提供5个子程序:
1. 发送按键 sendkey
2. 检测是否有按键 testkey
3. 读取按键 getkey
4. 判断键盘缓冲区是否为空 bufempty
5. 判断键盘缓冲区是否已满 buffull
具体功能及参数描述如下
sendkey proc far |
; more source code at http://www.ahjoe.com/source/srcdown.asp
.286
public sendkey, getkey, testkey, buffull, bufempty
code segment
assume cs:code, ds:code
sendkey proc far
; ax=charcode
push ax
push bx
push si
push di
push ds
cmp ah, 0
jnz sendkj0
mov ah, 30h
sendkj0:
mov bx, 40h
mov ds, bx
mov di, ds:[1ch]
mov bx, di
call incptr
cmp bx, ds:[1ah]
jz fullk
mov ds:[di], ax
mov ds:[1ch], bx
fullk:
pop ds
pop di
pop si
pop bx
pop ax
retf
sendkey endp
getkey proc far
; out:
; ax=key code
; if buf empty, it will wait
push bx
push si
push ds
mov ax, 40h
mov ds, ax
getkeyrep:
mov si, ds:[1ah]
cmp si, ds:[1ch]
jz getkeyrep
mov ax, [si]
mov bx, si
call incptr
mov ds:[1ah], bx
pop ds
pop si
pop bx
retf
getkey endp
testkey proc far
; out:
; zf=1 buff empty;
; zf=0 ax=key code
push si
push ds
mov ax, 40h
mov ds, ax
mov si, ds:[1ah]
mov ax, [si]
cmp si, ds:[1ch]
pop ds
pop si
retf
testkey endp
bufempty proc far ; test key buffer be empty or not
; out:
; zf=0 not empty; zf=1 empty
push si
push ds
mov si, 40h
mov ds, si
mov si, ds:[1ah]
cmp si, ds:[1ch]
pop ds
pop si
retf
bufempty endp
buffull proc far ; test key buffer be full or not
; out:
; zf=0 not full; zf=1 full
push ds
push bx
mov bx, 40h
mov ds, bx
mov bx, ds:[1ch]
call incptr
cmp bx, ds:[1ah]
pop bx
pop ds
retf
buffull endp
incptr proc near
inc bx
inc bx
cmp bx, 3eh
jb incok
mov bx, 1eh
incok:
retn
incptr endp
decptr proc near
dec bx
dec bx
cmp bx, 1ch
ja decok
mov bx, 3ch
decok:
retn
decptr endp
code ends
end sendkey