Branch data Line data Source code
1 : : // SPDX-License-Identifier: LGPL-2.0+
2 : : /*
3 : : * Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
4 : : * This file is part of the GNU C Library.
5 : : * Contributed by Paul Eggert (eggert@twinsun.com).
6 : : *
7 : : * The GNU C Library is free software; you can redistribute it and/or
8 : : * modify it under the terms of the GNU Library General Public License as
9 : : * published by the Free Software Foundation; either version 2 of the
10 : : * License, or (at your option) any later version.
11 : : *
12 : : * The GNU C Library is distributed in the hope that it will be useful,
13 : : * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 : : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 : : * Library General Public License for more details.
16 : : *
17 : : * You should have received a copy of the GNU Library General Public
18 : : * License along with the GNU C Library; see the file COPYING.LIB. If not,
19 : : * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 : : * Boston, MA 02111-1307, USA.
21 : : */
22 : :
23 : : /*
24 : : * Converts the calendar time to broken-down time representation
25 : : * Based on code from glibc-2.6
26 : : *
27 : : * 2009-7-14:
28 : : * Moved from glibc-2.6 to kernel by Zhaolei<zhaolei@cn.fujitsu.com>
29 : : */
30 : :
31 : : #include <linux/time.h>
32 : : #include <linux/module.h>
33 : :
34 : : /*
35 : : * Nonzero if YEAR is a leap year (every 4 years,
36 : : * except every 100th isn't, and every 400th is).
37 : : */
38 : : static int __isleap(long year)
39 : : {
40 [ + + - + : 621 : return (year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0);
# # + - -
+ # # ]
41 : : }
42 : :
43 : : /* do a mathdiv for long type */
44 : : static long math_div(long a, long b)
45 : : {
46 : 1035 : return a / b - (a % b < 0);
47 : : }
48 : :
49 : : /* How many leap years between y1 and y2, y1 must less or equal to y2 */
50 : 207 : static long leaps_between(long y1, long y2)
51 : : {
52 : 621 : long leaps1 = math_div(y1 - 1, 4) - math_div(y1 - 1, 100)
53 : : + math_div(y1 - 1, 400);
54 : 621 : long leaps2 = math_div(y2 - 1, 4) - math_div(y2 - 1, 100)
55 : : + math_div(y2 - 1, 400);
56 : 207 : return leaps2 - leaps1;
57 : : }
58 : :
59 : : /* How many days come before each month (0-12). */
60 : : static const unsigned short __mon_yday[2][13] = {
61 : : /* Normal years. */
62 : : {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
63 : : /* Leap years. */
64 : : {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}
65 : : };
66 : :
67 : : #define SECS_PER_HOUR (60 * 60)
68 : : #define SECS_PER_DAY (SECS_PER_HOUR * 24)
69 : :
70 : : /**
71 : : * time64_to_tm - converts the calendar time to local broken-down time
72 : : *
73 : : * @totalsecs the number of seconds elapsed since 00:00:00 on January 1, 1970,
74 : : * Coordinated Universal Time (UTC).
75 : : * @offset offset seconds adding to totalsecs.
76 : : * @result pointer to struct tm variable to receive broken-down time
77 : : */
78 : 207 : void time64_to_tm(time64_t totalsecs, int offset, struct tm *result)
79 : : {
80 : : long days, rem, y;
81 : : int remainder;
82 : : const unsigned short *ip;
83 : :
84 : 207 : days = div_s64_rem(totalsecs, SECS_PER_DAY, &remainder);
85 : 207 : rem = remainder;
86 : 207 : rem += offset;
87 [ - + ]: 414 : while (rem < 0) {
88 : 0 : rem += SECS_PER_DAY;
89 : 0 : --days;
90 : : }
91 [ - + ]: 207 : while (rem >= SECS_PER_DAY) {
92 : 0 : rem -= SECS_PER_DAY;
93 : 0 : ++days;
94 : : }
95 : :
96 : 207 : result->tm_hour = rem / SECS_PER_HOUR;
97 : 207 : rem %= SECS_PER_HOUR;
98 : 207 : result->tm_min = rem / 60;
99 : 207 : result->tm_sec = rem % 60;
100 : :
101 : : /* January 1, 1970 was a Thursday. */
102 : 207 : result->tm_wday = (4 + days) % 7;
103 [ - + ]: 207 : if (result->tm_wday < 0)
104 : 0 : result->tm_wday += 7;
105 : :
106 : : y = 1970;
107 : :
108 [ - + + + : 1035 : while (days < 0 || days >= (__isleap(y) ? 366 : 365)) {
+ + ]
109 : : /* Guess a corrected year, assuming 365 days per year. */
110 : 207 : long yg = y + math_div(days, 365);
111 : :
112 : : /* Adjust DAYS and Y to match the guessed year. */
113 : 207 : days -= (yg - y) * 365 + leaps_between(y, yg);
114 : : y = yg;
115 : : }
116 : :
117 : 207 : result->tm_year = y - 1900;
118 : :
119 : 207 : result->tm_yday = days;
120 : :
121 : 207 : ip = __mon_yday[__isleap(y)];
122 [ + + ]: 1035 : for (y = 11; days < ip[y]; y--)
123 : 828 : continue;
124 : 207 : days -= ip[y];
125 : :
126 : 207 : result->tm_mon = y;
127 : 207 : result->tm_mday = days + 1;
128 : 207 : }
129 : : EXPORT_SYMBOL(time64_to_tm);
|
