forked from Imagelibrary/rtems
76 lines
1.9 KiB
C
76 lines
1.9 KiB
C
/**
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* @file
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* @brief PXA255 timer
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*/
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/*
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* PXA255 timer by Yang Xi <hiyangxi@gmail.com>
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* Copyright (c) 2004 by Jay Monkman <jtm@lopingdog.com>
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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 <bsp.h>
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#include <rtems.h>
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#include <rtems/btimer.h>
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#include <pxa255.h>
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uint32_t tstart;
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static uint32_t tick_time;
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bool benchmark_timer_find_average_overhead;
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bool benchmark_timer_is_initialized = false;
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/*
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* Use the timer count register to measure.
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* The frequency of it is 3.4864MHZ
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* The longest period we are able to capture is 4G/3.4864MHZ
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*/
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void benchmark_timer_initialize(void)
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{
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tick_time = XSCALE_OS_TIMER_TCR;
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}
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/*
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* The following controls the behavior of Read_timer().
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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 total;
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total = XSCALE_OS_TIMER_TCR;
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if(total>=tick_time)
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total -= tick_time;
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else
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total += 0xffffffff - tick_time; /*Round up but not overflow*/
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if ( benchmark_timer_find_average_overhead == true )
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return total; /*Counter cycles*/
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if ( total < LEAST_VALID )
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return 0; /* below timer resolution */
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return total;
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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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