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/* mbed Microcontroller Library
* Copyright (c) 2017-2017 ARM Limited
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mbed_mktime.h"
/* Time constants. */
#define SECONDS_BY_MINUTES 60
#define MINUTES_BY_HOUR 60
#define SECONDS_BY_HOUR (SECONDS_BY_MINUTES * MINUTES_BY_HOUR)
#define HOURS_BY_DAY 24
#define SECONDS_BY_DAY (SECONDS_BY_HOUR * HOURS_BY_DAY)
#define LAST_VALID_YEAR 206
/* Macros which will be used to determine if we are within valid range. */
#define EDGE_TIMESTAMP_FULL_LEAP_YEAR_SUPPORT 3220095 // 7th of February 1970 at 06:28:15
#define EDGE_TIMESTAMP_4_YEAR_LEAP_YEAR_SUPPORT 3133695 // 6th of February 1970 at 06:28:15
/*
* 2 dimensional array containing the number of seconds elapsed before a given
* month.
* The second index map to the month while the first map to the type of year:
* - 0: non leap year
* - 1: leap year
*/
static const uint32_t seconds_before_month[2][12] = {
{
0,
31 * SECONDS_BY_DAY,
(31 + 28) *SECONDS_BY_DAY,
(31 + 28 + 31) *SECONDS_BY_DAY,
(31 + 28 + 31 + 30) *SECONDS_BY_DAY,
(31 + 28 + 31 + 30 + 31) *SECONDS_BY_DAY,
(31 + 28 + 31 + 30 + 31 + 30) *SECONDS_BY_DAY,
(31 + 28 + 31 + 30 + 31 + 30 + 31) *SECONDS_BY_DAY,
(31 + 28 + 31 + 30 + 31 + 30 + 31 + 31) *SECONDS_BY_DAY,
(31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30) *SECONDS_BY_DAY,
(31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31) *SECONDS_BY_DAY,
(31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30) *SECONDS_BY_DAY,
},
{
0,
31 * SECONDS_BY_DAY,
(31 + 29) *SECONDS_BY_DAY,
(31 + 29 + 31) *SECONDS_BY_DAY,
(31 + 29 + 31 + 30) *SECONDS_BY_DAY,
(31 + 29 + 31 + 30 + 31) *SECONDS_BY_DAY,
(31 + 29 + 31 + 30 + 31 + 30) *SECONDS_BY_DAY,
(31 + 29 + 31 + 30 + 31 + 30 + 31) *SECONDS_BY_DAY,
(31 + 29 + 31 + 30 + 31 + 30 + 31 + 31) *SECONDS_BY_DAY,
(31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30) *SECONDS_BY_DAY,
(31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31) *SECONDS_BY_DAY,
(31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30) *SECONDS_BY_DAY,
}
};
bool _rtc_is_leap_year(int year, rtc_leap_year_support_t leap_year_support)
{
/*
* since in practice, the value manipulated by this algorithm lie in the
* range: [70 : 206] the algorithm can be reduced to: year % 4 with exception for 200 (year 2100 is not leap year).
* The algorithm valid over the full range of value is:
year = 1900 + year;
if (year % 4) {
return false;
} else if (year % 100) {
return true;
} else if (year % 400) {
return false;
}
return true;
*/
if (leap_year_support == RTC_FULL_LEAP_YEAR_SUPPORT && year == 200) {
return false; // 2100 is not a leap year
}
return (year) % 4 ? false : true;
}
bool _rtc_maketime(const struct tm *time, time_t *seconds, rtc_leap_year_support_t leap_year_support)
{
if (seconds == NULL || time == NULL) {
return false;
}
/* Partial check for the upper bound of the range - check years only. Full check will be performed after the
* elapsed time since the beginning of the year is calculated.
*/
if ((time->tm_year < 70) || (time->tm_year > LAST_VALID_YEAR)) {
return false;
}
uint32_t result = time->tm_sec;
result += time->tm_min * SECONDS_BY_MINUTES;
result += time->tm_hour * SECONDS_BY_HOUR;
result += (time->tm_mday - 1) * SECONDS_BY_DAY;
result += seconds_before_month[_rtc_is_leap_year(time->tm_year, leap_year_support)][time->tm_mon];
/* Check if we are within valid range. */
if (time->tm_year == LAST_VALID_YEAR) {
if ((leap_year_support == RTC_FULL_LEAP_YEAR_SUPPORT && result > EDGE_TIMESTAMP_FULL_LEAP_YEAR_SUPPORT) ||
(leap_year_support == RTC_4_YEAR_LEAP_YEAR_SUPPORT && result > EDGE_TIMESTAMP_4_YEAR_LEAP_YEAR_SUPPORT)) {
return false;
}
}
if (time->tm_year > 70) {
/* Valid in the range [70:206]. */
uint32_t count_of_leap_days = ((time->tm_year - 1) / 4) - (70 / 4);
if (leap_year_support == RTC_FULL_LEAP_YEAR_SUPPORT) {
if (time->tm_year > 200) {
count_of_leap_days--; // 2100 is not a leap year
}
}
result += (((time->tm_year - 70) * 365) + count_of_leap_days) * SECONDS_BY_DAY;
}
*seconds = result;
return true;
}
bool _rtc_localtime(time_t timestamp, struct tm *time_info, rtc_leap_year_support_t leap_year_support)
{
if (time_info == NULL) {
return false;
}
uint32_t seconds = (uint32_t)timestamp;
time_info->tm_sec = seconds % 60;
seconds = seconds / 60; // timestamp in minutes
time_info->tm_min = seconds % 60;
seconds = seconds / 60; // timestamp in hours
time_info->tm_hour = seconds % 24;
seconds = seconds / 24; // timestamp in days;
/* Compute the weekday.
* The 1st of January 1970 was a Thursday which is equal to 4 in the weekday representation ranging from [0:6].
*/
time_info->tm_wday = (seconds + 4) % 7;
/* Years start at 70. */
time_info->tm_year = 70;
while (true) {
if (_rtc_is_leap_year(time_info->tm_year, leap_year_support) && seconds >= 366) {
++time_info->tm_year;
seconds -= 366;
} else if (!_rtc_is_leap_year(time_info->tm_year, leap_year_support) && seconds >= 365) {
++time_info->tm_year;
seconds -= 365;
} else {
/* The remaining days are less than a years. */
break;
}
}
time_info->tm_yday = seconds;
/* Convert days into seconds and find the current month. */
seconds *= SECONDS_BY_DAY;
time_info->tm_mon = 11;
bool leap = _rtc_is_leap_year(time_info->tm_year, leap_year_support);
for (uint32_t i = 0; i < 12; ++i) {
if ((uint32_t) seconds < seconds_before_month[leap][i]) {
time_info->tm_mon = i - 1;
break;
}
}
/* Remove month from timestamp and compute the number of days.
* Note: unlike other fields, days are not 0 indexed.
*/
seconds -= seconds_before_month[leap][time_info->tm_mon];
time_info->tm_mday = (seconds / SECONDS_BY_DAY) + 1;
return true;
}