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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, 1990, 1991, 1992, 1993, 1994.
* On-Line Applications Research Corporation (OAR).
* All rights assigned to U.S. Government, 1994.
*
* This material may be reproduced by or for the U.S. Government pursuant
* to the copyright license under the clause at DFARS 252.227-7013. This
* notice must appear in all copies of this file and its derivatives.
*
* 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.
*
* $Id$
*/
#include <rtems.h>
#include <bsp.h>
/* Periodic tick interval */
#define TICK_INTERVAL 0x10000
#define TIMER_INT_LEVEL 6
int Ttimer_val;
rtems_boolean Timer_driver_Find_average_overhead;
rtems_isr timerisr();
void Timer_initialize()
{
(void) set_vector( timerisr, (VECTOR_BASE >> 28) * 0x10 + 0x8, 0 );
Ttimer_val = 0; /* clear timer ISR count */
lcsr->vector_base = 0x67800000; /* set vb, enable interrupts */
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, clear-ovfl-cnt */
lcsr->intr_level[0] |= TIMER_INT_LEVEL; /* set int level */
lcsr->intr_ena |= 0x01000000; /* enable tick timer 1 interrupt */
}
#define AVG_OVERHEAD 6 /* It typically takes 3.0 microseconds */
/* (6 countdowns) to start/stop the timer. */
#define LEAST_VALID 10 /* Don't trust a value lower than this */
int Read_timer()
{
unsigned long 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); /* in musec units */
}
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;
}
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