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// Copyright 2015 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#if defined(_MSC_VER)
#include <stdlib.h>
#endif
#include "common_funcs.h"
#include "common_types.h"
#include "hash.h"
namespace Common {
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.
// Block read - if your platform needs to do endian-swapping or can only handle aligned reads, do
// the conversion here
static FORCE_INLINE u32 getblock32(const u32* p, int i) {
return p[i];
}
static FORCE_INLINE u64 getblock64(const u64* p, int i) {
return p[i];
}
// Finalization mix - force all bits of a hash block to avalanche
static FORCE_INLINE u32 fmix32(u32 h) {
h ^= h >> 16;
h *= 0x85ebca6b;
h ^= h >> 13;
h *= 0xc2b2ae35;
h ^= h >> 16;
return h;
}
static FORCE_INLINE u64 fmix64(u64 k) {
k ^= k >> 33;
k *= 0xff51afd7ed558ccdllu;
k ^= k >> 33;
k *= 0xc4ceb9fe1a85ec53llu;
k ^= k >> 33;
return k;
}
// This is the 128-bit variant of the MurmurHash3 hash function that is targetted for 64-bit
// platforms (MurmurHash3_x64_128). It was taken from:
// https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp
void MurmurHash3_128(const void* key, int len, u32 seed, void* out) {
const u8 * data = (const u8*)key;
const int nblocks = len / 16;
u64 h1 = seed;
u64 h2 = seed;
const u64 c1 = 0x87c37b91114253d5llu;
const u64 c2 = 0x4cf5ad432745937fllu;
// Body
const u64 * blocks = (const u64 *)(data);
for (int i = 0; i < nblocks; i++) {
u64 k1 = getblock64(blocks,i*2+0);
u64 k2 = getblock64(blocks,i*2+1);
k1 *= c1; k1 = _rotl64(k1,31); k1 *= c2; h1 ^= k1;
h1 = _rotl64(h1,27); h1 += h2; h1 = h1*5+0x52dce729;
k2 *= c2; k2 = _rotl64(k2,33); k2 *= c1; h2 ^= k2;
h2 = _rotl64(h2,31); h2 += h1; h2 = h2*5+0x38495ab5;
}
// Tail
const u8 * tail = (const u8*)(data + nblocks*16);
u64 k1 = 0;
u64 k2 = 0;
switch (len & 15) {
case 15: k2 ^= ((u64)tail[14]) << 48;
case 14: k2 ^= ((u64)tail[13]) << 40;
case 13: k2 ^= ((u64)tail[12]) << 32;
case 12: k2 ^= ((u64)tail[11]) << 24;
case 11: k2 ^= ((u64)tail[10]) << 16;
case 10: k2 ^= ((u64)tail[ 9]) << 8;
case 9: k2 ^= ((u64)tail[ 8]) << 0;
k2 *= c2; k2 = _rotl64(k2,33); k2 *= c1; h2 ^= k2;
case 8: k1 ^= ((u64)tail[ 7]) << 56;
case 7: k1 ^= ((u64)tail[ 6]) << 48;
case 6: k1 ^= ((u64)tail[ 5]) << 40;
case 5: k1 ^= ((u64)tail[ 4]) << 32;
case 4: k1 ^= ((u64)tail[ 3]) << 24;
case 3: k1 ^= ((u64)tail[ 2]) << 16;
case 2: k1 ^= ((u64)tail[ 1]) << 8;
case 1: k1 ^= ((u64)tail[ 0]) << 0;
k1 *= c1; k1 = _rotl64(k1,31); k1 *= c2; h1 ^= k1;
};
// Finalization
h1 ^= len; h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
h2 += h1;
((u64*)out)[0] = h1;
((u64*)out)[1] = h2;
}
} // namespace Common
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