Как узнать количество CD в системе?

Code:

function GetNumberOfCDDrives: Byte;

var

  drivemap, mask: DWORD;

  i: integer;

  root: string;

begin

  Result := 0;

  root := 'A:\';

  drivemap := GetLogicalDrives;

  mask := 1;

  for i := 1 to 32 do

  begin

    if (mask and drivemap) <> 0 then

      if GetDriveType(PChar(root)) = DRIVE_CDROM then

      begin

        Inc(Result);

      end;

    mask := mask shl 1;

    Inc(root[1]);

  end;

end;

procedure TForm1.Button1Click(Sender: TObject);

begin

  Label1.Caption := IntToStr(GetNumCDDrives);

end;