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Merge pull request #1146 from Kijewski/struct-tm-utils
sys: add utility functions for `struct tm`
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‎sys/include/tm.h

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/**
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* @addtogroup sys_timex
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* @{
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* @brief Utility library for `struct tm`.
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*/
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#ifndef __SYS__TIMEX__TM__H
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#define __SYS__TIMEX__TM__H
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#include <time.h>
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#include <sys/time.h>
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#include <stdint.h>
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#include "attributes.h"
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#define TM_WDAY_SUN (0) /**< Sunday in `struct tm::tm_wday`. */
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#define TM_WDAY_MON (1) /**< Monday in `struct tm::tm_wday`. */
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#define TM_WDAY_TUE (2) /**< Tuesday in `struct tm::tm_wday`. */
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#define TM_WDAY_WED (3) /**< Wednesday in `struct tm::tm_wday`. */
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#define TM_WDAY_THU (4) /**< Thursday in `struct tm::tm_wday`. */
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#define TM_WDAY_FRI (5) /**< Friday in `struct tm::tm_wday`. */
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#define TM_WDAY_SAT (6) /**< Saturday in `struct tm::tm_wday`. */
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#define TM_MON_JAN ( 0) /**< January in `struct tm::tm_mon` */
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#define TM_MON_FEB ( 1) /**< February in `struct tm::tm_mon` */
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#define TM_MON_MAR ( 2) /**< March in `struct tm::tm_mon` */
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#define TM_MON_APR ( 3) /**< April in `struct tm::tm_mon` */
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#define TM_MON_MAY ( 4) /**< May in `struct tm::tm_mon` */
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#define TM_MON_JUN ( 5) /**< June in `struct tm::tm_mon` */
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#define TM_MON_JUL ( 6) /**< July in `struct tm::tm_mon` */
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#define TM_MON_AUG ( 7) /**< August in `struct tm::tm_mon` */
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#define TM_MON_SEP ( 8) /**< September in `struct tm::tm_mon` */
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#define TM_MON_OCT ( 9) /**< October in `struct tm::tm_mon` */
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#define TM_MON_NOV (10) /**< November in `struct tm::tm_mon` */
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#define TM_MON_DEC (11) /**< December in `struct tm::tm_mon` */
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/**
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* @brief The number of days in common years.
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* @see http://oeis.org/A008685
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*/
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extern const int8_t TM_MON_DAYS[12];
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/**
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* @brief The prefixsum of the number of days in common years.
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* @see http://oeis.org/A061251
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*/
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extern const int16_t TM_MON_DAYS_ACCU[12];
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/**
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* @brief Tells if a given year is a leap year in the Gregorian calendar.
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* @param[in] year The year. Probably should be ≥ 1582, but needs to be ≥ 1.
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* @returns `1` if it is a leap year, `0` if it is a common year.
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*/
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int tm_is_leap_year(unsigned year) CONST;
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/**
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* @brief Returns the congruent weekday of the Doomsday (March 0).
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* @details Only applies for years in the Gregorian calendar.
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* @param[in] year The year. Probably should be ≥ 1582, but needs to be ≥ 1.
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* @returns The result `% 7` is the weekday of the Doomsday of the given year.
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*/
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int tm_doomsday(int year) CONST;
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/**
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* @brief Calculates the day of the year and the weekday of a given date.
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* @details Illegal dates are not catched.
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* @param[in] year The year. Probably should be ≥ 1582, but needs to be ≥ 1.
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* @param[in] mon The month, TM_MON_JAN to TM_MON_DEC.
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* @param[in] day The day in the month, 1 to 31.
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* @param[out] wday Returns the day of the week.
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* @param[out] yday Returns the day of the year (Jan 1st is 0).
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*/
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void tm_get_wyday(int year, int mon, int mday, int *wday, int *yday);
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/**
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* @brief Fills in `struct tm::tm_wday` and `struct tm::tm_yday` given a date.
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* @details `struct tm::tm_year`, `struct tm::tm_mon`, and `struct tm::tm_mday`
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* need to be set before you call this function.
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* @param[in,out] The datum to operate on.
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*/
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void tm_fill_derived_values(struct tm *tm);
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/**
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* @brief Tests if a date is valid.
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* @details Dates before 1582-10-15 are invalid.
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* @param[in] year The year.
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* @param[in] mon The month.
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* @param[in] day The day in the month.
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* @returns 0 iff the date is invalid.
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*/
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int tm_is_valid_date(int year, int mon, int mday) CONST;
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/**
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* @brief Shallow test if a time is valid.
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* @details This function accepts leap seconds at any given time, because the timezone is unknown.
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* @param[in] hour The hour.
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* @param[in] min The minutes.
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* @param[in] sec The seconds.
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* @returns 0 iff the time is invalid.
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*/
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int tm_is_valid_time(int hour, int min, int sec) CONST;
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#endif

