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| 1 | +#!/usr/bin/env python |
| 2 | +# |
| 3 | +# Taken from https://cloud.google.com/appengine/docs/standard/python/refdocs/\ |
| 4 | +# modules/google/appengine/api/files/crc32c?hl=ru |
| 5 | +# |
| 6 | +# Copyright 2007 Google Inc. |
| 7 | +# |
| 8 | +# Licensed under the Apache License, Version 2.0 (the "License"); |
| 9 | +# you may not use this file except in compliance with the License. |
| 10 | +# You may obtain a copy of the License at |
| 11 | +# |
| 12 | +# http://www.apache.org/licenses/LICENSE-2.0 |
| 13 | +# |
| 14 | +# Unless required by applicable law or agreed to in writing, software |
| 15 | +# distributed under the License is distributed on an "AS IS" BASIS, |
| 16 | +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 17 | +# See the License for the specific language governing permissions and |
| 18 | +# limitations under the License. |
| 19 | +# |
| 20 | +"""Implementation of CRC-32C checksumming as in rfc3720 section B.4. |
| 21 | +See http://en.wikipedia.org/wiki/Cyclic_redundancy_check for details on CRC-32C |
| 22 | +This code is a manual python translation of c code generated by |
| 23 | +pycrc 0.7.1 (http://www.tty1.net/pycrc/). Command line used: |
| 24 | +'./pycrc.py --model=crc-32c --generate c --algorithm=table-driven' |
| 25 | +""" |
| 26 | + |
| 27 | +import array |
| 28 | + |
| 29 | +CRC_TABLE = ( |
| 30 | + 0x00000000, 0xf26b8303, 0xe13b70f7, 0x1350f3f4, |
| 31 | + 0xc79a971f, 0x35f1141c, 0x26a1e7e8, 0xd4ca64eb, |
| 32 | + 0x8ad958cf, 0x78b2dbcc, 0x6be22838, 0x9989ab3b, |
| 33 | + 0x4d43cfd0, 0xbf284cd3, 0xac78bf27, 0x5e133c24, |
| 34 | + 0x105ec76f, 0xe235446c, 0xf165b798, 0x030e349b, |
| 35 | + 0xd7c45070, 0x25afd373, 0x36ff2087, 0xc494a384, |
| 36 | + 0x9a879fa0, 0x68ec1ca3, 0x7bbcef57, 0x89d76c54, |
| 37 | + 0x5d1d08bf, 0xaf768bbc, 0xbc267848, 0x4e4dfb4b, |
| 38 | + 0x20bd8ede, 0xd2d60ddd, 0xc186fe29, 0x33ed7d2a, |
| 39 | + 0xe72719c1, 0x154c9ac2, 0x061c6936, 0xf477ea35, |
| 40 | + 0xaa64d611, 0x580f5512, 0x4b5fa6e6, 0xb93425e5, |
| 41 | + 0x6dfe410e, 0x9f95c20d, 0x8cc531f9, 0x7eaeb2fa, |
| 42 | + 0x30e349b1, 0xc288cab2, 0xd1d83946, 0x23b3ba45, |
| 43 | + 0xf779deae, 0x05125dad, 0x1642ae59, 0xe4292d5a, |
| 44 | + 0xba3a117e, 0x4851927d, 0x5b016189, 0xa96ae28a, |
| 45 | + 0x7da08661, 0x8fcb0562, 0x9c9bf696, 0x6ef07595, |
| 46 | + 0x417b1dbc, 0xb3109ebf, 0xa0406d4b, 0x522bee48, |
| 47 | + 0x86e18aa3, 0x748a09a0, 0x67dafa54, 0x95b17957, |
| 48 | + 0xcba24573, 0x39c9c670, 0x2a993584, 0xd8f2b687, |
| 49 | + 0x0c38d26c, 0xfe53516f, 0xed03a29b, 0x1f682198, |
| 50 | + 0x5125dad3, 0xa34e59d0, 0xb01eaa24, 0x42752927, |
| 51 | + 0x96bf4dcc, 0x64d4cecf, 0x77843d3b, 0x85efbe38, |
| 52 | + 0xdbfc821c, 0x2997011f, 0x3ac7f2eb, 0xc8ac71e8, |
| 53 | + 0x1c661503, 0xee0d9600, 0xfd5d65f4, 0x0f36e6f7, |
| 54 | + 0x61c69362, 0x93ad1061, 0x80fde395, 0x72966096, |
| 55 | + 0xa65c047d, 0x5437877e, 0x4767748a, 0xb50cf789, |
| 56 | + 0xeb1fcbad, 0x197448ae, 0x0a24bb5a, 0xf84f3859, |
| 57 | + 0x2c855cb2, 0xdeeedfb1, 0xcdbe2c45, 0x3fd5af46, |
| 58 | + 0x7198540d, 0x83f3d70e, 0x90a324fa, 0x62c8a7f9, |
| 59 | + 0xb602c312, 0x44694011, 0x5739b3e5, 0xa55230e6, |
| 60 | + 0xfb410cc2, 0x092a8fc1, 0x1a7a7c35, 0xe811ff36, |
| 61 | + 0x3cdb9bdd, 0xceb018de, 0xdde0eb2a, 0x2f8b6829, |
| 62 | + 0x82f63b78, 0x709db87b, 0x63cd4b8f, 0x91a6c88c, |
| 63 | + 0x456cac67, 0xb7072f64, 0xa457dc90, 0x563c5f93, |
