EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/X64/EfiCopyMemRep1.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # Copyright (c) 2008, 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 #   EfiCopyMemRep1.S
  15 #
  16 # Abstract:
  17 #
  18 #   CopyMem function
  19 #
  20 # Notes:
  21 #
  22 #------------------------------------------------------------------------------
  23 #include <EfiBind.h>
  24
  25     .code:
  26
  27 .global ASM_PFX(EfiCommonLibCopyMem)
  28
  29 #------------------------------------------------------------------------------
  30 # VOID
  31 # EfiCommonLibCopyMem (
  32 #   OUT     VOID                      *Destination,
  33 #   IN      VOID                      *Source,
  34 #   IN      UINTN                     Count
  35 #   );
  36 #------------------------------------------------------------------------------
  37 ASM_PFX(EfiCommonLibCopyMem):
  38       push   %rsi
  39       push   %rdi
  40       cmp    %rcx,%rdx
  41       je     CopyMemDone
  42       cmp    $0x0,%r8
  43       je     CopyMemDone
  44       mov    %rdx,%rsi
  45       mov    %rcx,%rdi
  46       lea    -1(%r8,%rsi,1),%r9
  47       cmp    %rdi,%rsi
  48       jae    CopyBytes
  49       cmp    %rdi,%r9
  50       jb     CopyBytes
  51       mov    %r9,%rsi
  52       lea    -1(%r8,%rdi,1),%rdi
  53       std
  54
  55 CopyBytes:
  56       mov    %r8,%rcx
  57       rep movsb %ds:(%rsi),%es:(%rdi)
  58       cld
  59
  60 CopyMemDone:
  61       pop    %rdi
  62       pop    %rsi
  63       retq
  64
  65
  66