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/**
* @file
* @ingroup sparc_leon2
* @brief Implement a benchmark timer using timer 2
*/
/* timer.c
*
* This file implements a benchmark timer using timer 2.
*
* COPYRIGHT (c) 1989-1998.
* 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.org/license/LICENSE.
*
* Ported to LEON implementation of the SPARC by On-Line Applications
* Research Corporation (OAR) under contract to the European Space
* Agency (ESA).
*
* LEON modifications of respective RTEMS file: COPYRIGHT (c) 1995.
* European Space Agency.
*/
#include <bsp.h>
#include <rtems/btimer.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 */
LEON_REG.Timer_Counter_2 = 0xffffff;
LEON_REG.Timer_Reload_2 = 0xffffff;
} else {
benchmark_timer_is_initialized = true;
}
LEON_REG.Timer_Control_2 = (
LEON_REG_TIMER_COUNTER_ENABLE_COUNTING |
LEON_REG_TIMER_COUNTER_LOAD_COUNTER
);
}
#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 */
benchmark_timer_t benchmark_timer_read(void)
{
uint32_t total;
total = LEON_REG.Timer_Counter_2;
total = 0xffffff - 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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