From d67e2f78b77c0739caa8c6a915685aa8961a519c Mon Sep 17 00:00:00 2001
From: bunnei <bunneidev@gmail.com>
Date: Tue, 21 Jul 2015 22:54:38 -0400
Subject: Common: Added MurmurHash3 hash function for general-purpose use.

---
 src/common/hash.cpp | 126 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 src/common/hash.cpp

(limited to 'src/common/hash.cpp')

diff --git a/src/common/hash.cpp b/src/common/hash.cpp
new file mode 100644
index 000000000..413e9c6f1
--- /dev/null
+++ b/src/common/hash.cpp
@@ -0,0 +1,126 @@
+// 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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