1 /* Add two struct timespec values.
3 Copyright (C) 2011-2016 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 <http://www.gnu.org/licenses/>. */
18 /* Written by Paul Eggert. */
20 /* Return the sum of two timespec values A and B. On overflow, return
21 an extremal value. This assumes 0 <= tv_nsec < TIMESPEC_RESOLUTION. */
29 timespec_add (struct timespec a, struct timespec b)
33 int ns = a.tv_nsec + b.tv_nsec;
34 int nsd = ns - TIMESPEC_RESOLUTION;
36 time_t tmin = TYPE_MINIMUM (time_t);
37 time_t tmax = TYPE_MAXIMUM (time_t);
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)
66 rns = TIMESPEC_RESOLUTION - 1;
70 return make_timespec (rs, rns);