* this function is called from a timer interruption. If an event has
* to be scheduled, it will execute the fonction (IRQ are allowed
* during the execution of the function). This interruption can be
* interrupted by itself too, in this case only events with a higher
* priority can be scheduled.
* this function is called from a timer interruption. If an event has
* to be scheduled, it will execute the fonction (IRQ are allowed
* during the execution of the function). This interruption can be
* interrupted by itself too, in this case only events with a higher
* priority can be scheduled.