+/**
+ * A macro that points to an offset into the data in the mbuf.
+ *
+ * The returned pointer is cast to type t. Before using this
+ * function, the user must ensure that the first segment is large
+ * enough to accommodate its data.
+ *
+ * @param m
+ * The packet mbuf.
+ * @param o
+ * The offset into the mbuf data.
+ * @param t
+ * The type to cast the result into.
+ */
+#define rte_pktmbuf_mtod_offset(m, t, o) \
+ ((t)((char *)(m)->buf_addr + (m)->data_off + (o)))
+