MdePkg/Library/BaseMemoryLibRepStr/Ia32/CopyMem.asm

   1 //
   2 // Include common header file for this module.
   3 //
   4 #include "CommonHeader.h"
   5
   6 ;------------------------------------------------------------------------------
   7 ;
   8 ; Copyright (c) 2006, Intel Corporation
   9 ; All rights reserved. This program and the accompanying materials
  10 ; are licensed and made available under the terms and conditions of the BSD License
  11 ; which accompanies this distribution.  The full text of the license may be found at
  12 ; http://opensource.org/licenses/bsd-license.php
  13 ;
  14 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  15 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  16 ;
  17 ; Module Name:
  18 ;
  19 ;   CopyMem.Asm
  20 ;
  21 ; Abstract:
  22 ;
  23 ;   CopyMem function
  24 ;
  25 ; Notes:
  26 ;
  27 ;------------------------------------------------------------------------------
  28
  29     .386
  30     .model  flat,C
  31     .code
  32
  33 ;------------------------------------------------------------------------------
  34 ;  VOID *
  35 ;  InternalMemCopyMem (
  36 ;    IN VOID   *Destination,
  37 ;    IN VOID   *Source,
  38 ;    IN UINTN  Count
  39 ;    )
  40 ;------------------------------------------------------------------------------
  41 InternalMemCopyMem  PROC    USES    esi edi
  42     mov     esi, [esp + 16]             ; esi <- Source
  43     mov     edi, [esp + 12]             ; edi <- Destination
  44     mov     edx, [esp + 20]             ; edx <- Count
  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     mov     eax, [esp + 12]             ; eax <- Destination as return value
  65     ret
  66 InternalMemCopyMem  ENDP
  67
  68     END