MdePkg/Library/BaseLib/GetPowerOfTwo64.c

   1 /** @file
   2   Math worker functions.
   3
   4   Copyright (c) 2006, Intel Corporation<BR>
   5   All rights reserved. This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 //
  16 // Include common header file for this module.
  17 //
  18 #include "CommonHeader.h"
  19
  20 #include "BaseLibInternals.h"
  21
  22 /**
  23   Returns the value of the highest bit set in a 64-bit value. Equivalent to
  24   1 << HighBitSet64(x).
  25
  26   This function computes the value of the highest bit set in the 64-bit value
  27   specified by Operand. If Operand is zero, then zero is returned.
  28
  29   @param  Operand The 64-bit operand to evaluate.
  30
  31   @return 1 << HighBitSet64(Operand)
  32   @retval 0 Operand is zero.
  33
  34 **/
  35 UINT64
  36 EFIAPI
  37 GetPowerOfTwo64 (
  38   IN      UINT64                    Operand
  39   )
  40 {
  41   if (Operand == 0) {
  42     return 0;
  43   }
  44
  45   return LShiftU64 (1, HighBitSet64 (Operand));
  46 }