I'm deprecating this project. I created rtmidi fork that adds almost the same C API instead (to bring build back system sanity). See https://github.com/atsushieno/rtmidi . Thanks to rtmidi hackers, my changes are even merged there.
C port to rtmidi C++ library, to make it usable with .NET P/Invoke.
(Windows and OSX build should be added. So far the build requires gcc and lacks any other additional configure flags and libs.)