AE_NEXTTX
for (i = txs->txs_firstdesc;; i = AE_NEXTTX(i)) {
AE_CDTXADDR(sc, AE_NEXTTX(i));
seg++, nexttx = AE_NEXTTX(nexttx)) {
for (seg = sc->sc_txnext;; seg = AE_NEXTTX(seg)) {