Category : C++ Source Code
Archive   : CPPTASK.ZIP
Filename : TSKKBD.ASM

;
; CTask - Keyboard handler module.
;
; Public Domain Software written by
; Thomas Wagner
; Patschkauer Weg 31
; D-1000 Berlin 33
; West Germany
;
; This module traps the keyboard interrupts to allow task switching
; on waiting for a character.
; All characters are put into a (word)pipe, and can either be
; read directly from the pipe, or through the normal INT 16 channels.
;
name tskkbd
.model large
;
public _tsk_install_kbd
public _tsk_remove_kbd
;
public _t_read_key
public _t_wait_key
public _t_keyhit
;
extrn _asm_read_wpipe: far
extrn _asm_check_wpipe: far
extrn _asm_c_write_wpipe: far
;
include tsk.mac
;
intseg segment at 0
org 09h*4
hwdoff dw ? ; keyboard hardware interrupt
hwdseg dw ?
org 16h*4
kbdoff dw ? ; keyboard I/O interrupt
kbdseg dw ?
;
intseg ends
;
;----------------------------------------------------------------------------
;
; Variables
;
extrn _key_avail: wpipe
;
.code
;
kbd_flag db 0
;
; Original Interrupt-Entries
;
savhwd label dword ; original hardware int entry
savhwdoff dw ?
savhwdseg dw ?
;
savkbd label dword ; original keyboard I/O entry
savkbdoff dw ?
savkbdseg dw ?
;
;
;---------------------------------------------------------------------------
;
.code
;
;
; void tsk_install_kbd (void)
;
; Install keyboard handler
;
_tsk_install_kbd proc far
;
;
; Save old interrupt vectors
;
push es
xor ax,ax
mov es,ax
;
assume es:intseg
;
mov ax,kbdoff
mov savkbdoff,ax
mov ax,kbdseg
mov savkbdseg,ax
;
mov ax,hwdoff
mov savhwdoff,ax
mov ax,hwdseg
mov savhwdseg,ax
;
; Enter new Interrupt-Entries
;
cli
mov kbdoff,offset kbdentry
mov kbdseg,cs
mov hwdoff,offset hwdentry
mov hwdseg,cs
sti
pop es
;
ret
;
assume es:nothing
;
_tsk_install_kbd endp
;
;
; void tsk_remove_kbd (void)
;
; Un-install keyboard handler
;
_tsk_remove_kbd proc far
;
push es
xor ax,ax
mov es,ax
;
assume es:intseg
;
; Restore interrupt entries
;
cli
;
mov ax,savkbdoff
mov kbdoff,ax
mov ax,savkbdseg
mov kbdseg,ax
;
mov ax,savhwdoff
mov hwdoff,ax
mov ax,savhwdseg
mov hwdseg,ax
;
sti
;
pop es
ret
;
assume es:nothing
;
_tsk_remove_kbd endp
;
;
;---------------------------------------------------------------------------
;
; int t_read_key (void)
;
; Waits for key from keyboard. Returns char in lower byte,
; Scan-Code in upper byte.
;
_t_read_key proc far
;
xor ax,ax ; no timeout
push ax
push ax
mov ax,offset _key_avail
push ds
push ax
call _asm_read_wpipe
add sp,8
ret
;
_t_read_key endp
;
;
; int t_wait_key (dword timeout)
;
; Waits for key from keyboard. Returns char in lower byte,
; Scan-Code in upper byte.
;
_t_wait_key proc far
;
push bp
mov bp,sp
push 8[bp] ; timeout
push 6[bp]
mov ax,offset _key_avail
push ds
push ax
call _asm_read_wpipe
add sp,8
pop bp
ret
;
_t_wait_key endp
;
;
; int t_keyhit (void)
;
; Checks if char is available. Returns -1 if not, else the
; character value. The character remains in the buffer.
;
_t_keyhit proc far
;
mov ax,offset _key_avail
push ds
push ax
call _asm_check_wpipe
add sp,4
ret
;
_t_keyhit endp
;
;---------------------------------------------------------------------------
;
; INT 9 - Keyboard hardware interrupt
;
hwdentry proc far
;
pushf
call cs:savhwd ; process key
push ds
push es
push ax
push bx
push cx
push dx
mov ax,seg dgroup
mov ds,ax
mov es,ax
;
mov ah,1
pushf
call cs:savkbd ; check if char available
jz hwd_ret ; return if not
;
xor ah,ah
pushf
call cs:savkbd ; get the key
;
push ax ; push key
mov ax,offset _key_avail
push ds
push ax
call _asm_c_write_wpipe
add sp,6
;
hwd_ret:
pop dx
pop cx
pop bx
pop ax
pop es
pop ds
iret
;
hwdentry endp
;
;---------------------------------------------------------------------------
;
; INT 16 - Keyboard I/O
;
kbdentry proc far
;
cmp ah,2
jb kbd_funcs
jmp cs:savkbd ; pass on functions >= 2
;
kbd_funcs:
sti
push ds
push es
push dx
push cx
push bx
mov bx,seg dgroup
mov ds,bx
mov es,bx
;
cmp ah,1
jb kbd_read
;
mov bx,offset _key_avail
push ds
push bx
call _asm_check_wpipe
add sp,4
cmp ax,0ffffh
jne kbd_gotone
xor ax,ax
kbd_gotone:
pop bx
pop cx
pop dx
pop es
pop ds
ret 2
;
kbd_read:
xor ax,ax
push ax
push ax
mov bx,offset _key_avail
push ds
push bx
call _asm_read_wpipe
add sp,8
pop bx
pop cx
pop dx
pop es
pop ds
iret
;
kbdentry endp
;
end