OVERLAY_F_IN_RX
ASSERT(flag == OVERLAY_F_IN_RX || flag == OVERLAY_F_IN_TX);
if (flag & OVERLAY_F_IN_RX)
ASSERT(flag == OVERLAY_F_IN_RX || flag == OVERLAY_F_IN_TX);
if (flag & OVERLAY_F_IN_RX) {
odd->odd_flags &= ~OVERLAY_F_IN_RX;
overlay_io_start(odd, OVERLAY_F_IN_RX);
overlay_io_done(odd, OVERLAY_F_IN_RX);
overlay_io_start(odd, OVERLAY_F_IN_RX);
overlay_io_done(odd, OVERLAY_F_IN_RX);