Arduino functions millis, micros and eventually some more to come
Arduino basic compatibility millis(), micros(), evtl. more to come.
micros() and millis() are uint32_t and have a correct overflow at 2^32-1. micros() has a granularity/resolution of 50. This can be changed by a define. 1 microsecond is not realistic because every count needs an irq. A resolution of 50 microseconds means 20KHz irq. That should not take away more than 1 percent overall processing time.