王爽汇编语言实验16

assume cs:code

code segment
start:
	mov ax,cs
	mov ds,ax ;设置ds
	mov si,offset int7c ;ds:si源地址
	
	mov ax,0
	mov es,ax
	mov di,200h ;es:di目的地址
	mov cx,offset int7cend-offset int7c ;cx为传输长度
	cld ;传输方向为正
	rep movsb ;开始传输
	
	cli
	mov ax,0
	mov es,ax
	mov word ptr es:[7ch*4],200h
	mov word ptr es:[7ch*4+2],0 ;设置新的int7c中断例程地址
	sti
	
	mov ax,4c00h
	int 21h
	
	org 200h ; ←←←←←←←←←重点
int7c:
	jmp short set
	table dw sub1,sub2,sub3,sub4
	set:
		push bx
		cmp ah,3
		ja sret
		mov bl,ah
		mov bh,0
		add bx,bx
		call word ptr table[bx]
	sret:
		pop bx
		iret
		
	sub1:
		push bx
		push cx
		push es
		mov bx,0b800h
		mov es,bx
		mov bx,0
		mov cx,2000
	sub1s:
		mov byte ptr es:[bx],' '
		add bx,2
		loop sub1s
		pop es
		pop cx
		pop bx
		ret
		
	sub2:
		push bx
		push cx
		push es
		mov bx,0b800h
		mov es,bx
		mov bx,1
		mov cx,2000
	sub2s:
		and byte ptr es:[bx],11111000b
		or es:[bx],al
		add bx,2
		loop sub2s
		
		pop es
		pop cx
		pop bx
		ret
		
	sub3:
		push bx
		push cx
		push es
		mov cl,4
		shl al,cl
		mov bx,0b800h
		mov es,bx
		mov bx,1
		mov cx,2000
	sub3s:
		and byte ptr es:[bx],10001111b
		or es:[bx],al
		add bx,2
		loop sub3s
		pop es
		pop cx
		pop bx
		ret
		
	sub4:
		push cx
		push si
		push di
		push es
		push ds
		
		mov si,0b800h
		mov es,si
		mov ds,si
		mov si,160
		mov di,0
		cld
		mov cx,24
	sub4s:
		push cx
		mov cx,160
		rep movsb
		pop cx
		loop sub4s
		
		mov cx,80
		mov si,0
	sub4s1:
		mov byte ptr [160*24+si],' '
		add si,2
		loop sub4s1
		pop ds
		pop es
		pop di
		pop si
		pop cx
		ret

int7cend:nop
code ends
end start

assume cs:code

code segment
start:
	;set front color
	mov ah,1
	mov al,3
	int 7ch
	call delay

	;set background color
	mov ah,2
	mov al,7
	int 7ch
	call delay

	mov ah,3
	int 7ch
	call delay
	
	;clean screen
	mov ah,0
	int 7ch
	
	mov ax,4c00h
	int 21h
	
delay:
	push ax
	push dx
	mov dx,0h
	mov ax,0ffffh
s1:	sub ax,1
	sbb,dx,0
	cmp ax,0
	jne s1
	cmp dx,0
	jne s1
	pop dx
	pop ax
	ret
	
code ends
end start