MdePkg/Library/BaseLib/Ia32/SwapBytes64.c

   1 /** @file
   2   Implementation of 64-bit swap bytes
   3
   4   Copyright (c) 2006 - 2007, 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 // Include common header file for this module.
  17 //
  18
  19
  20 /**
  21   Switches the endianess of a 64-bit integer.
  22
  23   This function swaps the bytes in a 64-bit unsigned value to switch the value
  24   from little endian to big endian or vice versa. The byte swapped value is
  25   returned.
  26
  27   @param  Operand A 64-bit unsigned value.
  28
  29   @return The byte swaped Operand.
  30
  31 **/
  32 UINT64
  33 EFIAPI
  34 InternalMathSwapBytes64 (
  35   IN      UINT64                    Operand
  36   )
  37 {
  38   _asm {
  39     mov     eax, dword ptr [Operand + 4]
  40     mov     edx, dword ptr [Operand + 0]
  41     bswap   eax
  42     bswap   edx
  43   }
  44 }
  45