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#----------------------------------------------------------------------------- # Copyright (c) 2010 Craig McQueen # # Permission is hereby granted, free of charge, to any person obtaining a copy # of this software and associated documentation files (the "Software"), to deal # in the Software without restriction, including without limitation the rights # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell # copies of the Software, and to permit persons to whom the Software is # furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included in # all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE # SOFTWARE. #----------------------------------------------------------------------------- ''' crcmod.predefined defines some well-known CRC algorithms. To use it, e.g.: import crcmod.predefined crc32func = crcmod.predefined.mkPredefinedCrcFun("crc-32") crc32class = crcmod.predefined.PredefinedCrc("crc-32") crcmod.predefined.Crc is an alias for crcmod.predefined.PredefinedCrc But if doing 'from crc.predefined import *', only PredefinedCrc is imported. ''' # local imports import crcmod __all__ = [ 'PredefinedCrc', 'mkPredefinedCrcFun', ] REVERSE = True NON_REVERSE = False # The following table defines the parameters of well-known CRC algorithms. # The "Check" value is the CRC for the ASCII byte sequence "123456789". It # can be used for unit tests. _crc_definitions_table = [ # Name Identifier-name, Poly Reverse Init-value XOR-out Check [ 'crc-8', 'Crc8', 0x107, NON_REVERSE, 0x00, 0x00, 0xF4, ], [ 'crc-8-darc', 'Crc8Darc', 0x139, REVERSE, 0x00, 0x00, 0x15, ], [ 'crc-8-i-code', 'Crc8ICode', 0x11D, NON_REVERSE, 0xFD, 0x00, 0x7E, ], [ 'crc-8-itu', 'Crc8Itu', 0x107, NON_REVERSE, 0x55, 0x55, 0xA1, ], [ 'crc-8-maxim', 'Crc8Maxim', 0x131, REVERSE, 0x00, 0x00, 0xA1, ], [ 'crc-8-rohc', 'Crc8Rohc', 0x107, REVERSE, 0xFF, 0x00, 0xD0, ], [ 'crc-8-wcdma', 'Crc8Wcdma', 0x19B, REVERSE, 0x00, 0x00, 0x25, ], [ 'crc-16', 'Crc16', 0x18005, REVERSE, 0x0000, 0x0000, 0xBB3D, ], [ 'crc-16-buypass', 'Crc16Buypass', 0x18005, NON_REVERSE, 0x0000, 0x0000, 0xFEE8, ], [ 'crc-16-dds-110', 'Crc16Dds110', 0x18005, NON_REVERSE, 0x800D, 0x0000, 0x9ECF, ], [ 'crc-16-dect', 'Crc16Dect', 0x10589, NON_REVERSE, 0x0001, 0x0001, 0x007E, ], [ 'crc-16-dnp', 'Crc16Dnp', 0x13D65, REVERSE, 0xFFFF, 0xFFFF, 0xEA82, ], [ 'crc-16-en-13757', 'Crc16En13757', 0x13D65, NON_REVERSE, 0xFFFF, 0xFFFF, 0xC2B7, ], [ 'crc-16-genibus', 'Crc16Genibus', 0x11021, NON_REVERSE, 0x0000, 0xFFFF, 0xD64E, ], [ 'crc-16-maxim', 'Crc16Maxim', 0x18005, REVERSE, 0xFFFF, 0xFFFF, 0x44C2, ], [ 'crc-16-mcrf4xx', 'Crc16Mcrf4xx', 0x11021, REVERSE, 0xFFFF, 0x0000, 0x6F91, ], [ 'crc-16-riello', 'Crc16Riello', 0x11021, REVERSE, 0x554D, 0x0000, 0x63D0, ], [ 'crc-16-t10-dif', 'Crc16T10Dif', 0x18BB7, NON_REVERSE, 0x0000, 0x0000, 0xD0DB, ], [ 'crc-16-teledisk', 'Crc16Teledisk', 0x1A097, NON_REVERSE, 0x0000, 0x0000, 0x0FB3, ], [ 'crc-16-usb', 'Crc16Usb', 0x18005, REVERSE, 0x0000, 0xFFFF, 0xB4C8, ], [ 'x-25', 'CrcX25', 0x11021, REVERSE, 0x0000, 0xFFFF, 0x906E, ], [ 'xmodem', 'CrcXmodem', 0x11021, NON_REVERSE, 0x0000, 0x0000, 0x31C3, ], [ 'modbus', 'CrcModbus', 0x18005, REVERSE, 0xFFFF, 0x0000, 0x4B37, ], # Note definitions of CCITT are disputable. See: # http://homepages.tesco.net/~rainstorm/crc-catalogue.htm # http://web.archive.org/web/20071229021252/http://www.joegeluso.com/software/articles/ccitt.htm [ 'kermit', 'CrcKermit', 0x11021, REVERSE, 0x0000, 0x0000, 0x2189, ], [ 