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/*
* This file implements a benchmark timer using a TX39 timer.
*
* NOTE: On the simulator, the count directly reflects instructions.
*
* COPYRIGHT (c) 1989-2000.
* 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.
*/
#include <assert.h>
#include <bsp.h>
#include <rtems/btimer.h>
bool benchmark_timer_find_average_overhead;
void benchmark_timer_initialize(void)
{
/*
* Programming the compare register as the maximum value should let
* it run long enough and accurate enough not to require an interrupt.
* but if it ever does generate an interrupt, we will simply fault.
*
* NOTE: This is similar to the clock driver initialization
* with the exception that the divider is disabled and
* the compare register is set to the maximum value.
*/
TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_TCR, 0x20 );
TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_CCDR, 0x3 );
TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_TRR, 0x0 );
TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_CPRA, 0xFFFFFFFF );
TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_TISR, 0x00 );
TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_ITMR, 0x0001 );
TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_TCR, 0xe0 );
}
#define AVG_OVERHEAD 0 /* It typically takes N instructions */
/* to start/stop the timer. */
#define LEAST_VALID 1 /* Don't trust a value lower than this */
/* tx39 simulator can count instructions. :) */
uint32_t benchmark_timer_read(void)
{
uint32_t total;
total = TX3904_TIMER_READ( TX3904_TIMER1_BASE, TX3904_TIMER_TRR );
if ( benchmark_timer_find_average_overhead == true )
return total; /* in one microsecond units */
if ( total < LEAST_VALID )
return 0; /* below timer resolution */
return total - AVG_OVERHEAD;
}
void benchmark_timer_disable_subtracting_average_overhead(
bool find_flag
)
{
benchmark_timer_find_average_overhead = find_flag;
}
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