PILA     SEGMENT   STACK 'stack'
	 db  128  dup (?)
PILA     ENDS

DATOS    SEGMENT
guarda_ip       dw (?)
guarda_cs       dw (?)
guarda_ip2       dw (?)
guarda_cs2       dw (?)
teclapul          db 'tecla pulsada',0ah,0dh,'$'
teclades          db 'tecla despulsada',0ah,0dh,'$'
msg             db '-> Segundos transcurridos: ','$'
msg_tic             db 10,13,'-> Tics transcurridos: ','$'	
contador_seg    dw 0
tecla           db ?
cuenta          db (0)
cuenta_tics     dw (0)
bcd             db 5 dup(?),'$'
DATOS    ENDS

INTER SEGMENT AT 0
org 4*9
vector_ip dw (?)
vector_cs dw (?)

org 8*4
TIC_IP  DW      ?
TIC_CS  DW      ?
INTER ENDS



CODIGO   SEGMENT
	 ASSUME CS:CODIGO,DS:DATOS,SS:PILA,ES:INTER
ppal proc far

	push ds
	xor ax,ax
	push ax
	mov ax,datos
	mov ds,ax

	mov ax,inter
	mov es,ax

	call cambia
	call cambia2
bucle:	cmp tecla,1
        jne bucle
		test tecla,80h
	    jnz cont3
		jmp bucle
   cont3:
	call restituye
	call restituye2
	
	mov dx,offset msg
	mov ah,09
	int 21h
	
	push contador_seg
	mov ax,offset bcd
	push ax
	call to_bcd
	
	mov dx,offset msg_tic
	mov ah,09
	int 21h
	
	push cuenta_tics
	mov ax,offset bcd
	push ax
	call to_bcd
	
	retf
ppal endp

cambia proc
	cli
	mov ax,vector_ip
	mov guarda_ip,ax
	mov ax,vector_cs
	mov guarda_cs,ax

	mov vector_ip,offset rutina
	mov vector_cs,cs

	sti
	ret
cambia endp

restituye proc
	cli
	mov ax,guarda_ip
	mov vector_ip,ax
	mov ax,guarda_cs
	mov vector_cs,ax
	sti
	ret
restituye endp

cambia2 proc
	cli
	mov ax,tic_cs
	mov guarda_cs2,ax
	mov ax,tic_ip
	mov guarda_ip2,ax

	mov tic_ip,offset rutina2
	mov tic_cs,seg rutina2
	sti
	ret
cambia2 endp 

restituye2 proc
	cli
	mov ax,guarda_cs2
	mov tic_cs,ax
	mov ax,guarda_ip2
	mov tic_ip,ax
	sti
	ret
restituye2 endp

rutina proc far
	cli
	in al,60h
	mov tecla,al
	test tecla,80h
	jnz cont
	mov dx,offset teclapul
	mov ah,9
	int 21h
	jmp fin
cont:mov dx,offset teclades
	mov ah,9
	int 21h

fin:mov al,20h
	out 20h,al	
	sti
	iret
rutina endp

rutina2 proc far
;	cli
	inc cuenta
	inc cuenta_tics
	cmp cuenta,19
	jnz cont2
	mov cuenta,0
	inc contador_seg
cont2:   mov al,20h
	out 20h,al
;	sti
	iret
rutina2 endp

to_bcd proc
;	cli
	push ax
	push bx
	push dx
	push bp
	push si
	push di

	mov bp,sp
	mov ax,10h[bp]
	mov di,0eh[bp]
	mov bx,5
	mov si,0ah
bucle2:  cmp ax,0
	jz final
	xor dx,dx
	div si
	add dl,'0'
	dec bx
	mov [di][bx],dl
	jnz bucle2

final:  mov dx,di	
	add dx,bx       
	mov ah,9
	int 21h

	pop di
	pop si
	pop bp
	pop dx
	pop bx
	pop ax
;	sti
	ret 4
to_bcd endp


CODIGO   ENDS
	 END ppal