Wikipedia
NxtOSEK
nxtOSEK is a Real-Time Operating System [RTOS] for the Lego Mindstorms programmable NXT controller. nxtOSEK consists of the I/O driver part of leJOS NXJ, TOPPERS OSEK RTOS, and glue code for them. nxtOSEK enables Lego Mindstorms NXT robots to be programmed in ANSI-C/C++.