Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753189AbZGTJza (ORCPT ); Mon, 20 Jul 2009 05:55:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753139AbZGTJz2 (ORCPT ); Mon, 20 Jul 2009 05:55:28 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:49408 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751693AbZGTJz1 (ORCPT ); Mon, 20 Jul 2009 05:55:27 -0400 Message-ID: <4A643F36.5090200@cn.fujitsu.com> Date: Mon, 20 Jul 2009 17:56:06 +0800 From: Zhaolei User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Andrew Morton CC: Pavel Machek , mingo@elte.hu, tglx@linutronix.de, hirofumi@mail.parknet.co.jp, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/2] Add function to convert between calendar time and broken-down time for universal use References: <4A5C3BC0.6020701@cn.fujitsu.com> <20090714151040.b7b3b26d.akpm@linux-foundation.org> <20090718115019.GH1433@ucw.cz> <04e101ca08e5$be078fa0$808410ac@zhaoleiwin> <20090719202018.497f7ec1.akpm@linux-foundation.org> <4A643EFE.7090103@cn.fujitsu.com> In-Reply-To: <4A643EFE.7090103@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8641 Lines: 277 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 convert, 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 --- include/linux/time.h | 66 +++++++++++++++++++++++ kernel/time/Makefile | 2 +- kernel/time/timeconv.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 205 insertions(+), 1 deletions(-) create mode 100644 kernel/time/timeconv.c diff --git a/include/linux/time.h b/include/linux/time.h index ea16c1a..d74bc0c 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -151,6 +151,72 @@ extern void update_xtime_cache(u64 nsec); struct tms; extern void do_sys_times(struct tms *); +/* + * Similar to the struct tm in userspace , but it needs to be here so + * that the kernel source is self contained. + */ +struct tm { + /* + * the number of seconds after the minute, normally in the range + * 0 to 59, but can be up to 60 to allow for leap seconds + */ + int tm_sec; + /* the number of minutes after the hour, in the range 0 to 59*/ + int tm_min; + /* the number of hours past midnight, in the range 0 to 23 */ + int tm_hour; + /* the day of the month, in the range 1 to 31 */ + int tm_mday; + /* the number of months since January, in the range 0 to 11 */ + int tm_mon; + /* the number of years since 1900 */ + int tm_year; + /* the number of days since Sunday, in the range 0 to 6 */ + int tm_wday; + /* the number of days since January 1, in the range 0 to 365 */ + int tm_yday; +}; + +extern struct tm *__offtime(__kernel_time_t totalsecs, int offset, + struct tm *result); + +/** + * gmtime_r - converts the calendar time to UTC broken-down time + * + * @totalsecs the number of seconds elapsed since 00:00:00 on January 1, 1970, + * Coordinated Universal Time (UTC). + * @result pointer to struct tm variable to receive broken-down time + * + * Return a pointer to the broken-down time result on success, + * and NULL on when the year does not fit into an integer. + * + * Similar to the gmtime_r() in glibc, broken-down time is expressed in + * Coordinated Universal Time (UTC). + */ +static inline struct tm *gmtime_r(__kernel_time_t totalsecs, struct tm *result) +{ + return __offtime(totalsecs, 0, result); +} + +/** + * localtime_r - converts the calendar time to local broken-down time + * + * @totalsecs the number of seconds elapsed since 00:00:00 on January 1, 1970, + * Coordinated Universal Time (UTC). + * @result pointer to struct tm variable to receive broken-down time + * + * Return a pointer to the broken-down time result on success, + * and NULL on when the year does not fit into an integer. + * + * Similar to the localtime_r() in glibc, broken-down time is expressed + * relative to sys_tz. + */ +static inline struct tm *localtime_r(__kernel_time_t totalsecs, + struct tm *result) +{ + return __offtime(totalsecs, -sys_tz.tz_minuteswest * 60, result); +} + /** * timespec_to_ns - Convert timespec to nanoseconds * @ts: pointer to the timespec variable to be converted diff --git a/kernel/time/Makefile b/kernel/time/Makefile index 0b0a636..ee26662 100644 --- a/kernel/time/Makefile +++ b/kernel/time/Makefile @@ -1,4 +1,4 @@ -obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o timecompare.o +obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o timecompare.o timeconv.o obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD) += clockevents.o obj-$(CONFIG_GENERIC_CLOCKEVENTS) += tick-common.o diff --git a/kernel/time/timeconv.c b/kernel/time/timeconv.c new file mode 100644 index 0000000..5a76581 --- /dev/null +++ b/kernel/time/timeconv.c @@ -0,0 +1,138 @@ +/* + * Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc. + * This file is part of the GNU C Library. + * Contributed by Paul Eggert (eggert@twinsun.com). + * + * The GNU C Library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * The GNU C Library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Library General Public License for more details. + * + * You should have received a copy of the GNU Library General Public + * License along with the GNU C Library; see the file COPYING.LIB. If not, + * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + */ + +/* + * Converts the calendar time to broken-down time representation + * Based on code from glibc-2.6 + * + * 2009-7-14: + * Moved from glibc-2.6 to kernel by Zhaolei + */ + +#include +#include + +/* + * Nonzero if YEAR is a leap year (every 4 years, + * except every 100th isn't, and every 400th is). + */ +static int __isleap(unsigned int year) +{ + return (year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0); +} + +/* do a mathdiv for long type */ +static long math_div(long a, long b) +{ + return a / b - (a % b < 0); +} + +/* How many leap years between y1 and y2, y1 must less or equal to y2 */ +static long leaps_between(long y1, long y2) +{ + long leaps1 = math_div(y1 - 1, 4) - math_div(y1 - 1, 100) + + math_div(y1 - 1, 400); + long leaps2 = math_div(y2 - 1, 4) - math_div(y2 - 1, 100) + + math_div(y2 - 1, 400); + return leaps2 - leaps1; +} + +/* How many days come before each month (0-12). */ +static const unsigned short __mon_yday[2][13] = { + /* Normal years. */ + {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365}, + /* Leap years. */ + {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366} +}; + +#define SECS_PER_HOUR (60 * 60) +#define SECS_PER_DAY (SECS_PER_HOUR * 24) + +/** + * __offtime - converts the calendar time to local broken-down time + * + * @totalsecs the number of seconds elapsed since 00:00:00 on January 1, 1970, + * Coordinated Universal Time (UTC). + * @offset offset seconds adding to totalsecs. + * @result pointer to struct tm variable to receive broken-down time + * + * Return a pointer to the broken-down time result on success, + * and NULL on when the year does not fit into an integer. + * + * This function is for internal use, call gmtime_r() and localtime_r() instead. + */ +struct tm *__offtime(__kernel_time_t totalsecs, int offset, struct tm *result) +{ + long days, rem, y; + const unsigned short *ip; + + days = totalsecs / SECS_PER_DAY; + rem = totalsecs % SECS_PER_DAY; + rem += offset; + while (rem < 0) { + rem += SECS_PER_DAY; + --days; + } + while (rem >= SECS_PER_DAY) { + rem -= SECS_PER_DAY; + ++days; + } + + result->tm_hour = rem / SECS_PER_HOUR; + rem %= SECS_PER_HOUR; + result->tm_min = rem / 60; + result->tm_sec = rem % 60; + + /* January 1, 1970 was a Thursday. */ + result->tm_wday = (4 + days) % 7; + if (result->tm_wday < 0) + result->tm_wday += 7; + + y = 1970; + + while (days < 0 || days >= (__isleap(y) ? 366 : 365)) { + /* Guess a corrected year, assuming 365 days per year. */ + long yg = y + math_div(days, 365); + + /* Adjust DAYS and Y to match the guessed year. */ + days -= (yg - y) * 365 + leaps_between(y, yg); + y = yg; + } + + result->tm_year = y - 1900; + if (result->tm_year != y - 1900) { + /* The year cannot be represented due to overflow. */ + return NULL; + } + + result->tm_yday = days; + + ip = __mon_yday[__isleap(y)]; + for (y = 11; days < ip[y]; y--) + continue; + days -= ip[y]; + + result->tm_mon = y; + result->tm_mday = days + 1; + + return result; +} +EXPORT_SYMBOL(__offtime); -- 1.5.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/