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