libcruft-util/hash/murmur/murmur1.hpp

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/*
* 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_MURMUR_MURMUR1_HPP
#define __UTIL_HASH_MURMUR_MURMUR1_HPP
#include "../../view.hpp"
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#include <cstdint>
#include <cstddef>
// Austin Appleby's MumurHash1
namespace util::hash {
class murmur1 {
public:
using digest_t = uint32_t;
using seed_t = uint32_t;
murmur1 (seed_t _seed):
m_seed (_seed)
{ ; }
static constexpr uint32_t mix (uint32_t h, uint32_t k)
{
constexpr uint32_t m = 0xc6a4a793;
h += k;
h *= m;
h ^= h >> 16;
return h;
}
digest_t operator() (util::view<const uint8_t*> data) const noexcept;
private:
seed_t m_seed;
};
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}
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#endif