MdePkg/Library/BaseMemoryLibOptDxe/X64/ZeroMem.nasm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
   4 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   5 ;
   6 ; Module Name:
   7 ;
   8 ;   ZeroMem.Asm
   9 ;
  10 ; Abstract:
  11 ;
  12 ;   ZeroMem function
  13 ;
  14 ; Notes:
  15 ;
  16 ;------------------------------------------------------------------------------
  17
  18     DEFAULT REL
  19     SECTION .text
  20
  21 ;------------------------------------------------------------------------------
  22 ;  VOID *
  23 ;  InternalMemZeroMem (
  24 ;    IN VOID   *Buffer,
  25 ;    IN UINTN  Count
  26 ;    );
  27 ;------------------------------------------------------------------------------
  28 global ASM_PFX(InternalMemZeroMem)
  29 ASM_PFX(InternalMemZeroMem):
  30     push    rdi
  31     push    rcx       ; push Buffer
  32     xor     rax, rax  ; rax = 0
  33     mov     rdi, rcx  ; rdi = Buffer
  34     mov     rcx, rdx  ; rcx = Count
  35     shr     rcx, 3    ; rcx = rcx / 8
  36     and     rdx, 7    ; rdx = rdx & 7
  37     cld
  38     rep     stosq
  39     mov     rcx, rdx  ; rcx = rdx
  40     rep     stosb
  41     pop     rax       ; rax = Buffer
  42     pop     rdi
  43     ret
  44