1 /* Subtract two struct timespec values.
3 Copyright (C) 2011-2021 Free Software Foundation, Inc.
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
18 /* Written by Paul Eggert. */
20 /* Return the difference between two timespec values A and B. On
21 overflow, return an extremal value. This assumes 0 <= tv_nsec <
30 timespec_sub (struct timespec a, struct timespec b)
34 int ns = a.tv_nsec - b.tv_nsec;
39 rns = ns + TIMESPEC_HZ;
41 if (!INT_ADD_WRAPV (bs, 1, &bs1))
43 else if (- TYPE_SIGNED (time_t) < rs)
49 if (INT_SUBTRACT_WRAPV (rs, bs, &rs))
54 rs = TYPE_MINIMUM (time_t);
59 rs = TYPE_MAXIMUM (time_t);
60 rns = TIMESPEC_HZ - 1;
64 return make_timespec (rs, rns);