2 * Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
3 * This file is part of the GNU C Library.
4 * Contributed by Paul Eggert (eggert@twinsun.com).
6 * The GNU C Library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public License as
8 * published by the Free Software Foundation; either version 2 of the
9 * 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 * Library General Public License for more details.
16 * You should have received a copy of the GNU Library General Public
17 * License along with the GNU C Library; see the file COPYING.LIB. If not,
18 * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 02111-1307, USA.
23 * Converts the calendar time to broken-down time representation
24 * Based on code from glibc-2.6
27 * Moved from glibc-2.6 to kernel by Zhaolei<zhaolei@cn.fujitsu.com>
30 #include <linux/time.h>
31 #include <linux/module.h>
34 * Nonzero if YEAR is a leap year (every 4 years,
35 * except every 100th isn't, and every 400th is).
37 static int __isleap(long year
)
39 return (year
) % 4 == 0 && ((year
) % 100 != 0 || (year
) % 400 == 0);
42 /* do a mathdiv for long type */
43 static long math_div(long a
, long b
)
45 return a
/ b
- (a
% b
< 0);
48 /* How many leap years between y1 and y2, y1 must less or equal to y2 */
49 static long leaps_between(long y1
, long y2
)
51 long leaps1
= math_div(y1
- 1, 4) - math_div(y1
- 1, 100)
52 + math_div(y1
- 1, 400);
53 long leaps2
= math_div(y2
- 1, 4) - math_div(y2
- 1, 100)
54 + math_div(y2
- 1, 400);
55 return leaps2
- leaps1
;
58 /* How many days come before each month (0-12). */
59 static const unsigned short __mon_yday
[2][13] = {
61 {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
63 {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}
66 #define SECS_PER_HOUR (60 * 60)
67 #define SECS_PER_DAY (SECS_PER_HOUR * 24)
70 * time_to_tm - converts the calendar time to local broken-down time
72 * @totalsecs the number of seconds elapsed since 00:00:00 on January 1, 1970,
73 * Coordinated Universal Time (UTC).
74 * @offset offset seconds adding to totalsecs.
75 * @result pointer to struct tm variable to receive broken-down time
77 void time_to_tm(time_t totalsecs
, int offset
, struct tm
*result
)
80 const unsigned short *ip
;
82 days
= totalsecs
/ SECS_PER_DAY
;
83 rem
= totalsecs
% SECS_PER_DAY
;
89 while (rem
>= SECS_PER_DAY
) {
94 result
->tm_hour
= rem
/ SECS_PER_HOUR
;
96 result
->tm_min
= rem
/ 60;
97 result
->tm_sec
= rem
% 60;
99 /* January 1, 1970 was a Thursday. */
100 result
->tm_wday
= (4 + days
) % 7;
101 if (result
->tm_wday
< 0)
102 result
->tm_wday
+= 7;
106 while (days
< 0 || days
>= (__isleap(y
) ? 366 : 365)) {
107 /* Guess a corrected year, assuming 365 days per year. */
108 long yg
= y
+ math_div(days
, 365);
110 /* Adjust DAYS and Y to match the guessed year. */
111 days
-= (yg
- y
) * 365 + leaps_between(y
, yg
);
115 result
->tm_year
= y
- 1900;
117 result
->tm_yday
= days
;
119 ip
= __mon_yday
[__isleap(y
)];
120 for (y
= 11; days
< ip
[y
]; y
--)
125 result
->tm_mday
= days
+ 1;
127 EXPORT_SYMBOL(time_to_tm
);
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