【中断例程】实现loop

assume cs:code

code segment

start:
	mov ax,0
	mov es,ax
	mov di,200h

	mov ax,cs
	mov ds,ax
	mov si,offset lp

	mov cx,offset lp_end - offset lp
	cld
	rep movsb

	mov word ptr es:[7ch*4],200h
	mov word ptr es:[7ch*4+2],0

	mov ax,4c00h
	int 21h

lp:
	push bp
	dec cx
	jcxz lp_ret
	mov bp,sp
	add [bp+2],bx ; 修改ip

lp_ret:
	pop bp
	iret

lp_end:
	nop

code ends

end start