mbed official / mbed-dev

mbed library sources. Supersedes mbed-src.

Dependents:   Nucleo_Hello_Encoder BLE_iBeaconScan AM1805_DEMO DISCO-F429ZI_ExportTemplate1 ... more

platform/mbed_mktime.c@181:57724642e740, 2018-02-16 (annotated)

Committer:
AnnaBridge
Date:
Fri Feb 16 16:09:33 2018 +0000
Revision:
181:57724642e740
Parent:
169:e3b6fe271b81
Child:
184:08ed48f1de7f
mbed-dev library. Release version 159.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AnnaBridge 167:e84263d55307 1 /* mbed Microcontroller Library
AnnaBridge 167:e84263d55307 2 * Copyright (c) 2017-2017 ARM Limited
AnnaBridge 167:e84263d55307 3 *
AnnaBridge 167:e84263d55307 4 * Licensed under the Apache License, Version 2.0 (the "License");
AnnaBridge 167:e84263d55307 5 * you may not use this file except in compliance with the License.
AnnaBridge 167:e84263d55307 6 * You may obtain a copy of the License at
AnnaBridge 167:e84263d55307 7 *
AnnaBridge 167:e84263d55307 8 * http://www.apache.org/licenses/LICENSE-2.0
AnnaBridge 167:e84263d55307 9 *
AnnaBridge 167:e84263d55307 10 * Unless required by applicable law or agreed to in writing, software
AnnaBridge 167:e84263d55307 11 * distributed under the License is distributed on an "AS IS" BASIS,
AnnaBridge 167:e84263d55307 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
AnnaBridge 167:e84263d55307 13 * See the License for the specific language governing permissions and
AnnaBridge 167:e84263d55307 14 * limitations under the License.
AnnaBridge 167:e84263d55307 15 */
AnnaBridge 167:e84263d55307 16
AnnaBridge 167:e84263d55307 17 #include "mbed_mktime.h"
AnnaBridge 167:e84263d55307 18
AnnaBridge 167:e84263d55307 19 /*
AnnaBridge 167:e84263d55307 20 * time constants
AnnaBridge 167:e84263d55307 21 */
AnnaBridge 167:e84263d55307 22 #define SECONDS_BY_MINUTES 60
AnnaBridge 167:e84263d55307 23 #define MINUTES_BY_HOUR 60
AnnaBridge 167:e84263d55307 24 #define SECONDS_BY_HOUR (SECONDS_BY_MINUTES * MINUTES_BY_HOUR)
AnnaBridge 167:e84263d55307 25 #define HOURS_BY_DAY 24
AnnaBridge 167:e84263d55307 26 #define SECONDS_BY_DAY (SECONDS_BY_HOUR * HOURS_BY_DAY)
AnnaBridge 167:e84263d55307 27
AnnaBridge 167:e84263d55307 28 /*
AnnaBridge 167:e84263d55307 29 * 2 dimensional array containing the number of seconds elapsed before a given
AnnaBridge 167:e84263d55307 30 * month.
AnnaBridge 167:e84263d55307 31 * The second index map to the month while the first map to the type of year:
AnnaBridge 167:e84263d55307 32 * - 0: non leap year
AnnaBridge 167:e84263d55307 33 * - 1: leap year
AnnaBridge 167:e84263d55307 34 */
AnnaBridge 167:e84263d55307 35 static const uint32_t seconds_before_month[2][12] = {
AnnaBridge 167:e84263d55307 36 {
AnnaBridge 167:e84263d55307 37 0,
AnnaBridge 167:e84263d55307 38 31 * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 39 (31 + 28) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 40 (31 + 28 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 41 (31 + 28 + 31 + 30) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 42 (31 + 28 + 31 + 30 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 43 (31 + 28 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 44 (31 + 28 + 31 + 30 + 31 + 30 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 45 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 46 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 47 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 48 (31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 49 },
AnnaBridge 167:e84263d55307 50 {
AnnaBridge 167:e84263d55307 51 0,
AnnaBridge 167:e84263d55307 52 31 * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 53 (31 + 29) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 54 (31 + 29 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 55 (31 + 29 + 31 + 30) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 56 (31 + 29 + 31 + 30 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 57 (31 + 29 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 58 (31 + 29 + 31 + 30 + 31 + 30 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 59 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 60 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 61 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 62 (31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30) * SECONDS_BY_DAY,
AnnaBridge 167:e84263d55307 63 }
AnnaBridge 167:e84263d55307 64 };
AnnaBridge 167:e84263d55307 65
AnnaBridge 167:e84263d55307 66 bool _rtc_is_leap_year(int year) {
AnnaBridge 167:e84263d55307 67 /*
AnnaBridge 167:e84263d55307 68 * since in practice, the value manipulated by this algorithm lie in the
AnnaBridge 167:e84263d55307 69 * range [70 : 138], the algorith can be reduced to: year % 4.