| 64 | + 0x082f63b7, 0xfa44e0b4, 0xe9141340, 0x1b7f9043, |
| 65 | + 0xcfb5f4a8, 0x3dde77ab, 0x2e8e845f, 0xdce5075c, |
| 66 | + 0x92a8fc17, 0x60c37f14, 0x73938ce0, 0x81f80fe3, |
| 67 | + 0x55326b08, 0xa759e80b, 0xb4091bff, 0x466298fc, |
| 68 | + 0x1871a4d8, 0xea1a27db, 0xf94ad42f, 0x0b21572c, |
| 69 | + 0xdfeb33c7, 0x2d80b0c4, 0x3ed04330, 0xccbbc033, |
| 70 | + 0xa24bb5a6, 0x502036a5, 0x4370c551, 0xb11b4652, |
| 71 | + 0x65d122b9, 0x97baa1ba, 0x84ea524e, 0x7681d14d, |
| 72 | + 0x2892ed69, 0xdaf96e6a, 0xc9a99d9e, 0x3bc21e9d, |
| 73 | + 0xef087a76, 0x1d63f975, 0x0e330a81, 0xfc588982, |
| 74 | + 0xb21572c9, 0x407ef1ca, 0x532e023e, 0xa145813d, |
| 75 | + 0x758fe5d6, 0x87e466d5, 0x94b49521, 0x66df1622, |
| 76 | + 0x38cc2a06, 0xcaa7a905, 0xd9f75af1, 0x2b9cd9f2, |
| 77 | + 0xff56bd19, 0x0d3d3e1a, 0x1e6dcdee, 0xec064eed, |
| 78 | + 0xc38d26c4, 0x31e6a5c7, 0x22b65633, 0xd0ddd530, |
| 79 | + 0x0417b1db, 0xf67c32d8, 0xe52cc12c, 0x1747422f, |
| 80 | + 0x49547e0b, 0xbb3ffd08, 0xa86f0efc, 0x5a048dff, |
| 81 | + 0x8ecee914, 0x7ca56a17, 0x6ff599e3, 0x9d9e1ae0, |
| 82 | + 0xd3d3e1ab, 0x21b862a8, 0x32e8915c, 0xc083125f, |
| 83 | + 0x144976b4, 0xe622f5b7, 0xf5720643, 0x07198540, |
| 84 | + 0x590ab964, 0xab613a67, 0xb831c993, 0x4a5a4a90, |
| 85 | + 0x9e902e7b, 0x6cfbad78, 0x7fab5e8c, 0x8dc0dd8f, |
| 86 | + 0xe330a81a, 0x115b2b19, 0x020bd8ed, 0xf0605bee, |
| 87 | + 0x24aa3f05, 0xd6c1bc06, 0xc5914ff2, 0x37faccf1, |
| 88 | + 0x69e9f0d5, 0x9b8273d6, 0x88d28022, 0x7ab90321, |
| 89 | + 0xae7367ca, 0x5c18e4c9, 0x4f48173d, 0xbd23943e, |
| 90 | + 0xf36e6f75, 0x0105ec76, 0x12551f82, 0xe03e9c81, |
| 91 | + 0x34f4f86a, 0xc69f7b69, 0xd5cf889d, 0x27a40b9e, |
| 92 | + 0x79b737ba, 0x8bdcb4b9, 0x988c474d, 0x6ae7c44e, |
| 93 | + 0xbe2da0a5, 0x4c4623a6, 0x5f16d052, 0xad7d5351, |
| 94 | +) |
| 95 | + |
| 96 | +CRC_INIT = 0 |
| 97 | +_MASK = 0xFFFFFFFF |
| 98 | + |
| 99 | + |
| 100 | +def crc_update(crc, data): |
| 101 | + """Update CRC-32C checksum with data. |
| 102 | + Args: |
| 103 | + crc: 32-bit checksum to update as long. |
| 104 | + data: byte array, string or iterable over bytes. |
| 105 | + Returns: |
| 106 | + 32-bit updated CRC-32C as long. |
| 107 | + """ |
| 108 | + if type(data) != array.array or data.itemsize != 1: |
| 109 | + buf = array.array("B", data) |
| 110 | + else: |
| 111 | + buf = data |
| 112 | + crc = crc ^ _MASK |
| 113 | + for b in buf: |
| 114 | + table_index = (crc ^ b) & 0xff |
| 115 | + crc = (CRC_TABLE[table_index] ^ (crc >> 8)) & _MASK |
| 116 | + return crc ^ _MASK |
| 117 | + |
| 118 | + |
| 119 | +def crc_finalize(crc): |
| 120 | + """Finalize CRC-32C checksum. |
| 121 | + This function should be called as last step of crc calculation. |
| 122 | + Args: |
| 123 | + crc: 32-bit checksum as long. |
| 124 | + Returns: |
| 125 | + finalized 32-bit checksum as long |
| 126 | + """ |
| 127 | + return crc & _MASK |
| 128 | + |
| 129 | + |
| 130 | +def crc(data): |
| 131 | + """Compute CRC-32C checksum of the data. |
| 132 | + Args: |
| 133 | + data: byte array, string or iterable over bytes. |
| 134 | + Returns: |
| 135 | + 32-bit CRC-32C checksum of data as long. |
| 136 | + """ |
| 137 | + return crc_finalize(crc_update(CRC_INIT, data)) |
| 138 | + |
| 139 | + |
| 140 | +if __name__ == "__main__": |
| 141 | + import sys |
| 142 | + data = sys.stdin.read() |
| 143 | + print(hex(crc(data))) |
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