90 lines
2.3 KiB
C++
90 lines
2.3 KiB
C++
/*
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* This file is part of libgim.
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*
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* Waif is free software: you can redistribute it and/or modify it under the
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* terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* Waif is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with libgim. If not, see <http://www.gnu.org/licenses/>.
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*
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* Copyright 2010 Danny Robson <danny@blubinc.net>
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*/
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#include "hash.hpp"
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uint32_t
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util::wang32 (uint32_t key) {
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uint32_t c2 = 0x27d4eb2d; // a prime or an odd constant
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key = (key ^ 61) ^ (key >> 16);
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key = key + (key << 3);
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key = key ^ (key >> 4);
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key = key * c2;
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key = key ^ (key >> 15);
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return key;
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}
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uint64_t
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util::wang64 (uint64_t key) {
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key = (~key) + (key << 21); // key = (key << 21) - key - 1;
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key = key ^ (key >> 24);
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key = (key + (key << 3)) + (key << 8); // key * 265
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key = key ^ (key >> 14);
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key = (key + (key << 2)) + (key << 4); // key * 21
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key = key ^ (key >> 28);
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key = key + (key << 31);
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return key;
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}
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// 32: 2^ 24 + 2^8 + 0x93
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// 64: 2^ 40 + 2^8 + 0xb3
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// 128: 2^ 88 + 2^8 + 0x3B
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// 256: 2^168 + 2^8 + 0x63
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// 512: 2^344 + 2^8 + 0x57
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// 1024: 2^680 + 2^8 + 0x8D
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static const uint32_t FNV_1a_32_PRIME = 16777619U;
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static const uint64_t FNV_1a_64_PRIME = 1099511628211U;
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// Bias is the FNV-0 hash of "chongo <Landon Curt Noll> /\\../\\"
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static const uint32_t FNV_1a_32_BIAS = 2166136261U;
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static const uint64_t FNV_1a_64_BIAS = 14695981039346656037U;
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uint32_t
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util::fnv1a32 (const void *_data, size_t size) {
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const uint8_t *data = static_cast<const uint8_t*> (_data);
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uint32_t result = FNV_1a_32_BIAS;
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for (size_t i = 0; i < size; ++i) {
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result ^= data[i];
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result *= FNV_1a_32_PRIME;
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}
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return result;
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}
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uint64_t
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util::fnv1a64 (const void *_data, size_t size) {
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const uint8_t *data = static_cast<const uint8_t*> (_data);
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uint64_t result = FNV_1a_64_BIAS;
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for (size_t i = 0; i < size; ++i) {
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result ^= data[i];
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result *= FNV_1a_64_PRIME;
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}
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return result;
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}
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