myfunction.vhd

来自「VHDL语言实现的16位快速乘法器」· VHDL 代码 · 共 33 行

Library IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
package MyFunc IS
    Function max(L, R: INTEGER) return INTEGER ;
	Function "+"(L:STD_LOGIC_VECTOR;R:STD_LOGIC_VECTOR) return STD_LOGIC_VECTOR;
END Package MyFunc;
Package Body MyFunc IS
    Function max(L, R: INTEGER) return INTEGER is
        variable result: INTEGER;
    begin
        if L > R then
            result := L;
        else
            result := R;
        end if;

        return result;
    end;
	Function "+"(L:STD_LOGIC_VECTOR;R:STD_LOGIC_VECTOR) return STD_LOGIC_VECTOR IS
		Constant Length : Integer :=max(L'Length,R'Length);
		Variable tmp :STD_LOGIC_VECTOR(Length Downto 1);
		Variable c0,c1 : STD_LOGIC;
	BEGIN
		c0:='0';
		For i In 1 downto Length Loop
			tmp(i):=(L(i) xor R(i)) xor c0;
			c1:=(L(i) and R(i)) or (L(i) and c0) or (R(i) and c0);
			c0:=c1;
		End Loop;
		return tmp;
	End;
END MyFunc;