libsanitizer/sanitizer_common/sanitizer_hash.h

   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