diff --git a/lib/math.c b/lib/math.c
new file mode 100644
index 0000000..376c1f5
--- /dev/null
+++ b/lib/math.c
@@ -0,0 +1,7 @@
+#include "types.h"
+
+u32 abs(int x)
+{
+if (x<0) x=-x;
+return (u32)x;
+}