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/*  timer.c

 *

 *  This file manages the interval timer on the PA-RISC.

 *

 *  NOTE: It is important that the timer start/stop overhead be

 *        determined when porting or modifying this code.

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  $Id: timer.c,v 1.2 2001-09-27 12:01:21 chris Exp $

 */

#include <rtems.h>

volatile rtems_unsigned32 Timer_starting;

rtems_boolean Timer_driver_Find_average_overhead;

void Timer_initialize()

{

  Timer_starting = get_itimer();

  set_eiem(0x80000000);

}

#define AVG_OVERHEAD      0  /* It typically takes 3.0 microseconds */

                             /* (6 countdowns) to start/stop the timer. */

#define LEAST_VALID       1  /* Don't trust a value lower than this */

int Read_timer()

{

  rtems_unsigned32 clicks;

  rtems_unsigned32 total;

  clicks = get_itimer();

  total = clicks - Timer_starting;

  if ( Timer_driver_Find_average_overhead == 1 )

    return total;          /* in XXX microsecond units */

  else {

    if ( total < LEAST_VALID )

      return 0;            /* below timer resolution */

    return (total - AVG_OVERHEAD);

  }

}

rtems_status_code Empty_function( void )

{

  return RTEMS_SUCCESSFUL;

}

void Set_find_average_overhead(

  rtems_boolean find_flag

)

{

  Timer_driver_Find_average_overhead = find_flag;

}