Takaaki Numai / mbed-dev

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Dependents:   Hobbyking_Cheetah_0511

platform/mbed_mktime.c@0:85b3fd62ea1a, 2020-03-16 (annotated)

Committer:
NYX
Date:
Mon Mar 16 06:35:48 2020 +0000
Revision:
0:85b3fd62ea1a
reinport to mbed;

Who changed what in which revision?

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NYX 0:85b3fd62ea1a 1 /* mbed Microcontroller Library
NYX 0:85b3fd62ea1a 2 * Copyright (c) 2017-2017 ARM Limited
NYX 0:85b3fd62ea1a 3 *
NYX 0:85b3fd62ea1a 4 * Licensed under the Apache License, Version 2.0 (the "License");
NYX 0:85b3fd62ea1a 5 * you may not use this file except in compliance with the License.
NYX 0:85b3fd62ea1a 6 * You may obtain a copy of the License at
NYX 0:85b3fd62ea1a 7 *
NYX 0:85b3fd62ea1a 8 * http://www.apache.org/licenses/LICENSE-2.0
NYX 0:85b3fd62ea1a 9 *
NYX 0:85b3fd62ea1a 10 * Unless required by applicable law or agreed to in writing, software
NYX 0:85b3fd62ea1a 11 * distributed under the License is distributed on an "AS IS" BASIS,
NYX 0:85b3fd62ea1a 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
NYX 0:85b3fd62ea1a 13 * See the License for the specific language governing permissions and
NYX 0:85b3fd62ea1a 14 * limitations under the License.
NYX 0:85b3fd62ea1a 15 */
NYX 0:85b3fd62ea1a 16
NYX 0:85b3fd62ea1a 17 #include "mbed_mktime.h"
NYX 0:85b3fd62ea1a 18
NYX 0:85b3fd62ea1a 19 /*
NYX 0:85b3fd62ea1a 20 * time constants
NYX 0:85b3fd62ea1a 21 */
NYX 0:85b3fd62ea1a 22 #define SECONDS_BY_MINUTES 60
NYX 0:85b3fd62ea1a 23 #define MINUTES_BY_HOUR 60
NYX 0:85b3fd62ea1a 24 #define SECONDS_BY_HOUR (SECONDS_BY_MINUTES * MINUTES_BY_HOUR)
NYX 0:85b3fd62ea1a 25 #define HOURS_BY_DAY 24
NYX 0:85b3fd62ea1a 26 #define SECONDS_BY_DAY (SECONDS_BY_HOUR * HOURS_BY_DAY)
NYX 0:85b3fd62ea1a 27
NYX 0:85b3fd62ea1a 28 /*
NYX 0:85b3fd62ea1a 29 * 2 dimensional array containing the number of seconds elapsed before a given
NYX 0:85b3fd62ea1a 30 * month.
NYX 0:85b3fd62ea1a 31 * The second index map to the month while the first map to the type of year:
NYX 0:85b3fd62ea1a 32 * - 0: non leap year
NYX 0:85b3fd62ea1a 33 * - 1: leap year
NYX 0:85b3fd62ea1a 34 */
NYX 0:85b3fd62ea1a 35 static const uint32_t seconds_before_month[2][12] = {
NYX 0:85b3fd62ea1a 36 {
NYX 0:85b3fd62ea1a 37 0,
NYX 0:85b3fd62ea1a 38 31 * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 39 (31 + 28) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 40 (31 + 28 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 41 (31 + 28 + 31 + 30) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 42 (31 + 28 + 31 + 30 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 43 (31 + 28 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 44 (31 + 28 + 31 + 30 + 31 + 30 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 45 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 46 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 47 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 48 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 49 },
