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c8fff863 PE |
1 | /* Convert double to timespec. |
2 | ||
ab422c4d | 3 | Copyright (C) 2011-2013 Free Software Foundation, Inc. |
c8fff863 PE |
4 | |
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. | |
9 | ||
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. | |
14 | ||
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/>. */ | |
17 | ||
18 | /* written by Paul Eggert */ | |
19 | ||
20 | /* Convert the double value SEC to a struct timespec. Round toward | |
21 | positive infinity. On overflow, return an extremal value. */ | |
22 | ||
23 | #include <config.h> | |
24 | ||
25 | #include "timespec.h" | |
26 | ||
27 | #include "intprops.h" | |
28 | ||
29 | struct timespec | |
30 | dtotimespec (double sec) | |
31 | { | |
32 | enum { BILLION = 1000 * 1000 * 1000 }; | |
33 | double min_representable = TYPE_MINIMUM (time_t); | |
34 | double max_representable = | |
35 | ((TYPE_MAXIMUM (time_t) * (double) BILLION + (BILLION - 1)) | |
36 | / BILLION); | |
37 | struct timespec r; | |
38 | ||
39 | if (! (min_representable < sec)) | |
40 | { | |
41 | r.tv_sec = TYPE_MINIMUM (time_t); | |
42 | r.tv_nsec = 0; | |
43 | } | |
44 | else if (! (sec < max_representable)) | |
45 | { | |
46 | r.tv_sec = TYPE_MAXIMUM (time_t); | |
47 | r.tv_nsec = BILLION - 1; | |
48 | } | |
49 | else | |
50 | { | |
51 | time_t s = sec; | |
52 | double frac = BILLION * (sec - s); | |
53 | long ns = frac; | |
54 | ns += ns < frac; | |
55 | s += ns / BILLION; | |
56 | ns %= BILLION; | |
57 | ||
58 | if (ns < 0) | |
59 | { | |
60 | s--; | |
61 | ns += BILLION; | |
62 | } | |
63 | ||
64 | r.tv_sec = s; | |
65 | r.tv_nsec = ns; | |
66 | } | |
67 | ||
68 | return r; | |
69 | } |