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0aee2be50e
* mpc5xx/.cvsignore, mpc5xx/Makefile.am: New. * mpc5xx/exceptions/asm_utils.S, mpc5xx/exceptions/raw_exception.c, mpc5xx/exceptions/raw_exception.h, mpc5xx/ictrl/ictrl.c, mpc5xx/ictrl/ictrl.h, mpc5xx/timer/timer.c: New (Submission from Wilfried Busalski <w.busalski@lancier-monitoring.de>).
71 lines
2.0 KiB
C
71 lines
2.0 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, 1990, 1991, 1992, 1993, 1994.
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* On-Line Applications Research Corporation (OAR).
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* All rights assigned to U.S. Government, 1994.
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*
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* This material may be reproduced by or for the U.S. Government pursuant
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* to the copyright license under the clause at DFARS 252.227-7013. This
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* notice must appear in all copies of this file and its derivatives.
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*
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* timer.c,v 1.2 1995/05/31 16:56:39 joel Exp
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*/
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#include <rtems.h>
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rtems_boolean Timer_driver_Find_average_overhead;
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static unsigned int volatile lastInitValue;
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void Timer_initialize( void )
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{
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asm volatile( " mftb %0": "=r" (lastInitValue) );
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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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rtems_unsigned32 value;
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asm volatile ( " mftb %0": "=r" (value) );
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return value - lastInitValue;
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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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