NYX 0:85b3fd62ea1a 50 {
NYX 0:85b3fd62ea1a 51 0,
NYX 0:85b3fd62ea1a 52 31 * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 53 (31 + 29) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 54 (31 + 29 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 55 (31 + 29 + 31 + 30) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 56 (31 + 29 + 31 + 30 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 57 (31 + 29 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 58 (31 + 29 + 31 + 30 + 31 + 30 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 59 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 60 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 61 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 62 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
NYX 0:85b3fd62ea1a 63 }
NYX 0:85b3fd62ea1a 64 };
NYX 0:85b3fd62ea1a 65
NYX 0:85b3fd62ea1a 66 bool _rtc_is_leap_year(int year) {
NYX 0:85b3fd62ea1a 67 /*
NYX 0:85b3fd62ea1a 68 * since in practice, the value manipulated by this algorithm lie in the
NYX 0:85b3fd62ea1a 69 * range [70 : 138], the algorith can be reduced to: year % 4.
NYX 0:85b3fd62ea1a 70 * The algorithm valid over the full range of value is:
NYX 0:85b3fd62ea1a 71
NYX 0:85b3fd62ea1a 72 year = 1900 + year;
NYX 0:85b3fd62ea1a 73 if (year % 4) {
NYX 0:85b3fd62ea1a 74 return false;
NYX 0:85b3fd62ea1a 75 } else if (year % 100) {
NYX 0:85b3fd62ea1a 76 return true;
NYX 0:85b3fd62ea1a 77 } else if (year % 400) {
NYX 0:85b3fd62ea1a 78 return false;
NYX 0:85b3fd62ea1a 79 }
NYX 0:85b3fd62ea1a 80 return true;
NYX 0:85b3fd62ea1a 81
NYX 0:85b3fd62ea1a 82 */
NYX 0:85b3fd62ea1a 83 return (year) % 4 ? false : true;
NYX 0:85b3fd62ea1a 84 }
NYX 0:85b3fd62ea1a 85
NYX 0:85b3fd62ea1a 86 time_t _rtc_mktime(const struct tm* time) {
NYX 0:85b3fd62ea1a 87 // partial check for the upper bound of the range
NYX 0:85b3fd62ea1a 88 // normalization might happen at the end of the function
NYX 0:85b3fd62ea1a 89 // this solution is faster than checking if the input is after the 19th of
NYX 0:85b3fd62ea1a 90 // january 2038 at 03:14:07.
NYX 0:85b3fd62ea1a 91 if ((time->tm_year < 70) || (time->tm_year > 138)) {
NYX 0:85b3fd62ea1a 92 return ((time_t) -1);
NYX 0:85b3fd62ea1a 93 }
NYX 0:85b3fd62ea1a 94
NYX 0:85b3fd62ea1a 95 uint32_t result = time->tm_sec;
NYX 0:85b3fd62ea1a 96 result += time->tm_min * SECONDS_BY_MINUTES;
NYX 0:85b3fd62ea1a 97 result += time->tm_hour * SECONDS_BY_HOUR;
NYX 0:85b3fd62ea1a 98 result += (time->tm_mday - 1) * SECONDS_BY_DAY;
NYX 0:85b3fd62ea1a 99 result += seconds_before_month[_rtc_is_leap_year(time->tm_year)][time->tm_mon];
NYX 0:85b3fd62ea1a 100
NYX 0:85b3fd62ea1a 101 if (time->tm_year > 70) {
NYX 0:85b3fd62ea1a 102 // valid in the range [70:138]
NYX 0:85b3fd62ea1a 103 uint32_t count_of_leap_days = ((time->tm_year - 1) / 4) - (70 / 4);
NYX 0:85b3fd62ea1a 104 result += (((time->tm_year - 70) * 365) + count_of_leap_days) * SECONDS_BY_DAY;
