X86汇编统计字母大小写

dseg    segment 

str_source  db "HelloWorld$"
str1        db 20 dup(0)
str2        db 20 dup(0)
int_caption db 0
int_lower   db 0

dseg    ends 

cseg    segment                         ;设置代码段
        assume   cs:cseg,ds:dseg
start: 
        mov ax , dseg                   ;初始化ds
        mov ds , ax
        mov si , offset str_source      ;offset str_source-->si 变址
        xor ax , ax
        push ax
        push ax                         ;str1,str2指针入栈

read_loop:
        mov al , [si]                   ;取[si]中的内容，即偏移量
        cmp al , ‘$‘
        je  exit

        cmp al , ‘Z‘
        ja  lower_case
        pop di                          ;大写
        mov al , [si]
        mov [di] , al
        inc di
        push di
        inc int_caption                
        inc si
        jmp read_loop  
lower_case:                             ;小写
        inc int_lower
        inc si
        jmp read_loop  



exit:   
        mov dl , int_caption
        add dl , 30h
        mov ah , 02h
        int 21h

        mov dl , 0ah                    ;回车换行
        mov ah , 02h
        int 21h
        mov dl , 0dh
        mov ah , 02h
        int 21h

        mov dl , int_lower
        add dl , 30h
        mov ah , 02h
        int 21h

        mov dl , 0ah                    ;回车换行
        mov ah , 02h
        int 21h
        mov dl , 0dh
        mov ah , 02h
        int 21h

        pop di
        mov al ,‘$‘
        mov [di] , al
        mov dl , offset str1
        mov ah , 09h
        int 21h

        mov ax , 4c00h                  ;返回DOS
        int 21h                    
cseg    ends                            ;代码段结束

end     start                           ;汇编语言源程序结束