1 //===-- sanitizer_common.h --------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements a simple hash function.
10 //===----------------------------------------------------------------------===//
11 
12 #ifndef SANITIZER_HASH_H
13 #define SANITIZER_HASH_H
14 
15 #include "sanitizer_internal_defs.h"
16 
17 namespace __sanitizer {
18 class MurMur2HashBuilder {
19   static const u32 m = 0x5bd1e995;
20   static const u32 seed = 0x9747b28c;
21   static const u32 r = 24;
22   u32 h;
23 
24  public:
25   explicit MurMur2HashBuilder(u32 init = 0) { h = seed ^ init; }
26   void add(u32 k) {
27     k *= m;
28     k ^= k >> r;
29     k *= m;
30     h *= m;
31     h ^= k;
32   }
33   u32 get() {
34     u32 x = h;
35     x ^= x >> 13;
36     x *= m;
37     x ^= x >> 15;
38     return x;
39   }
40 };
41 
42 class MurMur2Hash64Builder {
43   static const u64 m = 0xc6a4a7935bd1e995ull;
44   static const u64 seed = 0x9747b28c9747b28cull;
45   static const u64 r = 47;
46   u64 h;
47 
48  public:
49   explicit MurMur2Hash64Builder(u64 init = 0) { h = seed ^ (init * m); }
50   void add(u64 k) {
51     k *= m;
52     k ^= k >> r;
53     k *= m;
54     h ^= k;
55     h *= m;
56   }
57   u64 get() {
58     u64 x = h;
59     x ^= x >> r;
60     x *= m;
61     x ^= x >> r;
62     return x;
63   }
64 };
65 }  //namespace __sanitizer
66 
67 #endif  // SANITIZER_HASH_H
68