1/*
2 * Copyright (c) 2011 Cyril Hrubis <chrubis@suse.cz>
3 *
4 * This file is licensed under the GPL license.  For the full content
5 * of this license, see the COPYING file at the top level of this
6 * source tree.
7 */
8
9/*
10 * Here comes common funcions to correctly compute difference between two
11 * struct timespec values.
12 */
13
14#define NSEC_IN_SEC 1000000000
15
16#ifndef TIME_T_MAX
17#	define TIME_T_MAX	(time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1)
18#endif
19
20/*
21 * Returns difference between two struct timespec values. If difference is
22 * greater that 1 sec, 1 sec is returned.
23 */
24static inline long timespec_nsec_diff(struct timespec *t1, struct timespec *t2)
25{
26	time_t sec_diff;
27	long nsec_diff;
28
29	if (t2->tv_sec > t1->tv_sec) {
30		struct timespec *tmp;
31		tmp = t1;
32		t1  = t2;
33		t2  = tmp;
34	}
35
36	sec_diff  = t1->tv_sec - t2->tv_sec;
37	nsec_diff = t1->tv_nsec - t2->tv_nsec;
38
39	if (sec_diff > 1 || (sec_diff == 1 && nsec_diff >= 0))
40		return NSEC_IN_SEC;
41
42	return labs(nsec_diff + NSEC_IN_SEC * sec_diff);
43}
44