-/* Return yx_uint16 coordinate one step from coordinate yx in direction dir. */
-extern struct yx_uint16 mv_yx_in_dir(enum dir d, struct yx_uint16 yx);
+/* Return 1 if two yx_uint16 coordinates at "a" and "b" are equal, else 0. */
+extern uint8_t yx_uint16_cmp(struct yx_uint16 * a, struct yx_uint16 * b);
+
+/* Return yx_uint16 coordinate one step from "yx" in direction "dir" (east: 'E',
+ * west: 'W', north: 'N', south: 'S'). An invalid dir leaves "yx" unchanged.
+ */
+extern struct yx_uint16 mv_yx_in_dir(char dir, struct yx_uint16 yx);
+
+