EL4121 Embedded System / mbed-os

mbed-os

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platform/mbed_mktime.c@0:b74591d5ab33, 2017-12-11 (annotated)

Committer:
be_bryan
Date:
Mon Dec 11 17:54:04 2017 +0000
Revision:
0:b74591d5ab33
motor ++

Who changed what in which revision?

UserRevisionLine numberNew contents of line
be_bryan 0:b74591d5ab33 1 /* mbed Microcontroller Library
be_bryan 0:b74591d5ab33 2 * Copyright (c) 2017-2017 ARM Limited
be_bryan 0:b74591d5ab33 3 *
be_bryan 0:b74591d5ab33 4 * Licensed under the Apache License, Version 2.0 (the "License");
be_bryan 0:b74591d5ab33 5 * you may not use this file except in compliance with the License.
be_bryan 0:b74591d5ab33 6 * You may obtain a copy of the License at
be_bryan 0:b74591d5ab33 7 *
be_bryan 0:b74591d5ab33 8 * http://www.apache.org/licenses/LICENSE-2.0
be_bryan 0:b74591d5ab33 9 *
be_bryan 0:b74591d5ab33 10 * Unless required by applicable law or agreed to in writing, software
be_bryan 0:b74591d5ab33 11 * distributed under the License is distributed on an "AS IS" BASIS,
be_bryan 0:b74591d5ab33 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
be_bryan 0:b74591d5ab33 13 * See the License for the specific language governing permissions and
be_bryan 0:b74591d5ab33 14 * limitations under the License.
be_bryan 0:b74591d5ab33 15 */
be_bryan 0:b74591d5ab33 16
be_bryan 0:b74591d5ab33 17 #include "mbed_mktime.h"
be_bryan 0:b74591d5ab33 18
be_bryan 0:b74591d5ab33 19 /*
be_bryan 0:b74591d5ab33 20 * time constants
be_bryan 0:b74591d5ab33 21 */
be_bryan 0:b74591d5ab33 22 #define SECONDS_BY_MINUTES 60
be_bryan 0:b74591d5ab33 23 #define MINUTES_BY_HOUR 60
be_bryan 0:b74591d5ab33 24 #define SECONDS_BY_HOUR (SECONDS_BY_MINUTES * MINUTES_BY_HOUR)
be_bryan 0:b74591d5ab33 25 #define HOURS_BY_DAY 24
be_bryan 0:b74591d5ab33 26 #define SECONDS_BY_DAY (SECONDS_BY_HOUR * HOURS_BY_DAY)
be_bryan 0:b74591d5ab33 27
be_bryan 0:b74591d5ab33 28 /*
be_bryan 0:b74591d5ab33 29 * 2 dimensional array containing the number of seconds elapsed before a given
be_bryan 0:b74591d5ab33 30 * month.
be_bryan 0:b74591d5ab33 31 * The second index map to the month while the first map to the type of year:
be_bryan 0:b74591d5ab33 32 * - 0: non leap year
be_bryan 0:b74591d5ab33 33 * - 1: leap year
be_bryan 0:b74591d5ab33 34 */
be_bryan 0:b74591d5ab33 35 static const uint32_t seconds_before_month[2][12] = {
be_bryan 0:b74591d5ab33 36 {
be_bryan 0:b74591d5ab33 37 0,
be_bryan 0:b74591d5ab33 38 31 * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 39 (31 + 28) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 40 (31 + 28 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 41 (31 + 28 + 31 + 30) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 42 (31 + 28 + 31 + 30 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 43 (31 + 28 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 44 (31 + 28 + 31 + 30 + 31 + 30 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 45 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 46 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 47 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 48 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 49 },
