_PR_ClockInterrupt();
_PR_INTSOFF(is);   _PR_ClockInterrupt();
pascal void TimerCallback(TMTaskPtr tmTaskPtr){    _PRCPU *cpu = _PR_MD_CURRENT_CPU();    if (_PR_MD_GET_INTSOFF()) {        cpu->u.missed[cpu->where] |= _PR_MISSED_CLOCK;		PrimeTime((QElemPtr)tmTaskPtr, kMacTimerInMiliSecs);		return;    }    _PR_MD_SET_INTSOFF(1);	//	And tell nspr that a clock interrupt occured.	_PR_ClockInterrupt();		if ((_PR_RUNQREADYMASK(cpu)) >> ((_PR_MD_CURRENT_THREAD()->priority)))		_PR_SET_RESCHED_FLAG();	    _PR_MD_SET_INTSOFF(0);	//	Reset the clock timer so that we fire again.	PrimeTime((QElemPtr)tmTaskPtr, kMacTimerInMiliSecs);}