TS_ERASE
if (tp->t_state & TS_ERASE) {
tp->t_state &= ~TS_ERASE;
if (!(tp->t_state & TS_ERASE)) {
tp->t_state |= TS_ERASE;
tp->t_state &= ~(TS_QUOT|TS_ERASE|TS_SLNCH);
tp->t_state &= ~TS_ERASE;