unadjust_unlocked

Converts the given external clock time to the internal time of this, using the rate and reference time set with set_calibration.

This function should be called with the clock's OBJECT_LOCK held and is mainly used by clock subclasses.

This function is the reverse of adjust_unlocked.

Parameters:

this	a Clock to use
external	an external clock time

Returns:

the internal time of the clock corresponding to external.