be_bryan 0:b74591d5ab33 50 {
be_bryan 0:b74591d5ab33 51 0,
be_bryan 0:b74591d5ab33 52 31 * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 53 (31 + 29) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 54 (31 + 29 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 55 (31 + 29 + 31 + 30) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 56 (31 + 29 + 31 + 30 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 57 (31 + 29 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 58 (31 + 29 + 31 + 30 + 31 + 30 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 59 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 60 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 61 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 62 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
be_bryan 0:b74591d5ab33 63 }
be_bryan 0:b74591d5ab33 64 };
be_bryan 0:b74591d5ab33 65
be_bryan 0:b74591d5ab33 66 bool _rtc_is_leap_year(int year) {
be_bryan 0:b74591d5ab33 67 /*
be_bryan 0:b74591d5ab33 68 * since in practice, the value manipulated by this algorithm lie in the
be_bryan 0:b74591d5ab33 69 * range [70 : 138], the algorith can be reduced to: year % 4.
be_bryan 0:b74591d5ab33 70 * The algorithm valid over the full range of value is:
be_bryan 0:b74591d5ab33 71
be_bryan 0:b74591d5ab33 72 year = 1900 + year;
be_bryan 0:b74591d5ab33 73 if (year % 4) {
be_bryan 0:b74591d5ab33 74 return false;
be_bryan 0:b74591d5ab33 75 } else if (year % 100) {
be_bryan 0:b74591d5ab33 76 return true;
be_bryan 0:b74591d5ab33 77 } else if (year % 400) {
be_bryan 0:b74591d5ab33 78 return false;
be_bryan 0:b74591d5ab33 79 }
be_bryan 0:b74591d5ab33 80 return true;
be_bryan 0:b74591d5ab33 81
be_bryan 0:b74591d5ab33 82 */
be_bryan 0:b74591d5ab33 83 return (year) % 4 ? false : true;
be_bryan 0:b74591d5ab33 84 }
be_bryan 0:b74591d5ab33 85
be_bryan 0:b74591d5ab33 86 time_t _rtc_mktime(const struct tm* time) {
be_bryan 0:b74591d5ab33 87 // partial check for the upper bound of the range
be_bryan 0:b74591d5ab33 88 // normalization might happen at the end of the function
be_bryan 0:b74591d5ab33 89 // this solution is faster than checking if the input is after the 19th of
be_bryan 0:b74591d5ab33 90 // january 2038 at 03:14:07.
be_bryan 0:b74591d5ab33 91 if ((time->tm_year < 70) || (time->tm_year > 138)) {
be_bryan 0:b74591d5ab33 92 return ((time_t) -1);
be_bryan 0:b74591d5ab33 93 }
be_bryan 0:b74591d5ab33 94
be_bryan 0:b74591d5ab33 95 uint32_t result = time->tm_sec;
be_bryan 0:b74591d5ab33 96 result += time->tm_min * SECONDS_BY_MINUTES;
be_bryan 0:b74591d5ab33 97 result += time->tm_hour * SECONDS_BY_HOUR;
be_bryan 0:b74591d5ab33 98 result += (time->tm_mday - 1) * SECONDS_BY_DAY;
be_bryan 0:b74591d5ab33 99 result += seconds_before_month[_rtc_is_leap_year(time->tm_year)][time->tm_mon];
be_bryan 0:b74591d5ab33 100
be_bryan 0:b74591d5ab33 101 if (time->tm_year > 70) {
be_bryan 0:b74591d5ab33 102 // valid in the range [70:138]
be_bryan 0:b74591d5ab33 103 uint32_t count_of_leap_days = ((time->tm_year - 1) / 4) - (70 / 4);
be_bryan 0:b74591d5ab33 104 result += (((time->tm_year - 70) * 365) + count_of_leap_days) * SECONDS_BY_DAY;
be_bryan 0:b74591d5ab33 105 }
be_bryan 0:b74591d5ab33 106
