48 lines
1.2 KiB
C++
48 lines
1.2 KiB
C++
/*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*
|
|
* Copyright 2015 Danny Robson <danny@nerdcruft.net>
|
|
*/
|
|
|
|
#ifndef __UTIL_HASH_FASTHASH_HPP
|
|
#define __UTIL_HASH_FASTHASH_HPP
|
|
|
|
#include "../view.hpp"
|
|
|
|
#include <cstddef>
|
|
#include <cstdint>
|
|
|
|
|
|
// Zilong Tan's FastHash, via George Marsaglia's "Xorshift RNGs"
|
|
namespace util::hash {
|
|
template <typename ValueT>
|
|
struct fasthash {
|
|
using digest_t = ValueT;
|
|
|
|
static constexpr
|
|
uint64_t mix (uint64_t v)
|
|
{
|
|
v ^= v >> 23;
|
|
v *= 0x2127599bf4325c37;
|
|
v ^= v >> 47;
|
|
|
|
return v;
|
|
}
|
|
|
|
|
|
digest_t operator() (uint64_t seed, util::view<const uint8_t*>) const;
|
|
};
|
|
}
|
|
|
|
#endif
|