+#define TX_DESC(tx, num) ((tx)->chan.ring_virt[(num) & (TX_RING_SIZE-1)])
+#define TX_DESC_INFO(tx, num) ((tx)->ring_info[(num) & (TX_RING_SIZE-1)])
+#define RX_DESC(rx, num) ((rx)->chan.ring_virt[(num) & (RX_RING_SIZE-1)])
+#define RX_DESC_INFO(rx, num) ((rx)->ring_info[(num) & (RX_RING_SIZE-1)])
+#define RX_BUFF(rx, num) ((rx)->buffers[(num) & (RX_RING_SIZE-1)])
+#define CS_DESC(cs, num) ((cs)->chan.ring_virt[(num) & (CS_RING_SIZE-1)])
+
+#define RING_USED(ring) (((ring)->next_to_fill - (ring)->next_to_clean) \
+ & ((ring)->size - 1))
+#define RING_AVAIL(ring) ((ring->size) - RING_USED(ring))