EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/EfiCopyMemRep1.c

   1 /*++
   2
   3 Copyright (c) 2007, Intel Corporation. All rights reserved.<BR>
   4 This program and the accompanying materials
   5 are licensed and made available under the terms and conditions of the BSD License
   6 which accompanies this distribution.  The full text of the license may be found at
   7 http://opensource.org/licenses/bsd-license.php
   8
   9 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11
  12 Module Name:
  13
  14   EfiCopyMemRep1.c
  15
  16 Abstract:
  17
  18   This is the code that uses rep movsb CopyMem service
  19
  20 --*/
  21
  22 #include "Tiano.h"
  23
  24 VOID
  25 EfiCommonLibCopyMem (
  26   IN VOID   *Destination,
  27   IN VOID   *Source,
  28   IN UINTN  Count
  29   )
  30 /*++
  31
  32 Routine Description:
  33
  34   Copy Length bytes from Source to Destination.
  35
  36 Arguments:
  37
  38   Destination - Target of copy
  39
  40   Source      - Place to copy from
  41
  42   Length      - Number of bytes to copy
  43
  44 Returns:
  45
  46   None
  47
  48 --*/
  49 {
  50   __asm {
  51     mov     esi, Source                  ; esi <- Source
  52     mov     edi, Destination             ; edi <- Destination
  53     mov     edx, Count                   ; edx <- Count
  54     cmp     esi, edi
  55     je      _CopyDone
  56     cmp     edx, 0
  57     je      _CopyDone
  58     lea     eax, [esi + edx - 1]         ; eax <- End of Source
  59     cmp     esi, edi
  60     jae     _CopyBytes
  61     cmp     eax, edi
  62     jb      _CopyBytes                   ; Copy backward if overlapped
  63     mov     esi, eax                     ; esi <- End of Source
  64     lea     edi, [edi + edx - 1]         ; edi <- End of Destination
  65     std
  66 _CopyBytes:
  67     mov     ecx, edx
  68     rep     movsb                        ; Copy bytes backward
  69     cld
  70 _CopyDone:
  71   }
  72 }
  73