module BinData::IO::Common::SeekableStream

def num_bytes_remaining
  start_mark = @raw_io.pos
  @raw_io.seek(0, ::IO::SEEK_END)
  end_mark = @raw_io.pos
  if @buffer_end_points
    if @buffer_end_points[1] < end_mark
      end_mark = @buffer_end_points[1]
    end
  end
  bytes_remaining = end_mark - start_mark
  @raw_io.seek(start_mark, ::IO::SEEK_SET)
  bytes_remaining
end