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/*  Timer_init()

 *

 *  This routine initializes the PCC timer on the MVME147 board.

 *

 *  Input parameters:  NONE

 *

 *  Output parameters:  NONE

 *

 *  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.

 *

 *  MVME147 port for TNI - Telecom Bretagne

 *  by Dominique LE CAMPION (Dominique.LECAMPION@enst-bretagne.fr)

 *  May 1996

 *

 *  $Id: timer.c,v 1.2 2001-09-27 12:00:16 chris Exp $

 */

#include <bsp.h>

#define TIMER_INT_LEVEL 6

#define COUNTDOWN_VALUE 0

/* Allows 0.4096 second delay betwin ints */

/* Each tick is 6.25 us */

int Ttimer_val;

rtems_boolean Timer_driver_Find_average_overhead;

rtems_isr timerisr();

void Timer_initialize()

{

  (void) set_vector(timerisr, TIMER_1_VECTOR, 0); /* install ISR */

  Ttimer_val = 0;                 /* clear timer ISR count */

  pcc->timer1_int_control = 0x00; /* Disable T1 Interr. */

  pcc->timer1_preload = COUNTDOWN_VALUE;

  /* write countdown preload value */

  pcc->timer1_control = 0x00; /* load preload value */

  pcc->timer1_control = 0x07; /* clear T1 overflow counter, enable counter */

  pcc->timer1_int_control = TIMER_INT_LEVEL|0x08;

  /* Enable Timer 1 and set its int. level */

}

#define AVG_OVERHEAD      0  /* No need to start/stop the timer to read

                                its value on the MVME147 PCC: reads are not

                                synchronized whith the counter updates*/

#define LEAST_VALID       10 /* Don't trust a value lower than this */

int Read_timer()

{

  rtems_unsigned32 total;

  rtems_unsigned16 counter_value;

  counter_value = pcc->timer1_count; /* read the counter value */

  total = ((Ttimer_val * 0x10000) + counter_value); /* in 6.25 us units */

  /* DC note : just look at the assembly generated

     to see gcc's impressive optimization ! */

  return total;

}

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;

}