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 #include "BaseLibInternals.h"
  16
  17 /**
  18   Returns the value of the highest bit set in a 64-bit value. Equivalent to
  19   1 << HighBitSet64(x).
  20
  21   This function computes the value of the highest bit set in the 64-bit value
  22   specified by Operand. If Operand is zero, then zero is returned.
  23
  24   @param  Operand The 64-bit operand to evaluate.
  25
  26   @return 1 << HighBitSet64(Operand)
  27   @retval 0 Operand is zero.
  28
  29 **/
  30 UINT64
  31 EFIAPI
  32 GetPowerOfTwo64 (
  33   IN      UINT64                    Operand
  34   )
  35 {
  36   if (Operand == 0) {
  37     return 0;
  38   }
  39
  40   return LShiftU64 (1, HighBitSet64 (Operand));
  41 }