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/* timer.c
*
* This file implements a benchmark timer using the General Purpose Timer on
* the MEC.
*
* COPYRIGHT (c) 1989-1999.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in found in the file LICENSE in this distribution or at
* http://www.OARcorp.com/rtems/license.html.
*
* Ported to ERC32 implementation of the SPARC by On-Line Applications
* Research Corporation (OAR) under contract to the European Space
* Agency (ESA).
*
* ERC32 modifications of respective RTEMS file: COPYRIGHT (c) 1995.
* European Space Agency.
*
* $Id$
*/
#include <assert.h>
#include <bsp.h>
rtems_unsigned64 Timer_driver_Start_time;
rtems_boolean Timer_driver_Find_average_overhead;
void Timer_initialize()
{
/*
* Timer runs long and accurate enough not to require an interrupt.
*/
Timer_driver_Start_time = PPC_Get_timebase_register();
}
#define AVG_OVERHEAD 24 /* It typically takes 24 instructions */
/* to start/stop the timer. */
#define LEAST_VALID 1 /* Don't trust a value lower than this */
/* psim can count instructions. :) */
int Read_timer()
{
rtems_unsigned64 clicks;
rtems_unsigned64 total64;
rtems_unsigned32 total;
/* approximately CLOCK_SPEED clicks per microsecond */
clicks = PPC_Get_timebase_register();
assert( clicks > Timer_driver_Start_time );
total64 = clicks - Timer_driver_Start_time;
assert( total64 <= 0xffffffff ); /* fits into a unsigned32 */
total = (rtems_unsigned32) total64;
if ( Timer_driver_Find_average_overhead == 1 )
return total; /* in one microsecond units */
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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