| // Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| #ifndef RUNTIME_VM_HASH_H_ |
| #define RUNTIME_VM_HASH_H_ |
| |
| #include "platform/globals.h" |
| |
| namespace dart { |
| |
| inline uint32_t CombineHashes(uint32_t hash, uint32_t other_hash) { |
| hash += other_hash; |
| hash += hash << 10; |
| hash ^= hash >> 6; // Logical shift, unsigned hash. |
| return hash; |
| } |
| |
| inline uint32_t FinalizeHash(uint32_t hash, intptr_t hashbits) { |
| hash += hash << 3; |
| hash ^= hash >> 11; // Logical shift, unsigned hash. |
| hash += hash << 15; |
| // FinalizeHash gets called with values for hashbits that are bigger than 31 |
| // (like kBitsPerWord - 1). Therefore we are careful to use a type |
| // (uintptr_t) big enough to avoid undefined behavior with the left shift. |
| hash &= (static_cast<uintptr_t>(1) << hashbits) - 1; |
| return (hash == 0) ? 1 : hash; |
| } |
| |
| inline uint32_t HashBytes(const uint8_t* bytes, intptr_t size) { |
| uint32_t hash = size; |
| while (size > 0) { |
| hash = CombineHashes(hash, *bytes); |
| bytes++; |
| size--; |
| } |
| return hash; |
| } |
| |
| } // namespace dart |
| |
| #endif // RUNTIME_VM_HASH_H_ |