crc - CRC generator for ruby

This is a general CRC (Cyclic Redundancy Check) generator for ruby.

It is written by pure ruby with based on slice-by-eight algorithm (byte-order-free slice-by-16 algorithm).

Included built-in CRC modules are CRC-32, CRC-64-ECMA, CRC-64-ISO, CRC-16-CCITT, CRC-16-IBM, CRC-8, CRC-5-USB, CRC-5-EPC and more.

And your defined CRC modules to use.

This is slower than x95+ of zlib/crc32, and slower than x135+ of extlzma/crc32 on FreeBSD 10.3R amd64.

If you need more speed, please use crc-turbo.

SUMMARY

  • package name: crc
  • author: dearblue (mailto:[email protected])
  • report issue to: https://osdn.jp/projects/rutsubo/ticket/
  • how to install: gem install crc
  • version: 0.1
  • release quality: thechnical preview
  • licensing: BSD-2-Clause
  • dependency gems: none
  • dependency external c libraries: none
  • bundled external c libraries: none

FEATURES

  • CRC.crc32(seq, init = 0) -> crc-32 integer (likely as Zlib.crc32)
  • CRC::CRC32.crc(seq, init = 0) -> crc-32 integer (likely as Zlib.crc32)
  • CRC::CRC32.digest(seq, init = 0) -> crc-32 digest (likely as Digest::XXXX.digest)
  • CRC::CRC32.hexdigest(seq, init = 0) -> crc-32 hex-digest (likely as Digest::XXXX.hexdigest)
  • CRC::CRC32.new(init = 0) -> crc-32 context (likely as Digest::XXXX.new)
  • CRC::CRC32#update(seq) -> self (likely as Digest::XXXX#update)
  • CRC::CRC32#finish -> crc-32 integer (likely as Digest::XXXX#finish)
  • CRC.crc("crc-32", seq, init = 0) -> crc-32 integer
  • CRC.digest("crc-32", seq, init = 0) -> crc-32 digest
  • CRC.hexdigest("crc-32", seq, init = 0) -> crc-32 hex-digest

  • CRC.create_module(bitsize, poly, init_state, refin, refout, xorout) -> new crc module class

    MyCRC32 = CRC.create_module(32, 0x04C11DB7)
p MyCRC32.class  # => Class
p MyCRC32.hexdigest("123456789")  # => "CBF43926"

BUILD-IN CRC MODULES

% ruby -rcrc -e 'puts CRC::MODULE_TABLE.values.uniq.map { |m| m::TRAITS.name }.join(", ")'

CRC-1, CRC-3-ROHC, CRC-4-ITU, CRC-5-EPC, CRC-5-ITU, CRC-5-USB, CRC-6-CDMA2000-A, CRC-6-CDMA2000-B, CRC-6-DARC, CRC-6-ITU, CRC-7, CRC-7-MVB, CRC-8, CRC-8-CCITT, CRC-8-Dallas/Maxim, CRC-8-DARC, CRC-8-SAE, CRC-8-WCDMA, CRC-10, CRC-10-CDMA2000, CRC-11, CRC-12, CRC-12-CDMA2000, CRC-13-BBC, CRC-14-DARC, CRC-15-CAN, CRC-15-MPT1327, Chakravarty, CRC-16-ARINC, CRC-16-CCITT, CRC-16-CDMA2000, CRC-16-DECT, CRC-16-T10-DIF, CRC-16-DNP, CRC-16-IBM, CRC-16-LZH, CRC-17-CAN, CRC-21-CAN, CRC-24, CRC-24-Radix-64, CRC-30, CRC-32, CRC-32C, CRC-32K, CRC-32K2, CRC-32Q, CRC-40-GSM, CRC-64-ECMA, CRC-64-ISO

ENVIRONMENT VARIABLES FOR BEHAVIOR

  • RUBY_CRC_NOFAST=1: Force use ruby implementation with slice-by-16 algorithm. Not used "crc-turbo".
  • RUBY_CRC_NOFAST=2: Switch to lookup table algorithm from slice-by-16 algorithm. Slower to about 52% (when CRC-32).
  • RUBY_CRC_NOFAST=3: Switch to reference algorithm from slice-by-16 algorithm. Slower to about 7% (when CRC-32).