rom/timer/readeclock.c

   1 /*
   2     Copyright © 1995-2011, 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 <exec/execbase.h>
  13 #include <devices/timer.h>
  14 #include <proto/timer.h>
  15 #include <proto/exec.h>
  16
  17 #include "timer_intern.h"
  18
  19         AROS_LH1(ULONG, ReadEClock,
  20
  21 /*  SYNOPSIS */
  22         AROS_LHA(struct EClockVal *, dest, A0),
  23
  24 /*  LOCATION */
  25         struct TimerBase *, TimerBase, 10, Timer)
  26
  27 /*  FUNCTION
  28         ReadEClock() reads current value of E-Clock and stores
  29         it in the destination EClockVal structure passed as
  30         argument. It also returns the frequency of EClock of the
  31         system.
  32
  33         This call is supposed to be very fast.
  34     INPUTS
  35         dest    -   Destination EClockVal
  36
  37     RESULT
  38         The EClock frequency (tics/s)
  39
  40     NOTES
  41         This function is safe to call from interrupts.
  42
  43     EXAMPLE
  44
  45     BUGS
  46
  47     SEE ALSO
  48
  49     INTERNALS
  50
  51     HISTORY
  52         19-08-2005  schulz   Implemented.
  53
  54 *****************************************************************************/
  55 {
  56     AROS_LIBFUNC_INIT
  57
  58     Disable();
  59
  60     EClockUpdate(TimerBase);
  61     dest->ev_hi = (ULONG)(TimerBase->tb_ticks_total >> 32);
  62     dest->ev_lo = (ULONG)(TimerBase->tb_ticks_total & 0xffffffff);
  63
  64     Enable();
  65
  66     /* We could use SysBase->ex_EClockFrequency here, but we avoid it for
  67        the case if some dumb head attempts to change it */
  68     return TimerBase->tb_eclock_rate;
  69
  70     AROS_LIBFUNC_EXIT
  71 } /* CmpTime */
  72