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/* 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>
#if defined(RTEMS_MULTIPROCESSING)
#define LEON3_TIMER_INDEX \
((rtems_configuration_get_user_multiprocessing_table()) ? \
(rtems_configuration_get_user_multiprocessing_table()->node) - 1 : 1)
#else
#define LEON3_TIMER_INDEX 0
#endif
bool benchmark_timer_find_average_overhead;
bool benchmark_timer_is_initialized = false;
extern volatile struct gptimer_regs *LEON3_Timer_Regs;
void benchmark_timer_initialize(void)
{
/*
* Timer runs long and accurate enough not to require an interrupt.
*/
if (LEON3_Timer_Regs) {
if ( benchmark_timer_is_initialized == false ) {
/* approximately 1 us per countdown */
LEON3_Timer_Regs->timer[LEON3_TIMER_INDEX].reload = 0xffffff;
LEON3_Timer_Regs->timer[LEON3_TIMER_INDEX].value = 0xffffff;
} else {
benchmark_timer_is_initialized = true;
}
LEON3_Timer_Regs->timer[LEON3_TIMER_INDEX].ctrl =
GPTIMER_TIMER_CTRL_EN | GPTIMER_TIMER_CTRL_LD;
}
}
#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 */
uint32_t benchmark_timer_read(void)
{
uint32_t total;
if (LEON3_Timer_Regs) {
total = LEON3_Timer_Regs->timer[LEON3_TIMER_INDEX].value;
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;
}
return 0;
}
void benchmark_timer_disable_subtracting_average_overhead(
bool find_flag
)
{
benchmark_timer_find_average_overhead = find_flag;
}
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