（汇编语言）实验11 编写子程序

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编写一个子程序，将包含任意字符，以0结尾的字符串中的小写转大写

首先先用不是子程序的方法来解决一下：

assume cs:code
 
data segment
	
	db "ZouZeBin is a handsome boy!!",0
	
	
data ends
 


code segment
start:	

mov ax,data
mov ds,ax
mov si,0
s:

mov al,[si]
cmp al,0
je ok

cmp al,'A'
jb next
cmp al,'z'
ja next

cmp al,'Z'
ja ltoh
or byte ptr [si],00100000b
jmp short next

ltoh:
and byte ptr [si],11011111b


next:

inc si	
jmp short s
ok:
mov ax,4c00h	
int 21h
		
		
		
	
code ends
end start

截图：

接下来实现一种用子程序来解决的方法：

assume cs:code
 
data segment
	
	db "ZouZeBin is a handsome boy!!",0
	
	
data ends
 


code segment
start:	

mov ax,data
mov ds,ax
mov si,0
call letterc
mov ax,4c00h	
int 21h


letterc:

push ax
push ds
push si

s:

mov al,[si]
cmp al,0
je ok

cmp al,'A'
jb next
cmp al,'z'
ja next

cmp al,'Z'
ja ltoh
or byte ptr [si],00100000b
jmp short next

ltoh:
and byte ptr [si],11011111b


next:

inc si	
jmp short s
ok:

pop si
pop ds
pop ax
ret

code ends
end start

截图：