Tim Starling
102 linhas
3.0 KiB
C++
102 linhas
3.0 KiB
C++
/*
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+----------------------------------------------------------------------+
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| HipHop for PHP |
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+----------------------------------------------------------------------+
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| Copyright (c) 2010-2013 Facebook, Inc. (http://www.facebook.com) |
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| Copyright (c) 1997-2010 The PHP Group |
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+----------------------------------------------------------------------+
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| This source file is subject to version 3.01 of the PHP license, |
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| that is bundled with this package in the file LICENSE, and is |
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| available through the world-wide-web at the following url: |
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| http://www.php.net/license/3_01.txt |
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| If you did not receive a copy of the PHP license and are unable to |
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| obtain it through the world-wide-web, please send a note to |
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| license@php.net so we can mail you a copy immediately. |
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+----------------------------------------------------------------------+
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*/
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/**
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* This file contains code from MurmurHash, by Austin Appleby. The licensing
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* information for MurmurHash as specified on its website,
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* http://sites.google.com/site/murmurhash/, is as follows: "For business
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* purposes, Murmurhash is under the MIT license.
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*/
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#include <stddef.h>
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#include <stdint.h>
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#include "hphp/runtime/ext/hash/hash_murmur.h"
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namespace HPHP {
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/**
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* MurmurHash2, 64-bit versions, by Austin Appleby
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*
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* The same caveats as 32-bit MurmurHash2 apply here - beware of alignment
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* and endian-ness issues if used across multiple platforms.
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*
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* 64-bit hash for 64-bit platforms
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*/
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uint64_t murmur_hash_64A(const void* const key, const size_t len,
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const uint32_t seed) {
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const uint64_t m = 0xc6a4a7935bd1e995ULL;
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const int r = 47;
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uint64_t h = seed ^ (len * m);
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const uint64_t * data = (const uint64_t *)key;
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const uint64_t * end = data + (len/8);
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while(data != end) {
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uint64_t k = *data++;
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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}
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const uint8_t * data2 = (const uint8_t*)data;
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switch(len & 7) {
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case 7: h ^= (uint64_t)data2[6] << 48;
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case 6: h ^= (uint64_t)data2[5] << 40;
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case 5: h ^= (uint64_t)data2[4] << 32;
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case 4: h ^= (uint64_t)data2[3] << 24;
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case 3: h ^= (uint64_t)data2[2] << 16;
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case 2: h ^= (uint64_t)data2[1] << 8;
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case 1: h ^= (uint64_t)data2[0];
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h *= m;
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};
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h ^= h >> r;
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h *= m;
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h ^= h >> r;
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return h;
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}
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/* MurmurHash64A performance-optimized for hash of uint64_t keys and seed = M0 */
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uint64_t murmur_rehash_64A(uint64_t k) {
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const uint64_t m = 0xc6a4a7935bd1e995ULL;
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const int r = 47;
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uint64_t h = (uint64_t)SEED ^ (sizeof(uint64_t) * m);
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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h ^= h >> r;
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h *= m;
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h ^= h >> r;
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return h;
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}
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}
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