67 lines
2.3 KiB
C++
67 lines
2.3 KiB
C++
/*
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* Copyright (C) 2011 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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#include "memory_region.h"
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#include <stdint.h>
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#include <string.h>
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#include "base/logging.h"
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#include "globals.h"
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namespace art {
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void MemoryRegion::CopyFrom(size_t offset, const MemoryRegion& from) const {
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CHECK(from.pointer() != nullptr);
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CHECK_GT(from.size(), 0U);
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CHECK_GE(this->size(), from.size());
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CHECK_LE(offset, this->size() - from.size());
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memmove(reinterpret_cast<void*>(begin() + offset), from.pointer(), from.size());
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}
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void MemoryRegion::StoreBits(uintptr_t bit_offset, uint32_t value, size_t length) {
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DCHECK_LE(value, MaxInt<uint32_t>(length));
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DCHECK_LE(length, BitSizeOf<uint32_t>());
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DCHECK_LE(bit_offset + length, size_in_bits());
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if (length == 0) {
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return;
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}
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// Bits are stored in this order {7 6 5 4 3 2 1 0}.
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// How many remaining bits in current byte is (bit_offset % kBitsPerByte) + 1.
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uint8_t* out = ComputeInternalPointer<uint8_t>(bit_offset >> kBitsPerByteLog2);
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size_t orig_len = length;
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uint32_t orig_value = value;
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uintptr_t bit_remainder = bit_offset % kBitsPerByte;
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while (true) {
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const uintptr_t remaining_bits = kBitsPerByte - bit_remainder;
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if (length <= remaining_bits) {
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// Length is smaller than all of remainder bits.
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size_t mask = ((1 << length) - 1) << bit_remainder;
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*out = (*out & ~mask) | (value << bit_remainder);
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break;
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}
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// Copy remaining bits in current byte.
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size_t value_mask = (1 << remaining_bits) - 1;
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*out = (*out & ~(value_mask << bit_remainder)) | ((value & value_mask) << bit_remainder);
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value >>= remaining_bits;
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bit_remainder = 0;
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length -= remaining_bits;
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++out;
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}
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DCHECK_EQ(LoadBits(bit_offset, orig_len), orig_value) << bit_offset << " " << orig_len;
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}
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} // namespace art
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