1 /* Subtract two struct timespec values.
2 Copyright (C) 2011-2023 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.
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.
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.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
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 (struct timespec) { .tv_sec = rs, .tv_nsec = rns };