anchor.diff:        FOnProgress   : TAbProgressStep;
         FSlidePoint   : PAnsiChar;
         FStart        : PAnsiChar;
  -      FStartOffset  : longint;
  +      FStartOffset  : Int64;
         FStream       : TStream;
         FStreamSize   : Int64;
         FUseCRC32     : boolean;
  
positive.code:                           const aPrevMatch   : TAbDfMatch) : boolean;
        function GetNextChar : AnsiChar;
        function GetNextKeyLength : integer;
        function Position : longint;
        procedure ReadBuffer(var aBuffer; aCount  : longint;
                                          aOffset : Int64);
  
  
negative.code:   iwReadFromStream;
  end;
  {--------}
  function TAbDfInputWindow.Position : Int64;
  begin
    Result := (FCurrent - FStart) + FStartOffset;
  end;
  