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// 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_