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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_
#define ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_
#include "locks.h"
namespace art {
namespace mirror {
class Object;
// Classes shared with the managed side of the world need to be packed so that they don't have
// extra platform specific padding.
#define MANAGED PACKED(4)
// Value type representing a reference to a mirror::Object of type MirrorType.
template<bool kPoisonReferences, class MirrorType>
class MANAGED ObjectReference {
public:
MirrorType* AsMirrorPtr() const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return UnCompress();
}
void Assign(MirrorType* other) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
reference_ = Compress(other);
}
void Clear() {
reference_ = 0;
}
uint32_t AsVRegValue() const {
return reference_;
}
protected:
ObjectReference<kPoisonReferences, MirrorType>(MirrorType* mirror_ptr)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: reference_(Compress(mirror_ptr)) {
}
// Compress reference to its bit representation.
static uint32_t Compress(MirrorType* mirror_ptr) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
uintptr_t as_bits = reinterpret_cast<uintptr_t>(mirror_ptr);
return static_cast<uint32_t>(kPoisonReferences ? -as_bits : as_bits);
}
// Uncompress an encoded reference from its bit representation.
MirrorType* UnCompress() const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
uintptr_t as_bits = kPoisonReferences ? -reference_ : reference_;
return reinterpret_cast<MirrorType*>(as_bits);
}
friend class Object;
// The encoded reference to a mirror::Object.
uint32_t reference_;
};
// References between objects within the managed heap.
template<class MirrorType>
class MANAGED HeapReference : public ObjectReference<false, MirrorType> {
public:
static HeapReference<MirrorType> FromMirrorPtr(MirrorType* mirror_ptr)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return HeapReference<MirrorType>(mirror_ptr);
}
private:
HeapReference<MirrorType>(MirrorType* mirror_ptr) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: ObjectReference<false, MirrorType>(mirror_ptr) {}
};
} // namespace mirror
} // namespace art
#endif // ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_