1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ART_RUNTIME_BIT_MEMORY_REGION_H_ 18 #define ART_RUNTIME_BIT_MEMORY_REGION_H_ 19 20 #include "memory_region.h" 21 22 namespace art { 23 24 // Bit memory region is a bit offset subregion of a normal memoryregion. This is useful for 25 // abstracting away the bit start offset to avoid needing passing as an argument everywhere. 26 class BitMemoryRegion FINAL : public ValueObject { 27 public: 28 BitMemoryRegion() = default; 29 ALWAYS_INLINE BitMemoryRegion(MemoryRegion region, size_t bit_offset, size_t bit_size) { 30 bit_start_ = bit_offset % kBitsPerByte; 31 const size_t start = bit_offset / kBitsPerByte; 32 const size_t end = (bit_offset + bit_size + kBitsPerByte - 1) / kBitsPerByte; 33 region_ = region.Subregion(start, end - start); 34 } 35 36 void* pointer() const { return region_.pointer(); } 37 size_t size() const { return region_.size(); } 38 size_t BitOffset() const { return bit_start_; } 39 size_t size_in_bits() const { 40 return region_.size_in_bits(); 41 } 42 43 ALWAYS_INLINE BitMemoryRegion Subregion(size_t bit_offset, size_t bit_size) const { 44 return BitMemoryRegion(region_, bit_start_ + bit_offset, bit_size); 45 } 46 47 // Load a single bit in the region. The bit at offset 0 is the least 48 // significant bit in the first byte. 49 ALWAYS_INLINE bool LoadBit(uintptr_t bit_offset) const { 50 return region_.LoadBit(bit_offset + bit_start_); 51 } 52 53 ALWAYS_INLINE void StoreBit(uintptr_t bit_offset, bool value) const { 54 region_.StoreBit(bit_offset + bit_start_, value); 55 } 56 57 ALWAYS_INLINE uint32_t LoadBits(uintptr_t bit_offset, size_t length) const { 58 return region_.LoadBits(bit_offset + bit_start_, length); 59 } 60 61 // Store at a bit offset from inside the bit memory region. 62 ALWAYS_INLINE void StoreBits(uintptr_t bit_offset, uint32_t value, size_t length) { 63 region_.StoreBits(bit_offset + bit_start_, value, length); 64 } 65 66 private: 67 MemoryRegion region_; 68 size_t bit_start_ = 0; 69 }; 70 71 } // namespace art 72 73 #endif // ART_RUNTIME_BIT_MEMORY_REGION_H_ 74
