nsprpub/pr/src/misc/prlog2.c

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "prbit.h"
   7
   8 /*
   9 ** Compute the log of the least power of 2 greater than or equal to n
  10 */
  11 PR_IMPLEMENT(PRIntn) PR_CeilingLog2(PRUint32 n) {
  12   PRIntn log2;
  13   PR_CEILING_LOG2(log2, n);
  14   return log2;
  15 }
  16
  17 /*
  18 ** Compute the log of the greatest power of 2 less than or equal to n.
  19 ** This really just finds the highest set bit in the word.
  20 */
  21 PR_IMPLEMENT(PRIntn) PR_FloorLog2(PRUint32 n) {
  22   PRIntn log2;
  23   PR_FLOOR_LOG2(log2, n);
  24   return log2;
  25 }