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/*
Copyright (C) 2009 Red Hat, Inc.
This program 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 2 of
the License, or (at your option) any later version.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
//Some modifications by Red Hat any bug is probably our fault
//-----------------------------------------------------------------------------
// MurmurHash2A, by Austin Appleby
// This is a variant of MurmurHash2 modified to use the Merkle-Damgard
// construction. Bulk speed should be identical to Murmur2, small-key speed
// will be 10%-20% slower due to the added overhead at the end of the hash.
// This variant fixes a minor issue where null keys were more likely to
// collide with each other than expected, and also makes the algorithm
// more amenable to incremental implementations. All other caveats from
// MurmurHash2 still apply.
#ifndef __MURMUR_HASH2A_H
#define __MURMUR_HASH2A_H
#include <windef.h>
#include "os_dep.h"
typedef UINT32 uint32_t;
typedef UINT16 uint16_t;
typedef UINT8 uint8_t;
#define mmix(h,k) { k *= m; k ^= k >> r; k *= m; h *= m; h ^= k; }
_inline uint32_t MurmurHash2A(const void * key, uint32_t len, uint32_t seed )
{
const uint32_t m = 0x5bd1e995;
const uint32_t r = 24;
uint32_t l = len;
uint32_t t = 0;
const uint8_t * data = (const uint8_t *)key;
uint32_t h = seed;
while (len >= 4) {
uint32_t k = *(uint32_t*)data;
mmix(h,k);
data += 4;
len -= 4;
}
switch (len) {
case 3: t ^= data[2] << 16;
case 2: t ^= data[1] << 8;
case 1: t ^= data[0];
};
mmix(h,t);
mmix(h,l);
h ^= h >> 13;
h *= m;
h ^= h >> 15;
return h;
}
_inline uint32_t MurmurHash2AJump3(const uint32_t * key, uint32_t len, uint32_t seed )
{
uint32_t m = 0x5bd1e995;
uint32_t r = 24;
uint32_t l = len << 2;
const uint8_t * data = (const uint8_t *)key;
uint32_t h = seed;
while (len >= 4) {
uint32_t k = *(uint32_t*)data;
uint32_t tmp;
data += 4;
tmp = *(uint32_t *)data;
k = k << 8;
k |= (uint8_t)tmp;
mmix(h,k);
k = tmp << 8;
k = k & 0xffff0000;
data += 4;
tmp = *(uint32_t *)data;
k |= (uint16_t)(tmp >> 8);
mmix(h,k);
data += 4;
k = *(uint32_t *)data;
k = k << 8;
k |= (uint8_t)tmp;
mmix(h,k);
data += 4;
len -= 4;
}
while (len >= 1) {
uint32_t k = *(uint32_t*)data;
k = k << 8;
mmix(h,k);
data += 4;
len--;
}
h *= m;
mmix(h,l);
h ^= h >> 13;
h *= m;
h ^= h >> 15;
return h;
}
_inline uint32_t murmurhash2a(const void *key, size_t length, uint32_t initval)
{
return MurmurHash2A(key, length, initval);
}
_inline uint32_t murmurhash2ajump3(const uint32_t *key, size_t length, uint32_t initval)
{
return MurmurHash2AJump3(key, length, initval);
}
#endif
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