MdePkg/Library/BaseMemoryLibOptPei/Ia32/CopyMem.nasm

   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     SECTION .text
  25
  26 ;------------------------------------------------------------------------------
  27 ;  VOID *
  28 ;  InternalMemCopyMem (
  29 ;    IN VOID   *Destination,
  30 ;    IN VOID   *Source,
  31 ;    IN UINTN  Count
  32 ;    )
  33 ;------------------------------------------------------------------------------
  34 global ASM_PFX(InternalMemCopyMem)
  35 ASM_PFX(InternalMemCopyMem):
  36     push    esi
  37     push    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     @CopyBytes
  48     cmp     eax, edi
  49     jb      @CopyBytes                   ; Copy backward if overlapped
  50     mov     esi, eax                     ; esi <- End of Source
  51     lea     edi, [edi + edx - 1]         ; edi <- End of Destination
  52     std
  53 @CopyBytes:
  54     mov     ecx, edx
  55     rep     movsb                        ; Copy bytes backward
  56     cld
  57 @CopyDone:
  58     mov     eax, [esp + 12]             ; eax <- Destination as return value
  59     pop     edi
  60     pop     esi
  61     ret
  62