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/*
* Copyright 2022 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.cloud.storage;
class Crc32cUtility {
private Crc32cUtility() {}
/**
* Straight forward implementation to combine two crc32c values
*
* There is a more efficient implementation in https://github.com/google/crc32c, however for
* brevity we are following the byte by byte computation, implemented in:
* https://github.com/google/crc32c/blob/main/src/crc32c_portable.cc#L252-L257
*
* @param crc1 crc32c int of an object to combine crc2 with
* @param crc2 crc32c int of the second object
* @param crc2ObjectSize byte length of object which generated crc2
* @return
* @see https://github.com/google/crc32c/blob/21fc8ef30415a635e7351ffa0e5d5367943d4a94/src/crc32c_portable.cc#L252-L257
*/
public static int crc32cCombineGoogle(int crc1, int crc2, long crc2ObjectSize) {
int l = crc1;
// run number of 0's based on size
for (long i = 0; i < crc2ObjectSize; i++) {
l = (l >>> 8) ^ kByteExtensionTable[l & 0xff];
}
return l ^ crc2;
}
// Ported from:
// https://github.com/google/crc32c/blob/21fc8ef30415a635e7351ffa0e5d5367943d4a94/src/crc32c_portable.cc#L16-L59
private static final int[] kByteExtensionTable =
new int[] {
0x00000000,
0xf26b8303,
0xe13b70f7,
0x1350f3f4,
0xc79a971f,
0x35f1141c,
0x26a1e7e8,
0xd4ca64eb,
0x8ad958cf,
0x78b2dbcc,
0x6be22838,
0x9989ab3b,
0x4d43cfd0,
0xbf284cd3,
0xac78bf27,
0x5e133c24,
0x105ec76f,
0xe235446c,
0xf165b798,
0x030e349b,
0xd7c45070,
0x25afd373,
0x36ff2087,
0xc494a384,
0x9a879fa0,
0x68ec1ca3,
0x7bbcef57,
0x89d76c54,
0x5d1d08bf,
0xaf768bbc,
0xbc267848,
0x4e4dfb4b,
0x20bd8ede,
0xd2d60ddd,
0xc186fe29,
0x33ed7d2a,
0xe72719c1,
0x154c9ac2,
0x061c6936,
0xf477ea35,
0xaa64d611,
0x580f5512,
0x4b5fa6e6,
0xb93425e5,
0x6dfe410e,
0x9f95c20d,
0x8cc531f9,
0x7eaeb2fa,
0x30e349b1,
0xc288cab2,
0xd1d83946,
0x23b3ba45,
0xf779deae,
0x05125dad,
0x1642ae59,
0xe4292d5a,
0xba3a117e,
0x4851927d,
0x5b016189,
0xa96ae28a,
0x7da08661,
0x8fcb0562,
0x9c9bf696,
0x6ef07595,
0x417b1dbc,
0xb3109ebf,
0xa0406d4b,
0x522bee48,
0x86e18aa3,
0x748a09a0,
0x67dafa54,
0x95b17957,
0xcba24573,
0x39c9c670,
0x2a993584,
0xd8f2b687,
0x0c38d26c,
0xfe53516f,
0xed03a29b,
0x1f682198,
0x5125dad3,
0xa34e59d0,
0xb01eaa24,
0x42752927,
0x96bf4dcc,
0x64d4cecf,
0x77843d3b,
0x85efbe38,
0xdbfc821c,
0x2997011f,
0x3ac7f2eb,
0xc8ac71e8,
0x1c661503,
0xee0d9600,
0xfd5d65f4,
0x0f36e6f7,
0x61c69362,
0x93ad1061,
0x80fde395,
0x72966096,
0xa65c047d,
0x5437877e,
0x4767748a,
0xb50cf789,
0xeb1fcbad,
0x197448ae,
0x0a24bb5a,
0xf84f3859,
0x2c855cb2,
0xdeeedfb1,
0xcdbe2c45,
0x3fd5af46,
0x7198540d,
0x83f3d70e,
0x90a324fa,
0x62c8a7f9,
0xb602c312,
0x44694011,
0x5739b3e5,
0xa55230e6,
0xfb410cc2,
0x092a8fc1,
0x1a7a7c35,
0xe811ff36,
0x3cdb9bdd,
0xceb018de,
0xdde0eb2a,
0x2f8b6829,
0x82f63b78,
0x709db87b,
0x63cd4b8f,
0x91a6c88c,
0x456cac67,
0xb7072f64,
0xa457dc90,
0x563c5f93,
0x082f63b7,
0xfa44e0b4,
0xe9141340,
0x1b7f9043,
0xcfb5f4a8,
0x3dde77ab,
0x2e8e845f,
0xdce5075c,
0x92a8fc17,
0x60c37f14,
0x73938ce0,
0x81f80fe3,
0x55326b08,
0xa759e80b,
0xb4091bff,
0x466298fc,
0x1871a4d8,
0xea1a27db,
0xf94ad42f,
0x0b21572c,
0xdfeb33c7,
0x2d80b0c4,
0x3ed04330,
0xccbbc033,
0xa24bb5a6,
0x502036a5,
0x4370c551,
0xb11b4652,
0x65d122b9,
0x97baa1ba,
0x84ea524e,
0x7681d14d,
0x2892ed69,
0xdaf96e6a,
0xc9a99d9e,
0x3bc21e9d,
0xef087a76,
0x1d63f975,
0x0e330a81,
0xfc588982,
0xb21572c9,
0x407ef1ca,
0x532e023e,
0xa145813d,
0x758fe5d6,
0x87e466d5,
0x94b49521,
0x66df1622,
0x38cc2a06,
0xcaa7a905,
0xd9f75af1,
0x2b9cd9f2,
0xff56bd19,
0x0d3d3e1a,
0x1e6dcdee,
0xec064eed,
0xc38d26c4,
0x31e6a5c7,
0x22b65633,
0xd0ddd530,
0x0417b1db,
0xf67c32d8,
0xe52cc12c,
0x1747422f,
0x49547e0b,
0xbb3ffd08,
0xa86f0efc,
0x5a048dff,
0x8ecee914,
0x7ca56a17,
0x6ff599e3,
0x9d9e1ae0,
0xd3d3e1ab,
0x21b862a8,
0x32e8915c,
0xc083125f,
0x144976b4,
0xe622f5b7,
0xf5720643,
0x07198540,
0x590ab964,
0xab613a67,
0xb831c993,
0x4a5a4a90,
0x9e902e7b,
0x6cfbad78,
0x7fab5e8c,
0x8dc0dd8f,
0xe330a81a,
0x115b2b19,
0x020bd8ed,
0xf0605bee,
0x24aa3f05,
0xd6c1bc06,
0xc5914ff2,
0x37faccf1,
0x69e9f0d5,
0x9b8273d6,
0x88d28022,
0x7ab90321,
0xae7367ca,
0x5c18e4c9,
0x4f48173d,
0xbd23943e,
0xf36e6f75,
0x0105ec76,
0x12551f82,
0xe03e9c81,
0x34f4f86a,
0xc69f7b69,
0xd5cf889d,
0x27a40b9e,
0x79b737ba,
0x8bdcb4b9,
0x988c474d,
0x6ae7c44e,
0xbe2da0a5,
0x4c4623a6,
0x5f16d052,
0xad7d5351
};
}