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0458ed8c JG |
1 | /* |
2 | * Copyright (C) - 2015 Jérémie Galarneau <jeremie.galarneau@efficios.com> | |
3 | * | |
4 | * This library is free software; you can redistribute it and/or modify it | |
5 | * under the terms of the GNU Lesser General Public License as published by the | |
6 | * Free Software Foundation; version 2.1 of the License. | |
7 | * | |
8 | * This library is distributed in the hope that it will be useful, but WITHOUT | |
9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License | |
11 | * for more details. | |
12 | * | |
13 | * You should have received a copy of the GNU Lesser General Public License | |
14 | * along with this library; if not, write to the Free Software Foundation, | |
15 | * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
16 | */ | |
17 | ||
18 | #include <stdint.h> | |
19 | #include <time.h> | |
20 | #include <assert.h> | |
21 | #include <unistd.h> | |
22 | #include <stdio.h> | |
23 | #include <errno.h> | |
24 | ||
25 | #define NSEC_PER_SEC 1000000000ULL | |
26 | #define NSEC_PER_USEC 1000ULL | |
27 | ||
28 | static inline | |
29 | int64_t elapsed_time_ns(struct timespec *t1, struct timespec *t2) | |
30 | { | |
31 | struct timespec delta; | |
32 | ||
33 | assert(t1 && t2); | |
34 | delta.tv_sec = t2->tv_sec - t1->tv_sec; | |
35 | delta.tv_nsec = t2->tv_nsec - t1->tv_nsec; | |
36 | return ((int64_t) NSEC_PER_SEC * (int64_t) delta.tv_sec) + | |
37 | (int64_t) delta.tv_nsec; | |
38 | } | |
39 | ||
40 | int usleep_safe(useconds_t usec) | |
41 | { | |
42 | int ret = 0; | |
43 | struct timespec t1, t2; | |
44 | int64_t time_remaining_ns = (int64_t) usec * (int64_t) NSEC_PER_USEC; | |
45 | ||
46 | ret = clock_gettime(CLOCK_MONOTONIC, &t1); | |
47 | if (ret) { | |
48 | ret = -1; | |
49 | perror("clock_gettime"); | |
50 | goto end; | |
51 | } | |
52 | ||
53 | while (time_remaining_ns > 0) { | |
54 | ret = usleep(time_remaining_ns / (int64_t) NSEC_PER_USEC); | |
55 | if (ret && errno != EINTR) { | |
56 | perror("usleep"); | |
57 | goto end; | |
58 | } | |
59 | ||
60 | ret = clock_gettime(CLOCK_MONOTONIC, &t2); | |
61 | if (ret) { | |
62 | perror("clock_gettime"); | |
63 | goto end; | |
64 | } | |
65 | ||
66 | time_remaining_ns -= elapsed_time_ns(&t1, &t2); | |
67 | } | |
68 | end: | |
69 | return ret; | |
70 | } |