libcruft-util/hash/fasthash.hpp

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/*
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* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
* Copyright 2015 Danny Robson <danny@nerdcruft.net>
*/
#ifndef __UTIL_HASH_FASTHASH_HPP
#define __UTIL_HASH_FASTHASH_HPP
#include "../view.hpp"
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#include <cstddef>
#include <cstdint>
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// Zilong Tan's FastHash, via George Marsaglia's "Xorshift RNGs"
namespace cruft::hash {
template <typename ValueT>
struct fasthash {
using digest_t = ValueT;
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static constexpr
uint64_t mix (uint64_t v)
{
v ^= v >> 23;
v *= 0x2127599bf4325c37;
v ^= v >> 47;
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return v;
}
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digest_t operator() (uint64_t seed, cruft::view<const uint8_t*>) const;
};
}
#endif