arch/m68k-amiga/timer/readeclock.c

   1 /*
   2     Copyright © 1995-2007, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: ReadEClock() - read the base frequency of timers.
   6     Lang: english
   7 */
   8
   9 /*****************************************************************************
  10
  11     NAME */
  12 #include <devices/timer.h>
  13 #include <proto/timer.h>
  14 #include <proto/exec.h>
  15
  16 #include <timer_intern.h>
  17
  18         AROS_LH1(ULONG, ReadEClock,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(struct EClockVal *, dest, A0),
  22
  23 /*  LOCATION */
  24         struct TimerBase *, TimerBase, 10, Timer)
  25
  26 /*  FUNCTION
  27         ReadEClock() reads current value of E-Clock and stores
  28         it in the destination EClockVal structure passed as
  29         argument. It also returns the frequency of EClock of the
  30         system.
  31
  32         This call is supposed to be very fast.
  33     INPUTS
  34         dest    -   Destination EClockVal
  35
  36     RESULT
  37         The EClock frequency (tics/s)
  38
  39     NOTES
  40         This function is safe to call from interrupts.
  41
  42     EXAMPLE
  43
  44     BUGS
  45
  46     SEE ALSO
  47
  48     INTERNALS
  49
  50     HISTORY
  51         19-08-2005  schulz   Implemented.
  52
  53 *****************************************************************************/
  54 {
  55     AROS_LIBFUNC_INIT
  56
  57     ULONG eclock, old;
  58
  59     Disable();
  60     old = dest->ev_lo = TimerBase->tb_eclock.ev_lo;
  61     dest->ev_hi = TimerBase->tb_eclock.ev_hi;
  62     eclock = GetEClock(TimerBase);
  63     Enable();
  64     dest->ev_lo += eclock;
  65     if (old > dest->ev_lo)
  66         dest->ev_hi++;
  67     return TimerBase->tb_eclock_rate;
  68
  69     AROS_LIBFUNC_EXIT
  70 } /* CmpTime */
  71