module ChunkyPNG::Canvas::Adam7Interlacing

def adam7_pass_size(pass, original_width, original_height)
  m_o = adam7_multiplier_offset(pass)
  [ (original_width  - m_o[:x_offset] + (1 << m_o[:x_shift]) - 1) >> m_o[:x_shift],
    (original_height - m_o[:y_offset] + (1 << m_o[:y_shift]) - 1) >> m_o[:y_shift]]
end