;擴充鍵盤處理功能
;---------------------------------------------------------------
stack    segment    para   stack   'stack'
         db         256    dup(0)
stack    ends
;---------------------------------------------------------------
data     segment    para    public  'data'
buffer   db         16h     dup(0)
bufpt1   dw         0
bufpt2   dw         0
kbflag   db         0
kbflag1  db         0
prompt   db '---kbd_io program begin---',0dh,0ah,'$'
scantab  db 0,0,'1234567890-=',8,0
         db 'qwertyuiop[]',0dh,0
         db 'asdfghjkl;',27h,0,0,0
         db 'zxcvbnm,./',0,0,0
         db ' ',0,0,0,0,0,0,0,0,0,0,0,0,0
         db '789-456+1230.'
shiftab  db 0,0,'!@#$%^&*()_+',0,0
         db 'QWERTYUIOP{}',0DH,0
         db 'ASDFGHJKL:"',0,0,0
         db 'ZXCVBNM<>?',0,0,0
         db ' ',26 dup(0)
even
oldcs9   dw ?
oldip9   dw ?
data     ends
;-----------------------------------------------------------------
code     segment    para   public    'code'
start    proc       far
         assume     cs:code,ds:data
         push       ds
         mov        ax,0
         push       ax
         mov        ax,data
         mov        ds,ax
         ;
         cli
         mov        al,09
         mov        ah,35h
         int        21h
         mov        oldcs9,es
         mov        oldip9,bx
         ;
         push       ds
         mov        dx,offset kbint
         mov        ax,seg kbint
         mov        ds,ax
         mov        al,09
         mov        ah,25h
         int        21h
         pop        ds
         ;
         in         al,21h
         and        al,0fdh
         out        21h,al
         ;
         mov        dx,offset prompt
         mov        ah,9
         int        21h
         sti
forever:
         call       kbget
         test       kbflag,80h
         jnz        endint
         push       ax
         call       dispchar
         pop        ax
         cmp        al,0dh
         jnz        forever
         mov        al,0ah
         call       dispchar
         jmp        forever
endint:
         mov        dx,oldip9
         mov        ax,oldcs9
         mov        ds,ax
         mov        al,09h
         mov        ah,25h
         int        21h
         ;
         ret
start    endp
;-------------------------------------------------------
kbget    proc       near
         push       bx
         cli
         mov        bx,bufpt1
         cmp        bx,bufpt2
         jnz        kbget2
         cmp        kbflag,0
         jnz        kbget3
         sti
         pop        bx
         jmp        kbget
kbget2:
         mov        al,[buffer+bx]
         inc        bx
         cmp        bx,16
         jc         kbget3
         mov        bx,0
kbget3:
         mov        bufpt1,bx
         pop        bx
         ret
kbget    endp
;-----------------------------------------------------
kbint    proc       far
         push       bx
         push       ax
         ;
         in         al,60h
         push       ax
         in         al,61h
         or         al,80h
         out        61h,al
         and        al,7fh
         out        61h,al
         ;
         pop        ax
         test       al,80h
         jnz        kbint2
         ;
         cmp al,2ah			;是left_shift嗎？
         jnz shift5
         cmp kbflag1,1      ;不是left_shift，再判斷標志位是否為1
         jz shift1
         mov kbflag1,1		;不是1，置為1
         jmp shift1
shift5:      
		 cmp al,36h			;是right_shift嗎？
         jnz shift2
         cmp kbflag1,1		;不是right_shift，再判斷標志位是否為1
         jz shift1
         mov kbflag1,1		;不是1，置為1
         jmp shift1
shift2:     				;不是shift鍵，
	     cmp kbflag1,1      ;再判斷標志位
         jnz shift3
         lea bx,shiftab     ;標志位為1，表明shift鍵按下，采用shiftab換碼，ASCII碼放在AL里
         xlat 
         jmp shift4         
shift3:      				;不是shift鍵，標志位又不是1
         lea bx,scantab 	;采用scantab換碼，ASCII碼放在AL里
         xlat 
shift4:      
         cmp        al,0		;ASCII碼為0，表明為shift以外的功能鍵，準備退出
         jnz        kbint4
         mov        kbflag,80h  ;置退出標志位
         jmp        kbint2
kbint4:
         mov        bx,bufpt2
         mov        [buffer+bx],al
         inc        bx
         cmp        bx,16
         jc         kbint3
         mov        bx,0
kbint3:
         cmp        bx,bufpt1
         jz         kbint2
         mov        bufpt2,bx
kbint2:
         cmp al,0aah	       ;判斷left_shift是否松開
         jnz shift6
         mov kbflag1,0		   ;松開即復位標志位為0
shift6:      
         cmp al,0b6h		   ;判斷right_shift是否松開
         jnz shift1
         mov kbflag1,0		   ;松開即復位標志位為0
shift1:      				   ;鍵盤中斷結束
         cli
         mov        al,20h
         out        20h,al
         pop        ax
         pop        bx
         sti
         iret
kbint    endp
;------------------------------------------------------
dispchar   proc     near
           push     bx
           mov      bx,0
           mov      ah,0eh
           int      10h
           pop      bx
           ret
dispchar   endp
;------------------------------------------------------
code       ends
           end      start