Greetings, PSAS might want to look at using the new libusb 1.0 for host-side sensor software. It looks fairly nice from the description, and I've chatted with Daniel Drake about his improvements. I think he would be willing to work with us to add improvements or help if we get stuck.
Sarah Sharp ---------- Forwarded message ---------- From: Daniel Drake <d...@gentoo.org> To: libusb-de...@lists.sourceforge.net Date: Sat, 13 Dec 2008 21:53:03 +0000 Subject: [Libusb-devel] libusb-1.0.0 released! Hi, I'm happy to announce the release of libusb-1.0.0. Homepage: http://libusb.sourceforge.net Source download link: http://sourceforge.net/project/showfiles.php?group_id=1674&package_id=277626&release_id=647007 Although this release is an almost-rewrite, this new library hopes to build on the success of the previous version, libusb-0.1, which was developed by Johannes Erdfelt and others. libusb-0.1 has enjoyed tremendous success (over 150,000 source downloads of the latest release) and is used in many applications. libusb-1.0 has has been in development and testing for several months. Many thanks to everyone who has tested, sent feedback, and provided patches. Features, improvements and notes: - Support for isochronous endpoints. Iso endpoints are present on devices such as webcams, which libusb-0.1 was unable to work with. - Asynchronous device I/O. You can now perform I/O to any endpoint type in asynchronous matter - allowing a single thread to be performing I/O with multiple endpoints on multiple devices. This is a very flexible interface which allows for many application designs that were not possible with libusb-0.1, as well as the possibility of cancelling transfers and so on. - A simpler, synchronous interface is also offered, in the style of libusb-0.1. - Lightweight. libusb is compact, with very few dependencies (only libc and pthread). It does not create any internal library threads and is designed with efficiency in mind. - Thread safety: libusb-1.0 is thread safe. You can operate it from multiple threads. Certain well-documented considerations apply in the more advanced scenarios. - Main loop integration. libusb's asynchronous I/O model fits nicely into applications that revolve around the idea of polling file descriptors in a main loop. It also works nicely with applications built around other models. - Power saving. libusb-0.1 wakes up all of the suspended USB devices attached to the system every time you start an application based on libusb-0.1. On sufficiently modern Linux kernels, this no longer happens with libusb-1.0. - Reduced CPU usage. libusb-0.1 polls active bulk transfers every millisecond, resulting in high CPU wakeups and utilisation. libusb-1.0 relies on a wakeup mechanism, where the library does not become active unless events are happening. This also improves power usage, and the more precise wakeup times result in a performance improvement as high as 20% in some applications. - Improved bulk performance. For transfers of more than 16kb, libusb-1.0 allows the kernel to queue larger proportions of the requested transfer (often all of it) at the hardware level. This results in a substantial performance gain for applications that perform these large transfers. - Documentation. libusb-1.0 features detailed API documentation at http://libusb.sourceforge.net/api-1.0/ Porting your application: - libusb-1.0 is not backwards compatible with libusb-0.1 - *everything* in the API has a different name, and the library has a different name too. - libusb-1.0 can be installed on the same system as libusb-0.1 without conflict. It has been designed in this way. It does not cause problems to have both installed. It is also no problem for multiple applications to be running, some using 0.1 and others using 1.0. - A compatibility layer, libusb-compat-0.1, is offered as a replacement for libusb-0.1. It allows libusb-0.1 programs to use the libusb-1.0 library despite the API incompatibilities (it is a wrapper). This is optional; you can alternatively stay with libusb-0.1, or you can have a system with no libusb-0.1 implementation at all. See http://libusb.wiki.sourceforge.net/LibusbCompat0.1 - Straightforward porting your application from libusb-0.1 to libusb-1.0's synchronous API is quite easy, as that aspect of the API is quite similar to the great work that it built upon. - Porting your application to benefit from the asynchronous API requires more thought, because asynchronous design in any context is something that must be carried out carefully. And some final caveats: - Imperfections in the library are documented at http://libusb.sourceforge.net/api-1.0/caveats.html - libusb-0.1 was partially portable to non-Linux systems. So far, I have been unable to drum up any code from non-Linux OS developers, so libusb-1.0 is Linux only. I am still keen on working with other OS developers on this, please get in contact. There will be challenges, and we may need to make changes - I will help you, and we will figure it out. Future plans: - libusb-1.1 is planned to feature some internal improvements, hotplug device notifications, better materials for beginners (documentation and examples), and more! There will be no API changes, only additions. - If we need to make API changes, then those will be deferred until libusb-2.0. There are currently no plans for that release. - I won't be doing any more libusb-0.1 releases, unless some critical security issues turn up. Questions, bug reports and constructive criticisms are welcome on this mailing list (https://lists.sourceforge.net/lists/listinfo/libusb-devel). Please do not mail developers directly. Thanks! Daniel --- Changes since libusb-0.9.4 (the previous beta release): Daniel Drake (5): SourceForge website upload system changed Improvements to multi-threaded I/O system Fix double free in descriptor parsing error path Linux: fix reading of active configuration v1.0.0 release Mikhail Gusarov (1): EOL-whitespace fixes ------------------------------------------------------------------------------ SF.Net email is Sponsored by MIX09, March 18-20, 2009 in Las Vegas, Nevada. The future of the web can't happen without you. Join us at MIX09 to help pave the way to the Next Web now. 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