52 lines
1.5 KiB
C++
52 lines
1.5 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 2010-2015 Danny Robson <danny@nerdcruft.net>
|
|
*/
|
|
|
|
#ifdef __UTIL_HASH_WANG_IPP
|
|
#error
|
|
#endif
|
|
#define __UTIL_HASH_WANG_IPP
|
|
|
|
|
|
//-----------------------------------------------------------------------------
|
|
constexpr uint32_t
|
|
util::hash::wang (uint32_t key) {
|
|
// a prime or an odd constant
|
|
constexpr uint32_t c2 = 0x27d4eb2d;
|
|
|
|
key = (key ^ 61) ^ (key >> 16);
|
|
key = key + (key << 3);
|
|
key = key ^ (key >> 4);
|
|
key = key * c2;
|
|
key = key ^ (key >> 15);
|
|
|
|
return key;
|
|
}
|
|
|
|
|
|
//-----------------------------------------------------------------------------
|
|
constexpr uint64_t
|
|
util::hash::wang (uint64_t key) {
|
|
key = ~key + (key << 21); // key = (key << 21) - key - 1;
|
|
key = key ^ (key >> 24);
|
|
key = (key + (key << 3)) + (key << 8); // key * 265
|
|
key = key ^ (key >> 14);
|
|
key = (key + (key << 2)) + (key << 4); // key * 21
|
|
key = key ^ (key >> 28);
|
|
key = key + (key << 31);
|
|
|
|
return key;
|
|
}
|