MdePkg/Library/BaseMemoryLibOptPei/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 ;------------------------------------------------------------------------------
  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     cmp     esi, edi
  41     je      @CopyDone
  42     cmp     edx, 0
  43     je      @CopyDone
  44     lea     eax, [esi + edx - 1]         ; eax <- End of Source
  45     cmp     esi, edi
  46     jae     @CopyBytes
  47     cmp     eax, edi
  48     jb      @CopyBytes                   ; Copy backward if overlapped
  49     mov     esi, eax                     ; esi <- End of Source
  50     lea     edi, [edi + edx - 1]         ; edi <- End of Destination
  51     std
  52 @CopyBytes:
  53     mov     ecx, edx
  54     rep     movsb                        ; Copy bytes backward
  55     cld
  56 @CopyDone:
  57     mov     eax, [esp + 12]             ; eax <- Destination as return value
  58     ret
  59 InternalMemCopyMem  ENDP
  60
  61     END