如何处理 Assembly 中连接两个字符串的错误？

Question

对于我的作业，我想连接两个字符串。到目前为止，这是我的代码。结果应该是 helloworld ，但它只显示 hello :-(

如何在 destination 的 end 添加 source 字符串？

我错过了什么？

;--------------------In main.CPP

    extern "C" void __stdcall StrCatAsm(char[], char[]);

    ;main
              char str1[] = {'h','e','l','l','o',0};
              char str2[] = {'w','o','r','l','d',0};
              StrCatAsm(str1,str2)
              string1 = 'h','e','l','l','o','w','o','r','l','d',0
    ;------------------In main.asm

    Concat PROC  uses eax edi ecx esi,
                        destination:DWORD,
                        source:DWORD

        mov al,0             ;looking for zero terminated
        mov ecx,100          ;number of possible loop
        mov edi, source    
        repne scasb           ;look for end of source
        not ecx               ;ecx is 6
        mov esi, destination  
        rep movsb            ;loop for copy ESI into EDI

        ret
    Concat ENDP

Answer 1

这里是字符串连接的伪代码：

t1 = get string length of str1         ; find length not including zero terminate
t2 = get string length of str2         ; find length not including zero terminate
ct = (t1 + t2) + 1                     ; total length + 1 for zero terminate
dest = allocate memory for size ct     ; get total string length

n = 0
nt = 0

while str1[n] != 0                      ; Until you hit str1 zero terminate
   dest[nt] = str1[n]
   n = n + 1
   nt = nt+1

n = 0

while str2[n] != 0                      ; Until you hit str1 zero terminate
   dest[nt] = str2[n]
   n = n + 1
   nt = nt + 1

dest[nt] = 0                            ; final terminate string

Answer 2

How should I add source string at the end of destination ?

如果这是您所需要的，那么您应该在 destination 中查找终止零（而不是像您的代码那样在源代码中查找！）。
一旦找到终止零，您的 EDI 寄存器将超过其位置，因此您需要备份 1 个位置！

mov  al, 0             ;looking for zero terminated
mov  ecx, 100          ;any large number will do!
mov  edi, DESTINATION
repne scasb            ;look for end of DESTINATION
DEC  EDI
mov  ecx, 6            ;length of SOURCE {'w','o','r','l','d',0};
mov  esi, SOURCE  
rep movsb              ;loop for copy ESI into EDI

如何处理 Assembly 中连接两个字符串的错误？

How to handle error on concatenation two string in Assembly?

x86

assembly

masm

masm32

irvine32