'crc-ccitt-false', 'CrcCcittFalse', 0x11021, NON_REVERSE, 0xFFFF, 0x0000, 0x29B1, ], [ 'crc-aug-ccitt', 'CrcAugCcitt', 0x11021, NON_REVERSE, 0x1D0F, 0x0000, 0xE5CC, ], [ 'crc-24', 'Crc24', 0x1864CFB, NON_REVERSE, 0xB704CE, 0x000000, 0x21CF02, ], [ 'crc-24-flexray-a', 'Crc24FlexrayA', 0x15D6DCB, NON_REVERSE, 0xFEDCBA, 0x000000, 0x7979BD, ], [ 'crc-24-flexray-b', 'Crc24FlexrayB', 0x15D6DCB, NON_REVERSE, 0xABCDEF, 0x000000, 0x1F23B8, ], [ 'crc-32', 'Crc32', 0x104C11DB7, REVERSE, 0x00000000, 0xFFFFFFFF, 0xCBF43926, ], [ 'crc-32-bzip2', 'Crc32Bzip2', 0x104C11DB7, NON_REVERSE, 0x00000000, 0xFFFFFFFF, 0xFC891918, ], [ 'crc-32c', 'Crc32C', 0x11EDC6F41, REVERSE, 0x00000000, 0xFFFFFFFF, 0xE3069283, ], [ 'crc-32d', 'Crc32D', 0x1A833982B, REVERSE, 0x00000000, 0xFFFFFFFF, 0x87315576, ], [ 'crc-32-mpeg', 'Crc32Mpeg', 0x104C11DB7, NON_REVERSE, 0xFFFFFFFF, 0x00000000, 0x0376E6E7, ], [ 'posix', 'CrcPosix', 0x104C11DB7, NON_REVERSE, 0xFFFFFFFF, 0xFFFFFFFF, 0x765E7680, ], [ 'crc-32q', 'Crc32Q', 0x1814141AB, NON_REVERSE, 0x00000000, 0x00000000, 0x3010BF7F, ], [ 'jamcrc', 'CrcJamCrc', 0x104C11DB7, REVERSE, 0xFFFFFFFF, 0x00000000, 0x340BC6D9, ], [ 'xfer', 'CrcXfer', 0x1000000AF, NON_REVERSE, 0x00000000, 0x00000000, 0xBD0BE338, ], # 64-bit # Name Identifier-name, Poly Reverse Init-value XOR-out Check [ 'crc-64', 'Crc64', 0x1000000000000001B, REVERSE, 0x0000000000000000, 0x0000000000000000, 0x46A5A9388A5BEFFE, ], [ 'crc-64-we', 'Crc64We', 0x142F0E1EBA9EA3693, NON_REVERSE, 0x0000000000000000, 0xFFFFFFFFFFFFFFFF, 0x62EC59E3F1A4F00A, ], [ 'crc-64-jones', 'Crc64Jones', 0x1AD93D23594C935A9, REVERSE, 0xFFFFFFFFFFFFFFFF, 0x0000000000000000, 0xCAA717168609F281, ], ] def _simplify_name(name): """ Reduce CRC definition name to a simplified form: * lowercase * dashes removed * spaces removed * any initial "CRC" string removed """ name = name.lower() name = name.replace('-', '') name = name.replace(' ', '') if name.startswith('crc'): name = name[len('crc'):] return name _crc_definitions_by_name = {} _crc_definitions_by_identifier = {} _crc_definitions = [] _crc_table_headings = [ 'name', 'identifier', 'poly', 'reverse', 'init', 'xor_out', 'check' ] for table_entry in _crc_definitions_table: crc_definition = dict(zip(_crc_table_headings, table_entry)) _crc_definitions.append(crc_definition) name = _simplify_name(table_entry[0]) if name in _crc_definitions_by_name: raise Exception("Duplicate entry for '%s' in CRC table" % name) _crc_definitions_by_name[name] = crc_definition _crc_definitions_by_identifier[table_entry[1]] = crc_definition def _get_definition_by_name(crc_name): definition = _crc_definitions_by_name.get(_simplify_name(crc_name), None) if not definition: definition = _crc_definitions_by_identifier.get(crc_name, None) if not definition: raise KeyError("Unkown CRC name '%s'" % crc_name) return definition class PredefinedCrc(crcmod.Crc): def __init__(self, crc_name): definition = _get_definition_by_name(crc_name) crcmod.Crc.__init__(self, poly=definition['poly'], initCrc=definition['init'], rev=definition['reverse'], xorOut=definition['xor_out']) # crcmod.predefined.Crc is an alias for crcmod.predefined.PredefinedCrc Crc = PredefinedCrc def mkPredefinedCrcFun(crc_name): definition = _get_definition_by_name(crc_name) return crcmod.mkCrcFun(poly=definition['poly'], initCrc=definition['init'], rev=definition['reverse'], xorOut=definition['xor_out']) # crcmod.predefined.mkCrcFun is an alias for crcmod.predefined.mkPredefinedCrcFun mkCrcFun = mkPredefinedCrcFun