MGE_TX_DESC_NUM
(++sc->tx_desc_used_idx) % MGE_TX_DESC_NUM;
bus_dma_segment_t segs[MGE_TX_DESC_NUM];
sc->tx_desc_curr = (++sc->tx_desc_curr) % MGE_TX_DESC_NUM;
if (sc->tx_desc_used_count + 1 >= MGE_TX_DESC_NUM) {
MGE_TX_DESC_NUM;
mge_alloc_desc_dma(sc, sc->mge_tx_desc, MGE_TX_DESC_NUM,
mge_free_desc(sc, sc->mge_tx_desc, MGE_TX_DESC_NUM, sc->mge_tx_dtag, 0);
if_setsendqlen(ifp, MGE_TX_DESC_NUM - 1);
struct mge_desc_wrapper mge_tx_desc[MGE_TX_DESC_NUM];