+/**
+ * Blocking delay function.
+ *
+ * @param us
+ * Number of microseconds to wait.
+ */
+void rte_delay_us_block(unsigned int us);
+
+/**
+ * Replace rte_delay_us with user defined function.
+ *
+ * @param userfunc
+ * User function which replaces rte_delay_us. rte_delay_us_block restores
+ * buildin block delay function.
+ */
+void rte_delay_us_callback_register(void(*userfunc)(unsigned int));
+