# File lib/win32/file.rb, line 788
   def compressed=(bool)     
      in_buf = bool ? COMPRESSION_FORMAT_DEFAULT : COMPRESSION_FORMAT_NONE
      in_buf = [in_buf].pack('L')
      bytes  = [0].pack('L')
      
      handle = CreateFile(
         self.path,
         FILE_READ_DATA | FILE_WRITE_DATA,
         FILE_SHARE_READ | FILE_SHARE_WRITE,
         0,
         OPEN_EXISTING,
         0,
         0
      )
      
      if handle == INVALID_HANDLE_VALUE
         raise ArgumentError, get_last_error
      end
      
      val = DeviceIoControl(
         handle,
         FSCTL_SET_COMPRESSION(),
         in_buf,
         in_buf.length,
         0,
         0,
         bytes,
         0
      )
      
      if val == 0
         raise ArgumentError, get_last_error
      end
      
      self
   end