Class: Archive::DOSTime

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/archive/support/time.rb

Overview

A representation of the DOS time structure which can be converted into instances of Time.

Instance Method Summary collapse

Constructor Details

#initialize(dos_time = nil) ⇒ DOSTime

Creates a new instance of DOSTime. dos_time is a 4 byte String or unsigned number (Integer) representing an MS-DOS time structure where:

Bits 0-4

2 second increments (0-29)

Bits 5-10

minutes (0-59)

Bits 11-15

hours (0-24)

Bits 16-20

day (1-31)

Bits 21-24

month (1-12)

Bits 25-31

four digit year minus 1980 (0-119)

If dos_time is ommitted or nil, a new instance is created based on the current time.



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# File 'lib/archive/support/time.rb', line 45

def initialize(dos_time = nil)
  case dos_time
  when nil
    @dos_time = Time.now.to_dos_time.to_i
  when Integer
    @dos_time = dos_time
  else
    unless dos_time.length == 4 then
      raise ArgumentError, 'length of DOS time structure is not 4'
    end
    @dos_time = dos_time.unpack('V')[0]
  end

  validate
end

Instance Method Details

#cmp(other) ⇒ Object Also known as: <=>

Returns -1 if other is a time earlier than this one, 0 if other is the same time, and 1 if other is a later time.



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# File 'lib/archive/support/time.rb', line 63

def cmp(other)
  to_i <=> other.to_i
end

#pack ⇒ Object

Returns the 32 bit integer that backs this object packed into a String in little endian format. This is suitable for use with #new.



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# File 'lib/archive/support/time.rb', line 76

def pack
  [to_i].pack('V')
end

#to_i ⇒ Object

Returns the time value of this object as an integer representing the DOS time structure.



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# File 'lib/archive/support/time.rb', line 70

def to_i
  @dos_time
end

#to_time ⇒ Object

Returns a Time instance which is equivalent to the time represented by this object.



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# File 'lib/archive/support/time.rb', line 82

def to_time
  second = ((0b11111         & @dos_time)      ) * 2
  minute = ((0b111111  << 5  & @dos_time) >>  5)
  hour   = ((0b11111   << 11 & @dos_time) >> 11)
  day    = ((0b11111   << 16 & @dos_time) >> 16)
  month  = ((0b1111    << 21 & @dos_time) >> 21)
  year   = ((0b1111111 << 25 & @dos_time) >> 25) + 1980
  return Time.local(year, month, day, hour, minute, second)
end

#validate ⇒ Object (private) 



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# File 'lib/archive/support/time.rb', line 94

def validate
  second = (0b11111         & @dos_time)
  minute = (0b111111  << 5  & @dos_time) >>  5
  hour   = (0b11111   << 11 & @dos_time) >> 11
  day    = (0b11111   << 16 & @dos_time) >> 16
  month  = (0b1111    << 21 & @dos_time) >> 21
  year   = (0b1111111 << 25 & @dos_time) >> 25

  if second > 29
    raise ArgumentError, 'second must not be greater than 29'
  elsif minute > 59
    raise ArgumentError, 'minute must not be greater than 59'
  elsif hour > 24
    raise ArgumentError, 'hour must not be greater than 24'
  elsif day < 1
    raise ArgumentError, 'day must not be less than 1'
  elsif month < 1
    raise ArgumentError, 'month must not be less than 1'
  elsif month > 12
    raise ArgumentError, 'month must not be greater than 12'
  elsif year > 119
    raise ArgumentError, 'year must not be greater than 119'
  end
end