_nt_highMask = (_nt_highMask << 1)+1;
_PR_MD_INTERVAL_INIT(){    LARGE_INTEGER count;    if (QueryPerformanceFrequency(&count)) {        PR_ASSERT(count.HighPart == 0);        while(count.LowPart > PR_INTERVAL_MAX) {            count.LowPart >>= 1;            _nt_bitShift++;            _nt_highMask = (_nt_highMask << 1)+1;        }        _nt_ticksPerSec = count.LowPart;        PR_ASSERT(_nt_ticksPerSec > PR_INTERVAL_MIN);    } else         _nt_ticksPerSec = -1;}