TPMASK
if (newval < 0 || newval > (tp[TPMASK] == 0 ? 255 : 1))
error = trackpoint_command(sc, tp[TPMASK] == 0 ? 0x81 : 0x47,
tp[TPLOC], tp[TPMASK] == 0 ? newval : tp[TPMASK]);