/*
 * 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;
}