87 lines
2 KiB
C++
87 lines
2 KiB
C++
/*
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* Copyright (C) 2015 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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#ifndef _LINKER_LEB128_H
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#define _LINKER_LEB128_H
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#include <stdint.h>
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// Helper classes for decoding LEB128, used in packed relocation data.
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// http://en.wikipedia.org/wiki/LEB128
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class leb128_decoder {
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public:
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leb128_decoder(const uint8_t* buffer, size_t count)
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: current_(buffer), end_(buffer + count) { }
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size_t pop_front() {
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size_t value = 0;
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size_t shift = 0;
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uint8_t byte;
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do {
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if (current_ >= end_) {
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__libc_fatal("leb128_decoder ran out of bounds");
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}
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byte = *current_++;
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value |= static_cast<size_t>(byte & 127) << shift;
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shift += 7;
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} while (byte & 128);
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return value;
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}
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private:
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const uint8_t* current_;
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const uint8_t* const end_;
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};
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class sleb128_decoder {
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public:
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sleb128_decoder(const uint8_t* buffer, size_t count)
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: current_(buffer), end_(buffer+count) { }
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size_t pop_front() {
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size_t value = 0;
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static const size_t size = CHAR_BIT * sizeof(value);
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size_t shift = 0;
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uint8_t byte;
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do {
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if (current_ >= end_) {
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__libc_fatal("leb128_decoder ran out of bounds");
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}
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byte = *current_++;
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value |= (static_cast<size_t>(byte & 127) << shift);
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shift += 7;
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} while (byte & 128);
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if (shift < size && (byte & 64)) {
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value |= -(static_cast<size_t>(1) << shift);
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}
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return value;
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}
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private:
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const uint8_t* current_;
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const uint8_t* const end_;
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};
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#endif // __LINKER_LEB128_H
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