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51983996 MC |
1 | /* Add two struct timespec values. |
2 | Copyright (C) 2011-2019 Free Software Foundation, Inc. | |
3 | This file is part of the GNU C Library and is also part of gnulib. | |
4 | Patches to this file should be submitted to both projects. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Lesser General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public | |
17 | License along with the GNU C Library; if not, see | |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
51983996 MC |
19 | |
20 | /* Return the sum of two timespec values A and B. On overflow, return | |
21 | an extremal value. This assumes 0 <= tv_nsec < TIMESPEC_HZ. */ | |
22 | ||
23 | #include <config.h> | |
24 | #include "timespec.h" | |
25 | ||
26 | #include "intprops.h" | |
27 | ||
28 | struct timespec | |
29 | timespec_add (struct timespec a, struct timespec b) | |
30 | { | |
31 | time_t rs = a.tv_sec; | |
32 | time_t bs = b.tv_sec; | |
33 | int ns = a.tv_nsec + b.tv_nsec; | |
34 | int nsd = ns - TIMESPEC_HZ; | |
35 | int rns = ns; | |
36 | time_t tmin = TYPE_MINIMUM (time_t); | |
37 | time_t tmax = TYPE_MAXIMUM (time_t); | |
38 | ||
39 | if (0 <= nsd) | |
40 | { | |
41 | rns = nsd; | |
42 | if (bs < tmax) | |
43 | bs++; | |
44 | else if (rs < 0) | |
45 | rs++; | |
46 | else | |
47 | goto high_overflow; | |
48 | } | |
49 | ||
50 | /* INT_ADD_WRAPV is not appropriate since time_t might be unsigned. | |
51 | In theory time_t might be narrower than int, so plain | |
52 | INT_ADD_OVERFLOW does not suffice. */ | |
53 | if (! INT_ADD_OVERFLOW (rs, bs) && tmin <= rs + bs && rs + bs <= tmax) | |
54 | rs += bs; | |
55 | else | |
56 | { | |
57 | if (rs < 0) | |
58 | { | |
59 | rs = tmin; | |
60 | rns = 0; | |
61 | } | |
62 | else | |
63 | { | |
64 | high_overflow: | |
65 | rs = tmax; | |
66 | rns = TIMESPEC_HZ - 1; | |
67 | } | |
68 | } | |
69 | ||
70 | return make_timespec (rs, rns); | |
71 | } |