if (! TimingIsEnabled()) return PR_FALSE;
{ PRTime n; LL_UI2L(n, 1000000L); LL_MOD(tmUSec, time, n); LL_DIV(time, time, n); }
PR_EXTERN(PRBool)TimingStopClock(PRTime* result, const char* clock){    PRTime* start;    PRTime  stop = PR_Now();    if (! TimingIsEnabled())        return PR_FALSE;    if (! EnsureTimingTable())        return PR_FALSE;    if ((start = PL_HashTableLookup(_timingClockTable, clock)) != NULL) {        if (result != NULL)            LL_SUB(*result, stop, *start);        PL_HashTableRemove(_timingClockTable, clock);        return PR_TRUE;    } else {        *result = LL_ZERO;        return PR_FALSE;    }}