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/* SPDX-License-Identifier: BSD-2-Clause */
/**
* @file
* @brief
*
* This file implements a benchmark timer using the PPC Timebase Register.
*/
/*
* COPYRIGHT (c) 1989-2014.
* On-Line Applications Research Corporation (OAR).
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <bsp.h>
#include <rtems.h>
#include <rtems/btimer.h>
#include <assert.h>
#include <libcpu/powerpc-utility.h>
#ifndef BSP_Convert_decrementer
#define BSP_Convert_decrementer(value) (value)
#endif
uint64_t Timer_driver_Start_time;
bool benchmark_timer_find_average_overhead = false;
unsigned clicks_overhead = 0;
/*
* Timer Get overhead
*/
static 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
*/
benchmark_timer_t 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);
}
void benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
{
benchmark_timer_find_average_overhead = find_flag;
}
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