-------------------------------------
-- Build an 8-bit latch using latch4.
--------------------------------------

ENTITY latch8 IS
  PORT( d: IN bit_vector(7 DOWNTO 0);
        en,clk: IN bit;
        q: OUT bit_vector(7 DOWNTO 0));
END ENTITY latch8;

ARCHITECTURE struct OF latch8 IS
  COMPONENT latch4
    PORT( d: IN bit_vector(3 DOWNTO 0);
          en,clk: IN bit;
          q: OUT bit_vector(3 DOWNTO 0));
  END COMPONENT latch4;

  FOR msb: latch4 USE ENTITY WORK.latch4(behav);
  FOR lsb: latch4 USE ENTITY WORK.latch4(behav);
BEGIN
  msb: latch4  PORT MAP (d(7 DOWNTO 4), en, clk, q(7 DOWNTO 4));
  lsb: latch4  PORT MAP (d(3 DOWNTO 0),en, clk, q(3 DOWNTO 0));
END ARCHITECTURE struct;