90 lines
2.3 KiB
C++
90 lines
2.3 KiB
C++
/*
|
|
* This file is part of libgim.
|
|
*
|
|
* libgim is free software: you can redistribute it and/or modify it under the
|
|
* terms of the GNU General Public License as published by the Free Software
|
|
* Foundation, either version 3 of the License, or (at your option) any later
|
|
* version.
|
|
*
|
|
* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
|
|
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
|
|
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
|
|
* details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
|
|
*
|
|
* Copyright 2010 Danny Robson <danny@nerdcruft.net>
|
|
*/
|
|
|
|
#include "hash.hpp"
|
|
|
|
|
|
uint32_t
|
|
util::wang32 (uint32_t key) {
|
|
uint32_t c2 = 0x27d4eb2d; // a prime or an odd constant
|
|
key = (key ^ 61) ^ (key >> 16);
|
|
key = key + (key << 3);
|
|
key = key ^ (key >> 4);
|
|
key = key * c2;
|
|
key = key ^ (key >> 15);
|
|
return key;
|
|
}
|
|
|
|
|
|
uint64_t
|
|
util::wang64 (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;
|
|
}
|
|
|
|
|
|
|
|
// 32: 2^ 24 + 2^8 + 0x93
|
|
// 64: 2^ 40 + 2^8 + 0xb3
|
|
// 128: 2^ 88 + 2^8 + 0x3B
|
|
// 256: 2^168 + 2^8 + 0x63
|
|
// 512: 2^344 + 2^8 + 0x57
|
|
// 1024: 2^680 + 2^8 + 0x8D
|
|
static const uint32_t FNV_1a_32_PRIME = 16777619U;
|
|
static const uint64_t FNV_1a_64_PRIME = 1099511628211U;
|
|
|
|
// Bias is the FNV-0 hash of "chongo <Landon Curt Noll> /\\../\\"
|
|
static const uint32_t FNV_1a_32_BIAS = 2166136261U;
|
|
static const uint64_t FNV_1a_64_BIAS = 14695981039346656037U;
|
|
|
|
|
|
uint32_t
|
|
util::fnv1a32 (const void *_data, size_t size) {
|
|
const uint8_t *data = static_cast<const uint8_t*> (_data);
|
|
uint32_t result = FNV_1a_32_BIAS;
|
|
|
|
for (size_t i = 0; i < size; ++i) {
|
|
result ^= data[i];
|
|
result *= FNV_1a_32_PRIME;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
uint64_t
|
|
util::fnv1a64 (const void *_data, size_t size) {
|
|
const uint8_t *data = static_cast<const uint8_t*> (_data);
|
|
uint64_t result = FNV_1a_64_BIAS;
|
|
|
|
for (size_t i = 0; i < size; ++i) {
|
|
result ^= data[i];
|
|
result *= FNV_1a_64_PRIME;
|
|
}
|
|
|
|
return result;
|
|
}
|