RING_NEXT
*slot = RING_NEXT(*slot, sky2->tx_ring_size);
sky2->rx_put = RING_NEXT(sky2->rx_put, RX_LE_SIZE);
for (i = sky2->tx_prod; i != slot; i = RING_NEXT(i, sky2->tx_ring_size)) {
idx = RING_NEXT(idx, sky2->tx_ring_size)) {
sky2->tx_next = RING_NEXT(idx, sky2->tx_ring_size);
hw->st_idx = RING_NEXT(hw->st_idx, hw->st_size);
idx = RING_NEXT(idx, hw->st_size)) {
idx = RING_NEXT(idx, sky2->tx_ring_size)) {