STGE_NEXTTX
STGE_CDTXADDR(sc, STGE_NEXTTX(i)));
firsttx = STGE_NEXTTX(sc->sc_txlast);
nexttx = STGE_NEXTTX(sc->sc_txlast);
i = STGE_NEXTTX(i), sc->sc_txpending--) {