MdePkg/Library/BaseMemoryLibOptDxe/X64/SetMem.S

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2006, 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 ;   SetMem.Asm
  15 ;
  16 ; Abstract:
  17 ;
  18 ;   SetMem function
  19 ;
  20 ; Notes:
  21 ;
  22 ;------------------------------------------------------------------------------
  23
  24     .code
  25
  26 ;------------------------------------------------------------------------------
  27 ;  VOID *
  28 ;  EFIAPI
  29 ;  InternalMemSetMem (
  30 ;    IN VOID   *Buffer,
  31 ;    IN UINTN  Count,
  32 ;    IN UINT8  Value
  33 ;    )
  34 ;------------------------------------------------------------------------------
  35 .intel_syntax noprefix
  36 .globl ASM_PFX(InternalMemSetMem)
  37 ASM_PFX(InternalMemZeroMem):
  38 InternalMemSetMem   PROC    USES    rdi rbx
  39     push    rdi
  40     push    rbx
  41     push    rcx       ; push Buffer
  42     mov     rax, r8   ; rax = Value
  43     and     rax, 0ffh ; rax = lower 8 bits of r8, upper 56 bits are 0
  44     mov     ah,  al   ; ah  = al
  45     mov     bx,  ax   ; bx  = ax
  46     shl     rax, 10h  ; rax = ax << 16
  47     mov     ax,  bx   ; ax  = bx
  48     mov     rbx, rax  ; ebx = eax
  49     shl     rax, 20h  ; rax = rax << 32
  50     or      rax, rbx  ; eax = ebx
  51     mov     rdi, rcx  ; rdi = Buffer
  52     mov     rcx, rdx  ; rcx = Count
  53     shr     rcx, 3    ; rcx = rcx / 8
  54     cld
  55     rep     stosq
  56     mov     rcx, rdx  ; rcx = rdx
  57     and     rcx, 7    ; rcx = rcx & 7
  58     rep     stosb
  59     pop     rax       ; rax = Buffer
  60     pop     rbx
  61     pop     rdi
  62     ret
  63 InternalMemSetMem   ENDP
  64
  65     END