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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) 1989-1997.
* 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.
*
* MVME147 port for TNI - Telecom Bretagne
* by Dominique LE CAMPION (Dominique.LECAMPION@enst-bretagne.fr)
* May 1996
*
* $Id$
*/
#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;
}
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