code: def write_data_chunksize
        p = FFI::MemoryPointer.new(:uint, 1)
        check_result(Ftdi.ftdi_write_data_get_chunksize(ctx, p))
        p.read_uint
      end
docs: Gets write buffer chunk size.
   @return [Fixnum] Write buffer chunk size.
   @raise [StatusCodeError] libftdi reports error.
   @see #write_data_chunksize=