| 69 | } |
| 70 | |
| 71 | void FourBytes_MurmurHash2(const unsigned char* data, IncrementalHashInfo& prev) |
| 72 | { |
| 73 | if (prev.len >= 4) { |
| 74 | // Not the final mix |
| 75 | uint32_t k = *(uint32_t*)data; |
| 76 | |
| 77 | k *= m; |
| 78 | k ^= k >> r; |
| 79 | k *= m; |
| 80 | |
| 81 | prev.h *= m; |
| 82 | prev.h ^= k; |
| 83 | |
| 84 | prev.len -= 4; |
| 85 | } else { |
| 86 | // The final mix |
| 87 | |
| 88 | // Handle the last few bytes of the input array |
| 89 | switch (prev.len) { |
| 90 | case 3: |
| 91 | prev.h ^= data[2] << 16; |
| 92 | [[fallthrough]]; |
| 93 | case 2: |
| 94 | prev.h ^= data[1] << 8; |
| 95 | [[fallthrough]]; |
| 96 | case 1: |
| 97 | prev.h ^= data[0]; |
| 98 | prev.h *= m; |
| 99 | }; |
| 100 | |
| 101 | // Do a few final mixes of the hash to ensure the last few |
| 102 | // bytes are well-incorporated. |
| 103 | |
| 104 | prev.h ^= prev.h >> 13; |
| 105 | prev.h *= m; |
| 106 | prev.h ^= prev.h >> 15; |
| 107 | |
| 108 | prev.len = 0; |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | //----------------------------------------------------------------------------- |