MdePkg/Library/BaseMemoryLibOptDxe/X64/CompareMem.nasm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
   4 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   5 ;
   6 ; Module Name:
   7 ;
   8 ;   CompareMem.Asm
   9 ;
  10 ; Abstract:
  11 ;
  12 ;   CompareMem function
  13 ;
  14 ; Notes:
  15 ;
  16 ;   The following BaseMemoryLib instances contain the same copy of this file:
  17 ;
  18 ;       BaseMemoryLibRepStr
  19 ;       BaseMemoryLibMmx
  20 ;       BaseMemoryLibSse2
  21 ;       BaseMemoryLibOptDxe
  22 ;       BaseMemoryLibOptPei
  23 ;
  24 ;------------------------------------------------------------------------------
  25
  26     DEFAULT REL
  27     SECTION .text
  28
  29 ;------------------------------------------------------------------------------
  30 ; INTN
  31 ; EFIAPI
  32 ; InternalMemCompareMem (
  33 ;   IN      CONST VOID                *DestinationBuffer,
  34 ;   IN      CONST VOID                *SourceBuffer,
  35 ;   IN      UINTN                     Length
  36 ;   );
  37 ;------------------------------------------------------------------------------
  38 global ASM_PFX(InternalMemCompareMem)
  39 ASM_PFX(InternalMemCompareMem):
  40     push    rsi
  41     push    rdi
  42     mov     rsi, rcx
  43     mov     rdi, rdx
  44     mov     rcx, r8
  45     repe    cmpsb
  46     movzx   rax, byte [rsi - 1]
  47     movzx   rdx, byte [rdi - 1]
  48     sub     rax, rdx
  49     pop     rdi
  50     pop     rsi
  51     ret
  52