]>
Commit | Line | Data |
---|---|---|
28f540f4 RM |
1 | /* Copyright (C) 1991, 1993 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. | |
3 | ||
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. | |
8 | ||
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. | |
13 | ||
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 | |
16 | not, write to the Free Software Foundation, Inc., 675 Mass Ave, | |
17 | Cambridge, MA 02139, USA. */ | |
18 | ||
19 | #include <ansidecl.h> | |
20 | #include <time.h> | |
21 | ||
22 | ||
23 | /* Defined in mktime.c. */ | |
24 | extern CONST unsigned short int __mon_lengths[2][12]; | |
25 | ||
26 | #define SECS_PER_HOUR (60 * 60) | |
27 | #define SECS_PER_DAY (SECS_PER_HOUR * 24) | |
28 | ||
29 | /* Returns the `struct tm' representation of *T, | |
30 | offset OFFSET seconds east of UCT. */ | |
31 | struct tm * | |
32 | DEFUN(__offtime, (t, offset), CONST time_t *t AND long int offset) | |
33 | { | |
34 | static struct tm tbuf; | |
35 | register long int days, rem; | |
36 | register int y; | |
37 | register CONST unsigned short int *ip; | |
38 | ||
39 | if (t == NULL) | |
40 | return NULL; | |
41 | ||
42 | days = *t / SECS_PER_DAY; | |
43 | rem = *t % SECS_PER_DAY; | |
44 | rem += offset; | |
45 | while (rem < 0) | |
46 | { | |
47 | rem += SECS_PER_DAY; | |
48 | --days; | |
49 | } | |
50 | while (rem >= SECS_PER_DAY) | |
51 | { | |
52 | rem -= SECS_PER_DAY; | |
53 | ++days; | |
54 | } | |
55 | tbuf.tm_hour = rem / SECS_PER_HOUR; | |
56 | rem %= SECS_PER_HOUR; | |
57 | tbuf.tm_min = rem / 60; | |
58 | tbuf.tm_sec = rem % 60; | |
59 | /* January 1, 1970 was a Thursday. */ | |
60 | tbuf.tm_wday = (4 + days) % 7; | |
61 | if (tbuf.tm_wday < 0) | |
62 | tbuf.tm_wday += 7; | |
63 | y = 1970; | |
64 | while (days >= (rem = __isleap(y) ? 366 : 365)) | |
65 | { | |
66 | ++y; | |
67 | days -= rem; | |
68 | } | |
69 | while (days < 0) | |
70 | { | |
71 | --y; | |
72 | days += __isleap(y) ? 366 : 365; | |
73 | } | |
74 | tbuf.tm_year = y - 1900; | |
75 | tbuf.tm_yday = days; | |
76 | ip = __mon_lengths[__isleap(y)]; | |
77 | for (y = 0; days >= ip[y]; ++y) | |
78 | days -= ip[y]; | |
79 | tbuf.tm_mon = y; | |
80 | tbuf.tm_mday = days + 1; | |
81 | tbuf.tm_isdst = -1; | |
82 | ||
83 | return &tbuf; | |
84 | } |