MdePkg/Library/BaseLib/GetPowerOfTwo64.c

   1 /** @file
   2   Math worker functions.
   3
   4   Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "BaseLibInternals.h"
  10
  11 /**
  12   Returns the value of the highest bit set in a 64-bit value. Equivalent to
  13   1 << log2(x).
  14
  15   This function computes the value of the highest bit set in the 64-bit value
  16   specified by Operand. If Operand is zero, then zero is returned.
  17
  18   @param  Operand The 64-bit operand to evaluate.
  19
  20   @return 1 << HighBitSet64(Operand)
  21   @retval 0 Operand is zero.
  22
  23 **/
  24 UINT64
  25 EFIAPI
  26 GetPowerOfTwo64 (
  27   IN      UINT64  Operand
  28   )
  29 {
  30   if (Operand == 0) {
  31     return 0;
  32   }
  33
  34   return LShiftU64 (1, (UINTN)HighBitSet64 (Operand));
  35 }