73 lines
2.5 KiB
C++
73 lines
2.5 KiB
C++
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_RUNTIME_BIT_MEMORY_REGION_H_
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#define ART_RUNTIME_BIT_MEMORY_REGION_H_
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#include "memory_region.h"
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namespace art {
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// Bit memory region is a bit offset subregion of a normal memoryregion. This is useful for
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// abstracting away the bit start offset to avoid needing passing as an argument everywhere.
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class BitMemoryRegion FINAL : public ValueObject {
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public:
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BitMemoryRegion() = default;
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ALWAYS_INLINE BitMemoryRegion(MemoryRegion region, size_t bit_offset, size_t bit_size) {
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bit_start_ = bit_offset % kBitsPerByte;
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const size_t start = bit_offset / kBitsPerByte;
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const size_t end = (bit_offset + bit_size + kBitsPerByte - 1) / kBitsPerByte;
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region_ = region.Subregion(start, end - start);
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}
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void* pointer() const { return region_.pointer(); }
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size_t size() const { return region_.size(); }
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size_t BitOffset() const { return bit_start_; }
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size_t size_in_bits() const {
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return region_.size_in_bits();
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}
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ALWAYS_INLINE BitMemoryRegion Subregion(size_t bit_offset, size_t bit_size) const {
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return BitMemoryRegion(region_, bit_start_ + bit_offset, bit_size);
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}
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// Load a single bit in the region. The bit at offset 0 is the least
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// significant bit in the first byte.
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ALWAYS_INLINE bool LoadBit(uintptr_t bit_offset) const {
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return region_.LoadBit(bit_offset + bit_start_);
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}
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ALWAYS_INLINE void StoreBit(uintptr_t bit_offset, bool value) const {
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region_.StoreBit(bit_offset + bit_start_, value);
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}
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ALWAYS_INLINE uint32_t LoadBits(uintptr_t bit_offset, size_t length) const {
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return region_.LoadBits(bit_offset + bit_start_, length);
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}
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// Store at a bit offset from inside the bit memory region.
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ALWAYS_INLINE void StoreBits(uintptr_t bit_offset, uint32_t value, size_t length) {
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region_.StoreBits(bit_offset + bit_start_, value, length);
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}
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private:
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MemoryRegion region_;
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size_t bit_start_ = 0;
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};
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} // namespace art
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#endif // ART_RUNTIME_BIT_MEMORY_REGION_H_
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