diff -r 000000000000 -r 6474c204b198 nsprpub/pr/src/misc/prlog2.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nsprpub/pr/src/misc/prlog2.c	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "prbit.h"
+
+/*
+** Compute the log of the least power of 2 greater than or equal to n
+*/
+PR_IMPLEMENT(PRIntn) PR_CeilingLog2(PRUint32 n)
+{
+    PRIntn log2;
+    PR_CEILING_LOG2(log2, n);
+    return log2;
+}
+
+/*
+** Compute the log of the greatest power of 2 less than or equal to n.
+** This really just finds the highest set bit in the word.
+*/
+PR_IMPLEMENT(PRIntn) PR_FloorLog2(PRUint32 n)
+{
+    PRIntn log2;
+    PR_FLOOR_LOG2(log2, n);
+    return log2;
+}