‎sys/timex/tm.c

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/*
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* Copyright (C) 2014 René Kijewski <[email protected]>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* @author René Kijewski <[email protected]>
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*/
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#include "tm.h"
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#include <stdint.h>
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const int8_t TM_MON_DAYS[12] = {
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31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
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};
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const int16_t TM_MON_DAYS_ACCU[12] = {
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0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
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};
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int tm_is_leap_year(unsigned year)
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{
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return ((year & 3) == 0) && ((year % 400 == 0) || (year % 100 != 0));
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}
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int tm_doomsday(int year)
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{
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int result;
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result = TM_WDAY_TUE;
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result += year;
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result += year >>= 2;
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result -= year /= 25;
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result += year >>= 2;
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return result;
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}
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void tm_get_wyday(int year, int mon, int mday, int *wday, int *yday)
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{
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int is_leap_year = tm_is_leap_year(year);
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*yday = TM_MON_DAYS_ACCU[mon] + mday + (mon <= TM_MON_FEB ? 0 : is_leap_year) - 1;
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int jan1 = tm_doomsday(year) - 2 - is_leap_year;
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*wday = (jan1 + *yday) % 7;
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}
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void tm_fill_derived_values(struct tm *tm)
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{
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tm_get_wyday(tm->tm_year + 1900, tm->tm_mon, tm->tm_mday, &tm->tm_wday, &tm->tm_yday);
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}
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int tm_is_valid_date(int year, int mon, int mday)
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{
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if ((mon < TM_MON_JAN) || (mon > TM_MON_DEC)) {
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return 0;
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}
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if ((mday <= 0) || (mday > TM_MON_DAYS[mon])) {
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if ((mday != 29) || (mon != TM_MON_FEB) || !tm_is_leap_year(year)) {
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return 0;
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}
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}
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if (year <= 1582) {
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if (year < 1582) {
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return 0;
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}
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if ((mon < TM_MON_OCT) || ((mon == TM_MON_OCT) && (mday < 15))) {
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return 0;
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}
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}
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return 1;
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}
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int tm_is_valid_time(int hour, int min, int sec)
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{
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return (hour >= 0) && (hour < 24) &&
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(min >= 0) && (min < 60) &&
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(sec >= 0) && (sec <= 60);
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}

‎tests/test_struct_tm_utility/Makefile

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PROJECT = test_struct_tm_utility
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include ../Makefile.tests_common
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DISABLE_MODULE += auto_init
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USEMODULE += shell
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USEMODULE += posix
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USEMODULE += timex
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# The MSP-430 toolchain lacks sscanf:
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BOARD_BLACKLIST := chronos msb-430 msb-430h telosb wsn430-v1_3b wsn430-v1_4 z1
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# Too little RAM
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BOARD_BLACKLIST += redbee-econotag
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include $(RIOTBASE)/Makefile.include

