1 files changed, 10 insertions, 0 deletions
diff --git a/crawl-ref/source/externs.h b/crawl-ref/source/externs.h
index 5f4f5e7e40..1c3a962d5d 100644
--- a/crawl-ref/source/externs.h
+++ b/crawl-ref/source/externs.h
@@ -92,6 +92,11 @@ class KillMaster;
 class ghost_demon;
 struct glyph;
 
+template <typename Z> inline Z sgn(Z x)
+{
+    return (x < 0 ? -1 : (x > 0 ? 1 : 0));
+}
+
 struct coord_def
 {
     int         x;
@@ -215,6 +220,11 @@ struct coord_def
         return (copy *= mul);
     }
 
+    coord_def sgn() const
+    {
+        return coord_def(::sgn(x), ::sgn(y));
+    }
+
     int abs() const
     {
         return (x * x + y * y);