RXPKT_SIZE
SWO(bitmode, ((char *)sc->p_rda + (rdamark * RXPKT_SIZE(sc))),
(rdamark * RXPKT_SIZE(sc))),
rda = (char *)sc->p_rda + (sc->sc_rxmark * RXPKT_SIZE(sc));
sc->sc_nrda = PAGE_SIZE / RXPKT_SIZE(sc);
p_rda = (char *)sc->p_rda + (i * RXPKT_SIZE(sc));
v_rda = sc->v_rda + ((i+1) * RXPKT_SIZE(sc));
p_rda = (char *)sc->p_rda + ((sc->sc_nrda - 1) * RXPKT_SIZE(sc));
rda = (char *)sc->p_rda + (sc->sc_rxmark * RXPKT_SIZE(sc));