329 lines
9.0 KiB
C
329 lines
9.0 KiB
C
/****************************************************************************
|
|
* examples/calib_udelay/calib_udelay_main.c
|
|
*
|
|
* Copyright (C) 2017 Haltian Ltd All rights reserved.
|
|
* Author: Jussi Kivilinna <jussi.kivilinna@haltian.com>
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* 3. Neither the name NuttX nor the names of its contributors may be
|
|
* used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
#include <time.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <math.h>
|
|
|
|
/****************************************************************************
|
|
* Pre-processor Definitions
|
|
****************************************************************************/
|
|
|
|
#ifndef CONFIG_EXAMPLES_CALIB_UDELAY_NUM_MEASUREMENTS
|
|
# define CONFIG_EXAMPLES_CALIB_UDELAY_NUM_MEASUREMENTS 3
|
|
#endif
|
|
|
|
#ifndef CONFIG_EXAMPLES_CALIB_UDELAY_NUM_RESULTS
|
|
# define CONFIG_EXAMPLES_CALIB_UDELAY_NUM_RESULTS 20
|
|
#endif
|
|
|
|
#define DELAY_TEST_ITERS 100000
|
|
|
|
/****************************************************************************
|
|
* Private Types
|
|
****************************************************************************/
|
|
|
|
struct measurement_s
|
|
{
|
|
int count;
|
|
uint64_t nsecs;
|
|
};
|
|
|
|
/****************************************************************************
|
|
* Private Functions
|
|
****************************************************************************/
|
|
|
|
static uint64_t gettime_nsecs(void)
|
|
{
|
|
struct timespec ts;
|
|
uint64_t nsecs;
|
|
|
|
(void)clock_gettime(CLOCK_MONOTONIC, &ts);
|
|
|
|
nsecs = ts.tv_sec;
|
|
nsecs *= 1000 * 1000 * 1000;
|
|
nsecs += ts.tv_nsec;
|
|
|
|
return nsecs;
|
|
}
|
|
|
|
static int compare_measurements(const void *va, const void *vb)
|
|
{
|
|
const struct measurement_s *a = va;
|
|
const struct measurement_s *b = vb;
|
|
|
|
if (a->nsecs == b->nsecs)
|
|
{
|
|
return 0;
|
|
}
|
|
else if (a->nsecs < b->nsecs)
|
|
{
|
|
return -1;
|
|
}
|
|
else
|
|
{
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
static void __attribute__((noinline)) calib_udelay_test(uint32_t count)
|
|
{
|
|
volatile int i;
|
|
|
|
while (count > 0)
|
|
{
|
|
for (i = 0; i < DELAY_TEST_ITERS; i++)
|
|
{
|
|
}
|
|
|
|
count--;
|
|
}
|
|
}
|
|
|
|
static void perform_measurements(int loop_count,
|
|
FAR struct measurement_s *measurements,
|
|
int num_measurements)
|
|
{
|
|
int n;
|
|
|
|
memset(measurements, 0, sizeof(*measurements) * num_measurements);
|
|
|
|
for (n = 0; n < num_measurements; n++)
|
|
{
|
|
measurements[n].nsecs = gettime_nsecs();
|
|
calib_udelay_test(loop_count);
|
|
measurements[n].nsecs = gettime_nsecs() - measurements[n].nsecs;
|
|
measurements[n].count = loop_count;
|
|
}
|
|
|
|
qsort(measurements, num_measurements, sizeof(measurements[0]),
|
|
compare_measurements);
|
|
}
|
|
|
|
static double getx(FAR struct measurement_s *point)
|
|
{
|
|
return point->count * (double)DELAY_TEST_ITERS;
|
|
}
|
|
|
|
static double gety(struct measurement_s *point)
|
|
{
|
|
return point->nsecs;
|
|
}
|
|
|
|
static int linreg(FAR struct measurement_s *point, int num_points,
|
|
FAR double *m, FAR double *b, FAR double *r2)
|
|
{
|
|
double sumx = 0.0;
|
|
double sumx2 = 0.0;
|
|
double sumxy = 0.0;
|
|
double sumy = 0.0;
|
|
double sumy2 = 0.0;
|
|
double x;
|
|
double y;
|
|
double denom;
|
|
double inv_denom;
|
|
int i;
|
|
|
|
for (i = 0; i < num_points; i++)
|
|
{
|
|
x = getx(point + i);
|
|
y = gety(point + i);
|
|
sumx += x;
|
|
sumx2 += x * x;
|
|
sumxy += x * y;
|
|
sumy += y;
|
|
sumy2 += y * y;
|
|
}
|
|
|
|
denom = num_points * sumx2 - sumx * sumx;
|
|
if (denom == 0)
|
|
{
|
|
*m = 0;
|
|
*b = 0;
|
|
|
|
if (r2)
|
|
{
|
|
*r2 = 0;
|
|
}
|
|
|
|
return ERROR;
|
|
}
|
|
|
|
inv_denom = 1.0 / denom;
|
|
|
|
*m = ((num_points * sumxy) - (sumx * sumy)) * inv_denom;
|
|
*b = ((sumy * sumx2) - (sumx * sumxy)) * inv_denom;
|
|
|
|
if (r2)
|
|
{
|
|
double term1 = ((num_points * sumxy) - (sumx * sumy));
|
|
double term2 = ((num_points * sumx2) - (sumx * sumx));
|
|
double term3 = ((num_points * sumy2) - (sumy * sumy));
|
|
double term23 = (term2 * term3);
|
|
|
|
*r2 = 1.0;
|
|
if (fabs(term23) > 1e-10)
|
|
{
|
|
*r2 = (term1 * term1) / term23;
|
|
}
|
|
}
|
|
|
|
return OK;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* calib_udelay_main
|
|
****************************************************************************/
|
|
|
|
#ifdef CONFIG_BUILD_KERNEL
|
|
int main(int argc, FAR char *argv[])
|
|
#else
|
|
int calib_udelay_main(int argc, char *argv[])
|
|
#endif
|
|
{
|
|
const int num_measurements = CONFIG_EXAMPLES_CALIB_UDELAY_NUM_MEASUREMENTS;
|
|
const int num_results = CONFIG_EXAMPLES_CALIB_UDELAY_NUM_RESULTS;
|
|
const int min_timer_resolution_steps = 3;
|
|
const int calibration_step_multiplier = 10;
|
|
struct measurement_s measurements[num_measurements];
|
|
struct measurement_s result;
|
|
struct measurement_s results[num_results];
|
|
double iters_per_nsec;
|
|
double iters_per_msec;
|
|
uint64_t timer_resolution;
|
|
double slope_m, slope_b, slope_r2;
|
|
int min_step;
|
|
int loop_count;
|
|
double duration;
|
|
int i;
|
|
|
|
printf("\n");
|
|
|
|
sched_lock();
|
|
|
|
printf("Calibrating timer for main calibration...\n");
|
|
usleep(200 * 1000);
|
|
|
|
/* Find out timer resolution. */
|
|
|
|
loop_count = 0;
|
|
do
|
|
{
|
|
loop_count++;
|
|
perform_measurements(loop_count, measurements, num_measurements);
|
|
result = measurements[0];
|
|
}
|
|
while (result.nsecs == 0);
|
|
|
|
timer_resolution = result.nsecs;
|
|
|
|
/* Find first loop count where timer steps five times. */
|
|
|
|
do
|
|
{
|
|
loop_count++;
|
|
perform_measurements(loop_count, measurements, num_measurements);
|
|
result = measurements[0];
|
|
}
|
|
while (result.nsecs < timer_resolution * min_timer_resolution_steps);
|
|
|
|
min_step = result.count;
|
|
|
|
/* Get calibration slope for loop function. */
|
|
|
|
for (duration = 0, loop_count = min_step, i = 0; i < num_results; i++,
|
|
loop_count += min_step * calibration_step_multiplier)
|
|
{
|
|
duration += (double)num_measurements * loop_count *
|
|
timer_resolution * min_timer_resolution_steps / min_step;
|
|
}
|
|
|
|
printf("Performing main calibration for udelay. This will take approx. %.3f seconds.\n",
|
|
duration * 1e-9);
|
|
usleep(200 * 1000);
|
|
|
|
for (loop_count = min_step, i = 0; i < num_results; i++,
|
|
loop_count += min_step * calibration_step_multiplier)
|
|
{
|
|
perform_measurements(loop_count, measurements, num_measurements);
|
|
results[i] = measurements[0];
|
|
}
|
|
|
|
if (linreg(results, num_results, &slope_m, &slope_b, &slope_r2) == OK)
|
|
{
|
|
printf("Calibration slope for udelay:\n"
|
|
" Y = m*X + b, where\n"
|
|
" X is loop iterations,\n"
|
|
" Y is time in nanoseconds,\n"
|
|
" b is base overhead,\n"
|
|
" m is nanoseconds per loop iteration.\n\n"
|
|
|
|
" m = %.08f nsec/iter\n"
|
|
" b = %.08f nsec\n\n"
|
|
|
|
" Correlation coefficient, R² = %.4f\n\n",
|
|
slope_m, slope_b, slope_r2);
|
|
|
|
iters_per_nsec = (1.0 / slope_m);
|
|
iters_per_msec = iters_per_nsec * 1000 * 1000;
|
|
|
|
printf("Without overhead, %.8f iterations per nanosecond and %.2f "
|
|
"iterations per millisecond.\n\n",
|
|
iters_per_nsec, iters_per_msec);
|
|
|
|
printf("Recommended setting for CONFIG_BOARD_LOOPSPERMSEC:\n"
|
|
" CONFIG_BOARD_LOOPSPERMSEC=%.0f\n", ceil(iters_per_msec));
|
|
}
|
|
else
|
|
{
|
|
printf("cannot solve\n");
|
|
}
|
|
|
|
sched_unlock();
|
|
return 0;
|
|
}
|