forked from Imagelibrary/rtems
94 lines
2.3 KiB
C
94 lines
2.3 KiB
C
/* timer.c
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*
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* This file implements a benchmark timer using the General Purpose Timer on
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* the MEC.
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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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* Ported to ERC32 implementation of the SPARC by On-Line Applications
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* Research Corporation (OAR) under contract to the European Space
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* Agency (ESA).
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*
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* ERC32 modifications of respective RTEMS file: COPYRIGHT (c) 1995.
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* European Space Agency.
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*
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* $Id$
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*/
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#include <bsp.h>
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rtems_boolean Timer_driver_Find_average_overhead;
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rtems_boolean Timer_driver_Is_initialized = FALSE;
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void Timer_initialize(void)
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{
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/*
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* Timer runs long and accurate enough not to require an interrupt.
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*/
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if ( Timer_driver_Is_initialized == FALSE ) {
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/* approximately 1 us per countdown */
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ERC32_MEC.General_Purpose_Timer_Scalar = CLOCK_SPEED - 1;
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ERC32_MEC.General_Purpose_Timer_Counter = 0xffffffff;
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} else {
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Timer_driver_Is_initialized = TRUE;
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}
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ERC32_MEC_Set_General_Purpose_Timer_Control(
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ERC32_MEC_TIMER_COUNTER_ENABLE_COUNTING |
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ERC32_MEC_TIMER_COUNTER_LOAD_COUNTER
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);
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ERC32_MEC_Set_General_Purpose_Timer_Control(
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ERC32_MEC_TIMER_COUNTER_ENABLE_COUNTING
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);
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}
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#if ENABLE_SIS_QUIRKS
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#define AVG_OVERHEAD 8 /* It typically takes 3.0 microseconds */
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/* to start/stop the timer. */
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#define LEAST_VALID 9 /* Don't trust a value lower than this */
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#else
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#define AVG_OVERHEAD 12 /* It typically takes 3.0 microseconds */
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/* to start/stop the timer. */
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#define LEAST_VALID 13 /* Don't trust a value lower than this */
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#endif
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int Read_timer(void)
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{
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uint32_t total;
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total = ERC32_MEC.General_Purpose_Timer_Counter;
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total = 0xffffffff - total;
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if ( Timer_driver_Find_average_overhead == 1 )
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return total; /* in one microsecond units */
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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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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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