+
+/* 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 coordinate yx in direction dir.
+ *
+ * If an invalid dir "d" is passed, "yx" remains unchanged.
+ */