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/* timer.c
*
* This file manages the interval timer on the PA-RISC.
*
* NOTE: It is important that the timer start/stop overhead be
* determined when porting or modifying this code.
*
* COPYRIGHT (c) 1989-1998.
* On-Line Applications Research Corporation (OAR).
* Copyright assigned to U.S. Government, 1994.
*
* 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.
*
* $Id$
*/
#include <rtems.h>
volatile rtems_unsigned32 Timer_starting;
rtems_boolean Timer_driver_Find_average_overhead;
void Timer_initialize()
{
Timer_starting = get_itimer();
set_eiem(0x80000000);
}
#define AVG_OVERHEAD 0 /* It typically takes 3.0 microseconds */
/* (6 countdowns) to start/stop the timer. */
#define LEAST_VALID 1 /* Don't trust a value lower than this */
int Read_timer()
{
rtems_unsigned32 clicks;
rtems_unsigned32 total;
clicks = get_itimer();
total = clicks - Timer_starting;
if ( Timer_driver_Find_average_overhead == 1 )
return total; /* in XXX microsecond units */
else {
if ( total < LEAST_VALID )
return 0; /* below timer resolution */
return (total - 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;
}
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