+ Protothreads and Other Wicked C Tricks !!! +

For those of you interested in interesting hard-core C programming tricks: Adam Dunkels' protothreads library implements an unusually lightweight type of threads. Protothreads are not real threads, but rather something in between an event-driven state machine and regular threads. But they are implemented in 100% portable ANSI C and with an interesting but quite unintuitive use of the switch/case construct. The same trick has previously been used by Simon Tatham to implement coroutines in C. The trick was originally invented by Tom Duff and dubbed Duff's device. You either love it or you hate it!..

http://en.wikipedia.org/wiki/Duff's_device