1 /* 2 * Copyright (C) 2011 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 #include "memory_region.h" 18 19 #include <stdint.h> 20 #include <string.h> 21 22 namespace art { 23 24 void MemoryRegion::CopyFrom(size_t offset, const MemoryRegion& from) const { 25 CHECK(from.pointer() != nullptr); 26 CHECK_GT(from.size(), 0U); 27 CHECK_GE(this->size(), from.size()); 28 CHECK_LE(offset, this->size() - from.size()); 29 memmove(reinterpret_cast<void*>(begin() + offset), from.pointer(), from.size()); 30 } 31 32 void MemoryRegion::StoreBits(uintptr_t bit_offset, uint32_t value, size_t length) { 33 DCHECK_LE(value, MaxInt<uint32_t>(length)); 34 DCHECK_LE(length, BitSizeOf<uint32_t>()); 35 DCHECK_LE(bit_offset + length, size_in_bits()); 36 if (length == 0) { 37 return; 38 } 39 // Bits are stored in this order {7 6 5 4 3 2 1 0}. 40 // How many remaining bits in current byte is (bit_offset % kBitsPerByte) + 1. 41 uint8_t* out = ComputeInternalPointer<uint8_t>(bit_offset >> kBitsPerByteLog2); 42 size_t orig_len = length; 43 uint32_t orig_value = value; 44 uintptr_t bit_remainder = bit_offset % kBitsPerByte; 45 while (true) { 46 const uintptr_t remaining_bits = kBitsPerByte - bit_remainder; 47 if (length <= remaining_bits) { 48 // Length is smaller than all of remainder bits. 49 size_t mask = ((1 << length) - 1) << bit_remainder; 50 *out = (*out & ~mask) | (value << bit_remainder); 51 break; 52 } 53 // Copy remaining bits in current byte. 54 size_t value_mask = (1 << remaining_bits) - 1; 55 *out = (*out & ~(value_mask << bit_remainder)) | ((value & value_mask) << bit_remainder); 56 value >>= remaining_bits; 57 bit_remainder = 0; 58 length -= remaining_bits; 59 ++out; 60 } 61 DCHECK_EQ(LoadBits(bit_offset, orig_len), orig_value) << bit_offset << " " << orig_len; 62 } 63 64 } // namespace art 65
