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
  10
  11
  12 #include "BaseLibInternals.h"
  13
  14 /**
  15   Returns the value of the highest bit set in a 64-bit value. Equivalent to
  16   1 << log2(x).
  17
  18   This function computes the value of the highest bit set in the 64-bit value
  19   specified by Operand. If Operand is zero, then zero is returned.
  20
  21   @param  Operand The 64-bit operand to evaluate.
  22
  23   @return 1 << HighBitSet64(Operand)
  24   @retval 0 Operand is zero.
  25
  26 **/
  27 UINT64
  28 EFIAPI
  29 GetPowerOfTwo64 (
  30   IN      UINT64                    Operand
  31   )
  32 {
  33   if (Operand == 0) {
  34     return 0;
  35   }
  36
  37   return LShiftU64 (1, (UINTN) HighBitSet64 (Operand));
  38 }