mhsw-espurna/code/espurna/ntp_timelib.h

/*

Part of NTP MODULE

*/

// Based on https://github.com/PaulStoffregen/time

#pragma once

#include <time.h>
#include <sys/time.h>

constexpr time_t daysPerWeek = 7;

constexpr time_t secondsPerMinute = 60;
constexpr time_t secondsPerHour = 3600;
constexpr time_t secondsPerDay = secondsPerHour * 24;
constexpr time_t secondsPerWeek = daysPerWeek * secondsPerDay;

constexpr time_t secondsPerYear = secondsPerWeek * 52;
constexpr time_t secondsY2K = 946684800; // the time at the start of y2k

// wall clock values
template <typename T>
constexpr const T numberOfSeconds(T ts) {
    return (ts % (T)secondsPerMinute);
}  

template <typename T>
constexpr const T numberOfMinutes(T ts) {
    return ((ts / (T)secondsPerMinute) % (T)secondsPerMinute);
}

template <typename T>
constexpr const time_t numberOfHours(T ts) {
    return ((ts % (T)secondsPerDay) / (T)secondsPerHour);
}

// week starts with sunday as number 1, monday as 2 etc.
constexpr const int dayOfWeek(time_t ts) {
    return ((ts / secondsPerDay + 4) % daysPerWeek) + 1;
}

// the number of days since 0 (Jan 1 1970 in case of time_t values)
constexpr const int elapsedDays(uint32_t ts) {
    return (ts / secondsPerDay);
}

// the number of seconds since last midnight 
constexpr const uint32_t elapsedSecsToday(uint32_t ts) {
    return (ts % (uint32_t)secondsPerDay);
}

// note that week starts on day 1
constexpr const uint32_t elapsedSecsThisWeek(uint32_t ts) {
    return elapsedSecsToday(ts) + ((dayOfWeek(ts) - 1) * (uint32_t)secondsPerDay);
}

// The following methods are used in calculating alarms and assume the clock is set to a date later than Jan 1 1971
// Always set the correct time before settting alarms

// time at the start of the given day
constexpr const time_t previousMidnight(time_t ts) {
    return ((ts / secondsPerDay) * secondsPerDay);
}

// time at the end of the given day 
constexpr const time_t nextMidnight(time_t ts) {
    return previousMidnight(ts) + secondsPerDay;
}

// time at the start of the week for the given time
constexpr const time_t previousSunday(time_t ts) {
    return ts - elapsedSecsThisWeek(ts);
}

// time at the end of the week for the given time
constexpr const time_t nextSunday(time_t ts) {
    return previousSunday(ts) + secondsPerWeek;
}

int utc_hour(time_t ts);
int utc_minute(time_t ts);
int utc_second(time_t ts);
int utc_day(time_t ts);
int utc_weekday(time_t ts);
int utc_month(time_t ts);
int utc_year(time_t ts);

int hour(time_t ts);
int minute(time_t ts);
int second(time_t ts);
int day(time_t ts);
int weekday(time_t ts);
int month(time_t ts);
int year(time_t ts);

int hour();
int minute();
int second();
int day();
int weekday();
int month();
int year();

time_t now();