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/* timer.c
*
* This file implements a benchmark timer using the General Purpose Timer on
* the MEC.
*
* The license and distribution terms for this file are in
* the file LICENSE in this distribution or at
* http://www.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <assert.h>
#include <bsp.h>
rtems_unsigned64 Timer_driver_Start_time;
rtems_boolean Timer_driver_Find_average_overhead;
/*PAGE
*
* Timer_initialize
*
* This routine initializes the timer.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* Return values: NONE
*
*/
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 */
/* PAGE
*
* Read_timer
*
* This routine reads the timer.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* Return values: timer in ms units
*
*/
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;
}
/* PAGE
*
* Empty_function
*
* This routine is called during the idle loop.
*
* Input parameters: NONE
*
* Output parameters:
* status code of successful
*
* Return values: NONE
*
*/
rtems_status_code Empty_function( void )
{
return RTEMS_SUCCESSFUL;
}
/* PAGE
*
* Set_find_average_overhead
*
* This routine sets a global boolean to the value passed in.
*
* Input parameters:
* find_flag - flag to indicate to find the average overhead.
*
* Output parameters: NONE
*
* Return values: NONE
*
*/
void Set_find_average_overhead(
rtems_boolean find_flag
)
{
Timer_driver_Find_average_overhead = find_flag;
}
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