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47 lines
1.2 KiB
47 lines
1.2 KiB
#include <array>
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#include <cstddef>
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#include <unordered_hash.hpp>
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namespace detail {
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static inline size_t rtol_64(size_t val, size_t shift)
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{
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return (val >> shift) | (val << (64 - shift));
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}
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static inline size_t mix_last_64(size_t seed, size_t h)
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{
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h *= 0x87c37b91114253d5L;
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h = rtol_64(h, 31);
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h *= 0x4cf5ad432745937fL;
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return seed ^ h;
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}
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static inline size_t mix_64(size_t seed, size_t h)
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{
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h = mix_last_64(seed, h);
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h = rtol_64(h, 27);
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return h * 5 + 0x52dce729;
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}
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static inline size_t avalanche_64(size_t h)
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{
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h ^= h >> 33;
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h *= 0xff51afd7ed558ccdL;
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h ^= h >> 33;
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h *= 0xc4ceb9fe1a85ec53L;
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h ^= h >> 33;
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return h;
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}
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size_t unordered_hash_32(uint32_t* data, size_t length, size_t seed)
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{
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std::array<size_t, 4> intermediate{};
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ispc::pre_unordered_hash_32bit(data, length, intermediate.data());
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seed = mix_64(seed, intermediate[0]);
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seed = mix_64(seed, intermediate[1]);
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seed = mix_last_64(seed, intermediate[2]);
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return avalanche_64(seed ^ intermediate[3]);
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}
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}
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