Hi all：
The following code is a functional assembly version of 'itoa', the question I have was that the placement of "mov dx, 0": To avoid "divide overflow" happens, the dx was set to zero, when it was place at #1 everything work well, but place it at #2 will cause "divide overflow". However, I don't see the difference between these two placements, cause either of them will set dx to zero before 'div'.
assume cs:code,ds:data
data segment
dw 12, 23, 34, 45, 56, 12666
data ends
display segment
db '000000000000000', 0
display ends
code segment
start:
mov ax, data
mov es, ax
mov ax, display
mov ds, ax
call dtoc
mov si, 0
mov dh, 8
mov dl, 3
mov cl, 2
call show_str
mov ax,4c00h
int 21h
dtoc:
mov di, 0
mov cx, 6
s:
mov ax, es:[di]
mov bx, 0AH
s0: mov dx, 0 ; #1
div bx
add dl, 30h
mov byte ptr ds:[si], dl
cmp ax, 0
jz ok
inc si
； #2
jmp short s0
ok:inc si
add di, 2
loop s
ret
If you mov the mov dx, 0 from position #1 then it is possible that it will overflow when you initially hit that loop.