x86汇编语言之DI和SI寄存器

assume cs:code,ds:data

;需求:字符串复制到...位置
data segment
	db 'welcome to masm!'
	db '................'
data ends

code segment
	start:
		mov ax,data
		mov ds,ax
		mov es,ax
		
		mov si,0
		mov di,16
		
		mov cx, 8
copydata:
		mov dx,ds:[si]
		mov es:[di],dx
		add si,2
		add di,2
		loop copydata
		
code ends


end start

assume cs:code,ds:data

;需求:字符串复制到...位置
data segment
	db 'welcome to masm!'
	db '................'
data ends

stack segment
	db 32 dup(0)
stack ends

code segment
	start:
		mov ax,data
		mov ds,ax
		mov es,ax
		
		mov ax,stack
		mov ss,ax
		mov sp,32
		
		mov si,0
		mov di,16
		
		mov cx, 8
copydata:
		push ds:[si]
		pop es:[di]
		add si,2
		add di,2
		loop copydata
		
code ends


end start

assume cs:code ,ds:data
; 需求:首字母变成大写
data segment
	db '1. file         '
	db '2. edit         '
	db '3. search       '
data ends


code segment
	start:
		mov ax,data
		mov ds,ax
		mov es,ax
		
		mov bx,0
		mov si,3
		
		mov cx,3
upLetter:
		mov dl,ds:[bx+si]
		and dl,11011111B
		mov es:[bx+si],dl
		add bx,16
		loop upLetter
		
code ends

end start

assume cs:code ,ds:data，ss:stack
; 需求:所有字母变成大写
data segment
	db '1. file         '
	db '2. edit         '
	db '3. sear         '
data ends

stack segment
	db 32 dup(0)
stack ends


code segment
	start:
		mov ax,data
		mov ds,ax
		mov es,ax
		
		mov ax,stack
		mov ss,ax
		mov sp,32
		
		mov bx,0
		mov si,3
		
		mov cx,3
upRow: ;使用两层循环， 因为内循环需要用到cx和si寄存器，避免数据被覆盖，使用栈临时保护
		push cx
		push si
		
		mov cx,4
upLetter:
		mov dl,ds:[bx+si]
		and dl,11011111B
		mov es:[bx+si],dl
		inc si
		loop upLetter
		
        add bx,16
        pop si
        pop cx
        loop upRow
		
code ends

end start