be_bryan 0:b74591d5ab33 107 if (result > INT32_MAX) {
be_bryan 0:b74591d5ab33 108 return (time_t) -1;
be_bryan 0:b74591d5ab33 109 }
be_bryan 0:b74591d5ab33 110
be_bryan 0:b74591d5ab33 111 return result;
be_bryan 0:b74591d5ab33 112 }
be_bryan 0:b74591d5ab33 113
be_bryan 0:b74591d5ab33 114 bool _rtc_localtime(time_t timestamp, struct tm* time_info) {
be_bryan 0:b74591d5ab33 115 if (((int32_t) timestamp) < 0) {
be_bryan 0:b74591d5ab33 116 return false;
be_bryan 0:b74591d5ab33 117 }
be_bryan 0:b74591d5ab33 118
be_bryan 0:b74591d5ab33 119 time_info->tm_sec = timestamp % 60;
be_bryan 0:b74591d5ab33 120 timestamp = timestamp / 60; // timestamp in minutes
be_bryan 0:b74591d5ab33 121 time_info->tm_min = timestamp % 60;
be_bryan 0:b74591d5ab33 122 timestamp = timestamp / 60; // timestamp in hours
be_bryan 0:b74591d5ab33 123 time_info->tm_hour = timestamp % 24;
be_bryan 0:b74591d5ab33 124 timestamp = timestamp / 24; // timestamp in days;
be_bryan 0:b74591d5ab33 125
be_bryan 0:b74591d5ab33 126 // compute the weekday
be_bryan 0:b74591d5ab33 127 // The 1st of January 1970 was a Thursday which is equal to 4 in the weekday
be_bryan 0:b74591d5ab33 128 // representation ranging from [0:6]
be_bryan 0:b74591d5ab33 129 time_info->tm_wday = (timestamp + 4) % 7;
be_bryan 0:b74591d5ab33 130
be_bryan 0:b74591d5ab33 131 // years start at 70
be_bryan 0:b74591d5ab33 132 time_info->tm_year = 70;
be_bryan 0:b74591d5ab33 133 while (true) {
be_bryan 0:b74591d5ab33 134 if (_rtc_is_leap_year(time_info->tm_year) && timestamp >= 366) {
be_bryan 0:b74591d5ab33 135 ++time_info->tm_year;
be_bryan 0:b74591d5ab33 136 timestamp -= 366;
be_bryan 0:b74591d5ab33 137 } else if (!_rtc_is_leap_year(time_info->tm_year) && timestamp >= 365) {
be_bryan 0:b74591d5ab33 138 ++time_info->tm_year;
be_bryan 0:b74591d5ab33 139 timestamp -= 365;
be_bryan 0:b74591d5ab33 140 } else {
be_bryan 0:b74591d5ab33 141 // the remaining days are less than a years
be_bryan 0:b74591d5ab33 142 break;
be_bryan 0:b74591d5ab33 143 }
be_bryan 0:b74591d5ab33 144 }
be_bryan 0:b74591d5ab33 145
be_bryan 0:b74591d5ab33 146 time_info->tm_yday = timestamp;
be_bryan 0:b74591d5ab33 147
be_bryan 0:b74591d5ab33 148 // convert days into seconds and find the current month
be_bryan 0:b74591d5ab33 149 timestamp *= SECONDS_BY_DAY;
be_bryan 0:b74591d5ab33 150 time_info->tm_mon = 11;
be_bryan 0:b74591d5ab33 151 bool leap = _rtc_is_leap_year(time_info->tm_year);
be_bryan 0:b74591d5ab33 152 for (uint32_t i = 0; i < 12; ++i) {
be_bryan 0:b74591d5ab33 153 if ((uint32_t) timestamp < seconds_before_month[leap][i]) {
be_bryan 0:b74591d5ab33 154 time_info->tm_mon = i - 1;
be_bryan 0:b74591d5ab33 155 break;
be_bryan 0:b74591d5ab33 156 }
be_bryan 0:b74591d5ab33 157 }
be_bryan 0:b74591d5ab33 158
be_bryan 0:b74591d5ab33 159 // remove month from timestamp and compute the number of days.
be_bryan 0:b74591d5ab33 160 // note: unlike other fields, days are not 0 indexed.
be_bryan 0:b74591d5ab33 161 timestamp -= seconds_before_month[leap][time_info->tm_mon];
be_bryan 0:b74591d5ab33 162 time_info->tm_mday = (timestamp / SECONDS_BY_DAY) + 1;
be_bryan 0:b74591d5ab33 163
be_bryan 0:b74591d5ab33 164 return true;
be_bryan 0:b74591d5ab33 165 }