【X86組語】作業二-第二版

;;修正第二運算元，第二運算元如果只有一位元，可以選擇按enter鍵即進行運算。
;;前一版請參考http://new-acos.blogspot.com/2007/10/x86_21.html
GETCHAR     MACRO   char
          push    ax
          mov     ah,01h
          int     21h
          mov     char,al
          pop     ax
          ENDM
PUTCHAR     MACRO   char
          push    dx
          push    ax
          mov     dl,char


          mov     ah,02h
          int     21h
          pop     ax
          pop     dx
          ENDM
END_PROCESS MACRO
          mov     ah,4ch
          int     21h
          ENDM

.MODEL      SMALL
.DATA
values      db      2 dup(?)
operator    db      1 dup(?)
answer      db      1 dup(?)

.STACK

.CODE
main_pro    proc    far


          mov     dl,3
count_loop: mov     si,0
keyin_loop: GETCHAR bl
          cmp     bl,'+'
          je      go_1
          cmp     bl,'-'
          jne     continue
go_1:       cmp     si,0
          je      invalid
          mov     [operator],bl
          jmp     keyin_loop
go_2:       mov     [operator],bl
          jmp     finish

continue:   call    check_num
          mov     cl,bl
          GETCHAR bl
          cmp     bl,'+'
          je      go_2
          cmp     bl,'-'
          je      go_2
          cmp      bl,0dh
          je       finish
          mov     al,10
          mul     cl
          mov     cl,al
          call    check_num
          add     cl,bl
finish:     mov     [values+si],cl
          inc     si
          cmp     si,2
          jne     keyin_loop

          mov     al,[values]
          mov     bl,[values+1]
          mov     cl,[operator]
          cmp     cl,'-'

          jne     do_add
          sub     al,bl
          mov      [answer],al
          call    print_ans
          jmp     ok
do_add:     add     al,bl
           mov     [answer],al
          call    print_ans
ok:         dec     dl
          jnz     count_loop

          END_PROCESS
main_pro    endp

check_num   proc    far
          cmp     bl,'0'

          jl      invalid
          cmp     bl,'9'
          jg      invalid
          sub     bl,'0'

          ret
check_num   endp

print_ans   proc    far
           call    cr
           xor     ax,ax
           mov     al,[values]
           call    print_num
           PUTCHAR [operator]
           xor     ax,ax
           mov     al,[values+1]
           call    print_num
          PUTCHAR '='
          xor      ax,ax
          mov      al,[answer]
          call     print_num
          call    lf
          ret
print_ans   endp

print_num   proc    far
           push    cx
           mov     ch,1
           cmp     al,100
          jb      ignore_h
          xor      ch,ch
          PUTCHAR '1'
          sub     al,100
ignore_h:   mov     cl,10
          div     cl
          cmp      al,0
          jne      go_3
          cmp      ch,0
          jne      go_4
go_3:      add     al,'0'

          PUTCHAR al
go_4:       add     ah,'0'
          PUTCHAR ah
          pop      cx
           ret
print_num   endp

cr          proc    near
           push    ax
          push    dx
          mov     ah,2
           mov     dl,0dh
          int     21h
          pop     dx
          pop     ax
          ret
cr          endp

lf       proc    far
          push    ax
          push    dx
          call     cr
          mov     ah,2
          mov     dl,0ah
          int     21h
          pop     dx
          pop     ax
          ret
lf       endp


invalid:    PUTCHAR '!'
           END_PROCESS
END