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/*  timer.c

 *

 *  This file implements a benchmark timer using the General Purpose Timer.

 *

 *  Notes:

 *

 *  BSP_TIMER_AVG_OVERHEAD and BSP_TIMER_LEAST_VALID are required to be

 *  provided in bsp.h

 *

 *  COPYRIGHT (c) 1989-1997.

 *  On-Line Applications Research Corporation (OAR).

 *  Copyright assigned to U.S. Government, 1994.

 *

 *  The license and distribution terms for this file may 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 12:00:59 chris Exp $

 */

#include <assert.h>

#include <bsp.h>

rtems_unsigned64 Timer_driver_Start_time;

rtems_boolean Timer_driver_Find_average_overhead;

/*

 * Timer_initialize

 */

void Timer_initialize()

{

  /*

   *  Timer runs long and accurate enough not to require an interrupt.

   */

  Timer_driver_Start_time = PPC_Get_timebase_register();

}

/*

 *  Read_timer

 */

int Read_timer()

{

  rtems_unsigned64  clicks;

  rtems_unsigned64  total64;

  rtems_unsigned32  total;

  /* approximately CLOCK_SPEED clicks per microsecond */

  clicks = PPC_Get_timebase_register();

  assert( clicks > Timer_driver_Start_time );

  total64 = clicks - Timer_driver_Start_time;

  assert( total64 <= 0xffffffff );  /* fits into a unsigned32 */

  total = (rtems_unsigned32) total64;

  if ( Timer_driver_Find_average_overhead == 1 )

    return total;          /* in "clicks" of the decrementer units */

  if ( total < BSP_TIMER_LEAST_VALID )

    return 0;            /* below timer resolution */

  return BSP_Convert_decrementer(total - BSP_TIMER_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;

}