/* get next usable tpd Note: should call atl1e_tdp_avail to make sure there is enough tpd to use  */
static struct atl1e_tpd_desc* atl1e_get_tpd(struct atl1e_adapter *adapter)
/* get next usable tpd Note: should call atl1e_tdp_avail to make sure there is enough tpd to use  */
static struct atl1e_tpd_desc* atl1e_get_tpd(struct atl1e_adapter *adapter)
{
	struct atl1e_tx_ring *tx_ring = &adapter->tx_ring;
	u16 next_to_use = 0;
	next_to_use = tx_ring->next_to_use;
	if (++tx_ring->next_to_use == tx_ring->count)
		tx_ring->next_to_use = 0;
	memset(&tx_ring->desc[next_to_use], 0, sizeof(struct atl1e_tpd_desc));
	return (struct atl1e_tpd_desc *)&tx_ring->desc[next_to_use];
}