entity COUNTER is
  generic(DEL:TIME := 2 ns);
  port(RESET,LOAD,COUNT,UP,CLK: in BIT;
       DATA_IN: in BIT_VECTOR(3 downto 0);
       CNT: inout BIT_VECTOR(3 downto 0));
end COUNTER;
use work.PRIMS.all;

architecture ALG of COUNTER is
begin
  process(CLK)
  begin
    if CLK = '1' then
      if RESET = '1' then
        CNT <= "0000" after DEL;
      elsif LOAD ='1' then
        CNT <= DATA_IN after DEL;
      elsif COUNT ='1' then
        if UP = '1' then
          CNT <= INC(CNT) after DEL;
        else
          CNT <= DEC(CNT) after DEL;
        end if;
      end if;
    end if;
  end process;
end ALG;
--Figure 4.36 Counter primitive.