569a752689
Some of the commentary in relocation packer code is relevant only to the packing strategy employed by chromium, and no longer applies here. This change fixes or deletes it. Code comment change only; no functional effect. Change-Id: Id229ee1d802bba608be15b79bc75bf90df557dab Signed-off-by: Simon Baldwin <simonb@google.com>
77 lines
2.2 KiB
C++
77 lines
2.2 KiB
C++
// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// SLEB128 encoder and decoder for packed relative relocations.
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//
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// Packed relocations consist of a large number of relatively small
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// integer values. Encoding these as LEB128 saves space.
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//
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// For more on LEB128 see http://en.wikipedia.org/wiki/LEB128.
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#ifndef TOOLS_RELOCATION_PACKER_SRC_SLEB128_H_
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#define TOOLS_RELOCATION_PACKER_SRC_SLEB128_H_
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#include <stdint.h>
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#include <unistd.h>
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#include <vector>
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#include "elf_traits.h"
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namespace relocation_packer {
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// Encode packed words as a signed LEB128 byte stream.
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template<typename int_t>
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class Sleb128Encoder {
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public:
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// Explicit (but empty) constructor and destructor, for chromium-style.
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Sleb128Encoder();
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~Sleb128Encoder();
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// Add a value to the encoding stream.
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// |value| is the signed int to add.
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void Enqueue(int_t value);
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// Add a vector of values to the encoding stream.
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// |values| is the vector of signed ints to add.
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void EnqueueAll(const std::vector<int_t>& values);
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// Retrieve the encoded representation of the values.
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// |encoding| is the returned vector of encoded data.
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void GetEncoding(std::vector<uint8_t>* encoding) { *encoding = encoding_; }
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private:
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// Growable vector holding the encoded LEB128 stream.
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std::vector<uint8_t> encoding_;
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};
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// Decode a LEB128 byte stream to produce packed words.
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template <typename int_t>
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class Sleb128Decoder {
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public:
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// Create a new decoder for the given encoded stream.
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// |encoding| is the vector of encoded data.
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explicit Sleb128Decoder(const std::vector<uint8_t>& encoding, size_t start_with);
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// Explicit (but empty) destructor, for chromium-style.
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~Sleb128Decoder();
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// Retrieve the next value from the encoded stream.
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int_t Dequeue();
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// Retrieve all remaining values from the encoded stream.
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// |values| is the vector of decoded data.
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void DequeueAll(std::vector<int_t>* values);
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private:
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// Encoded LEB128 stream.
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std::vector<uint8_t> encoding_;
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// Cursor indicating the current stream retrieval point.
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size_t cursor_;
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};
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} // namespace relocation_packer
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#endif // TOOLS_RELOCATION_PACKER_SRC_SLEB128_H_
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