px4-firmware/apps/px4/tests/test_time.c

161 lines
4.9 KiB
C

/****************************************************************************
* px4/tests/test_time.c
*
* Copyright (C) 2012 PX4 Development Team. All rights reserved.
*
* 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 PX4 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 <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <debug.h>
#include <arch/board/board.h>
#include "tests.h"
#include <math.h>
#include <float.h>
#include <drivers/drv_hrt.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/* emulate hrt_absolute_time using the cycle counter */
static hrt_abstime
cycletime(void)
{
static uint64_t basetime;
static uint32_t lasttime;
uint32_t cycles;
cycles = *(unsigned long *)0xe0001004;
if (cycles < lasttime)
basetime += 0x100000000ULL;
lasttime = cycles;
return (basetime + cycles) / 168; /* XXX magic number */
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: test_led
****************************************************************************/
int test_time(int argc, char *argv[])
{
hrt_abstime h, c;
int64_t lowdelta, maxdelta = 0;
int64_t delta, deltadelta;
/* enable the cycle counter */
(*(unsigned long *)0xe000edfc) |= (1 << 24); /* DEMCR |= DEMCR_TRCENA */
(*(unsigned long *)0xe0001000) |= 1; /* DWT_CTRL |= DWT_CYCCNT_ENA */
/* get an average delta between the two clocks - this should stay roughly the same */
delta = 0;
for (unsigned i = 0; i < 100; i++) {
uint32_t flags = irqsave();
h = hrt_absolute_time();
c = cycletime();
irqrestore(flags);
delta += h - c;
}
lowdelta = abs(delta / 100);
/* loop checking the time */
for (unsigned i = 0; i < 100; i++) {
usleep(rand());
uint32_t flags = irqsave();
c = cycletime();
h = hrt_absolute_time();
irqrestore(flags);
delta = abs(h - c);
deltadelta = abs(delta - lowdelta);
if (deltadelta > maxdelta)
maxdelta = deltadelta;
if (deltadelta > 1000)
fprintf(stderr, "h %llu c %llu d %lld\n", h, c, delta - lowdelta);
}
printf("Maximum jitter %lldus\n", maxdelta);
return 0;
}