Class: Digest::CRC

Inherits:
Class
  • Object
show all
Includes:
Instance
Defined in:
lib/digest/crc.rb

Overview

Base class for all CRC algorithms.

Direct Known Subclasses

CRC1, CRC16, CRC24, CRC32, CRC5, CRC64, CRC8

Constant Summary collapse

INIT_CRC =

The initial value of the CRC checksum

0x00
XOR_MASK =

The XOR mask to apply to the resulting CRC checksum

0x00
WIDTH =

The bit width of the CRC checksum

0
TABLE =

Default place holder CRC table

[].freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ CRC

Initializes the CRC checksum.



52
53
54
55
56
57
58
59
 
# File 'lib/digest/crc.rb', line 52

def initialize
  @init_crc = self.class.const_get(:INIT_CRC)
  @xor_mask = self.class.const_get(:XOR_MASK)
  @width    = self.class.const_get(:WIDTH)
  @table    = self.class.const_get(:TABLE)

  reset
end

Class Method Details

.checksum(data) ⇒ Integer

Calculates the CRC checksum.

Parameters:

  • data (String) —

    The given data.

Returns:

  • (Integer) —

    The CRC checksum.



32
33
34
35
36
37
 
# File 'lib/digest/crc.rb', line 32

def self.checksum(data)
  crc = self.new
  crc << data

  return crc.checksum
end

.pack(crc) ⇒ String

Packs the given CRC checksum.

Returns:

  • (String) —

    The packed CRC checksum.



45
46
47
 
# File 'lib/digest/crc.rb', line 45

def self.pack(crc)
  ''
end

Instance Method Details

#<<(data) ⇒ Object

See Also:

  • Digest::CRC.{{#update}


92
93
94
95
 
# File 'lib/digest/crc.rb', line 92

def <<(data)
  update(data)
  return self
end

#block_length ⇒ 1

The input block length.

Returns:

  • (1) 


66
67
68
 
# File 'lib/digest/crc.rb', line 66

def block_length
  1
end

#checksum ⇒ Integer

The resulting CRC checksum.

Returns:

  • (Integer) —

    The resulting CRC checksum.



113
114
115
 
# File 'lib/digest/crc.rb', line 113

def checksum
  @crc ^ @xor_mask
end

#digest_length ⇒ Integer

The length of the digest.

Returns:

  • (Integer) —

    The length in bytes.



76
77
78
 
# File 'lib/digest/crc.rb', line 76

def digest_length
  (@width / 8.0).ceil
end

#finish ⇒ Object

Finishes the CRC checksum calculation.

See Also:

  • {pack}


122
123
124
 
# File 'lib/digest/crc.rb', line 122

def finish
  self.class.pack(checksum)
end

#reset ⇒ Integer

Resets the CRC checksum.

Returns:

  • (Integer) —

    The default value of the CRC checksum.



103
104
105
 
# File 'lib/digest/crc.rb', line 103

def reset
  @crc = @init_crc
end

#update(data) ⇒ Object

Updates the CRC checksum with the given data.

Parameters:

  • data (String) —

    The data to update the CRC checksum with.



86
87
 
# File 'lib/digest/crc.rb', line 86

def update(data)
end