Class: Digest::CRC5

Inherits:
CRC
  • Object
show all
Defined in:
lib/digest/crc5.rb

Overview

Implements the CRC5 algorithm.

Constant Summary collapse

WIDTH =
5
INIT_CRC =
0x1f
XOR_MASK =
0x1f
CRC_MASK =
(0x1f << 3)
TABLE =

Generated by ./pycrc.py --algorithm=table-driven --model=crc-5 --generate=c

[
  0x00, 0x70, 0xe0, 0x90, 0x88, 0xf8, 0x68, 0x18, 0x58, 0x28, 0xb8, 0xc8, 0xd0, 0xa0, 0x30, 0x40,
  0xb0, 0xc0, 0x50, 0x20, 0x38, 0x48, 0xd8, 0xa8, 0xe8, 0x98, 0x08, 0x78, 0x60, 0x10, 0x80, 0xf0,
  0x28, 0x58, 0xc8, 0xb8, 0xa0, 0xd0, 0x40, 0x30, 0x70, 0x00, 0x90, 0xe0, 0xf8, 0x88, 0x18, 0x68,
  0x98, 0xe8, 0x78, 0x08, 0x10, 0x60, 0xf0, 0x80, 0xc0, 0xb0, 0x20, 0x50, 0x48, 0x38, 0xa8, 0xd8,
  0x50, 0x20, 0xb0, 0xc0, 0xd8, 0xa8, 0x38, 0x48, 0x08, 0x78, 0xe8, 0x98, 0x80, 0xf0, 0x60, 0x10,
  0xe0, 0x90, 0x00, 0x70, 0x68, 0x18, 0x88, 0xf8, 0xb8, 0xc8, 0x58, 0x28, 0x30, 0x40, 0xd0, 0xa0,
  0x78, 0x08, 0x98, 0xe8, 0xf0, 0x80, 0x10, 0x60, 0x20, 0x50, 0xc0, 0xb0, 0xa8, 0xd8, 0x48, 0x38,
  0xc8, 0xb8, 0x28, 0x58, 0x40, 0x30, 0xa0, 0xd0, 0x90, 0xe0, 0x70, 0x00, 0x18, 0x68, 0xf8, 0x88,
  0xa0, 0xd0, 0x40, 0x30, 0x28, 0x58, 0xc8, 0xb8, 0xf8, 0x88, 0x18, 0x68, 0x70, 0x00, 0x90, 0xe0,
  0x10, 0x60, 0xf0, 0x80, 0x98, 0xe8, 0x78, 0x08, 0x48, 0x38, 0xa8, 0xd8, 0xc0, 0xb0, 0x20, 0x50,
  0x88, 0xf8, 0x68, 0x18, 0x00, 0x70, 0xe0, 0x90, 0xd0, 0xa0, 0x30, 0x40, 0x58, 0x28, 0xb8, 0xc8,
  0x38, 0x48, 0xd8, 0xa8, 0xb0, 0xc0, 0x50, 0x20, 0x60, 0x10, 0x80, 0xf0, 0xe8, 0x98, 0x08, 0x78,
  0xf0, 0x80, 0x10, 0x60, 0x78, 0x08, 0x98, 0xe8, 0xa8, 0xd8, 0x48, 0x38, 0x20, 0x50, 0xc0, 0xb0,
  0x40, 0x30, 0xa0, 0xd0, 0xc8, 0xb8, 0x28, 0x58, 0x18, 0x68, 0xf8, 0x88, 0x90, 0xe0, 0x70, 0x00,
  0xd8, 0xa8, 0x38, 0x48, 0x50, 0x20, 0xb0, 0xc0, 0x80, 0xf0, 0x60, 0x10, 0x08, 0x78, 0xe8, 0x98,
  0x68, 0x18, 0x88, 0xf8, 0xe0, 0x90, 0x00, 0x70, 0x30, 0x40, 0xd0, 0xa0, 0xb8, 0xc8, 0x58, 0x28
].freeze

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from CRC

#<<, #block_length, checksum, #checksum, #digest_length, #finish, #reset

Constructor Details

#initializeCRC5

Initializes the CRC5 instance.


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# File 'lib/digest/crc5.rb', line 40

def initialize
  @crc_mask = self.class.const_get(:CRC_MASK)

  super
end

Class Method Details

.pack(crc) ⇒ String

Packs the CRC8 checksum.

Parameters:

  • crc (Integer)

    The checksum to pack.

Returns:

  • (String)

    The packed checksum.


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# File 'lib/digest/crc5.rb', line 55

def self.pack(crc)
  (crc & CRC_MASK).chr
end

Instance Method Details

#update(data) ⇒ Object

Updates the CRC5 checksum.

Parameters:

  • data (String)

    The data to update the checksum with.


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# File 'lib/digest/crc5.rb', line 65

def update(data)
  data.each_byte do |b|
    @crc = ((@table[((@crc >> 3) ^ b) & 0xff] ^ (@crc >> 8)) & @crc_mask)
  end

  return self
end