NYX 0:85b3fd62ea1a 105 }
NYX 0:85b3fd62ea1a 106
NYX 0:85b3fd62ea1a 107 if (result > INT32_MAX) {
NYX 0:85b3fd62ea1a 108 return (time_t) -1;
NYX 0:85b3fd62ea1a 109 }
NYX 0:85b3fd62ea1a 110
NYX 0:85b3fd62ea1a 111 return result;
NYX 0:85b3fd62ea1a 112 }
NYX 0:85b3fd62ea1a 113
NYX 0:85b3fd62ea1a 114 bool _rtc_localtime(time_t timestamp, struct tm* time_info) {
NYX 0:85b3fd62ea1a 115 if (((int32_t) timestamp) < 0) {
NYX 0:85b3fd62ea1a 116 return false;
NYX 0:85b3fd62ea1a 117 }
NYX 0:85b3fd62ea1a 118
NYX 0:85b3fd62ea1a 119 time_info->tm_sec = timestamp % 60;
NYX 0:85b3fd62ea1a 120 timestamp = timestamp / 60; // timestamp in minutes
NYX 0:85b3fd62ea1a 121 time_info->tm_min = timestamp % 60;
NYX 0:85b3fd62ea1a 122 timestamp = timestamp / 60; // timestamp in hours
NYX 0:85b3fd62ea1a 123 time_info->tm_hour = timestamp % 24;
NYX 0:85b3fd62ea1a 124 timestamp = timestamp / 24; // timestamp in days;
NYX 0:85b3fd62ea1a 125
NYX 0:85b3fd62ea1a 126 // compute the weekday
NYX 0:85b3fd62ea1a 127 // The 1st of January 1970 was a Thursday which is equal to 4 in the weekday
NYX 0:85b3fd62ea1a 128 // representation ranging from [0:6]
NYX 0:85b3fd62ea1a 129 time_info->tm_wday = (timestamp + 4) % 7;
NYX 0:85b3fd62ea1a 130
NYX 0:85b3fd62ea1a 131 // years start at 70
NYX 0:85b3fd62ea1a 132 time_info->tm_year = 70;
NYX 0:85b3fd62ea1a 133 while (true) {
NYX 0:85b3fd62ea1a 134 if (_rtc_is_leap_year(time_info->tm_year) && timestamp >= 366) {
NYX 0:85b3fd62ea1a 135 ++time_info->tm_year;
NYX 0:85b3fd62ea1a 136 timestamp -= 366;
NYX 0:85b3fd62ea1a 137 } else if (!_rtc_is_leap_year(time_info->tm_year) && timestamp >= 365) {
NYX 0:85b3fd62ea1a 138 ++time_info->tm_year;
NYX 0:85b3fd62ea1a 139 timestamp -= 365;
NYX 0:85b3fd62ea1a 140 } else {
NYX 0:85b3fd62ea1a 141 // the remaining days are less than a years
NYX 0:85b3fd62ea1a 142 break;
NYX 0:85b3fd62ea1a 143 }
NYX 0:85b3fd62ea1a 144 }
NYX 0:85b3fd62ea1a 145
NYX 0:85b3fd62ea1a 146 time_info->tm_yday = timestamp;
NYX 0:85b3fd62ea1a 147
NYX 0:85b3fd62ea1a 148 // convert days into seconds and find the current month
NYX 0:85b3fd62ea1a 149 timestamp *= SECONDS_BY_DAY;
NYX 0:85b3fd62ea1a 150 time_info->tm_mon = 11;
NYX 0:85b3fd62ea1a 151 bool leap = _rtc_is_leap_year(time_info->tm_year);
NYX 0:85b3fd62ea1a 152 for (uint32_t i = 0; i < 12; ++i) {
NYX 0:85b3fd62ea1a 153 if ((uint32_t) timestamp < seconds_before_month[leap][i]) {
NYX 0:85b3fd62ea1a 154 time_info->tm_mon = i - 1;
NYX 0:85b3fd62ea1a 155 break;
NYX 0:85b3fd62ea1a 156 }
NYX 0:85b3fd62ea1a 157 }
NYX 0:85b3fd62ea1a 158
NYX 0:85b3fd62ea1a 159 // remove month from timestamp and compute the number of days.
NYX 0:85b3fd62ea1a 160 // note: unlike other fields, days are not 0 indexed.
NYX 0:85b3fd62ea1a 161 timestamp -= seconds_before_month[leap][time_info->tm_mon];
NYX 0:85b3fd62ea1a 162 time_info->tm_mday = (timestamp / SECONDS_BY_DAY) + 1;
NYX 0:85b3fd62ea1a 163
NYX 0:85b3fd62ea1a 164 return true;
NYX 0:85b3fd62ea1a 165 }