HPET_IE
if ((devp->hd_flags & (HPET_IE | HPET_PERIODIC)) == HPET_IE) {
devp->hd_flags &= ~(HPET_OPEN | HPET_IE | HPET_PERIODIC);
if (devp->hd_flags & HPET_IE) {
devp->hd_flags |= HPET_IE;
devp->hd_flags ^= HPET_IE;
if ((devp->hd_flags & HPET_IE) == 0)
devp->hd_flags ^= HPET_IE;