; Keyboard driver.

KB_init:
        push    es              
        push    0
        pop     es
        mov     eax, [es:9*4]           ; save old int vectar
        mov     [KB_OldVect], eax 
        mov     ax, cs                  ; set new int vector
        shl     eax, 16
        mov     ax, KB_IntHandler
        mov     [es:9*4], eax
        pop     es
        ret

KB_restore:
        mov     eax, [KB_OldVect]
        push    es
        push    0
        pop     es
        mov     [es:9*4], eax 
        pop     es
        ret

KB_IntHandler:
        pusha
        in      al, 60h
        mov     bx, [cs:KB_pntin]
        mov     byte [cs:bx+KB_buf], al
	inc	bx
	cmp	bx, 128
	jng	KB_l1
	mov	bx, 0
KB_l1:	mov	[cs:KB_pntin], bx
        popa
        pushf                   ; Execute default code in old int vector
        call    dword [cs:KB_OldVect]
        iret

KB_read:	; returns scan code in: dl
	mov	dl, 0
	mov	bx, [KB_pntout]
	cmp	bx, [KB_pntin]
	je	KB_l2
	mov	dl, [bx+KB_buf]
	inc	bx
	cmp	bx, 128
	jng	KB_l3
	mov	bx, 0
KB_l3:	mov	[KB_pntout], bx
KB_l2:	ret

KB_OldVect dd 0
KB_pntin dw 0
KB_pntout dw 0
KB_buf	db 0
times 127 db 0