function.vhd

用于视频运动图像编码的HUFFMAN编码

---------      电子系                 学号：J02301                姓名：张宗旺----
library ieee;
	use ieee.std_logic_1164.all;
	use ieee.std_logic_unsigned.all;
	
package MYFUNCTION is
	function ADD(A,B:std_logic_vector;CI:std_logic) return std_logic_vector;
	function SHIFT(A:std_logic_vector) return std_logic_vector;
end package MYFUNCTION;
package body  MYFUNCTION is
	function ADD(A,B:std_logic_vector;CI:std_logic) return std_logic_vector	is
		variable RESULT,AV,BV:std_logic_vector(A'length-1 downto 0);
		variable CIV:std_logic;
	begin
		AV:=A;
		BV:=B;
		CIV:=CI;
		RESULT:=AV+BV+CIV;
		return RESULT;
	end ADD;
	function SHIFT(A:std_logic_vector) return std_logic_vector is
		variable RESULT,AV:std_logic_vector(A'length-1 downto 0);
	begin
		AV:=A;
		for INDEX in 0 to A'length-2 loop
			RESULT(INDEX):=AV(INDEX+1);
		end loop;
		RESULT(A'length-1):='0';
		return RESULT;
	end SHIFT;
end MYFUNCTION;