‎tests/test_struct_tm_utility/main.c

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/**
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* @ingroup tests
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* @{
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* @file
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* @brief Test the `struct tm` helpers in "tm.h" of the module "timex".
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* @author René Kijewski <[email protected]>
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* @}
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*/
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#include <stdio.h>
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#include "shell.h"
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#include "posix_io.h"
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#include "board_uart0.h"
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#include "tm.h"
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#define SHELL_BUFSIZE (UART0_BUFSIZE)
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static const char MON_NAMES[12][3] = {
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"JAN", "FEB", "MAR", "APR",
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"MAY", "JUN", "JUL", "AUG",
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"SEP", "OCT", "NOV", "DEC",
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};
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static const char DAY_NAMES[7][3] = {
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"SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT"
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};
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static const char BOOL_NAMES[2][3] = { "NO", "YES" };
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static void cmd_days_in(int argc, char **argv)
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{
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int mon;
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if ((argc != 2) || (sscanf(argv[1], "%d", &mon) != 1) || (mon < 1) || (mon > 12)) {
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printf("Usage: %s <Month[1..12]>\n", argv[0]);
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}
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else {
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printf("There are %d days in %.3s in common years.\n",
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TM_MON_DAYS[mon - 1], MON_NAMES[mon - 1]);
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}
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}
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static void cmd_leap_year(int argc, char **argv)
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{
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int year;
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if ((argc != 2) || (sscanf(argv[1], "%d", &year) != 1)) {
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printf("Usage: %s <Year>\n", argv[0]);
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}
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else {
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printf("Was %d a leap year? %.3s.\n",
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year, BOOL_NAMES[tm_is_leap_year(year)]);
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}
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}
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static void cmd_doomsday(int argc, char **argv)
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{
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int year;
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if ((argc != 2) || (sscanf(argv[1], "%d", &year) != 1)) {
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printf("Usage: %s <Year>\n", argv[0]);
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}
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else {
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printf("What weekday was MAR 0 of %d? %.3s.\n",
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year, DAY_NAMES[tm_doomsday(year) % 7]);
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}
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}
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static void cmd_day(int argc, char **argv)
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{
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int year, mon, day;
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if ((argc != 4) || (sscanf(argv[1], "%d", &year) != 1)
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|| (sscanf(argv[2], "%d", &mon) != 1)
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|| (sscanf(argv[3], "%d", &day) != 1)) {
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printf("Usage: %s <Year> <Month[1..12]> <Day[1..31]>\n", argv[0]);
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}
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else {
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if (!tm_is_valid_date(year, mon - 1, day)) {
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puts("The supplied date is invalid, but no error should occur.");
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}
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int wday, yday;
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tm_get_wyday(year, mon - 1, day, &wday, &yday);
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printf("What weekday was %04d-%02d-%02d? The %d(th) day of the year was a %.3s.\n",
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year, mon, day, yday + 1, DAY_NAMES[wday]);
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}
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}
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static const shell_command_t shell_commands[] = {
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{ "days_in", "Tells you the number of days in a month.", cmd_days_in },
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{ "leap_year", "Tells you if a supplied year is a leap year.", cmd_leap_year },
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{ "doomsday", "Tells you the wday Doomsday of the supplied year.", cmd_doomsday },
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{ "day", "Tells you the day of the supplied date.", cmd_day },
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{ NULL, NULL, NULL }
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};
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static int shell_readc(void)
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{
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char c;
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int result = posix_read(uart0_handler_pid, &c, 1);
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if (result != 1) {
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return -1;
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}
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return (unsigned char) c;
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}
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static void shell_putchar(int c)
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{
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putchar(c);
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}
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int main(void)
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{
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board_uart0_init();
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posix_open(uart0_handler_pid, 0);
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shell_t shell;
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shell_init(&shell, shell_commands, SHELL_BUFSIZE, shell_readc, shell_putchar);
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puts("`struct tm` utility shell.");
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shell_run(&shell);
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return 0;
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}

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