[linux.git] / drivers / rtc / rtc-lib.c

/*
 * rtc and date/time utility functions
 *
 * Copyright (C) 2005-06 Tower Technologies
 * Author: Alessandro Zummo <[email protected]>
 *
 * based on arch/arm/common/rtctime.c and other bits
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
*/

#include <linux/module.h>
#include <linux/rtc.h>

static const unsigned char rtc_days_in_month[] = {
	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};

static const unsigned short rtc_ydays[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 LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
#define LEAP_YEAR(year) ((!(year % 4) && (year % 100)) || !(year % 400))

/*
 * The number of days in the month.
 */
int rtc_month_days(unsigned int month, unsigned int year)
{
	return rtc_days_in_month[month] + (LEAP_YEAR(year) && month == 1);
}
EXPORT_SYMBOL(rtc_month_days);

/*
 * The number of days since January 1. (0 to 365)
 */
int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
{
	return rtc_ydays[LEAP_YEAR(year)][month] + day-1;
}
EXPORT_SYMBOL(rtc_year_days);

/*
 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
 */
void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
{
	register int days, month, year;

	days = time / 86400;
	time -= days * 86400;

	/* day of the week, 1970-01-01 was a Thursday */
	tm->tm_wday = (days + 4) % 7;

	year = 1970 + days / 365;
	days -= (year - 1970) * 365
		+ LEAPS_THRU_END_OF(year - 1)
		- LEAPS_THRU_END_OF(1970 - 1);
	if (days < 0) {
		year -= 1;
		days += 365 + LEAP_YEAR(year);
	}
	tm->tm_year = year - 1900;
	tm->tm_yday = days + 1;

	for (month = 0; month < 11; month++) {
		int newdays;

		newdays = days - rtc_month_days(month, year);
		if (newdays < 0)
			break;
		days = newdays;
	}
	tm->tm_mon = month;
	tm->tm_mday = days + 1;

	tm->tm_hour = time / 3600;
	time -= tm->tm_hour * 3600;
	tm->tm_min = time / 60;
	tm->tm_sec = time - tm->tm_min * 60;
}
EXPORT_SYMBOL(rtc_time_to_tm);

/*
 * Does the rtc_time represent a valid date/time?
 */
int rtc_valid_tm(struct rtc_time *tm)
{
	if (tm->tm_year < 70
		|| ((unsigned)tm->tm_mon) >= 12
		|| tm->tm_mday < 1
		|| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
		|| ((unsigned)tm->tm_hour) >= 24
		|| ((unsigned)tm->tm_min) >= 60
		|| ((unsigned)tm->tm_sec) >= 60)
		return -EINVAL;

	return 0;
}
EXPORT_SYMBOL(rtc_valid_tm);

/*
 * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
 */
int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time)
{
	*time = mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
			tm->tm_hour, tm->tm_min, tm->tm_sec);
	return 0;
}
EXPORT_SYMBOL(rtc_tm_to_time);

MODULE_LICENSE("GPL");
Commit	Line	Data
c58411e9 AZ	1	/*
	2	* rtc and date/time utility functions
	3	*
	4	* Copyright (C) 2005-06 Tower Technologies
	5	* Author: Alessandro Zummo <[email protected]>
	6	*
	7	* based on arch/arm/common/rtctime.c and other bits
	8	*
	9	* This program is free software; you can redistribute it and/or modify
	10	* it under the terms of the GNU General Public License version 2 as
	11	* published by the Free Software Foundation.
	12	*/
	13
	14	#include <linux/module.h>
	15	#include <linux/rtc.h>
	16
	17	static const unsigned char rtc_days_in_month[] = {
	18	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
	19	};
	20
8232212e AV	21	static const unsigned short rtc_ydays[2][13] = {
	22	/* Normal years */
	23	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
	24	/* Leap years */
	25	{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
	26	};
	27
c58411e9 AZ	28	#define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
	29	#define LEAP_YEAR(year) ((!(year % 4) && (year % 100)) \|\| !(year % 400))
	30
8232212e AV	31	/*
	32	* The number of days in the month.
	33	*/
c58411e9 AZ	34	int rtc_month_days(unsigned int month, unsigned int year)
	35	{
	36	return rtc_days_in_month[month] + (LEAP_YEAR(year) && month == 1);
	37	}
	38	EXPORT_SYMBOL(rtc_month_days);
	39
8232212e AV	40	/*
	41	* The number of days since January 1. (0 to 365)
	42	*/
	43	int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
	44	{
	45	return rtc_ydays[LEAP_YEAR(year)][month] + day-1;
	46	}
	47	EXPORT_SYMBOL(rtc_year_days);
	48
c58411e9 AZ	49	/*
	50	* Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
	51	*/
	52	void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
	53	{
	54	register int days, month, year;
	55
	56	days = time / 86400;
	57	time -= days * 86400;
	58
	59	/* day of the week, 1970-01-01 was a Thursday */
	60	tm->tm_wday = (days + 4) % 7;
	61
	62	year = 1970 + days / 365;
	63	days -= (year - 1970) * 365
	64	+ LEAPS_THRU_END_OF(year - 1)
	65	- LEAPS_THRU_END_OF(1970 - 1);
	66	if (days < 0) {
	67	year -= 1;
	68	days += 365 + LEAP_YEAR(year);
	69	}
	70	tm->tm_year = year - 1900;
	71	tm->tm_yday = days + 1;
	72
	73	for (month = 0; month < 11; month++) {
	74	int newdays;
	75
	76	newdays = days - rtc_month_days(month, year);
	77	if (newdays < 0)
	78	break;
	79	days = newdays;
	80	}
	81	tm->tm_mon = month;
	82	tm->tm_mday = days + 1;
	83
	84	tm->tm_hour = time / 3600;
	85	time -= tm->tm_hour * 3600;
	86	tm->tm_min = time / 60;
	87	tm->tm_sec = time - tm->tm_min * 60;
	88	}
	89	EXPORT_SYMBOL(rtc_time_to_tm);
	90
	91	/*
	92	* Does the rtc_time represent a valid date/time?
	93	*/
	94	int rtc_valid_tm(struct rtc_time *tm)
	95	{
	96	if (tm->tm_year < 70
db621f17	97	\|\| ((unsigned)tm->tm_mon) >= 12
c58411e9 AZ	98	\|\| tm->tm_mday < 1
c58411e9 AZ	99	\|\| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
db621f17 DB	100	\|\| ((unsigned)tm->tm_hour) >= 24
	101	\|\| ((unsigned)tm->tm_min) >= 60
	102	\|\| ((unsigned)tm->tm_sec) >= 60)
c58411e9 AZ	103	return -EINVAL;
	104
	105	return 0;
	106	}
	107	EXPORT_SYMBOL(rtc_valid_tm);
	108
	109	/*
	110	* Convert Gregorian date to seconds since 01-01-1970 00:00:00.
	111	*/
	112	int rtc_tm_to_time(struct rtc_time tm, unsigned long time)
	113	{
	114	*time = mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
	115	tm->tm_hour, tm->tm_min, tm->tm_sec);
	116	return 0;
	117	}
	118	EXPORT_SYMBOL(rtc_tm_to_time);
	119
	120	MODULE_LICENSE("GPL");