GENET_DMA_DESC_COUNT
#define TX_SKIP(n, o) (((n) + (o)) & (GENET_DMA_DESC_COUNT - 1))
#define RX_NEXT(n) (((n) + 1) & (GENET_DMA_DESC_COUNT - 1))
#define TX_DESC_COUNT GENET_DMA_DESC_COUNT
#define RX_DESC_COUNT GENET_DMA_DESC_COUNT
struct genet_bufmap buf_map[GENET_DMA_DESC_COUNT];