Does rtems have a portable, sort-of calibrated time-wasting loop?

[gregory.menke at gsfc.nasa.gov]

Perhaps something like Linux's udelay- it doesn't have to be fast, but
should cause the program to spin for the supplied interval.  It should
not itself reschedule, so rtems_wake_after is out- and should be
callable from an isr.

Thanks,

Gregm