Question

如果跳得太远，检查和调试的最佳方法是什么？

所以我有一个var inBuffer，其中BYTE长度为115。我将其移动到bufSize并尝试对一组3个密钥进行xor'ing以解密消息。我的代码编译但是我无法构建，除了这部分，它说我跳得太远了。

bufSize DWORD ?
mov eax,115
mov bufSize,eax

;-------------------------------------------------
AnalyzeBuffer PROC
;receives nothing
;returns nothing
;-------------------------------------------------
pushad          ; pushes all data in this method into a stack
mov ecx,bufSize ; loop count
mov esi,0       ; start at index 0 in translated buffer

top:
    cmp buffer[esi],20h    ; checks if character is space which is ok
    je yes

    cmp buffer[esi],2ch    ; checks if character is comma wich is okay
    je yes

    cmp buffer[esi],2eh    ; checks if character is period which is okay
    je yes

    cmp buffer[esi],41h     ; checks if character is above A in the ascii chart
    jb no

    ;the following are all unacceptable characters
    cmp buffer[esi],5bh     ;checks if character is [
    je no
    cmp buffer[esi],5ch     ; checks if character is \
    je no
    cmp buffer[esi],5dh     ;checks if character is ]
    je no
    cmp buffer[esi],5eh      ; checks if character is ^
    je no
    cmp buffer[esi],5fh     ; checks if character is _
    je no
    cmp buffer[esi],60h     ; checks if character is `
    je no
    cmp buffer[esi],7bh     ; checks if characre is {
    je no
    cmp buffer[esi],7ch     ; checks if character is |
    je no
    cmp buffer[esi],7dh     ; checks if }
    je no
    cmp buffer[esi],7eh     ; checks if ~
    je no
    cmp buffer[esi],7fh     ; checks if 
    je no



    yes:
        inc esi             ; going to next character
        loop top
        ;getting to this step means these keys worked for all characters in buffer

        mov edx,OFFSET goodMsg
        call WriteString
        call DisplayAllKeys ; shows 3 keys used
        call Crlf
        call Crlf
        mov edx,OFFSET buffer   ; displays decrypted message
        call WriteString
        call Crlf
        call Crlf

    no:
    ;the current character wasnt good so trying next key
    popad
    ret

AnalyzeBuffer ENDP

Answer 1

下次你应该告诉哪一行导致错误。我猜它是loop指令，因为它只存在8位偏移量。由于优化原因，建议不要使用它，这也将解决您的跳跃范围问题。因此，只需将其替换为dec ecx; jnz top。

你也可以优化你的支票，但这是另一个故事。

汇编语言：错误A2075跳转目标太远：30个字节

1 个答案: