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/* Timer_init()
*
* This routine initializes the MC68230 timer on the Motorola IDP board.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* NOTE: This routine will not work if the optimizer is enabled
* for some compilers. The multiple writes to the MC68230
* may be optimized away.
*
* It is important that the timer start/stop overhead be
* determined when porting or modifying this code.
*
* Code Modified for the MC68230 by Doug McBride, Colorado Space Grant College
*
* 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.rtems.com/license/LICENSE.
*
* $Id$
*/
#include <rtems.h>
#include <bsp.h>
#include <rtems/motorola/mc68230.h>
#define TIMER_VECTOR 0x4D
int Ttimer_val;
bool benchmark_timer_find_average_overhead;
rtems_isr timerisr(void);
void benchmark_timer_initialize(void)
{
(void) set_vector( timerisr, TIMER_VECTOR, 0 ); /* install ISR */
Ttimer_val = 0; /* clear timer ISR count */
/* some PI/T initialization stuff here */
/* Set up the interrupt vector on the MC68230 chip:
TIVR = TIMER_VECTOR; */
MC68230_WRITE (MC68230_TIVR, TIMER_VECTOR);
/* Set CPRH through CPRL to maximum count to reduce interrupt overhead
CPRH = 0xFF;
CPRM = 0xFF;
CPRL = 0xFF; */
MC68230_WRITE (MC68230_CPRH, 0xFF);
MC68230_WRITE (MC68230_CPRM, 0xFF);
MC68230_WRITE (MC68230_CPRL, 0xFF);
/* Enable timer and use it as an external periodic interrupt generator
TCR = 0xA1; */
MC68230_WRITE (MC68230_TCR, 0xA1);
}
#define AVG_OVERHEAD 9 /* may not be right -- do this later */
#define LEAST_VALID 10 /* Don't trust a value lower than this */
int benchmark_timer_read(void)
{
uint8_t data;
uint8_t msb, osb, lsb;
uint32_t remaining, total;
/* Disable timer so that timer can be read
data = MC68230_TCR;
MC68230_TCR = (data & 0xFE); */
MC68230_READ (MC68230_TCR, data);
MC68230_WRITE (MC68230_TCR, (data & 0xFE));
/* Read the counter value
msb = MC68230_CNTRH;
osb = MC68230_CNTRM;
lsb = MC68230_CNTRL; */
MC68230_READ (MC68230_CNTRH, msb);
MC68230_READ (MC68230_CNTRM, osb);
MC68230_READ (MC68230_CNTRL, lsb);
/* Calculate the time so far */
remaining = 0x1000000 - ((msb << 16) + (osb << 8) + lsb);
total = (Ttimer_val * 0x1000000) + remaining;
/* Enable timer so that timer can continue
MC68230_TCR = 0xA1; */
MC68230_WRITE (MC68230_TCR, 0xA1);
/* do not restore old vector */
if ( benchmark_timer_find_average_overhead == true )
return total; /* in countdown units */
if ( total < LEAST_VALID )
return 0; /* below timer resolution */
/* Clocked at 6.5 Mhz */
/* Avoid floating point problems, be lazy, and return the total minus
the average overhead */
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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