FL_WAIT_ACK
sc->state |= FL_WAIT_ACK;
if (sc->state & FL_WAIT_ACK) {
sc->state &= ~FL_WAIT_ACK;
sc->state &= ~(FL_WAIT_ACK | FL_NEED_RESEND);
sc->state &= ~(FL_WAIT_ACK | FL_NEED_RESEND);
sc->state &= ~(FL_WAIT_ACK | FL_NEED_RESEND);