MdePkg/Library/BaseMemoryLibRepStr/Ia32/CopyMem.asm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2006, 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 ;   CopyMem.Asm
  15 ;
  16 ; Abstract:
  17 ;
  18 ;   CopyMem function
  19 ;
  20 ; Notes:
  21 ;
  22 ;------------------------------------------------------------------------------
  23
  24     .386
  25     .model  flat,C
  26     .code
  27
  28 ;------------------------------------------------------------------------------
  29 ;  VOID *
  30 ;  InternalMemCopyMem (
  31 ;    IN VOID   *Destination,
  32 ;    IN VOID   *Source,
  33 ;    IN UINTN  Count
  34 ;    )
  35 ;------------------------------------------------------------------------------
  36 InternalMemCopyMem  PROC    USES    esi edi
  37     mov     esi, [esp + 16]             ; esi <- Source
  38     mov     edi, [esp + 12]             ; edi <- Destination
  39     mov     edx, [esp + 20]             ; edx <- Count
  40     lea     eax, [esi + edx - 1]        ; eax <- End of Source
  41     cmp     esi, edi
  42     jae     @F
  43     cmp     eax, edi
  44     jae     @CopyBackward               ; Copy backward if overlapped
  45 @@:
  46     mov     ecx, edx
  47     and     edx, 3
  48     shr     ecx, 2
  49     rep     movsd                       ; Copy as many Dwords as possible
  50     jmp     @CopyBytes
  51 @CopyBackward:
  52     mov     esi, eax                    ; esi <- End of Source
  53     lea     edi, [edi + edx - 1]        ; edi <- End of Destination
  54     std
  55 @CopyBytes:
  56     mov     ecx, edx
  57     rep     movsb                       ; Copy bytes backward
  58     cld
  59     mov     eax, [esp + 12]             ; eax <- Destination as return value
  60     ret
  61 InternalMemCopyMem  ENDP
  62
  63     END