pr,Q,m)

begin

if (pr ='0') then Q<="1111";

elsif (clr ='0') then Q<="0000";

elsif clk='0' and clk'event then

if m='0' then

Q<=Q + 1;

else Q<=Q - 1;

end if;

end if;

end process;

end behavioral;