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/* Timer_init()
*
* This routine initializes a timer in efi68k's DP8570A TCP
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* NOTE: It is important that the timer start/stop overhead be
* determined when porting or modifying this code.
*
* COPYRIGHT (c) 1989-1999.
* 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.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <bsp.h>
rtems_boolean Timer_driver_Find_average_overhead;
extern rtems_isr Clock_isr();
void Timer_initialize( void )
{
}
/*
* The following controls the behavior of Read_timer().
*
* FIND_AVG_OVERHEAD * instructs the routine to return the "raw" count.
*
* AVG_OVEREHAD is the overhead for starting and stopping the timer. It
* is usually deducted from the number returned.
*
* LEAST_VALID is the lowest number this routine should trust. Numbers
* below this are "noise" and zero is returned.
*/
#define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */
/* (Y countdowns) to start/stop the timer. */
/* This value is in microseconds. */
#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */
/*
* Return timer value in 1/2-microsecond units
*/
int Read_timer( void )
{
rtems_unsigned32 total;
total = 0;
if ( Timer_driver_Find_average_overhead == 1 )
return total; /* in XXX microsecond units */
if ( total < LEAST_VALID )
return 0; /* below timer resolution */
return (total - AVG_OVERHEAD);
}
/*
* Empty function call used in loops to measure basic cost of looping
* in Timing Test Suite.
*/
rtems_status_code Empty_function(void)
{
return RTEMS_SUCCESSFUL;
}
void Set_find_average_overhead(
rtems_boolean find_flag
)
{
Timer_driver_Find_average_overhead = find_flag;
}
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