1 files changed, 6 insertions, 0 deletions
diff --git a/tile.h b/tile.h
index bb5698f4c..aacda662a 100644
--- a/tile.h
+++ b/tile.h
@@ -44,6 +44,12 @@ typedef enum DiagonalDirections {
 	INVALID_DIAGDIR = 0xFF,
 } DiagDirection;
 
+static inline DiagDirection ReverseDiagDir(DiagDirection d)
+{
+	return 2 ^ d;
+}
+
+
 /* the 2 axis */
 typedef enum Axis {
 	AXIS_X = 0,