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 #include "base/logging.h"
23 #include "globals.h"
24
25 namespace art {
26
CopyFrom(size_t offset,const MemoryRegion & from) const27 void MemoryRegion::CopyFrom(size_t offset, const MemoryRegion& from) const {
28 CHECK(from.pointer() != nullptr);
29 CHECK_GT(from.size(), 0U);
30 CHECK_GE(this->size(), from.size());
31 CHECK_LE(offset, this->size() - from.size());
32 memmove(reinterpret_cast<void*>(begin() + offset), from.pointer(), from.size());
33 }
34
StoreBits(uintptr_t bit_offset,uint32_t value,size_t length)35 void MemoryRegion::StoreBits(uintptr_t bit_offset, uint32_t value, size_t length) {
36 DCHECK_LE(value, MaxInt<uint32_t>(length));
37 DCHECK_LE(length, BitSizeOf<uint32_t>());
38 DCHECK_LE(bit_offset + length, size_in_bits());
39 if (length == 0) {
40 return;
41 }
42 // Bits are stored in this order {7 6 5 4 3 2 1 0}.
43 // How many remaining bits in current byte is (bit_offset % kBitsPerByte) + 1.
44 uint8_t* out = ComputeInternalPointer<uint8_t>(bit_offset >> kBitsPerByteLog2);
45 size_t orig_len = length;
46 uint32_t orig_value = value;
47 uintptr_t bit_remainder = bit_offset % kBitsPerByte;
48 while (true) {
49 const uintptr_t remaining_bits = kBitsPerByte - bit_remainder;
50 if (length <= remaining_bits) {
51 // Length is smaller than all of remainder bits.
52 size_t mask = ((1 << length) - 1) << bit_remainder;
53 *out = (*out & ~mask) | (value << bit_remainder);
54 break;
55 }
56 // Copy remaining bits in current byte.
57 size_t value_mask = (1 << remaining_bits) - 1;
58 *out = (*out & ~(value_mask << bit_remainder)) | ((value & value_mask) << bit_remainder);
59 value >>= remaining_bits;
60 bit_remainder = 0;
61 length -= remaining_bits;
62 ++out;
63 }
64 DCHECK_EQ(LoadBits(bit_offset, orig_len), orig_value) << bit_offset << " " << orig_len;
65 }
66
67 } // namespace art
68