mirror of
https://github.com/wpilibsuite/allwpilib
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fbdc810887
* Use explicit this capture required by C++20 * Use C++20 span * Replace wpi::numbers with std::numbers * Fix C++20 clang-tidy warning false positive in fmt * Remove ciso646 include since C++20 removed that header * Fix global-buffer-overflow asan warnings in ntcore tests * Add DIOSetProxy constructor to HAL * Upgrade MSVC compiler to 2022 * Bump native-utils to 2023.2.7 (changes to std=c++20) Co-authored-by: Peter Johnson <johnson.peter@gmail.com>
112 lines
3.3 KiB
C++
112 lines
3.3 KiB
C++
// Copyright (c) FIRST and other WPILib contributors.
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// Open Source Software; you can modify and/or share it under the terms of
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// the WPILib BSD license file in the root directory of this project.
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#ifndef WPIUTIL_WPI_LEB128_H_
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#define WPIUTIL_WPI_LEB128_H_
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#include <stdint.h>
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#include <optional>
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#include <span>
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namespace wpi {
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template <typename T>
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class SmallVectorImpl;
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class raw_istream;
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class raw_ostream;
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/**
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* Get size of unsigned LEB128 data.
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*
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* Determine the number of bytes required to encode an unsigned LEB128 datum.
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* The algorithm is taken from Appendix C of the DWARF 3 spec. For information
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* on the encodings refer to section "7.6 - Variable Length Data". Return
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* the number of bytes required.
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*
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* @param val LEB128 data.
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*/
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uint64_t SizeUleb128(uint64_t val);
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/**
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* Write unsigned LEB128 data.
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*
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* Encode an unsigned LEB128 encoded datum. The algorithm is taken
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* from Appendix C of the DWARF 3 spec. For information on the
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* encodings refer to section "7.6 - Variable Length Data". Return
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* the number of bytes written.
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*
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* @param dest The address where the ULEB128 data is to be stored.
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* @param val Value to be stored.
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*/
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uint64_t WriteUleb128(SmallVectorImpl<char>& dest, uint64_t val);
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/**
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* Write unsigned LEB128 data.
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*
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* Encode an unsigned LEB128 encoded datum. The algorithm is taken
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* from Appendix C of the DWARF 3 spec. For information on the
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* encodings refer to section "7.6 - Variable Length Data".
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*
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* @param os Output stream.
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* @param val Value to be stored.
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*/
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void WriteUleb128(raw_ostream& os, uint64_t val);
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/**
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* Read unsigned LEB128 data.
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*
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* Decode an unsigned LEB128 encoded datum. The algorithm is taken
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* from Appendix C of the DWARF 3 spec. For information on the
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* encodings refer to section "7.6 - Variable Length Data". Return
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* the number of bytes read.
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*
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* @param addr The address where the ULEB128 data is stored.
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* @param ret Address to store the result.
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*/
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uint64_t ReadUleb128(const char* addr, uint64_t* ret);
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/**
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* Read unsigned LEB128 data from a stream.
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*
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* Decode an unsigned LEB128 encoded datum. The algorithm is taken
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* from Appendix C of the DWARF 3 spec. For information on the
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* encodings refer to section "7.6 - Variable Length Data". Return
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* false on stream error, true on success.
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*
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* @param is The input stream where the ULEB128 data is to be read from.
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* @param ret Address to store the result.
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*/
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bool ReadUleb128(raw_istream& is, uint64_t* ret);
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/**
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* Unsigned LEB128 streaming reader.
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*
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* Decode an unsigned LEB128 encoded datum. The algorithm is taken
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* from Appendix C of the DWARF 3 spec. For information on the
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* encodings refer to section "7.6 - Variable Length Data".
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*/
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class Uleb128Reader {
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public:
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/**
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* Decode a single ULEB128 value. Returns after a single ULEB128 value has
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* been read or insufficient input (call in a loop to get multiple values).
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* If a value is returned, internal state is reset so it's safe to immediately
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* call this function again to decode another value.
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*
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* @param in Input data; modified as data is consumed (any unconsumed data
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* is left when function returns).
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* @return value (in std::optional)
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*/
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std::optional<uint64_t> ReadOne(std::span<const uint8_t>* in);
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private:
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uint64_t m_result = 0;
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int m_shift = 0;
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};
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} // namespace wpi
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#endif // WPIUTIL_WPI_LEB128_H_
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