RX_NEXT
#define RX_NEXT(n) (((n) + 1) & (RX_DESC_COUNT - 1))
#define RX_NEXT(n) (((n) + 1) % RX_DESC_COUNT)
#define RX_NEXT(n) (((n) + 1) % RX_DESC_COUNT)
#define RX_NEXT(N) (((N) + 1) & (AWGE_RX_RING_COUNT - 1))