1/*
2 * util/timeval_func.c - helpers to work with struct timeval values.
3 *
4 * Copyright (c) 2023, NLnet Labs. All rights reserved.
5 *
6 * This software is open source.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36/**
37 * \file
38 *
39 * This file contains helpers to manipulate struct timeval values.
40 */
41
42#include "config.h"
43#include "timeval_func.h"
44
45/** subtract timers and the values do not overflow or become negative */
46void
47timeval_subtract(struct timeval* d, const struct timeval* end, const struct timeval* start)
48{
49#ifndef S_SPLINT_S
50	time_t end_usec = end->tv_usec;
51	d->tv_sec = end->tv_sec - start->tv_sec;
52	if(end_usec < start->tv_usec) {
53		end_usec += 1000000;
54		d->tv_sec--;
55	}
56	d->tv_usec = end_usec - start->tv_usec;
57#endif
58}
59
60/** add timers and the values do not overflow or become negative */
61void
62timeval_add(struct timeval* d, const struct timeval* add)
63{
64#ifndef S_SPLINT_S
65	d->tv_sec += add->tv_sec;
66	d->tv_usec += add->tv_usec;
67	if(d->tv_usec >= 1000000 ) {
68		d->tv_usec -= 1000000;
69		d->tv_sec++;
70	}
71#endif
72}
73
74/** divide sum of timers to get average */
75void
76timeval_divide(struct timeval* avg, const struct timeval* sum, long long d)
77{
78#ifndef S_SPLINT_S
79	long long leftover;
80	if(d <= 0) {
81		avg->tv_sec = 0;
82		avg->tv_usec = 0;
83		return;
84	}
85	avg->tv_sec = sum->tv_sec / d;
86	avg->tv_usec = sum->tv_usec / d;
87	/* handle fraction from seconds divide */
88	leftover = sum->tv_sec - avg->tv_sec*d;
89	if(leftover <= 0)
90		leftover = 0;
91	avg->tv_usec += (((long long)leftover)*((long long)1000000))/d;
92	if(avg->tv_sec < 0)
93		avg->tv_sec = 0;
94	if(avg->tv_usec < 0)
95		avg->tv_usec = 0;
96#endif
97}
98
99/** histogram compare of time values */
100int
101timeval_smaller(const struct timeval* x, const struct timeval* y)
102{
103#ifndef S_SPLINT_S
104	if(x->tv_sec < y->tv_sec)
105		return 1;
106	else if(x->tv_sec == y->tv_sec) {
107		if(x->tv_usec <= y->tv_usec)
108			return 1;
109		else	return 0;
110	}
111	else	return 0;
112#endif
113}
114