我试图使用一个链接列表程序来显示用户输入的反向字符串.以下是我的程序来反转用户输入的字符串.它还给出了字符串的长度：
- TITLE ReadStringProc (ReadStringProc.asm)
- include irvine32.inc
- ListNode STRUCT
- NodeData DWORD ?
- NextPtr DWORD ?
- ListNode ENDS
- NULL = 0
- Counter = 0
- .data
- input byte 100 dup(0)
- stringinput byte "Enter any string: ",0
- totallength byte "The total length is: ",0
- reverse byte "The reverse string is: ",0
- LinkedList LABEL DWORD
- REPT input
- Counter = Counter + 1
- ListNode <Counter,($+ Counter * SIZEOF ListNode)>
- ENDM
- ListNode <0,0> ; tail node
- .code
- stringLength proc
- push ebp
- mov ebp,esp
- push ebx
- push ecx
- mov eax,0
- mov ebx,[ebp+8]
- L1:
- mov ecx,[ebx] ;you can use ecx,cx,ch,cl
- cmp ecx,0 ;you can use ecx,cl
- JE L2
- add ebx,1
- add eax,1
- jmp L1
- L2:
- pop ecx
- pop ebx
- mov ebp,esp
- pop ebp
- ret 4
- stringLength endp
- swap MACRO first,last
- push eax
- mov ah,first
- mov al,last
- xor al,ah ;x
- xor ah,al ;y
- xor al,ah ;x
- mov last,al
- mov first,ah
- pop eax
- endM
- stringReverse proc
- push ebp
- mov ebp,esp
- push OFFSET input
- call stringLength
- mov edx,[ebp+8] ;edx = offset string to reverse
- mov esi,offset 0
- dec eax
- mov ebx,edx ;ebx stores the pointer to the first character
- add ebx,eax ;now ebx store the pointer to the last character before the '$'
- reverseloop:
- push edx
- push ebx
- swap [edx],[ebx]
- inc edx ;increment of the right-most pointer
- dec ebx ;decrement of the right-most pointer
- cmp edx,ebx ;compares the left-most pointer to the right-most
- jb reverseloop
- jmp stopEnd ;"ja",there is no need to check a condition twice
- stopEnd:
- mov esp,ebp
- pop ebp
- ret 4
- stringReverse endp
- main proc
- call clrscr
- mov edx,offset stringinput
- call writeString
- mov edx,offset input
- call writeString
- call stringLength
- mov edx,offset input
- mov ecx,sizeof input
- call readstring
- call crlf
- mov edx,offset totallength
- call writestring
- call writedec
- call crlf
- mov edx,offset reverse
- call crlf
- call writeString
- push offset input
- call stringReverse
- mov edx,offset input
- call writeString
- call crlf
- exit
- main endp
- end main
我的目标是找到一种方法来使用在Kip Irvine的Assembly x86书中找到的这段代码,并将其与我所使用的代码结合起来,以便我可以使用链接列表来显示反向字符串：
- ListNode STRUCT
- NodeData DWORD ?
- NextPtr DWORD ?
- ListNode ENDS
- TotalNodeCount = 15
- NULL = 0
- Counter = 0
- .data
- LinkedList LABEL DWORD
- REPT TotalNodeCount
- Counter = Counter + 1
- ListNode <Counter,0> ; tail node
- .code
- main PROC
- mov esi,OFFSET LinkedList
- ; Display the integers in the NodeData members.
- NextNode:
- ; Check for the tail node.
- mov eax,(ListNode PTR [esi]).NextPtr
- cmp eax,NULL
- je quit
- ; Display the node data.
- mov eax,(ListNode PTR [esi]).NodeData
- call WriteDec
- call Crlf
- ; Get pointer to next node.
- mov esi,(ListNode PTR [esi]).NextPtr
- jmp NextNode
- quit:
- exit
有人可以指导我走正确的道路.谢谢.
解决方法
您不需要链接列表来反转字符串.不,认真
但是,如果你坚持…
- stringReverse proc; <-- Warning: EBX and ESI are not preserved!
- push ebp;
- mov ebp,esp;
- mov ebx,[ebp + 8]; <-- EBX = target string pointer
- push ebx;
- call stringLength; <-- we trust that stringLength() preserves EBX
- ; mov ebx,[ebp + 8]; <-- uncomment this if it actually does not
- mov esi,ebx;
- xor edx,edx;
- add ebx,eax;
- neg eax;
- @fill:
- mov cl,[ebx + eax];
- sub esp,8; <-- allocating a new linked list item on stack
- mov [esp],cl; <-- 1st DWORD / 1st BYTE = current character
- mov [esp + 4],edx; <-- 2nd DWORD = next item pointer
- mov edx,esp; <-- EDX = current item pointer
- inc eax;
- jne @fill;
- @roll:
- mov cl,[edx];
- mov [esi],cl;
- inc esi;
- mov edx,[edx + 4]; <-- next item,here we go!
- test edx,edx; <-- what if we are done?
- jne @roll;
- mov esp,ebp; <-- discarding the allocated stack
- pop ebp;
- ret 4;
这样的东西
它应该工作,但我没有真正测试.
