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/*
* Copyright (C) 2017 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_BIT_MEMORY_REGION_H_
#define ART_RUNTIME_BIT_MEMORY_REGION_H_
#include "memory_region.h"
namespace art {
// Bit memory region is a bit offset subregion of a normal memoryregion. This is useful for
// abstracting away the bit start offset to avoid needing passing as an argument everywhere.
class BitMemoryRegion FINAL : public ValueObject {
public:
BitMemoryRegion() = default;
BitMemoryRegion(MemoryRegion region, size_t bit_offset, size_t bit_size) {
bit_start_ = bit_offset % kBitsPerByte;
const size_t start = bit_offset / kBitsPerByte;
const size_t end = (bit_offset + bit_size + kBitsPerByte - 1) / kBitsPerByte;
region_ = region.Subregion(start, end - start);
}
void* pointer() const { return region_.pointer(); }
size_t size() const { return region_.size(); }
size_t BitOffset() const { return bit_start_; }
size_t size_in_bits() const {
return region_.size_in_bits();
}
// Load a single bit in the region. The bit at offset 0 is the least
// significant bit in the first byte.
ALWAYS_INLINE bool LoadBit(uintptr_t bit_offset) const {
return region_.LoadBit(bit_offset + bit_start_);
}
ALWAYS_INLINE void StoreBit(uintptr_t bit_offset, bool value) const {
region_.StoreBit(bit_offset + bit_start_, value);
}
ALWAYS_INLINE uint32_t LoadBits(uintptr_t bit_offset, size_t length) const {
return region_.LoadBits(bit_offset + bit_start_, length);
}
// Store at a bit offset from inside the bit memory region.
ALWAYS_INLINE void StoreBits(uintptr_t bit_offset, uint32_t value, size_t length) {
region_.StoreBits(bit_offset + bit_start_, value, length);
}
private:
MemoryRegion region_;
size_t bit_start_ = 0;
};
} // namespace art
#endif // ART_RUNTIME_BIT_MEMORY_REGION_H_