76 lines
1.8 KiB
C
76 lines
1.8 KiB
C
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// Copyright (c) 2019 The Dash Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef SALTEDHASHER_H
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#define SALTEDHASHER_H
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#include "hash.h"
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#include "uint256.h"
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/** Helper classes for std::unordered_map and std::unordered_set hashing */
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template<typename T> struct SaltedHasherImpl;
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template<typename N>
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struct SaltedHasherImpl<std::pair<uint256, N>>
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{
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static std::size_t CalcHash(const std::pair<uint256, N>& v, uint64_t k0, uint64_t k1)
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{
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return SipHashUint256Extra(k0, k1, v.first, (uint32_t) v.second);
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}
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};
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template<typename N>
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struct SaltedHasherImpl<std::pair<N, uint256>>
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{
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static std::size_t CalcHash(const std::pair<N, uint256>& v, uint64_t k0, uint64_t k1)
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{
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return SipHashUint256Extra(k0, k1, v.second, (uint32_t) v.first);
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}
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};
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template<>
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struct SaltedHasherImpl<uint256>
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{
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static std::size_t CalcHash(const uint256& v, uint64_t k0, uint64_t k1)
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{
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return SipHashUint256(k0, k1, v);
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}
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};
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struct SaltedHasherBase
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{
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/** Salt */
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const uint64_t k0, k1;
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SaltedHasherBase();
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};
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/* Allows each instance of unordered maps/sest to have their own salt */
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template<typename T, typename S>
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struct SaltedHasher
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{
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S s;
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std::size_t operator()(const T& v) const
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{
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return SaltedHasherImpl<T>::CalcHash(v, s.k0, s.k1);
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}
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};
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/* Allows to use a static salt for all instances. The salt is a random value set at startup
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* (through static initialization)
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*/
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struct StaticSaltedHasher
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{
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static SaltedHasherBase s;
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template<typename T>
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std::size_t operator()(const T& v) const
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{
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return SaltedHasherImpl<T>::CalcHash(v, s.k0, s.k1);
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}
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};
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#endif//SALTEDHASHER_H
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