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实验12 编写0号中断的处理程序

Posted on Edited on In
Symbols count in article: 1.6k Reading time ≈ 1 mins.

编写0号中断处理程序，使得在除法溢出发生时，在屏幕中间显示字符串“divide error”,然后返回dos

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assume cs:code

code segment

start:			mov	ax,cs
				mov ds,ax
				mov si,offset do0		;设置ds:si指向源地址
				mov ax,0
				mov es,ax
				mov di,200h				;设置es:di指向目的地址
				;设置cx为传输长度
				mov cx,offset do0end-offset do0
				cld						;设置传输方向为正
				rep movsb
				
			;	设置中断向量
			
				mov ax,0
				mov es,ax
				mov word ptr es:[0*4],200h
				mov word ptr es:[0*4+2],0
				
do0:			jmp short do0start
				db "divide error!"
				
do0start:		mov ax,cs
				mov ds,ax
				mov si,202h				;设置ds:si字符串
				
				mov ax,0b800h
				mov es,ax
				mov di,12*160 + 36*2
				
				mov cx,13
			s:	mov al,[si]
				mov es:[di],al
				inc si
				add di,2
				loop s
				
				mov ax,4c00h
				int 21h
				
    	do0end: nop
			
code ends
end start
				
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assume cs:code,ds:data,ss:stack

data segment
    db  'divide error',0        ;会被覆盖掉 CPU需要立刻处理的程序
                                ;0:200 0:3FF
data ends

stack segment stack
    db  128 dup (0)
stack ends

code segment

start:          mov ax,stack
                mov ss,ax
                mov sp,128

                call cpy_new_int0 
                call set_new_int0
                
                mov ax,0
                mov dx,1
                mov bx,1
                div bx

                mov ax,4c00h
                int 21h


;===================================
set_new_int0:   mov bx,0
                mov es,bx

                mov word ptr es:[0*4],7e00h
                mov word ptr es:[0*4+2],0

                ret

;===================================
new_int0:       jmp newint0

string:         db  'divide error',0

newint0:        mov bx,0800h
                mov es,bx

                mov bx,0
                mov ds,bx

                mov di,160*10 + 30*2
                mov si,7e03h

                mov dl,ds:[si]
                cmp dl,0
                je showStringRet
                mov es:[di],dl
                add di,2
                inc si
                jmp showString

                mov ax,4c00h
                int 21h

new_int0_end:   nop

;===================================
cpy_new_int0:   mov bx,cs
                mov ds,bx
                mov si,offset new_int0

                mov bx,0
                mov es,bx
                mov di,7e00h

                mov cx,offset new_int0_end - new_int0
                cld
                rep movsb

                ret

code ends

end start