blob: eaaac6ad20c66b37e7a4ff8f69bcce4cc43a7667 (
plain) (
tree)
|
|
/* 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 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 <bsp.h>
rtems_boolean Timer_driver_Find_average_overhead;
rtems_boolean Timer_driver_Is_initialized = FALSE;
void Timer_initialize()
{
/*
* Timer runs long and accurate enough not to require an interrupt.
*/
if ( Timer_driver_Is_initialized == FALSE ) {
/* approximately 1 us per countdown */
ERC32_MEC.General_Purpose_Timer_Scalar = CLOCK_SPEED - 1;
ERC32_MEC.General_Purpose_Timer_Counter = 0xffffffff;
} else {
Timer_driver_Is_initialized = TRUE;
}
ERC32_MEC_Set_General_Purpose_Timer_Control(
ERC32_MEC_TIMER_COUNTER_ENABLE_COUNTING |
ERC32_MEC_TIMER_COUNTER_LOAD_COUNTER
);
ERC32_MEC_Set_General_Purpose_Timer_Control(
ERC32_MEC_TIMER_COUNTER_ENABLE_COUNTING
);
}
#define AVG_OVERHEAD 3 /* It typically takes 3.0 microseconds */
/* to start/stop the timer. */
#define LEAST_VALID 2 /* Don't trust a value lower than this */
int Read_timer()
{
rtems_unsigned32 total;
total = ERC32_MEC.General_Purpose_Timer_Counter;
total = 0xffffffff - total;
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;
}
|