Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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74 lines
1.6 KiB

//======= Copyright © Valve Corporation, All rights reserved. =================
//
// Public domain MurmurHash3 by Austin Appleby is a very solid general-purpose
// hash with a 32-bit output. References:
// http://code.google.com/p/smhasher/ (home of MurmurHash3)
// https://sites.google.com/site/murmurhash/avalanche
// http://www.strchr.com/hash_functions
//
//=============================================================================
#include <stdafx.h>
#include "murmurhash3.h"
//-----------------------------------------------------------------------------
uint32 MurmurHash3_32( const void * key, size_t len, uint32 seed, bool bCaselessStringVariant )
{
const uint8 * data = (const uint8*)key;
const ptrdiff_t nblocks = len / 4;
uint32 uSourceBitwiseAndMask = 0xDFDFDFDF | ((uint32)bCaselessStringVariant - 1);
uint32 h1 = seed;
//----------
// body
const uint32 * blocks = (const uint32 *)(data + nblocks*4);
for(ptrdiff_t i = -nblocks; i; i++)
{
uint32 k1 = LittleDWord(blocks[i]);
k1 &= uSourceBitwiseAndMask;
k1 *= 0xcc9e2d51;
k1 = (k1 << 15) | (k1 >> 17);
k1 *= 0x1b873593;
h1 ^= k1;
h1 = (h1 << 13) | (h1 >> 19);
h1 = h1*5+0xe6546b64;
}
//----------
// tail
const uint8 * tail = (const uint8*)(data + nblocks*4);
uint32 k1 = 0;
switch(len & 3)
{
case 3: k1 ^= tail[2] << 16;
case 2: k1 ^= tail[1] << 8;
case 1: k1 ^= tail[0];
k1 &= uSourceBitwiseAndMask;
k1 *= 0xcc9e2d51;
k1 = (k1 << 15) | (k1 >> 17);
k1 *= 0x1b873593;
h1 ^= k1;
};
//----------
// finalization
h1 ^= len;
h1 ^= h1 >> 16;
h1 *= 0x85ebca6b;
h1 ^= h1 >> 13;
h1 *= 0xc2b2ae35;
h1 ^= h1 >> 16;
return h1;
}