forked from Imagelibrary/rtems
79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
/* timer.c
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*
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* This file manages the interval timer on the PowerPC 405.
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* We shall use the bottom 32 bits of the timebase register,
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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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* Author: Andrew Bray <andy@i-cubed.co.uk>
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*
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* COPYRIGHT (c) 1995 by i-cubed ltd.
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*
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* To anyone who acknowledges that this file is provided "AS IS"
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* without any express or implied warranty:
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* permission to use, copy, modify, and distribute this file
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* for any purpose is hereby granted without fee, provided that
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* the above copyright notice and this notice appears in all
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* copies, and that the name of i-cubed limited not be used in
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* advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission.
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* i-cubed limited makes no representations about the suitability
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* of this software for any purpose.
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*
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* Derived from c/src/lib/libcpu/hppa1.1/timer/timer.c:
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*
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* COPYRIGHT (c) 1989-2007.
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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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* Modifications for PPC405GP by Dennis Ehlin
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*
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* Further mods for PPC405EX/EXr by Michael Hamel
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*
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* $Id$
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*
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*/
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#include <rtems.h>
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#include <libcpu/powerpc-utility.h>
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extern uint32_t bsp_timer_least_valid;
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extern uint32_t bsp_timer_average_overhead;
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static volatile uint32_t startedAt;
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static rtems_boolean subtractOverhead;
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void Timer_initialize(void)
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{
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/* We are going to rely on clock.c to sort out where the clock comes from */
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startedAt = ppc_time_base();
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}
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int Read_timer(void)
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{
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uint32_t clicks, total;
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clicks = ppc_time_base();
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total = clicks - startedAt;
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if ( ! subtractOverhead )
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return total; /* in XXX microsecond units */
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else if ( total < bsp_timer_least_valid )
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return 0; /* below timer resolution */
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else
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return (total - bsp_timer_average_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( rtems_boolean find_flag)
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{
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subtractOverhead = find_flag;
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}
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