03.asm

assume cs:code

Calculate segment
    db '1.3/1=          '
	db '2.5+3=          '
    db '3.9-3=          '
    db '4.4+5=          '
Calculate ends

stack segment
	db 16 dup (0)
stack ends

code segment
s1:
	mov cl,[bx+3]
	sub cl,'-'
	add cl,1
	loop s2

	;减法
	mov dl,[bx+4]
	sub dl,30h
	mov al,[bx]
	sub al,30h
	sub al,dl
	add al,30h
	mov [bx+6],al
	mov byte ptr [bx+7],'.'
	mov al,[bx+2]
	mov [bx+8],al
	add bx,10h
	pop cx
	loop s
	mov cx,1
	loop s0

s2:
	;除法
	mov dl,[bx+4]
	sub dl,30h
	mov al,[bx]
	sub al,30h
	div dl
	add al,30h
	mov [bx+6],al
	mov byte ptr [bx+7],'.'
	mov ah,0
	mov al,[bx+2]
	sub al,30h
	div dl
	add al,30h
	mov [bx+8],al
	add bx,10h
	pop cx
	loop s
	mov cx,1
	loop s0

	;程序入口
start:
	mov ax,stack
	mov ss,ax
	mov sp,16
	mov cx,4
	mov bx,0
	mov ax,Calculate
	mov ds,ax
	mov ah,0
	s:
	push cx
	mov cl,[bx+3]
	sub cl,'+'
	add cl,1
	loop s1

	;加法
	mov dl,[bx+4]
	sub dl,30h
	mov al,[bx]
	sub al,30h
	add al,dl
	add al,30h
	mov [bx+6],al
	mov byte ptr [bx+7],'.'
	mov al,[bx+2]
	mov [bx+8],al
	add bx,10h
	pop cx
	loop s
	mov cx,1
	loop s0

	;打印结果
s0:
	mov ax,Calculate 
	mov es,ax
	mov bx,0
	mov ax,0b878h
	mov ds,ax
	mov ah,10111b
	mov cx,64
s3:
	mov al,es:[bx]
	mov si,bx
	add si,bx
	mov [si],al
	mov [si+1],ah
	inc bx
	loop s3

	mov ax,4c00h
	int 21h
code ends
end start