sql server 位移函数

 1CREATE FUNCTION [dbo].[BitMove](@long bigint,@operator varchar(3),@len int)  
 2RETURNS bigint AS  
 3BEGIN
 4    if @len=0
 5        return @long
 6    declare @i bigint
 7    declare @j bigint
 8    set @i=cast(0x8000000000000000 as bigint)
 9    set @j=cast(0x4000000000000000 as bigint)
    if @operator='<<'
        begin
            while @len>0
                begin
                    set @len=@len-1
                    if (@i&@long)=@i
                        set @long=@long^@i
                    if (@j&@long)=@j
                        begin
                            set @long=@long^@j
                            set @long=@long*2
                            if @len=0
                                set @long=@long|@i
                        end
                    else
                        set @long=@long*2
                end
        end
    else
        begin
            set @len=@len-1
            set @long=@long/2
            if @operator='>>>' and (@i&@long)=@i
                set @long=@long^@i
            set @long=@long/power(2,@len)
        end
    return @long
END