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/* timer.c
*
* This file implements a benchmark timer using the PPC Timebase
*
* Notes: NONE
*
* COPYRIGHT (c) 1989-2000.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may in
* the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*
* $Id$
*/
#include <rtems/system.h>
#include <assert.h>
#include <rtems.h>
#include <bsp.h>
#include <libcpu/powerpc-utility.h>
uint64_t Timer_driver_Start_time;
bool benchmark_timer_find_average_overhead = false;
unsigned clicks_overhead = 0;
/*
* Timer Get overhead
*/
int Timer_get_clicks_overhead(void)
{
uint64_t clicks;
PPC_Set_timebase_register((uint64_t) 0);
clicks = PPC_Get_timebase_register();
assert(clicks <= 0xffffffff);
clicks_overhead = (unsigned) clicks;
return clicks_overhead;
}
/*
* benchmark_timer_initialize
*/
void benchmark_timer_initialize(void)
{
/*
* Timer runs long and accurate enough not to require an interrupt.
*/
if (clicks_overhead == 0) clicks_overhead = Timer_get_clicks_overhead();
PPC_Set_timebase_register((uint64_t) 0);
}
/*
* benchmark_timer_read
*/
int benchmark_timer_read(void)
{
uint64_t total64;
uint32_t total;
/* approximately CLOCK_SPEED clicks per microsecond */
total64 = PPC_Get_timebase_register();
assert( total64 <= 0xffffffff ); /* fits into a uint32_t */
total = (uint32_t) total64;
if ( benchmark_timer_find_average_overhead == true )
return total; /* in "clicks" of the decrementer units */
return (int) BSP_Convert_decrementer(total - clicks_overhead);
}
unsigned long long Read_long_timer(void)
{
uint64_t total64;
total64 = PPC_Get_timebase_register();
return BSP_Convert_decrementer(total64 - clicks_overhead);
}
void benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
{
benchmark_timer_find_average_overhead = find_flag;
}
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