MdePkg/Library/BaseMemoryLibRepStr/Ia32/CopyMem.asm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2006, Intel Corporation
   4 ; All rights reserved. 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 InternalMemCopyMem  PROC    USES    esi edi
  29     mov     esi, [esp + 16]             ; esi <- Source
  30     mov     edi, [esp + 12]             ; edi <- Destination
  31     mov     edx, [esp + 20]             ; edx <- Count
  32     lea     eax, [edi + edx - 1]        ; eax <- End of Destination
  33     cmp     esi, edi
  34     jae     @F
  35     cmp     eax, esi
  36     jae     @CopyBackward               ; Copy backward if overlapped
  37 @@:
  38     mov     ecx, edx
  39     and     edx, 3
  40     shr     ecx, 2
  41     rep     movsd                       ; Copy as many Dwords as possible
  42     jmp     @CopyBytes
  43 @CopyBackward:
  44     mov     edi, eax                    ; edi <- End of Destination
  45     lea     esi, [esi + edx - 1]        ; esi <- End of Source
  46     std
  47 @CopyBytes:
  48     mov     ecx, edx
  49     rep     movsb                       ; Copy bytes backward
  50     cld
  51     mov     eax, [esp + 12]             ; eax <- Destination as return value
  52     ret
  53 InternalMemCopyMem  ENDP
  54
  55     END