Update to NSS 3.12.7 and NSPR 4.8.6....

nss/mozilla/nsprpub/pr/src/misc/prlog2.c

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
  * The contents of this file are subject to the Mozilla Public License Version
  * 1.1 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/
  *
  * Software distributed under the License is distributed on an "AS IS" basis,
@@ skipping 24 matching lines @@
  *
  * ***** END LICENSE BLOCK ***** */
 
 #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 = 0;
-
-    if (n & (n-1))
-        log2++;
-    if (n >> 16)
-        log2 += 16, n >>= 16;
-    if (n >> 8)
-        log2 += 8, n >>= 8;
-    if (n >> 4)
-        log2 += 4, n >>= 4;
-    if (n >> 2)
-        log2 += 2, n >>= 2;
-    if (n >> 1)
-        log2++;
+    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 = 0;
-
-    if (n >> 16)
-        log2 += 16, n >>= 16;
-    if (n >> 8)
-        log2 += 8, n >>= 8;
-    if (n >> 4)
-        log2 += 4, n >>= 4;
-    if (n >> 2)
-        log2 += 2, n >>= 2;
-    if (n >> 1)
-        log2++;
+    PRIntn log2;
+    PR_FLOOR_LOG2(log2, n);
     return log2;
 }