135 lines
3.9 KiB
C++
135 lines
3.9 KiB
C++
/*
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* xxHash - Fast Hash algorithm
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* Copyright (C) 2012-2016, Yann Collet
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*
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* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* You can contact the author at :
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* - xxHash homepage: http://www.xxhash.com
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* - xxHash source repository : https://github.com/Cyan4973/xxHash
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*/
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/* based on revision d2df04efcbef7d7f6886d345861e5dfda4edacc1 Removed
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* everything but a simple interface for computing XXh64. */
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#include "llvm/Support/xxhash.h"
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#include "llvm/Support/Endian.h"
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#include <stdlib.h>
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#include <string.h>
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using namespace llvm;
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using namespace support;
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static uint64_t rotl64(uint64_t X, size_t R) {
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return (X << R) | (X >> (64 - R));
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}
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static const uint64_t PRIME64_1 = 11400714785074694791ULL;
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static const uint64_t PRIME64_2 = 14029467366897019727ULL;
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static const uint64_t PRIME64_3 = 1609587929392839161ULL;
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static const uint64_t PRIME64_4 = 9650029242287828579ULL;
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static const uint64_t PRIME64_5 = 2870177450012600261ULL;
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static uint64_t round(uint64_t Acc, uint64_t Input) {
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Acc += Input * PRIME64_2;
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Acc = rotl64(Acc, 31);
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Acc *= PRIME64_1;
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return Acc;
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}
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static uint64_t mergeRound(uint64_t Acc, uint64_t Val) {
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Val = round(0, Val);
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Acc ^= Val;
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Acc = Acc * PRIME64_1 + PRIME64_4;
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return Acc;
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}
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uint64_t llvm::xxHash64(StringRef Data) {
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size_t Len = Data.size();
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uint64_t Seed = 0;
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const char *P = Data.data();
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const char *const BEnd = P + Len;
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uint64_t H64;
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if (Len >= 32) {
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const char *const Limit = BEnd - 32;
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uint64_t V1 = Seed + PRIME64_1 + PRIME64_2;
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uint64_t V2 = Seed + PRIME64_2;
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uint64_t V3 = Seed + 0;
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uint64_t V4 = Seed - PRIME64_1;
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do {
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V1 = round(V1, endian::read64le(P));
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P += 8;
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V2 = round(V2, endian::read64le(P));
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P += 8;
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V3 = round(V3, endian::read64le(P));
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P += 8;
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V4 = round(V4, endian::read64le(P));
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P += 8;
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} while (P <= Limit);
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H64 = rotl64(V1, 1) + rotl64(V2, 7) + rotl64(V3, 12) + rotl64(V4, 18);
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H64 = mergeRound(H64, V1);
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H64 = mergeRound(H64, V2);
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H64 = mergeRound(H64, V3);
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H64 = mergeRound(H64, V4);
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} else {
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H64 = Seed + PRIME64_5;
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}
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H64 += (uint64_t)Len;
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while (P + 8 <= BEnd) {
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uint64_t const K1 = round(0, endian::read64le(P));
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H64 ^= K1;
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H64 = rotl64(H64, 27) * PRIME64_1 + PRIME64_4;
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P += 8;
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}
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if (P + 4 <= BEnd) {
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H64 ^= (uint64_t)(endian::read32le(P)) * PRIME64_1;
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H64 = rotl64(H64, 23) * PRIME64_2 + PRIME64_3;
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P += 4;
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}
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while (P < BEnd) {
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H64 ^= (*P) * PRIME64_5;
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H64 = rotl64(H64, 11) * PRIME64_1;
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P++;
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}
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H64 ^= H64 >> 33;
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H64 *= PRIME64_2;
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H64 ^= H64 >> 29;
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H64 *= PRIME64_3;
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H64 ^= H64 >> 32;
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return H64;
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}
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