UefiCpuPkg: Move AsmRelocateApLoopStart from Mpfuncs.nasm to AmdSev.nasm

[mirror_edk2.git] / MdePkg / Library / BaseLib / LowBitSet64.c

/** @file\r
  Math worker functions.\r
\r
  Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
\r
#include "BaseLibInternals.h"\r
\r
/**\r
  Returns the bit position of the lowest bit set in a 64-bit value.\r
\r
  This function computes the bit position of the lowest bit set in the 64-bit\r
  value specified by Operand. If Operand is zero, then -1 is returned.\r
  Otherwise, a value between 0 and 63 is returned.\r
\r
  @param  Operand The 64-bit operand to evaluate.\r
\r
  @retval 0..63  The lowest bit set in Operand was found.\r
  @retval -1     Operand is zero.\r
\r
\r
**/\r
INTN\r
EFIAPI\r
LowBitSet64 (\r
  IN      UINT64  Operand\r
  )\r
{\r
  INTN  BitIndex;\r
\r
  if (Operand == 0) {\r
    return -1;\r
  }\r
\r
  for (BitIndex = 0;\r
       (Operand & 1) == 0;\r
       BitIndex++, Operand = RShiftU64 (Operand, 1))\r
  {\r
  }\r
\r
  return BitIndex;\r
}\r