Editing Contiki (section)

==Programming model==
To run efficiently on small-memory systems, the Contiki programming model is based on [[protothreads]].<ref>{{Citation |first1= Adam |last1= Dunkels |first2= Oliver |last2= Schmidt |first3= Thiemo |last3= Voigt |first4= Muneeb |last4= Ali |contribution= Protothreads: Simplifying event-driven programming of memory-constrained embedded systems |title= Proceedings of the Fourth ACM Conference on Embedded Networked Sensor Systems (SenSys) |place= Boulder, [[Colorado|CO]], USA |date=November 2006}} {{Cite book |doi= 10.1145/1182807.1182811| chapter= Protothreads| title= Proceedings of the 4th international conference on Embedded networked sensor systems - Sen ''Sys'' '06| pages= 29| year= 2006| last1= Dunkels |first1= A. |last2= Schmidt |first2= O. |last3= Voigt |first3= T. |last4= Ali |first4= M. |isbn= 1595933433| s2cid= 983128}} ([http://dunkels.com/adam/dunkels06protothreads.pdf PDF], [http://dunkels.com/adam/dunkels06protothreads.ppt Presentation slides]).</ref><ref>{{Citation |title= Code |url= http://code.google.com/p/protothread/ |contribution= Protothread }}.</ref> A protothread is a memory-efficient programming abstraction that shares features of both [[Multithreading (software)|multithreading]] and [[event-driven programming]] to attain a low memory overhead of each protothread. The kernel invokes the protothread of a process in response to an internal or external event. Examples of internal events are timers that fire or messages being posted from other processes. Examples of external events are sensors that trigger or incoming packets from a radio neighbor.

Protothreads are cooperatively scheduled. Thus, a Contiki process must always explicitly yield control back to the kernel at regular intervals. Contiki processes may use a special protothread construct to block waiting for events while yielding control to the kernel between each event invocation.