-/* Directions available for movement. */
-enum dir
-{
- NORTH = 1,
- EAST,
- SOUTH,
- WEST
-};
-
-
-
/* 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.
+/* Return yx_uint16 coordinate one step from "yx" in direction "dir" (east: 'E',
+ * west: 'W', north: 'N', south: 'S'). If "dir" is invalid or would wrap the
+ * move around the edge of a 2^16x2^16 cells field, "yx" remains unchanged.
*/
-extern struct yx_uint16 mv_yx_in_dir(enum dir d, struct yx_uint16 yx);
+extern struct yx_uint16 mv_yx_in_dir(char dir, struct yx_uint16 yx);