;************************************
;*                                  *
;*(C)Copyright 1986 by Paul B. Loux *
;*                                  *
;* These routines are in the public *
;* domain,  and  are not to be sold *
;* for a profit. They may be freely *
;* distributed, provided  that this *
;* header remains in place. Use and *
;* enjoy! PBL, CIS 72337,2073.      *
;*                                  *
;************************************
;
; FILE: TIMERS.ACT
;
; This file contains a MODULE which 
; provides the  declarations needed
; to access the Atari OS timers. It
; includes the real-time  clock (or
; "jiffy counter") starting at $12,
; plus  the counters and  interrupt
; vectors for countdown timers 2-5. 
; In addition, a short demo program
; is provided to demonstrate how to
; install a timer-driven interrupt,
; and "multi-task" on your Atari.
;
; System timer 1 vectors are not in
; here, as they are used by the OS,
; to time I/O and other things.  It
; can be used in certain cases, but
; I try to get along without it.
;
;************************************
;
;     SIO system timer variables
;
MODULE
;
BYTE RTCLOK1=$12,   ; Real time clock
     RTCLOK2=$13,
     RTCLOK3=$14

CARD CDTMV2=$21A    ; SIO timer 2
CARD CDTMV3=$21C    ; SIO timer 3
CARD CDTMV4=$21E    ; SIO timer 4
CARD CDTMV5=$220    ; SIO timer 5
 
CARD CDTMA2=$228    ; timer 2 vector

BYTE CDTMF3=$22A    ; timer 3 flag
BYTE CDTMF4=$22C    ; timer 4 flag
BYTE CDTMF5=$22E    ; timer 5 flag
;
;************************************

MODULE
  CARD ctr,ctr2,limit



PROC SETCLOCK()        ; zero real-
  RTCLOK1=0            ; time clock 
  RTCLOK2=0
  RTCLOK3=0
RETURN



PROC READCLOCK()       ; show elapsed-
                       ; time in jiffies
  BYTE rt1,rt2,rt3

  rt1=RTCLOK1
  rt2=RTCLOK2
  rt3=RTCLOK3

  POSITION(10,20)
  PRINTB(rt1) PRINT("  ") 
  PRINTB(rt2) PRINT("  ") 
  PRINTB(rt3) PRINT("  ") 

RETURN



PROC INTRPT()          ; timer IRQ routine
  CDTMV2=limit         ; reset timer
  ctr==+1              ; # times here
RETURN



PROC TEST()
  BYTE CH=764          ; keystroke pending
  CARD save

  ctr=0  ctr2=0
  limit=60             ; 60 jiffy wait

  save=CDTMA2          ; save old vector
  SETCLOCK()           ; zero clock
  CDTMA2=INTRPT        ; point vector
  CDTMV2=limit         ; start countdown

  DO     
   ctr2==+1
   POSITION(10,10)
   PRINTC(ctr)         ; # of timer IRQ's
   POSITION(10,15)
   PRINTC(ctr2)        ; # of times here
   READCLOCK()         ; elapsed time
  UNTIL CH#255         ; press any
  OD                   ; key to stop

  limit=0
  CDTMA2=save          ; restore vector
  CH=255               ; clear keystroke
RETURN