co_usb is an asynchronous USB library using C++20 coroutines and Capy to create a high-level interface for libusb. It provides lightweight and feature-rich adaptors around libusb API to enable easy integration into the coroutine ecosystem.

Rationale

libusb asynchronous code is very efficient, but because it is a C library it is lacking in ergonomics when put into modern C++20 project, especially one utilizing coroutines. This library serves as a bridge between Capy based coroutine ecosystem and libusb asynchronous code.

What co_usb does

Asynchronous transfer submission for partial and complete I/O in a form of light adaptor types
Hotplug API for dynamically connecting devices with an Asio style acceptor loop
Wrappers around core libusb entities such as devices for smooth initialization of the library
Event handler system for easy extension and safe shutdown

What co_usb does not do

Querying information for devices and endpoint
Iteration over device list
Generally, everything that does not relate to asynchronous operations

Why not Asio?

Not all USB code needs a whole networking library. Using Capy allows the user to choose not to use networking code and just keep the coroutines.

If you need to use networking I advise use co_usb with Corosio, since both operate on shared Capy concepts the code is easily made interoperable.

License

Source code of the library is distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE.md or copy at https://www.boost.org/LICENSE_1_0.txt)

QEMU devices code at qemu/ is distributed under GNU General Public License v3. (See accompanying file qemu/LICENSE.md or copy at https://www.gnu.org/licenses/gpl-3.0.md)

Contributing

co_usb is open for contributions to:

documentation
test suite
bug fixes

New features can be submitted are subject to thorough review process.