Ilya Matveev
71 lines
1.5 KiB
C++
71 lines
1.5 KiB
C++
/*
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* Copyright 2010-2022 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
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* that can be found in the LICENSE file.
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*/
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#include "Utils.hpp"
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#include <climits>
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#include <cstdint>
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namespace {
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// Hash combine functions derived from boost ones.
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// Copyright 2005-2014 Daniel James.
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template <typename X, typename R>
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constexpr auto rotl32(X x, R r) noexcept { return (x << r) | (x >> (32 - r)); }
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template<size_t Bits>
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struct HashCompineImpl {
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template <typename SizeT>
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constexpr static SizeT fn(SizeT seed, SizeT value) {
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seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
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return seed;
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}
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};
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template<>
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struct HashCompineImpl<32> {
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constexpr static uint32_t fn(uint32_t h1, uint32_t k1) {
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const uint32_t c1 = 0xcc9e2d51;
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const uint32_t c2 = 0x1b873593;
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k1 *= c1;
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k1 = rotl32(k1,15);
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k1 *= c2;
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h1 ^= k1;
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h1 = rotl32(h1,13);
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h1 = h1*5+0xe6546b64;
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return h1;
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}
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};
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template<>
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struct HashCompineImpl<64> {
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constexpr static uint64_t fn(uint64_t h, uint64_t k) {
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const uint64_t m = (uint64_t(0xc6a4a793) << 32) + 0x5bd1e995;
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const int r = 47;
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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// Completely arbitrary number, to prevent 0's
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// from hashing to 0.
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h += 0xe6546b64;
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return h;
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}
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};
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} // namespace
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size_t kotlin::CombineHash(size_t seed, size_t value) {
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return HashCompineImpl<sizeof(std::size_t) * CHAR_BIT>::fn(seed, value);
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} |