TS_OFBLOCK
~(TS_TTSTOP|TS_OFBLOCK);
TS_OFBLOCK);
tp->t_state &= ~(TS_TTSTOP|TS_OFBLOCK);
tp->t_state &= ~(TS_TTSTOP|TS_OFBLOCK);
tp->t_state |= (TS_TTSTOP|TS_OFBLOCK);
tp->t_state &= ~(TS_TTSTOP|TS_OFBLOCK);