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data segment     ;定义数据段
     infon db 0dh,0ah,'Please input a year: $'
     Y db 0dh,0ah,'This is a leap year! $'
     N db 0dh,0ah,'This is not a leap year! $'
     w dw 0
     buf db 8
         db ?
         db 8 dup(?)
data ends
stack segment stack
     db 200 dup(0)
stack ends
code segment
           assume ds:data,ss:stack,cs:code
     start:mov ax,data
           mov ds,ax
          
           lea dx,infon   ;在屏幕上显示提示信息
           mov ah,9
           int 21h
           lea dx,buf     ;从键盘输入年份字符串
           mov ah,10
           int 21h
          
           mov cl, [buf+1]
           lea di,buf+2
           call datacate
           call ifyears
           jc a1
          
           lea dx,n
           mov ah,9
           int 21h
           jmp exit
     a1:    lea dx,y
           mov ah,9
           int 21h
     exit: mov ah,4ch
           int 21h
       
datacate proc near；
           push cx;                                                       
           dec cx
           lea si,buf+2


      tt1: inc si
           loop tt1
           ;lea si,cx[di]
           pop cx
     
      
           mov dh,30h
           mov bl,10
           mov ax,1
       l1: push ax
           sub   byte ptr   [si],dh
           mul   byte ptr [si]
           add w,ax
           pop ax
           mul bl
           dec si
           loop l1
           ret
datacate endp
    ifyears proc near
            push   bx
            push   cx
            push   dx
            mov ax,w
            mov    cx,ax
            mov   dx,0
            mov   bx,4
            div   bx
            cmp   dx,0
            jnz   lab1
            mov    ax,cx
            mov   bx,100
            div   bx
            cmp dx,0
            jnz   lab2
            mov   ax,cx
            mov bx,400
            div   bx
            cmp   dx,0
            jz   lab2
      lab1: clc
            jmp lab3
      lab2: stc
      lab3: pop   dx
            pop   cx
            pop   bx
            ret
    ifyears endp
code ends
    end start