AnnaBridge 167:e84263d55307 70 * The algorithm valid over the full range of value is:
AnnaBridge 167:e84263d55307 71
AnnaBridge 167:e84263d55307 72 year = 1900 + year;
AnnaBridge 167:e84263d55307 73 if (year % 4) {
AnnaBridge 167:e84263d55307 74 return false;
AnnaBridge 167:e84263d55307 75 } else if (year % 100) {
AnnaBridge 167:e84263d55307 76 return true;
AnnaBridge 167:e84263d55307 77 } else if (year % 400) {
AnnaBridge 167:e84263d55307 78 return false;
AnnaBridge 167:e84263d55307 79 }
AnnaBridge 167:e84263d55307 80 return true;
AnnaBridge 167:e84263d55307 81
AnnaBridge 167:e84263d55307 82 */
AnnaBridge 167:e84263d55307 83 return (year) % 4 ? false : true;
AnnaBridge 167:e84263d55307 84 }
AnnaBridge 167:e84263d55307 85
AnnaBridge 167:e84263d55307 86 time_t _rtc_mktime(const struct tm* time) {
AnnaBridge 167:e84263d55307 87 // partial check for the upper bound of the range
AnnaBridge 167:e84263d55307 88 // normalization might happen at the end of the function
AnnaBridge 167:e84263d55307 89 // this solution is faster than checking if the input is after the 19th of
AnnaBridge 167:e84263d55307 90 // january 2038 at 03:14:07.
AnnaBridge 167:e84263d55307 91 if ((time->tm_year < 70) || (time->tm_year > 138)) {
AnnaBridge 167:e84263d55307 92 return ((time_t) -1);
AnnaBridge 167:e84263d55307 93 }
AnnaBridge 167:e84263d55307 94
AnnaBridge 167:e84263d55307 95 uint32_t result = time->tm_sec;
AnnaBridge 167:e84263d55307 96 result += time->tm_min * SECONDS_BY_MINUTES;
AnnaBridge 167:e84263d55307 97 result += time->tm_hour * SECONDS_BY_HOUR;
AnnaBridge 167:e84263d55307 98 result += (time->tm_mday - 1) * SECONDS_BY_DAY;
AnnaBridge 167:e84263d55307 99 result += seconds_before_month[_rtc_is_leap_year(time->tm_year)][time->tm_mon];
AnnaBridge 167:e84263d55307 100
AnnaBridge 167:e84263d55307 101 if (time->tm_year > 70) {
AnnaBridge 167:e84263d55307 102 // valid in the range [70:138]
AnnaBridge 167:e84263d55307 103 uint32_t count_of_leap_days = ((time->tm_year - 1) / 4) - (70 / 4);
AnnaBridge 167:e84263d55307 104 result += (((time->tm_year - 70) * 365) + count_of_leap_days) * SECONDS_BY_DAY;
AnnaBridge 167:e84263d55307 105 }
AnnaBridge 167:e84263d55307 106
AnnaBridge 167:e84263d55307 107 if (result > INT32_MAX) {
Kojto 169:e3b6fe271b81 108 return (time_t) -1;
AnnaBridge 167:e84263d55307 109 }
AnnaBridge 167:e84263d55307 110
AnnaBridge 167:e84263d55307 111 return result;
AnnaBridge 167:e84263d55307 112 }
AnnaBridge 167:e84263d55307 113
AnnaBridge 167:e84263d55307 114 bool _rtc_localtime(time_t timestamp, struct tm* time_info) {
AnnaBridge 167:e84263d55307 115 if (((int32_t) timestamp) < 0) {
AnnaBridge 167:e84263d55307 116 return false;
AnnaBridge 167:e84263d55307 117 }
AnnaBridge 167:e84263d55307 118
AnnaBridge 167:e84263d55307 119 time_info->tm_sec = timestamp % 60;
