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

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ CRC

Initializes the CRC checksum.



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# File 'lib/digest/crc.rb', line 49

def initialize
  @crc = self.class.const_get(:INIT_CRC)
end

Class Method Details

.checksum(data) ⇒ Integer

Calculates the CRC checksum.

Parameters:

  • data (String) —

    The given data.

Returns:

  • (Integer) —

    The CRC checksum.



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# File 'lib/digest/crc.rb', line 29

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.



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# File 'lib/digest/crc.rb', line 42

def self.pack(crc)
  ''
end

Instance Method Details

#<<(data) ⇒ Object

See Also:

  • Digest::CRC.{{#update}


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# File 'lib/digest/crc.rb', line 84

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

#block_length ⇒ 1

The input block length.

Returns:

  • (1) 


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# File 'lib/digest/crc.rb', line 58

def block_length
  1
end

#checksum ⇒ Integer

The resulting CRC checksum.

Returns:

  • (Integer) —

    The resulting CRC checksum.



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

def checksum
  @crc ^ self.class.const_get(:XOR_MASK)
end

#digest_length ⇒ Integer

The length of the digest.

Returns:

  • (Integer) —

    The length in bytes.



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

def digest_length
  (self.class.const_get(:WIDTH) / 8.0).ceil
end

#finish ⇒ Object

Finishes the CRC checksum calculation.

See Also:

  • {pack}


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

def finish
  self.class.pack(checksum)
end

#reset ⇒ Integer

Resets the CRC checksum.

Returns:

  • (Integer) —

    The default value of the CRC checksum.



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

def reset
  @crc = self.class.const_get(: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.



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

def update(data)
end