test_time.c
3.56 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
/****************************************************************************
*
* Copyright (C) 2012-2019 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.
*
****************************************************************************/
/**
* @file test_time.c
* Tests clocks/timekeeping.
*/
#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/defines.h>
#include <px4_platform_common/posix.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include "tests_main.h"
#include <math.h>
#include <float.h>
#include <drivers/drv_hrt.h>
static hrt_abstime
cycletime(void)
{
/* emulate hrt_absolute_time using the cycle counter */
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 */
}
int test_time(int argc, char *argv[])
{
hrt_abstime h, c;
int lowdelta, maxdelta = 0;
int 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 = px4_enter_critical_section();
h = hrt_absolute_time();
c = cycletime();
px4_leave_critical_section(flags);
delta += h - c;
}
lowdelta = abs(delta / 100);
/* loop checking the time */
for (unsigned i = 0; i < 100; i++) {
usleep(rand() % SHRT_MAX);
uint32_t flags = px4_enter_critical_section();
c = cycletime();
h = hrt_absolute_time();
px4_leave_critical_section(flags);
delta = h - c;
deltadelta = abs(delta - lowdelta);
if (deltadelta > maxdelta) {
maxdelta = deltadelta;
}
if (deltadelta > 1000) {
fprintf(stderr, "h %" PRIu64 " c %" PRIu64 " d %d\n", h, c, delta - lowdelta);
}
}
printf("Maximum jitter %" PRId64 "us\n", maxdelta);
return 0;
}