汇编关于两个字符串比较的问题！请高手帮帮忙！

我给你写了个，仅供参考：

assume cs:code, ds:datas

datas segment
str1 db 32 dup(?) ;字符串1
str2 db 32 dup(?) ;字符串2
len1 dw 0 ;字符串1长度
len2 dw 0 ;字符串2长度

szYes db 'MATCH',0
szNo db 'UNMATCH',0
datas ends

code segment
start:
mov ax, datas
mov ds, ax
mov es, ax

mov bx, offset str1 ;输入
call input
mov len1, ax
mov bx, offset str2
call input
mov len2, ax

mov si, offset str1 ;比较
mov ax, len1
mov di, offset str2
mov bx, len2
call compare

cmp ax, 0 ;输出
jz notequal
mov bx, offset szYes
jmp print
notequal:
mov bx, offset szNo
print:
call output

mov ax, 4c00h
int 21h

; 比较函数
compare:
mov cx, ax
cmp cx, bx
jle next3
xchg cx, bx
cld
next3:
repe cmpsb
je equal
mov ax, 0
ret
e