diff --git a/js/x11/core/xutil.js b/js/x11/core/xutil.js
new file mode 100644
index 0000000..d75b2b6
--- /dev/null
+++ b/js/x11/core/xutil.js
@@ -0,0 +1,29 @@
+function padded_length(len)
+{
+   return ((len + 3) >> 2) << 2;
+   /*
+   var rem = len % 4;
+   var pl = len;
+   if (rem)
+       return len + 4 - rem;
+   return len;
+   */
+}
+
+// TODO: make it return buffer?
+// str += is slow
+function padded_string(str)
+{
+   if (str.length == 0)
+       return '';
+ 
+   var pad = padded_length(str.length) - str.length;
+   var res = str;
+   for (var i=0; i < pad; ++i)
+       res += String.fromCharCode(0);
+
+   return res;
+}
+
+module.exports.padded_length = padded_length;
+module.exports.padded_string = padded_string;