汇编函数万能字符输出以及字符大小转换

.MODEL SMALL
.STACK
.DATA
buf1 db ?
mALto db ?
mprint db ?
printhuan db 0dh,0ah,'$'
.CODE
start:
mov ax,@data
mov ds,ax
mov ah,01h
int 21h
mov buf1,al
mov al,buf1
mov mprint,al
call PRINT
mov mALto,al
call ALto
mov al,mALto
mov mprint,al
call PRINT
mov ah,4ch
int 21h
;用于将字母带大小相互转换
;入口参数:需要转换的字母
;出口参数：
ALto proc near
push dx
cmp mALto,'a'
jb DtoX
;小写转换为大写
mov dl,mALto
add dl,'A' - 'a'
loop TO
;大写转换为小写
DtoX:
mov dl,mALto
add dl,'a' - 'A'
TO:mov mALto,dl
pop dx
ret
ALto endp
;用于输出buf1里面的字符函数
;入口参数:需要输出的字符
;出口参数:无
PRINT proc near
push dx
push ax
lea dx,printhuan
mov ah,09h
int 21h
mov dl,mprint
mov ah,02h
int 21h
pop ax
pop dx
ret
PRINT endp
end start