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authorZhaolei <zhaolei@cn.fujitsu.com>2009-09-23 18:56:10 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-24 10:20:56 -0400
commit57f1f0874f426a9bdfc5cd3f886113dd5cd17834 (patch)
treef7938f5c195f7733543d3d86c6ae3c902fd7adef /kernel
parentef1ff6b8c08954bc203b59e887d1e580dd91755a (diff)
time: add function to convert between calendar time and broken-down time for universal use
There are many similar code in kernel for one object: convert time between calendar time and broken-down time. Here is some source I found: fs/ncpfs/dir.c fs/smbfs/proc.c fs/fat/misc.c fs/udf/udftime.c fs/cifs/netmisc.c net/netfilter/xt_time.c drivers/scsi/ips.c drivers/input/misc/hp_sdc_rtc.c drivers/rtc/rtc-lib.c arch/ia64/hp/sim/boot/fw-emu.c arch/m68k/mac/misc.c arch/powerpc/kernel/time.c arch/parisc/include/asm/rtc.h ... We can make a common function for this type of conversion, At least we can get following benefit: 1: Make kernel simple and unify 2: Easy to fix bug in converting code 3: Reduce clone of code in future For example, I'm trying to make ftrace display walltime, this patch will make me easy. This code is based on code from glibc-2.6 Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Pavel Machek <pavel@ucw.cz> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/Makefile2
-rw-r--r--kernel/time/timeconv.c127
2 files changed, 128 insertions, 1 deletions
diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index 0b0a6366c9d4..ee266620b06c 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -1,4 +1,4 @@
1obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o timecompare.o 1obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o timecompare.o timeconv.o
2 2
3obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD) += clockevents.o 3obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD) += clockevents.o
4obj-$(CONFIG_GENERIC_CLOCKEVENTS) += tick-common.o 4obj-$(CONFIG_GENERIC_CLOCKEVENTS) += tick-common.o
diff --git a/kernel/time/timeconv.c b/kernel/time/timeconv.c
new file mode 100644
index 000000000000..86628e755f38
--- /dev/null
+++ b/kernel/time/timeconv.c
@@ -0,0 +1,127 @@
1/*
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).
5 *
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.
10 *
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.
15 *
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.
20 */
21
22/*
23 * Converts the calendar time to broken-down time representation
24 * Based on code from glibc-2.6
25 *
26 * 2009-7-14:
27 * Moved from glibc-2.6 to kernel by Zhaolei<zhaolei@cn.fujitsu.com>
28 */
29
30#include <linux/time.h>
31#include <linux/module.h>
32
33/*
34 * Nonzero if YEAR is a leap year (every 4 years,
35 * except every 100th isn't, and every 400th is).
36 */
37static int __isleap(long year)
38{
39 return (year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0);
40}
41
42/* do a mathdiv for long type */
43static long math_div(long a, long b)
44{
45 return a / b - (a % b < 0);
46}
47
48/* How many leap years between y1 and y2, y1 must less or equal to y2 */
49static long leaps_between(long y1, long y2)
50{
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;
56}
57
58/* How many days come before each month (0-12). */
59static const unsigned short __mon_yday[2][13] = {
60 /* Normal years. */
61 {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
62 /* Leap years. */
63 {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}
64};
65
66#define SECS_PER_HOUR (60 * 60)
67#define SECS_PER_DAY (SECS_PER_HOUR * 24)
68
69/**
70 * time_to_tm - converts the calendar time to local broken-down time
71 *
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
76 */
77void time_to_tm(time_t totalsecs, int offset, struct tm *result)
78{
79 long days, rem, y;
80 const unsigned short *ip;
81
82 days = totalsecs / SECS_PER_DAY;
83 rem = totalsecs % SECS_PER_DAY;
84 rem += offset;
85 while (rem < 0) {
86 rem += SECS_PER_DAY;
87 --days;
88 }
89 while (rem >= SECS_PER_DAY) {
90 rem -= SECS_PER_DAY;
91 ++days;
92 }
93
94 result->tm_hour = rem / SECS_PER_HOUR;
95 rem %= SECS_PER_HOUR;
96 result->tm_min = rem / 60;
97 result->tm_sec = rem % 60;
98
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;
103
104 y = 1970;
105
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);
109
110 /* Adjust DAYS and Y to match the guessed year. */
111 days -= (yg - y) * 365 + leaps_between(y, yg);
112 y = yg;
113 }
114
115 result->tm_year = y - 1900;
116
117 result->tm_yday = days;
118
119 ip = __mon_yday[__isleap(y)];
120 for (y = 11; days < ip[y]; y--)
121 continue;
122 days -= ip[y];
123
124 result->tm_mon = y;
125 result->tm_mday = days + 1;
126}
127EXPORT_SYMBOL(time_to_tm);