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Little endian base 128 implementation, which stores arbitrarily large integers in a variable length format.

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bolderflight/leb128

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License: MIT

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Leb128

Signed little endian base 128 (LEB128) implementation, which stores arbitrarily large signed integers in a variable length format. This library is compatible with Arduino ARM and with CMake build systems. It would also be easy to include with other projects, since it is a header only library consisting of a single file.

Installation

Arduino

Use the Arduino Library Manager to install this library or clone to your Arduino/libraries folder. This library is added as:

#include "leb128.h"

An example Arduino executable is located at examples/arduino/leb128_example/leb128_example.ino. Teensy 3.x, 4.x, and LC devices are used for testing under Arduino and this library should be compatible with other ARM devices. This library is not expected to work on AVR devices.

CMake

CMake is used to build this library, which is exported as a library target called leb128. The header is added as:

#include "leb128.h"

The library can be also be compiled stand-alone using the CMake idiom of creating a build directory and then, from within that directory issuing:

cmake ..
make

This will build the library, an example executable called leb128_example, and an executable for testing using the Google Test framework, called leb128_test. The example executable source file is located at examples/cmake/leb128_example.cc.

Namespace

This library is within the namespace bfs.

Functions

std::size_t EncodeLeb128(int64_t val, uint8_t * const data, const std::size_t len) Encodes an int64_t val into a LEB128 variable length format stored in the array data of length len. Returns the number of bytes written if successful, otherwise, returns 0.

std::size_t DecodeLeb128(uint8_t const * const data, const std::size_t len, int64_t * const val) Decodes a LEB128 variable length value from the array data of length len into an int64_t variable val. Returns the number of bytes read if successful, otherwise, returns 0.

uint8_t buf[100];
int64_t read_val = 0;
int64_t orig_val = std::numeric_limits<int64_t>::max();
std::size_t bytes_written = bfs::EncodeLeb128(orig_val, buf, sizeof(buf));
std::size_t bytes_read = bfs::DecodeLeb128(buf, sizeof(buf), &read_val);

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Little endian base 128 implementation, which stores arbitrarily large integers in a variable length format.

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