/* mbed Microcontroller Library * Copyright (c) 2017-2017 ARM Limited * * 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; }