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/*  Timer_init()

 *

 *  This routine initializes the Tick Timer 1 on the MVME162 board.

 *

 *  Input parameters:  NONE

 *

 *  Output parameters:  NONE

 *

 *  NOTE: This routine will not work if the optimizer is enabled

 *        for some compilers.  The multiple writes

 *        may be optimized away.

 *

 *        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.

 *

 *  Modifications of respective RTEMS file: COPYRIGHT (c) 1994.

 *  EISCAT Scientific Association. M.Savitski

 *

 *  This material is a part of the MVME162 Board Support Package

 *  for the RTEMS executive. Its licensing policies are those of the

 *  RTEMS above.

 *

 *  $Id: timer.c,v 1.2 2001-09-27 12:00:18 chris Exp $

 */

#include <rtems.h>

#include <bsp.h>

/* Periodic tick interval */

#define TICK_INTERVAL         0x10000U

#define TIMER_INT_LEVEL       6

rtems_unsigned32    Ttimer_val;

rtems_boolean       Timer_driver_Find_average_overhead;

rtems_isr timerisr();

void Timer_initialize()

{

  (void) set_vector( timerisr, VBR0 * 0x10 + 0x8, 0 );

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

  lcsr->vector_base |= MASK_INT;      /* unmask VMEchip2 interrupts */

  lcsr->intr_clear |= 0x01000000;     /* clear pending interrupt */

  lcsr->to_ctl = 0xE7;                /* prescaler to 1 MHz (see Appendix A1) */

  lcsr->timer_cmp_1 = TICK_INTERVAL;

  lcsr->timer_cnt_1 = 0;              /* clear counter */

  lcsr->board_ctl |= 7;               /* increment, reset-on-compare, */

                                      /*   and clear-overflow-cnt */

  lcsr->intr_level[0] |= TIMER_INT_LEVEL; /* set int level */

  lcsr->intr_ena |= 0x01000000;           /* enable tick timer 1 interrupt */

}

#define AVG_OVERHEAD      3U    /* It typically takes 3.0 microseconds */

                                /* (3 countdowns) to start/stop the timer. */

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

int Read_timer()

{

  rtems_unsigned32    total;

  total = (Ttimer_val * TICK_INTERVAL) + lcsr->timer_cnt_1;

  if ( Timer_driver_Find_average_overhead == 1 )

    return total;          /* in one-half microsecond units */

  if ( total < LEAST_VALID )

    return 0;            /* below timer resolution */

  return (total-AVG_OVERHEAD) >> 1;

}

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;

}