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