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|
; $Id: memmove.asm $
;; @file
; IPRT - No-CRT memmove - AMD64 & X86.
;
;
; Copyright (C) 2006-2019 Oracle Corporation
;
; This file is part of VirtualBox Open Source Edition (OSE), as
; available from http://www.virtualbox.org. This file is free software;
; you can redistribute it and/or modify it under the terms of the GNU
; General Public License (GPL) as published by the Free Software
; Foundation, in version 2 as it comes in the "COPYING" file of the
; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
; VirtualBox OSE distribution, in which case the provisions of the
; CDDL are applicable instead of those of the GPL.
;
; You may elect to license modified versions of this file under the
; terms and conditions of either the GPL or the CDDL or both.
;
%include "iprt/asmdefs.mac"
BEGINCODE
;;
; @param pvDst gcc: rdi msc: rcx x86:[esp+4] wcall: eax
; @param pvSrc gcc: rsi msc: rdx x86:[esp+8] wcall: edx
; @param cb gcc: rdx msc: r8 x86:[esp+0ch] wcall: ebx
RT_NOCRT_BEGINPROC memmove
; Prolog.
%ifdef RT_ARCH_AMD64
%ifdef ASM_CALL64_MSC
mov r10, rdi ; save
mov r11, rsi ; save
mov rdi, rcx
mov rsi, rdx
mov rcx, r8
mov rdx, r8
%else
mov rcx, rdx
%endif
mov rax, rdi ; save the return value
%else
push edi
push esi
%ifdef ASM_CALL32_WATCOM
mov edi, eax
mov esi, edx
mov ecx, ebx
mov edx, ebx
%else
mov edi, [esp + 04h + 8]
mov esi, [esp + 08h + 8]
mov ecx, [esp + 0ch + 8]
mov edx, ecx
mov eax, edi ; save the return value
%endif
%endif
;
; Decide which direction to perform the copy in.
;
%if 1 ; keep it simple for now.
cmp xDI, xSI
jnb .backward
;
; Slow/simple forward copy.
;
cld
rep movsb
jmp .epilog
%else ; disabled - it seems to work, but play safe for now.
;sub xAX, xSI
;jnb .backward
cmp xDI, xSI
jnb .backward
;
; Fast forward copy.
;
.fast_forward:
cld
%ifdef RT_ARCH_AMD64
shr rcx, 3
rep movsq
%else
shr ecx, 2
rep movsd
%endif
; The remaining bytes.
%ifdef RT_ARCH_AMD64
test dl, 4
jz .forward_dont_move_dword
movsd
%endif
.forward_dont_move_dword:
test dl, 2
jz .forward_dont_move_word
movsw
.forward_dont_move_word:
test dl, 1
jz .forward_dont_move_byte
movsb
.forward_dont_move_byte:
%endif ; disabled
;
; The epilog.
;
.epilog:
%ifdef RT_ARCH_AMD64
%ifdef ASM_CALL64_MSC
mov rdi, r10
mov rsi, r11
%endif
%else
pop esi
pop edi
%endif
ret
;
; Slow/simple backward copy.
;
ALIGNCODE(16)
.backward:
;; @todo check if they overlap.
lea xDI, [xDI + xCX - 1]
lea xSI, [xSI + xCX - 1]
std
rep movsb
cld
jmp .epilog
ENDPROC RT_NOCRT(memmove)
|
