class Time 

  #MS-DOS File Date and Time format as used in Interrupt 21H Function 57H:
  #
  # Register CX, the Time:
  # Bits 0-4 2 second increments (0-29)
  # Bits 5-10 minutes (0-59)
  # bits 11-15 hours (0-24)
  #
  # Register DX, the Date:
  # Bits 0-4 day (1-31)
  # bits 5-8 month (1-12)
  # bits 9-15 year (four digit year minus 1980)


  def to_binary_dos_time
    (sec/2) +
      (min << 5) +
      (hour << 11)
  end

  def to_binary_dos_date
    (day) +
      (month << 5) +
      ((year - 1980) << 9)
  end

  # Dos time is only stored with two seconds accuracy
  def dos_equals(other)
    to_i/2 == other.to_i/2
  end

  def self.parse_binary_dos_format(binaryDosDate, binaryDosTime)
    second = 2 * ( 0b11111 & binaryDosTime)
    minute = ( 0b11111100000 & binaryDosTime) >> 5
    hour = (0b1111100000000000 & binaryDosTime) >> 11
    day = ( 0b11111 & binaryDosDate)
    month = ( 0b111100000 & binaryDosDate) >> 5
    year = ((0b1111111000000000 & binaryDosDate) >> 9) + 1980
    begin
      return Time.local(year, month, day, hour, minute, second)
    end
  end
end