forked from Imagelibrary/rtems
68f36fee74
* include/tm27.h, timer/timer.c: #include <rtems/tic4x/c4xio.h> instead of <rtems/tic4x/c4xio.h>.
116 lines
3.0 KiB
C
116 lines
3.0 KiB
C
/* timer.c
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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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* Timer_initialize() and Read_timer(). Read_timer() usually returns
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* the number of microseconds since Timer_initialize() exitted.
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*
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* NOTE: It is important that the timer start/stop overhead be
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* determined when porting or modifying this code.
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*
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* COPYRIGHT (c) 1989-1999.
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* On-Line Applications Research Corporation (OAR).
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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.com/license/LICENSE.
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*
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* $Id$
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*/
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#include <rtems.h>
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#include <bsp.h>
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#include <rtems/tic4x/c4xio.h>
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uint32_t Timer_interrupts;
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rtems_boolean Timer_driver_Find_average_overhead;
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static uint32_t start;
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void Timer_initialize( void )
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{
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/*
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* Timer has never overflowed. This may not be necessary on some
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* implemenations of timer but ....
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*/
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c4x_timer_stop(C4X_TIMER_0);
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c4x_timer_set_period(C4X_TIMER_0, 0xffffffff); /* so no interupts */
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c4x_timer_start(C4X_TIMER_0);
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start = c4x_timer_get_counter(C4X_TIMER_0);
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Timer_interrupts = 0;
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/*
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* Somehow start the timer
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*/
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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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int Read_timer( void )
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{
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uint32_t clicks;
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uint32_t total;
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int tmp;
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/*
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* Read the timer and see how many clicks it has been since we started.
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*/
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clicks = c4x_timer_get_counter(C4X_TIMER_0);
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clicks -= start;
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/*
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* Total is calculated by taking into account the number of timer overflow
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* interrupts since the timer was initialized and clicks since the last
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* interrupts.
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*/
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total = clicks * 1;
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if ( Timer_driver_Find_average_overhead == 1 ) {
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return total; /* in count units where each count is */
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/* 1 / (clock frequency/2) */
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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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tmp = (int) ((float) total * ((1.0 / 25.0)));
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return (tmp - AVG_OVERHEAD);
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}
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}
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/*
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* Empty function call used in loops to measure basic cost of looping
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* in Timing Test Suite.
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*/
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rtems_status_code Empty_function( void )
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{
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return RTEMS_SUCCESSFUL;
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}
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void Set_find_average_overhead(
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rtems_boolean find_flag
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)
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{
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Timer_driver_Find_average_overhead = find_flag;
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}
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