forked from Imagelibrary/rtems
65 lines
1.5 KiB
C
65 lines
1.5 KiB
C
/**
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* @file
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*
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* @ingroup RTEMSBSPsOR1K
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*
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* @brief Benchmark timer support.
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*/
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/*
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* Copyright (c) 2014-2015 by Hesham ALMatary
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.rtems.org/license/LICENSE
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*/
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#include <rtems.h>
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#include <rtems/btimer.h>
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#include <bsp/generic_or1k.h>
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#include <rtems/score/or1k-utility.h>
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#define OR1K_NANOSECONDS_PER_CLK_CYCLE 10
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static bool benchmark_timer_find_average_overhead = false;
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static uint64_t benchmark_timer_base;
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void benchmark_timer_initialize(void)
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{
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benchmark_timer_base = _OR1K_mfspr(CPU_OR1K_SPR_TTCR);
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}
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#define AVG_OVERHEAD 0
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#define LEAST_VALID 1
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benchmark_timer_t benchmark_timer_read( void )
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{
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uint64_t clicks;
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uint64_t total;
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uint64_t delta;
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/*
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* Read the timer and see how many clicks (clock cycles)
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* has passed since timer initialization.
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*/
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clicks = _OR1K_mfspr(CPU_OR1K_SPR_TTCR);
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delta = clicks - benchmark_timer_base;
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/* total in nanoseconds */
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total = OR1K_NANOSECONDS_PER_CLK_CYCLE * (delta);
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if ( benchmark_timer_find_average_overhead == true )
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return total; /* in nanoseconds microsecond units */
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else {
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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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}
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void benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
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{
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benchmark_timer_find_average_overhead = find_flag;
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}
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