MdePkg/Library/BaseLib/Ia32/SwapBytes64.c

   1 /** @file
   2   Implementation of 64-bit swap bytes
   3
   4   Copyright (c) 2006 - 2008, 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
  17
  18 /**
  19   Switches the endianess of a 64-bit integer.
  20
  21   This function swaps the bytes in a 64-bit unsigned value to switch the value
  22   from little endian to big endian or vice versa. The byte swapped value is
  23   returned.
  24
  25   @param  Operand A 64-bit unsigned value.
  26
  27   @return The byte swaped Operand.
  28
  29 **/
  30 UINT64
  31 EFIAPI
  32 InternalMathSwapBytes64 (
  33   IN      UINT64                    Operand
  34   )
  35 {
  36   _asm {
  37     mov     eax, dword ptr [Operand + 4]
  38     mov     edx, dword ptr [Operand + 0]
  39     bswap   eax
  40     bswap   edx
  41   }
  42 }
  43