MdePkg/Library/BaseMemoryLibOptDxe/X64/SetMem.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # Copyright (c) 2006 - 2009, 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.S
  15 #
  16 # Abstract:
  17 #
  18 #   SetMem function
  19 #
  20 # Notes:
  21 #
  22 #------------------------------------------------------------------------------
  23 #------------------------------------------------------------------------------
  24 #  VOID *
  25 #  EFIAPI
  26 #  InternalMemSetMem (
  27 #    IN VOID   *Buffer,
  28 #    IN UINTN  Count,
  29 #    IN UINT8  Value
  30 #    )
  31 #------------------------------------------------------------------------------
  32 ASM_GLOBAL ASM_PFX(InternalMemSetMem)
  33 ASM_PFX(InternalMemSetMem):
  34     pushq   %rdi
  35     pushq   %rbx
  36     pushq   %rcx        # push Buffer
  37     movq    %r8, %rax   # rax = Value
  38     andq    $0xff, %rax # rax = lower 8 bits of r8, upper 56 bits are 0
  39     movb    %al, %ah    # ah  = al
  40     movw    %ax, %bx    # bx  = ax
  41     shlq    $0x10, %rax # rax = ax << 16
  42     movw    %bx,  %ax   # ax  = bx
  43     movq    %rax, %rbx  # ebx = eax
  44     shlq    $0x20, %rax # rax = rax << 32
  45     orq     %rbx, %rax  # eax = ebx
  46     movq    %rcx, %rdi  # rdi = Buffer
  47     movq    %rdx, %rcx  # rcx = Count
  48     shrq    $3, %rcx    # rcx = rcx / 8
  49     cld
  50     rep     stosq
  51     movq    %rdx, %rcx  # rcx = rdx
  52     andq    $7, %rcx    # rcx = rcx & 7
  53     rep     stosb
  54     popq    %rax        # rax = Buffer
  55     popq    %rbx
  56     popq    %rdi
  57     ret