-
-
进来指点一下这个汇编程序[求助]
-
2006-6-17 13:36
-
.486
.model flat, stdcall
option casemap :none
include \masm32\include\windows.inc
include \masm32\include\user32.inc
include \masm32\include\kernel32.inc
includelib \masm32\lib\user32.lib
includelib \masm32\lib\kernel32.lib
.data
mystr db "abcd",0
.code
start:
mov si,0
mov cx,4
here:
mov al,mystr[si]
inc al
mov mystr[si],al
inc si
loop here
invoke MessageBox,NULL,addr mystr,NULL,MB_OK
invoke ExitProcess,NULL
end start
程序的目的是想变mystr "abcd"为"bcde"
但是出错了,
请指点,谢谢
.model flat, stdcall
option casemap :none
include \masm32\include\windows.inc
include \masm32\include\user32.inc
include \masm32\include\kernel32.inc
includelib \masm32\lib\user32.lib
includelib \masm32\lib\kernel32.lib
.data
mystr db "abcd",0
.code
start:
mov si,0
mov cx,4
here:
mov al,mystr[si]
inc al
mov mystr[si],al
inc si
loop here
invoke MessageBox,NULL,addr mystr,NULL,MB_OK
invoke ExitProcess,NULL
end start
程序的目的是想变mystr "abcd"为"bcde"
但是出错了,
请指点,谢谢
[CTF入门培训]顶尖高校博士及硕士团队亲授《30小时教你玩转CTF》，视频+靶场+题目！助力进入CTF世界
|
|
|---|---|
|
|
|
|
|
表面上看你的程序并没有错....上面版主给是正确的...但我还是找了下你错的原因...我想是.486的错误吧...用这个描述符之后指默认是32位下的指命格式....所以虽然你在用mov al mystr[si]取字符．．但是编译器在编译是确用了
MOV AL , MYSTR[ESI]这样当然就出错了呀．．．下我是用ＯＤ加载后的结果．． 00401000 >/$ 66:BE 0000 mov si, 0 00401004 |. 66:B9 0400 mov cx, 4 00401008 |> 8A0435 003040>/mov al, [esi+403000] ;esi FFFF0000 0040100F |. FEC0 |inc al 00401011 |. 880435 003040>|mov [esi+403000], al 00401018 |. 66:46 |inc si 0040101A |.^ E2 EC \loopd short 00401008 0040101C |. 6A 00 push 0 ; /Style = MB_OK|MB_APPLMODAL 0040101E |. 6A 00 push 0 ; |Title = NULL 00401020 |. 68 00304000 push 00403000 ; |Text = "abcd" 00401025 |. 6A 00 push 0 ; |hOwner = NULL 00401027 |. E8 08000000 call <jmp.&USER32.MessageBoxA> ; \MessageBoxA 0040102C |. 6A 00 push 0 ; /ExitCode = 0 0040102E \. E8 07000000 call <jmp.&KERNEL32.ExitProcess> ; \ExitProcess 00401033 CC int3 00401034 $- FF25 08204000 jmp [<&USER32.MessageBoxA>] ; USER32.MessageBoxA 0040103A .- FF25 00204000 jmp [<&KERNEL32.ExitProcess>] ; kernel32.ExitProcess 00401040 00 db 00 看到了吧．．．情况并不是你想的那样．．．．ＥＳＩ的高字是ＦＦＦＦ．．．．这样就引发了异常了．．．．．．  不知道你们怎么看．．．
|
|
|
|
|
|
非常感谢两位的解答~~~~~~~~
|
