這有什麼錯我的彙編代碼

Question

我想用JMP和JZ寫彙編階乘代碼，我是新來組裝

輸入應該是EAX和輸出是EBX

mov eax,3h ;factorial of 3 
    ;initialize registers 
    mov ebx,0h 
    mov ecx,eax 
    dec ecx 
    mov edx,0h 

loopstart: 
    mul ecx ;edx:eax = eax * ecx 
    add ebx,eax ;ebx = ebx + eax 
    dec ecx ;ecx = ecx - 1 
    jz exitloop ;jump to exitloop if the last math is zero (in this ex:dec) 
    jmp loopstart ;jump to loopstart 
exitloop: 
    ;mov eax,ebx 
    call ebxprint; should be 6 

查找EAX的階乘

輸入：2

輸出：2

輸入：3

輸出：12

輸入：4

輸出：60

所以，這裏有什麼問題嗎？

Answer 1

由於@PaulHankin

我必須刪除add ebx, eax並取消mov eax,ebx

下面是編輯後的代碼：

mov eax,3h ;factorial of 3 
    ;initialize registers 
    mov ebx,0h 
    mov ecx,eax 
    dec ecx 
    mov edx,0h 

loopstart: 
    mul ecx ;edx:eax = eax * ecx 
    dec ecx ;ecx = ecx - 1 
    jz exitloop ;jump to exitloop if the last math is zero (in this ex:dec) 
    jmp loopstart ;jump to loopstart 
exitloop: 
    mov eax,ebx 
    call ebxprint; should be 6