audk/MdePkg/Library/BaseMemoryLibOptDxe/X64/SetMem.asm

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;------------------------------------------------------------------------------
;
; Copyright (c) 2006 - 2008, Intel Corporation
; All rights reserved. This program and the accompanying materials
; are licensed and made available under the terms and conditions of the BSD License
; which accompanies this distribution. The full text of the license may be found at
; http://opensource.org/licenses/bsd-license.php
;
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
;
; Module Name:
;
; SetMem.Asm
;
; Abstract:
;
; SetMem function
;
; Notes:
;
;------------------------------------------------------------------------------
.code
;------------------------------------------------------------------------------
; VOID *
; EFIAPI
; InternalMemSetMem (
; IN VOID *Buffer,
; IN UINTN Count,
; IN UINT8 Value
; )
;------------------------------------------------------------------------------
InternalMemSetMem PROC USES rdi rbx
push rcx ; push Buffer
mov rax, r8 ; rax = Value
and rax, 0ffh ; rax = lower 8 bits of r8, upper 56 bits are 0
mov ah, al ; ah = al
mov bx, ax ; bx = ax
shl rax, 10h ; rax = ax << 16
mov ax, bx ; ax = bx
mov rbx, rax ; ebx = eax
shl rax, 20h ; rax = rax << 32
or rax, rbx ; eax = ebx
mov rdi, rcx ; rdi = Buffer
mov rcx, rdx ; rcx = Count
shr rcx, 3 ; rcx = rcx / 8
cld
rep stosq
mov rcx, rdx ; rcx = rdx
and rcx, 7 ; rcx = rcx & 7
rep stosb
pop rax ; rax = Buffer
ret
InternalMemSetMem ENDP
END