forked from Imagelibrary/rtems
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
/**
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* @file
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* @brief Timer for Blackfin
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*
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* This file manages the benchmark timer used by the RTEMS Timing Test
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* Suite. Each measured time period is demarcated by calls to
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* benchmark_timer_initialize() and benchmark_timer_read().
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* benchmark_timer_read() usually returns the number of microseconds
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* since benchmark_timer_initialize() exitted.
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*/
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/*
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* Copyright (c) 2006 by Atos Automacao Industrial Ltda.
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* written by Alain Schaefer <alain.schaefer@easc.ch>
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* and Antonio Giovanini <antonio@atos.com.br>
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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 <bsp.h>
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#include <rtems/btimer.h>
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uint32_t Timer_interrupts;
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bool benchmark_timer_find_average_overhead;
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/*
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* benchmark_timer_initialize
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*
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* Blackfin processor has a counter for clock cycles.
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*/
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void benchmark_timer_initialize( void )
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{
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/*reset counters*/
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__asm__ ("R2 = 0;");
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__asm__ ("CYCLES = R2;");
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__asm__ ("CYCLES2 = R2;");
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/*start counters*/
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__asm__ ("R2 = SYSCFG;");
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__asm__ ("BITSET(R2,1);");
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__asm__ ("SYSCFG = R2");
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}
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/*
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* The following controls the behavior of benchmark_timer_read().
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*
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* AVG_OVEREHAD is the overhead for starting and stopping the timer. It
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* is usually deducted from the number returned.
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*
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* LEAST_VALID is the lowest number this routine should trust. Numbers
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* below this are "noise" and zero is returned.
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*/
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#define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */
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/* (Y countdowns) to start/stop the timer. */
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/* This value is in microseconds. */
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#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */
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benchmark_timer_t benchmark_timer_read( void )
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{
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uint32_t clicks;
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uint32_t total;
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register uint32_t cycles __asm__ ("R2");
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/* stop counter */
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__asm__ ("R2 = SYSCFG;");
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__asm__ ("BITCLR(R2,1);");
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__asm__ ("SYSCFG = R2;");
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__asm__ ("R2 = CYCLES;");
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clicks = cycles; /* Clock cycles */
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/* converting to microseconds */
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total = clicks / (CCLK/1000000);
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if ( benchmark_timer_find_average_overhead == 1 )
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return total; /* in XXX 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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/*
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* Somehow convert total into microseconds
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*/
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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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