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