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/*
* rtc and date/time utility functions
*
* Copyright (C) 2005-06 Tower Technologies
* Author: Alessandro Zummo <a.zummo@towertech.it>
*
* 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);
/* Merge the valid (i.e. non-negative) fields of alarm into the current
* time. If the valid alarm fields are earlier than the equivalent
* fields in the time, carry one into the least significant invalid
* field, so that the alarm expiry is in the future. It assumes that the
* least significant invalid field is more significant than the most
* significant valid field, and that the seconds field is valid.
*
* This is used by alarms that take relative (rather than absolute)
* times, and/or have a simple binary second counter instead of
* day/hour/minute/sec registers.
*/
void rtc_merge_alarm(struct rtc_time *now, struct rtc_time *alarm)
{
int *alarmp = &alarm->tm_sec;
int *timep = &now->tm_sec;
int carry_into, i;
/* Ignore everything past the 6th element (tm_year). */
for (i = 5; i > 0; i--) {
if (alarmp[i] < 0)
alarmp[i] = timep[i];
else
break;
}
/* No carry needed if all fields are valid. */
if (i == 5)
return;
for (carry_into = i + 1; i >= 0; i--) {
if (alarmp[i] < timep[i])
break;
if (alarmp[i] > timep[i])
return;
}
switch (carry_into) {
case 1:
alarm->tm_min++;
if (alarm->tm_min < 60)
return;
alarm->tm_min = 0;
/* fall-through */
case 2:
alarm->tm_hour++;
if (alarm->tm_hour < 60)
return;
alarm->tm_hour = 0;
/* fall-through */
case 3:
alarm->tm_mday++;
if (alarm->tm_mday <= rtc_days_in_month[alarm->tm_mon])
return;
alarm->tm_mday = 1;
/* fall-through */
case 4:
alarm->tm_mon++;
if (alarm->tm_mon <= 12)
return;
alarm->tm_mon = 1;
/* fall-through */
case 5:
alarm->tm_year++;
}
}
EXPORT_SYMBOL(rtc_merge_alarm);
MODULE_LICENSE("GPL");
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