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0149e6e749
Updates the recently merged relicensed files with the 2-Clause BSD SPDX annotation. Closes #5208.
79 lines
2.6 KiB
C
79 lines
2.6 KiB
C
/* SPDX-License-Identifier: BSD-2-Clause */
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/*
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* This file implements a benchmark timer using the count/compare
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* CP0 registers.
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*/
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/*
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* Copyright (C) 2005 by Cogent Computer Systems
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* Written by Jay Monkman <jtm@lopingdog.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <assert.h>
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#include <bsp.h>
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#include <rtems/btimer.h>
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bool benchmark_timer_find_average_overhead;
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uint32_t tstart;
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void benchmark_timer_initialize(void)
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{
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__asm__ volatile ("mfc0 %0, $9\n" : "=r" (tstart));
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/* tick time in picooseconds */
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}
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#define AVG_OVERHEAD 0 /* It typically takes N instructions */
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/* to start/stop the timer. */
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#define LEAST_VALID 1 /* Don't trust a value lower than this */
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/* tx39 simulator can count instructions. :) */
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benchmark_timer_t benchmark_timer_read(void)
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{
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uint32_t total;
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uint32_t cnt;
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__asm__ volatile ("mfc0 %0, $9\n" : "=r" (cnt));
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total = cnt - tstart;
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total = (total * 1000) / 396; /* convert to nanoseconds */
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if ( benchmark_timer_find_average_overhead == true )
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return total; /* in one microsecond units */
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if ( total < LEAST_VALID )
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return 0; /* below timer resolution */
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return total - AVG_OVERHEAD;
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}
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void benchmark_timer_disable_subtracting_average_overhead(
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bool find_flag
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)
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{
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benchmark_timer_find_average_overhead = find_flag;
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}
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