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;------------------------------------------------------------------------------
;
; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
; SPDX-License-Identifier: BSD-2-Clause-Patent
;
; Module Name:
;
; CopyMem.Asm
;
; Abstract:
;
; CopyMem function
;
; Notes:
;
;------------------------------------------------------------------------------
SECTION .text
;------------------------------------------------------------------------------
; VOID *
; InternalMemCopyMem (
; IN VOID *Destination,
; IN VOID *Source,
; IN UINTN Count
; )
;------------------------------------------------------------------------------
global ASM_PFX(InternalMemCopyMem)
ASM_PFX(InternalMemCopyMem):
push esi
push edi
mov esi, [esp + 16] ; esi <- Source
mov edi, [esp + 12] ; edi <- Destination
mov edx, [esp + 20] ; edx <- Count
lea eax, [esi + edx - 1] ; eax <- End of Source
cmp esi, edi
jae .0
cmp eax, edi
jae @CopyBackward ; Copy backward if overlapped
.0:
mov ecx, edx
and edx, 3
shr ecx, 2
rep movsd ; Copy as many Dwords as possible
jmp @CopyBytes
@CopyBackward:
mov esi, eax ; esi <- End of Source
lea edi, [edi + edx - 1] ; edi <- End of Destination
std
@CopyBytes:
mov ecx, edx
rep movsb ; Copy bytes backward
cld
mov eax, [esp + 12] ; eax <- Destination as return value
pop edi
pop esi
ret
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