- [as555as] 感谢 scuzg 发表的评论,同时让我学到了一些书(汇编语言)上没有的东西!取反加1的的由来.其实 10/08 16:25
- [scuzg] “总结1”正确; 但“总结2”有几个问题: ①“取反加1”是对负数做求补的运算,对正数不适用。就 10/08 14:25
[2009-10-13 10:11] 实验十三第2题
assume cs:code
code segment
start:
call capital
mov ax,0b800h
mov es,ax
mov di,12*160
mov bx,offset s-offset se
mov cx,80
s:
mov byte ptr es:[di],'!'
add di,2
int 7ch
se:
nop
mov ax,4c00h
int 21h
capital:
mov ax,0
mov es,ax
mov word ptr es:[7ch*4+2],0
mov word ptr es:[7ch*4],200h
mov di,200h
mov ax,cs
mov ds,ax
mov si,offset do7ch
mov cx,offset do7chend-offset do7ch
cld
rep movsb
ret
do7ch:
dec cx
jcxz s1
pop ax
add ax,bx
push ax
s1:
iret
do7chend:
nop
code ends
end start
code segment
start:
call capital
mov ax,0b800h
mov es,ax
mov di,12*160
mov bx,offset s-offset se
mov cx,80
s:
mov byte ptr es:[di],'!'
add di,2
int 7ch
se:
nop
mov ax,4c00h
int 21h
capital:
mov ax,0
mov es,ax
mov word ptr es:[7ch*4+2],0
mov word ptr es:[7ch*4],200h
mov di,200h
mov ax,cs
mov ds,ax
mov si,offset do7ch
mov cx,offset do7chend-offset do7ch
cld
rep movsb
ret
do7ch:
dec cx
jcxz s1
pop ax
add ax,bx
push ax
s1:
iret
do7chend:
nop
code ends
end start
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