README.md

Endian

A small, but much needed utility library for any program that needs to handle numbers during network or file IO.

Usage

This is a header-only library, so just place endian.hpp in your system wide or project's include directory. Then, use the library by including endian, i.e.:

#include <endian.hpp>

Working with buffers

Convert from Network Byte Order to Host Byte Order, e.g. when using a receive buffer.

std::vector<char> buffer;
// ... receive data into buffer
const int64_t i = endian::read<endian::network, int64_t>(buffer.data());

Convert from Host Byte Order to Network Byte Order, e.g. when using a send buffer.

std::vector<char> buffer;
const int16_t number = 42; 
endian::write<endian::network>(number, buffer.data());

You can also read and parse arbitrary width integers in the range [1, 8] specified in bytes .

const uint32_t three_bytes = 0xaabbcc;
endian::write<endian::big, 3>(number, buffer.data());
auto res = endian::read<endian::big, 3>(buffer.data());
assert(res = three_bytes);

There are also aliases provided:

endian::write_le<3>(number, buffer.data());
endian::write_be<3>(number, buffer.data());
endian::write_le<int32_t>(number, buffer.data());
endian::write_be<int32_t>(number, buffer.data());

number = endian::read_le<5>(buffer.data());
number = endian::read_be<5>(buffer.data());
number = endian::read_le<int64_t>(buffer.data());
number = endian::read_be<int64_t>(buffer.data());

Platform specific functions

Note that these functions are only available if you're on one of the supported platforms (where host byte order could be determined). As such, the following functions are conditionally enabled with a preprocessor flag.

Reversing byte order

const int16_t a = 0x1234; 
const int16_t b = endian::reverse(a);
// b is 0x3412

Alternatively, only reverse byte order if target endianness and host's endianness differ.

const auto i = endian::conditional_reverse<endian::big>(42);

ntoh, hton

Convenience function to conditionally convert to Network Byte Order, same as the POSIX hton function.

const auto n = endian::host_to_network(h);

Convenience function to conditionally convert from Network Byte Order, same as the POSIX ntoh function.

const auto h = endian::network_to_host(n);