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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 the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*
* 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>
bool benchmark_timer_find_average_overhead;
bool benchmark_timer_is_initialized = false;
void benchmark_timer_initialize(void)
{
/*
* Timer runs long and accurate enough not to require an interrupt.
*/
if ( benchmark_timer_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 {
benchmark_timer_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
);
}
#if ENABLE_SIS_QUIRKS
#define AVG_OVERHEAD 8 /* It typically takes 3.0 microseconds */
/* to start/stop the timer. */
#define LEAST_VALID 9 /* Don't trust a value lower than this */
#else
#define AVG_OVERHEAD 12 /* It typically takes 3.0 microseconds */
/* to start/stop the timer. */
#define LEAST_VALID 13 /* Don't trust a value lower than this */
#endif
int benchmark_timer_read(void)
{
uint32_t total;
total = ERC32_MEC.General_Purpose_Timer_Counter;
total = 0xffffffff - total;
if ( benchmark_timer_find_average_overhead == true )
return total; /* in one microsecond units */
if ( total < LEAST_VALID )
return 0; /* below timer resolution */
return total - AVG_OVERHEAD;
}
void benchmark_timer_disable_subtracting_average_overhead(
bool find_flag
)
{
benchmark_timer_find_average_overhead = find_flag;
}
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