I would like to introduce you to my open-source RSTP/MSTP library: code.google.com/p/mstp-lib

It's completely platform-independent C++. I wrote it myself and I've been using it in firmware for some embedded systems, both Linux-based and bare metal (no OS).

I'm looking to get people to know about it and actually use it their projects. Just like that, I don't expect anything in exchange. :) (Though I'd greatly value any feedback.)