copymem.c

来自「EFI BIOS是Intel提出的下一代的BIOS标准。这里上传的Edk源代码是」· C语言 代码 · 共 66 行

/*++

Copyright (c) 2004 - 2006, Intel Corporation                                                         
All rights reserved. This program and the accompanying materials                          
are licensed and made available under the terms and conditions of the BSD License         
which accompanies this distribution.  The full text of the license may be found at        
http://opensource.org/licenses/bsd-license.php                                            
                                                                                          
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.  


Module Name:

  CopyMem.c
  
Abstract: 

  Internal CopyMem

--*/

#include "BaseMemoryLibInternal.h"

/**
  Copy Length bytes from Source to Destination.

  @param  Destination Target of copy
  @param  Source Place to copy from
  @param  Length Number of bytes to copy

  @return Destination

**/
VOID *
EFIAPI
InternalMemCopyMem (
  OUT     VOID                      *Destination,
  IN      CONST VOID                *Source,
  IN      UINTN                     Length
  )
{
  //
  // Declare the local variables that actually move the data elements as
  // volatile to prevent the optimizer from replacing this function with
  // the intrinsic memcpy()
  //
  volatile UINT8                    *Destination8;
  CONST UINT8                       *Source8;

  if (Source > Destination) {
    Destination8 = (UINT8*)Destination;
    Source8 = (CONST UINT8*)Source;
    while (Length-- != 0) {
      *(Destination8++) = *(Source8++);
    }
  } else if (Source < Destination) {
    Destination8 = (UINT8*)Destination + Length;
    Source8 = (CONST UINT8*)Source + Length;
    while (Length-- != 0) {
      *(--Destination8) = *(--Source8);
    }
  }
  return Destination;
}