【8086汇编】将十进制数转换为八进制数（输入范围：0~2559，含提示信息）

;This is the program from the other thread.
;It works fine but from 2560-9999 it returns properly convertet the last 3 numbers only.
stack	segment stack
        db 512 dup(?)
stack	ends

print macro msg
        mov ah, 09h
        lea dx, msg
        int 21h
        endm

data segment
        buf1 db "Enter a decimal number(0~2559): $"
        buf2 db 0ah, "Invalid number... $"
        buf3 db 0ah, "The octal number is: $"
        buf4 db 6
             db 0
             db 6 dup(0)
        multiplier db 0ah
data ends

code segment
        assume cs:code, ds:data, ss: stack
start :
        mov ax, data
        mov ds, ax
		mov ax, stack
		mov ss, ax
        mov es, ax

        print buf1

        mov ah, 0ah
        lea dx, buf4
        int 21h

        mov si, offset buf4 + 2
        mov cl, byte ptr [si-1]
        mov ch, 00h
subtract :
        mov al, byte ptr [si]	
        cmp al, 30h
        jnb cont1
        print buf2
cont1 :
        cmp al, 3ah
        jb cont2
        print buf2
        jmp stop
cont2 :
        sub al, 30h
        mov byte ptr [si], al

        inc si
        loop subtract

        mov si, offset buf4 + 2
        mov cl, byte ptr [si-1]
        mov ch, 00h
        mov ax, 0000h
calc :
        mul multiplier
        mov bl, byte ptr [si]
        mov bh, 00h
        add ax, bx
        inc si
        loop calc

        mov si, offset buf4 + 2
        mov bx, ax
        mov dx, 0000h
        mov ax, 8000h
convert :
        mov cx, 0000h
conv :
        cmp bx, ax
        jb cont3
        sub bx, ax
        inc cx
        jmp conv
cont3 :
        add cl, 30h
        mov byte ptr [si], cl
        inc si
        mov cx, 0008h
        div cx
        cmp ax, 0000h
        jnz convert

        mov byte ptr [si], '$'
        print buf3
        print buf4+2
stop :
        mov ax, 4c00h
        int 21h
code ends
        end start