f_adder.vhd

8位全加器的VHDL语言描述

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;

ENTITY f_adder IS
	PORT(ain,bin,cin:IN STD_LOGIC;
		cout,sum:OUT STD_LOGIC);
END ENTITY f_adder;

ARCHITECTURE fd1 OF f_adder is
	COMPONENT h_adder
	PORT(a,b:IN STD_LOGIC;
		co,so:OUT STD_LOGIC
		);
	END COMPONENT;
	COMPONENT or2a
	PORT(a,b:IN STD_LOGIC;
		c:OUT STD_LOGIC
		);
	END COMPONENT;

	SIGNAL d,e,f:STD_LOGIC;
	BEGIN
		u1:h_adder PORT MAP(a=>ain,b=>bin,co=>d,so=>e);
		u2:h_adder PORT MAP(a=>e,b=>cin,co=>f,so=>sum);
		u3:or2a	PORT MAP(a=>d,b=>f,c=>cout);
END ARCHITECTURE fd1;