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fd26970f UD |
1 | /* Copyright (C) 1991, 1993, 1997 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. | |
28f540f4 | 3 | |
fd26970f UD |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Library General Public License as | |
6 | published by the Free Software Foundation; either version 2 of the | |
7 | License, or (at your option) any later version. | |
28f540f4 | 8 | |
fd26970f UD |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | Library General Public License for more details. | |
28f540f4 | 13 | |
fd26970f UD |
14 | You should have received a copy of the GNU Library General Public |
15 | License along with the GNU C Library; see the file COPYING.LIB. If not, | |
16 | write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
17 | Boston, MA 02111-1307, USA. */ | |
28f540f4 | 18 | |
28f540f4 RM |
19 | #include <time.h> |
20 | ||
28f540f4 | 21 | /* Defined in mktime.c. */ |
fd26970f | 22 | extern const unsigned short int __mon_yday[2][13]; |
28f540f4 RM |
23 | |
24 | #define SECS_PER_HOUR (60 * 60) | |
25 | #define SECS_PER_DAY (SECS_PER_HOUR * 24) | |
26 | ||
c2216480 RM |
27 | /* Compute the `struct tm' representation of *T, |
28 | offset OFFSET seconds east of UTC, | |
29 | and store year, yday, mon, mday, wday, hour, min, sec into *TP. */ | |
30 | void | |
fd26970f UD |
31 | __offtime (t, offset, tp) |
32 | const time_t *t; | |
33 | long int offset; | |
34 | struct tm *tp; | |
28f540f4 | 35 | { |
9a0a462c UD |
36 | long int days, rem, y; |
37 | const unsigned short int *ip; | |
28f540f4 | 38 | |
28f540f4 RM |
39 | days = *t / SECS_PER_DAY; |
40 | rem = *t % SECS_PER_DAY; | |
41 | rem += offset; | |
42 | while (rem < 0) | |
43 | { | |
44 | rem += SECS_PER_DAY; | |
45 | --days; | |
46 | } | |
47 | while (rem >= SECS_PER_DAY) | |
48 | { | |
49 | rem -= SECS_PER_DAY; | |
50 | ++days; | |
51 | } | |
c2216480 | 52 | tp->tm_hour = rem / SECS_PER_HOUR; |
28f540f4 | 53 | rem %= SECS_PER_HOUR; |
c2216480 RM |
54 | tp->tm_min = rem / 60; |
55 | tp->tm_sec = rem % 60; | |
28f540f4 | 56 | /* January 1, 1970 was a Thursday. */ |
c2216480 RM |
57 | tp->tm_wday = (4 + days) % 7; |
58 | if (tp->tm_wday < 0) | |
59 | tp->tm_wday += 7; | |
28f540f4 | 60 | y = 1970; |
b20e47cb | 61 | |
fd26970f | 62 | #define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400) |
b20e47cb RM |
63 | |
64 | while (days < 0 || days >= (__isleap (y) ? 366 : 365)) | |
28f540f4 | 65 | { |
b20e47cb | 66 | /* Guess a corrected year, assuming 365 days per year. */ |
e61abf83 | 67 | long int yg = y + days / 365 - (days % 365 < 0); |
b20e47cb RM |
68 | |
69 | /* Adjust DAYS and Y to match the guessed year. */ | |
70 | days -= ((yg - y) * 365 | |
71 | + LEAPS_THRU_END_OF (yg - 1) | |
72 | - LEAPS_THRU_END_OF (y - 1)); | |
73 | y = yg; | |
28f540f4 | 74 | } |
c2216480 RM |
75 | tp->tm_year = y - 1900; |
76 | tp->tm_yday = days; | |
80fd7387 | 77 | ip = __mon_yday[__isleap(y)]; |
9a0a462c | 78 | for (y = 11; days < (long int) ip[y]; --y) |
80fd7387 RM |
79 | continue; |
80 | days -= ip[y]; | |
c2216480 RM |
81 | tp->tm_mon = y; |
82 | tp->tm_mday = days + 1; | |
28f540f4 | 83 | } |