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mbed_mktime.h
1 /* mbed Microcontroller Library
2  * Copyright (c) 2017-2019 ARM Limited
3  * SPDX-License-Identifier: Apache-2.0
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 
18 #ifndef MBED_MKTIME_H
19 #define MBED_MKTIME_H
20 
21 #include <time.h>
22 #include <stdbool.h>
23 #include <stdint.h>
24 
25 #ifdef __cplusplus
26 extern "C" {
27 #endif
28 
29 /** \addtogroup platform-public-api */
30 /** @{*/
31 
32 /**
33  * \defgroup platform_mktime mktime functions
34  * @{
35  */
36 
37 /* Time range across the whole 32-bit range should be supported which means that years in range 1970 - 2106 can be
38  * encoded. We have two types of RTC devices:
39  * a) RTCs which handles all leap years in the mentioned year range correctly. Leap year is determined by checking if
40  * the year counter value is divisible by 400, 100, and 4. No problem here.
41  * b) RTCs which handles leap years correctly up to 2100. The RTC does a simple bit comparison to see if the two
42  * lowest order bits of the year counter are zero. In this case 2100 year will be considered
43  * incorrectly as a leap year, so the last valid point in time will be 28.02.2100 23:59:59 and next day will be
44  * 29.02.2100 (invalid). So after 28.02.2100 the day counter will be off by a day.
45  */
46 typedef enum {
47  RTC_FULL_LEAP_YEAR_SUPPORT,
48  RTC_4_YEAR_LEAP_YEAR_SUPPORT
49 } rtc_leap_year_support_t;
50 
51 /** Compute if a year is a leap year or not.
52  *
53  * @param year The year to test it shall be in the range [70:206]. Year 0 is
54  * translated into year 1900 CE.
55  * @param leap_year_support use RTC_FULL_LEAP_YEAR_SUPPORT if RTC device is able
56  * to correctly detect all leap years in range [70:206] otherwise use RTC_4_YEAR_LEAP_YEAR_SUPPORT.
57  *
58  * @return true if the year in input is a leap year and false otherwise.
59  *
60  * @note For use by the HAL only
61  * @note Year 2100 is treated differently for devices with full leap year support and devices with
62  * partial leap year support. Devices with partial leap year support treats 2100 as a leap year.
63  */
64 bool _rtc_is_leap_year(int year, rtc_leap_year_support_t leap_year_support);
65 
66 /* Convert a calendar time into time since UNIX epoch as a time_t.
67  *
68  * This function is a thread safe (partial) replacement for mktime. It is
69  * tailored around RTC peripherals needs and is not by any mean a complete
70  * replacement of mktime.
71  *
72  * @param time The calendar time to convert into a time_t since epoch.
73  * The fields from tm used for the computation are:
74  * - tm_sec
75  * - tm_min
76  * - tm_hour
77  * - tm_mday
78  * - tm_mon
79  * - tm_year
80  * Other fields are ignored and won't be renormalized by a call to this function.
81  * A valid calendar time is comprised between:
82  * the 1st of January 1970 at 00:00:00 to the 7th of February 2106 at 06:28:15.
83  * @param leap_year_support use RTC_FULL_LEAP_YEAR_SUPPORT if RTC device is able
84  * to correctly detect all leap years in range [70:206] otherwise use RTC_4_YEAR_LEAP_YEAR_SUPPORT.
85  * @param seconds holder for the result - calendar time as seconds since UNIX epoch.
86  *
87  * @return true on success, false if conversion error occurred.
88  *
89  * @note Leap seconds are not supported.
90  * @note Values in output range from 0 to UINT_MAX.
91  * @note Full and partial leap years support.
92  * @note For use by the HAL only
93  */
94 bool _rtc_maketime(const struct tm *time, time_t *seconds, rtc_leap_year_support_t leap_year_support);
95 
96 /* Convert a given time in seconds since epoch into calendar time.
97  *
98  * This function is a thread safe (partial) replacement for localtime. It is
99  * tailored around RTC peripherals specification and is not by any means a
100  * complete of localtime.
101  *
102  * @param timestamp The time (in seconds) to convert into calendar time. Valid
103  * input are in the range [0 : UINT32_MAX].
104  * @param calendar_time Pointer to the object which will contain the result of
105  * the conversion. The tm fields filled by this function are:
106  * - tm_sec
107  * - tm_min
108  * - tm_hour
109  * - tm_mday
110  * - tm_mon
111  * - tm_year
112  * - tm_wday
113  * - tm_yday
114  * The object remains untouched if the time in input is invalid.
115  * @param leap_year_support use RTC_FULL_LEAP_YEAR_SUPPORT if RTC device is able
116  * to correctly detect all leap years in range [70:206] otherwise use RTC_4_YEAR_LEAP_YEAR_SUPPORT.
117  * @return true if the conversion was successful, false otherwise.
118  *
119  * @note For use by the HAL only.
120  * @note Full and partial leap years support.
121  */
122 bool _rtc_localtime(time_t timestamp, struct tm *time_info, rtc_leap_year_support_t leap_year_support);
123 
124 /** @}*/
125 
126 #ifdef __cplusplus
127 }
128 #endif
129 
130 #endif /* MBED_MKTIME_H */
131 
132 /** @}*/
_rtc_is_leap_year
bool _rtc_is_leap_year(int year, rtc_leap_year_support_t leap_year_support)
Compute if a year is a leap year or not.
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