sp_MSsetbit (Transact-SQL MetaData) Definition

Please note: that the following source code is provided and copyrighted by Microsoft and is for educational purpose only.
The meta data is from an SQL 2012 Server.

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Definition:

sys.sp_MSsetbit(smallint @coltoadd
, int @toset)

MetaData:

 create procedure sys.sp_MSsetbit  
    @bm varbinary(128) output,  
    @coltoadd smallint,  
    @toset    int = 1  
AS  
    declare @bytenum smallint  
    declare @bit smallint  
    declare @mask tinyint  
    declare @newbyte tinyint       
    declare @oldbyte tinyint  
              
    SELECT @bytenum = 1 + FLOOR((@coltoadd-1)/8)  
  
    IF @bytenum > 128 return 0  
  
    SELECT @bit = (@coltoadd-1) % 8  
  
    SET @mask = POWER(2, @bit)  
    if @toset = 0  
        SET @mask = (~@mask % 256)  
                  
    if @bm is null  
        set @bm = 0x0  
    while datalength(@bm) < @bytenum  
        set @bm = @bm + 0x00   
  
    SET @oldbyte = SUBSTRING( @bm, @bytenum, 1)  
    IF @oldbyte IS NULL SET @oldbyte = 0  
    if @toset <> 0              
        SET @newbyte = @oldbyte | @mask  
    else  
        SET @newbyte = @oldbyte & @mask  
  
    if (@bytenum = 1)  
        set @bm = convert(binary(1), @newbyte) + substring(@bm, 2, 127)  
    else  
        set @bm = substring(@bm, 1, @bytenum - 1) + convert(binary(1), @newbyte) + substring(@bm, @bytenum + 1, 128 - @bytenum)