AnnaBridge 167:e84263d55307 120 timestamp = timestamp / 60; // timestamp in minutes
AnnaBridge 167:e84263d55307 121 time_info->tm_min = timestamp % 60;
AnnaBridge 167:e84263d55307 122 timestamp = timestamp / 60; // timestamp in hours
AnnaBridge 167:e84263d55307 123 time_info->tm_hour = timestamp % 24;
AnnaBridge 167:e84263d55307 124 timestamp = timestamp / 24; // timestamp in days;
AnnaBridge 167:e84263d55307 125
AnnaBridge 167:e84263d55307 126 // compute the weekday
AnnaBridge 167:e84263d55307 127 // The 1st of January 1970 was a Thursday which is equal to 4 in the weekday
AnnaBridge 167:e84263d55307 128 // representation ranging from [0:6]
AnnaBridge 167:e84263d55307 129 time_info->tm_wday = (timestamp + 4) % 7;
AnnaBridge 167:e84263d55307 130
AnnaBridge 167:e84263d55307 131 // years start at 70
AnnaBridge 167:e84263d55307 132 time_info->tm_year = 70;
AnnaBridge 167:e84263d55307 133 while (true) {
AnnaBridge 167:e84263d55307 134 if (_rtc_is_leap_year(time_info->tm_year) && timestamp >= 366) {
AnnaBridge 167:e84263d55307 135 ++time_info->tm_year;
AnnaBridge 167:e84263d55307 136 timestamp -= 366;
AnnaBridge 167:e84263d55307 137 } else if (!_rtc_is_leap_year(time_info->tm_year) && timestamp >= 365) {
AnnaBridge 167:e84263d55307 138 ++time_info->tm_year;
AnnaBridge 167:e84263d55307 139 timestamp -= 365;
AnnaBridge 167:e84263d55307 140 } else {
AnnaBridge 167:e84263d55307 141 // the remaining days are less than a years
AnnaBridge 167:e84263d55307 142 break;
AnnaBridge 167:e84263d55307 143 }
AnnaBridge 167:e84263d55307 144 }
AnnaBridge 167:e84263d55307 145
AnnaBridge 167:e84263d55307 146 time_info->tm_yday = timestamp;
AnnaBridge 167:e84263d55307 147
AnnaBridge 167:e84263d55307 148 // convert days into seconds and find the current month
AnnaBridge 167:e84263d55307 149 timestamp *= SECONDS_BY_DAY;
AnnaBridge 167:e84263d55307 150 time_info->tm_mon = 11;
AnnaBridge 167:e84263d55307 151 bool leap = _rtc_is_leap_year(time_info->tm_year);
AnnaBridge 167:e84263d55307 152 for (uint32_t i = 0; i < 12; ++i) {
AnnaBridge 167:e84263d55307 153 if ((uint32_t) timestamp < seconds_before_month[leap][i]) {
AnnaBridge 167:e84263d55307 154 time_info->tm_mon = i - 1;
AnnaBridge 167:e84263d55307 155 break;
AnnaBridge 167:e84263d55307 156 }
AnnaBridge 167:e84263d55307 157 }
AnnaBridge 167:e84263d55307 158
AnnaBridge 167:e84263d55307 159 // remove month from timestamp and compute the number of days.
AnnaBridge 167:e84263d55307 160 // note: unlike other fields, days are not 0 indexed.
AnnaBridge 167:e84263d55307 161 timestamp -= seconds_before_month[leap][time_info->tm_mon];
AnnaBridge 167:e84263d55307 162 time_info->tm_mday = (timestamp / SECONDS_BY_DAY) + 1;
AnnaBridge 167:e84263d55307 163
AnnaBridge 167:e84263d55307 164 return true;
AnnaBridge 167:e84263d55307 165 }