+#if RTE_CACHE_LINE_SIZE < 128
+#define PROD_ALIGN (RTE_CACHE_LINE_SIZE * 2)
+#define CONS_ALIGN (RTE_CACHE_LINE_SIZE * 2)
+#else
+#define PROD_ALIGN RTE_CACHE_LINE_SIZE
+#define CONS_ALIGN RTE_CACHE_LINE_SIZE
+#endif
+
+/* structure to hold a pair of head/tail values and other metadata */
+struct rte_ring_headtail {
+ volatile uint32_t head; /**< Prod/consumer head. */
+ volatile uint32_t tail; /**< Prod/consumer tail. */
+ uint32_t size; /**< Size of ring. */
+ uint32_t mask; /**< Mask (size-1) of ring. */
+ uint32_t single; /**< True if single prod/cons */
+ uint32_t watermark; /**< Max items before EDQUOT in producer. */
+};
+