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;------------------------------------------------------------------------------
;
; Copyright (c) 2006 - 2022, Intel Corporation. All rights reserved.<BR>
; SPDX-License-Identifier: BSD-2-Clause-Patent
;
; Module Name:
;
; CopyMem.nasm
;
; Abstract:
;
; CopyMem function
;
; Notes:
;
;------------------------------------------------------------------------------
DEFAULT REL
SECTION .text
;------------------------------------------------------------------------------
; VOID *
; EFIAPI
; InternalMemCopyMem (
; OUT VOID *DestinationBuffer,
; IN CONST VOID *SourceBuffer,
; IN UINTN Length
; );
;------------------------------------------------------------------------------
global ASM_PFX(InternalMemCopyMem)
ASM_PFX(InternalMemCopyMem):
push rsi
push rdi
mov rsi, rdx ; rsi <- Source
mov rdi, rcx ; rdi <- Destination
lea r9, [rsi + r8 - 1] ; r9 <- End of Source
cmp rsi, rdi
mov rax, rdi ; rax <- Destination as return value
jae .0
cmp r9, rdi
jae @CopyBackward ; Copy backward if overlapped
.0:
mov rcx, r8
and r8, 7
shr rcx, 3 ; rcx <- # of Qwords to copy
jz @CopyBytes
movq r10, mm0
.1:
movq mm0, [rsi]
movntq [rdi], mm0
add rsi, 8
add rdi, 8
loop .1
mfence
movq mm0, r10
jmp @CopyBytes
@CopyBackward:
mov rsi, r9 ; rsi <- End of Source
lea rdi, [rdi + r8 - 1] ; rdi <- End of Destination
std ; set direction flag
@CopyBytes:
mov rcx, r8
rep movsb ; Copy bytes backward
cld
pop rdi
pop rsi
ret
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