EdkCompatibilityPkg/Foundation/Library/CompilerStub/Ia32/memcpyRep4.asm

   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 ;   CopyMem.asm
  15 ;
  16 ; Abstract:
  17 ;
  18 ;   memcpy function
  19 ;
  20 ; Notes:
  21 ;
  22 ;------------------------------------------------------------------------------
  23
  24     .686
  25     .model  flat,C
  26     .mmx
  27     .code
  28
  29 ;------------------------------------------------------------------------------
  30 ;  VOID *
  31 ;  memcpy (
  32 ;    IN VOID   *Destination,
  33 ;    IN VOID   *Source,
  34 ;    IN UINTN  Count
  35 ;    );
  36 ;------------------------------------------------------------------------------
  37 memcpy  PROC    USES    esi edi
  38     mov     esi, [esp + 16]             ; esi <- Source
  39     mov     edi, [esp + 12]             ; edi <- Destination
  40     mov     edx, [esp + 20]             ; edx <- Count
  41     cmp     esi, edi
  42     je      @CopyDone
  43     cmp     edx, 0
  44     je      @CopyDone
  45     lea     eax, [esi + edx - 1]         ; eax <- End of Source
  46     cmp     esi, edi
  47     jae     @F
  48     cmp     eax, edi
  49     jae     @CopyBackward                ; Copy backward if overlapped
  50 @@:
  51     mov     ecx, edx
  52     and     edx, 3
  53     shr     ecx, 2
  54     rep     movsd                        ; Copy as many Dwords as possible
  55     jmp     @CopyBytes
  56 @CopyBackward:
  57     mov     esi, eax                     ; esi <- End of Source
  58     lea     edi, [edi + edx - 1]         ; edi <- End of Destination
  59     std
  60 @CopyBytes:
  61     mov     ecx, edx
  62     rep     movsb                        ; Copy bytes backward
  63     cld
  64 @CopyDone:
  65     mov     eax, [esp + 12]
  66     ret
  67
  68 memcpy  ENDP
  69
  70     END