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51983996 | 1 | /* Subtract two struct timespec values. |
2b778ceb | 2 | Copyright (C) 2011-2021 Free Software Foundation, Inc. |
51983996 MC |
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 difference between two timespec values A and B. On | |
21 | overflow, return an extremal value. This assumes 0 <= tv_nsec < | |
22 | TIMESPEC_HZ. */ | |
23 | ||
24 | #include <config.h> | |
25 | #include "timespec.h" | |
26 | ||
27 | #include "intprops.h" | |
28 | ||
29 | struct timespec | |
30 | timespec_sub (struct timespec a, struct timespec b) | |
31 | { | |
32 | time_t rs = a.tv_sec; | |
33 | time_t bs = b.tv_sec; | |
34 | int ns = a.tv_nsec - b.tv_nsec; | |
35 | int rns = ns; | |
51983996 MC |
36 | |
37 | if (ns < 0) | |
38 | { | |
39 | rns = ns + TIMESPEC_HZ; | |
c1dac8f8 AZ |
40 | time_t bs1; |
41 | if (!INT_ADD_WRAPV (bs, 1, &bs1)) | |
42 | bs = bs1; | |
51983996 MC |
43 | else if (- TYPE_SIGNED (time_t) < rs) |
44 | rs--; | |
45 | else | |
46 | goto low_overflow; | |
47 | } | |
48 | ||
c1dac8f8 | 49 | if (INT_SUBTRACT_WRAPV (rs, bs, &rs)) |
51983996 | 50 | { |
c1dac8f8 | 51 | if (0 < bs) |
51983996 MC |
52 | { |
53 | low_overflow: | |
c1dac8f8 | 54 | rs = TYPE_MINIMUM (time_t); |
51983996 MC |
55 | rns = 0; |
56 | } | |
57 | else | |
58 | { | |
c1dac8f8 | 59 | rs = TYPE_MAXIMUM (time_t); |
51983996 MC |
60 | rns = TIMESPEC_HZ - 1; |
61 | } | |
62 | } | |
63 | ||
e9bc2b3b | 64 | return (struct timespec) { .tv_sec = rs, .tv_nsec = rns }; |
51983996 | 65 | } |