TX_RING
static struct ring_desc tx_ring[TX_RING];
static unsigned char txb[TX_RING * RX_NIC_BUFSIZE];
struct sk_buff *tx_skbuff[TX_RING];
u32 tx_dma[TX_RING];
for (i = 0; i < TX_RING; i++) {
((TX_RING - 1) << NVREG_RINGSZ_TXSHIFT),
int nr = np->next_tx % TX_RING;