+#include <stdint.h>
+
+/* Coordinates for maps of max. 65536x65536 cells. */
+struct yx_uint16
+{
+ uint16_t y;
+ uint16_t x;
+};
+
+/* This encodes directions. */
+
+enum dir
+{
+ NORTH = 1,
+ EAST = 2,
+ SOUTH = 3,
+ WEST = 4
+};
+
+/* Return 1 if two yx_uint16 coordinates a and b are equal, else 0. */
+extern char yx_uint16_cmp(struct yx_uint16 a, struct yx_uint16 b);