adder16.vhd

来自「一本很好的关于学习VHDL的书,Fundamentals of Digital 」· VHDL 代码 · 共 20 行

LIBRARY ieee ;
USE ieee.std_logic_1164.all ;
USE ieee.std_logic_signed.all ;

ENTITY adder16 IS
	PORT ( 	Cin 			: IN 	STD_LOGIC ;
			X, Y 			: IN 	STD_LOGIC_VECTOR(15 DOWNTO 0) ;
			S 				: OUT 	STD_LOGIC_VECTOR(15 DOWNTO 0) ;
			Cout, Overflow 	: OUT 	STD_LOGIC ) ;
END adder16 ;

ARCHITECTURE Behavior OF adder16 IS    
	SIGNAL Sum : STD_LOGIC_VECTOR(16 DOWNTO 0) ;
BEGIN
	Sum <= ('0' & X) + Y + Cin ;
	S <= Sum(15 DOWNTO 0) ;
	Cout <= Sum(16) ;
	Overflow <= Sum(16) XOR X(15) XOR Y(15) XOR Sum(15) ;
END Behavior ;