1// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
2// for details. All rights reserved. Use of this source code is governed by a
3// BSD-style license that can be found in the LICENSE file.
4
5#ifndef RUNTIME_VM_HASH_H_
6#define RUNTIME_VM_HASH_H_
7
8#include "platform/globals.h"
9
10namespace dart {
11
12inline uint32_t CombineHashes(uint32_t hash, uint32_t other_hash) {
13 hash += other_hash;
14 hash += hash << 10;
15 hash ^= hash >> 6; // Logical shift, unsigned hash.
16 return hash;
17}
18
19inline uint32_t FinalizeHash(uint32_t hash, intptr_t hashbits) {
20 hash += hash << 3;
21 hash ^= hash >> 11; // Logical shift, unsigned hash.
22 hash += hash << 15;
23 // FinalizeHash gets called with values for hashbits that are bigger than 31
24 // (like kBitsPerWord - 1). Therefore we are careful to use a type
25 // (uintptr_t) big enough to avoid undefined behavior with the left shift.
26 hash &= (static_cast<uintptr_t>(1) << hashbits) - 1;
27 return (hash == 0) ? 1 : hash;
28}
29
30inline uint32_t HashBytes(const uint8_t* bytes, intptr_t size) {
31 uint32_t hash = size;
32 while (size > 0) {
33 hash = CombineHashes(hash, *bytes);
34 bytes++;
35 size--;
36 }
37 return hash;
38}
39
40} // namespace dart
41
42#endif // RUNTIME_VM_HASH_H_
43