libcruft-util/hash.hpp

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/*
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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
*
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* 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.
*
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* Copyright 2010 Danny Robson <danny@nerdcruft.net>
*/
#ifndef __UTIL_HASH_HPP
#define __UTIL_HASH_HPP
#include <cstdint>
#include <cstdlib>
// All hashes are unsuitable for cryptographic operations nnless noted.
namespace util {
// Fast integer mixing operations by Thomas Wang.
uint32_t wang32 (uint32_t key);
uint64_t wang64 (uint64_t key);
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// Fast and general hashing using FNV-1a
uint32_t fnv1a32 (const void *, size_t);
uint64_t fnv1a64 (const void *, size_t);
// General hashes for when you really just don't care about implementation
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inline uint32_t hash (uint32_t key) { return wang32 (key); }
inline int32_t hash ( int32_t key) { return (int32_t) hash ((uint32_t)key); }
inline uint64_t hash (uint64_t key) { return wang64 (key); }
inline int64_t hash ( int64_t key) { return (int64_t) hash ((uint64_t)key); }
inline uintptr_t hash (const void *key) {
return sizeof (uintptr_t) == 32 ? wang32 (reinterpret_cast<uintptr_t> (key)) :
wang64 (reinterpret_cast<uintptr_t> (key));
}
}
#endif