diff options
| -rw-r--r-- | watch-library/watch/watch_utility.c | 76 | ||||
| -rw-r--r-- | watch-library/watch/watch_utility.h | 10 |
2 files changed, 86 insertions, 0 deletions
diff --git a/watch-library/watch/watch_utility.c b/watch-library/watch/watch_utility.c index 82ea5a6b..a1f696c4 100644 --- a/watch-library/watch/watch_utility.c +++ b/watch-library/watch/watch_utility.c @@ -74,6 +74,82 @@ uint32_t watch_utility_date_time_to_unix_time(watch_date_time date_time, uint32_ return watch_utility_convert_to_unix_time(date_time.unit.year + WATCH_RTC_REFERENCE_YEAR, date_time.unit.month, date_time.unit.day, date_time.unit.hour, date_time.unit.minute, date_time.unit.second, utc_offset); } +#define LEAPOCH (946684800LL + 86400*(31+29)) + +#define DAYS_PER_400Y (365*400 + 97) +#define DAYS_PER_100Y (365*100 + 24) +#define DAYS_PER_4Y (365*4 + 1) + +watch_date_time watch_utility_date_time_from_unix_time(uint32_t timestamp, uint32_t utc_offset) { + watch_date_time retval; + retval.reg = 0; + int32_t days, secs; + int32_t remdays, remsecs, remyears; + int32_t qc_cycles, c_cycles, q_cycles; + int32_t years, months; + int32_t wday, yday, leap; + static const int8_t days_in_month[] = {31,30,31,30,31,31,30,31,30,31,31,29}; + timestamp += utc_offset; + + secs = timestamp - LEAPOCH; + days = secs / 86400; + remsecs = secs % 86400; + if (remsecs < 0) { + remsecs += 86400; + days--; + } + + wday = (3+days)%7; + if (wday < 0) wday += 7; + + qc_cycles = (int)(days / DAYS_PER_400Y); + remdays = days % DAYS_PER_400Y; + if (remdays < 0) { + remdays += DAYS_PER_400Y; + qc_cycles--; + } + + c_cycles = remdays / DAYS_PER_100Y; + if (c_cycles == 4) c_cycles--; + remdays -= c_cycles * DAYS_PER_100Y; + + q_cycles = remdays / DAYS_PER_4Y; + if (q_cycles == 25) q_cycles--; + remdays -= q_cycles * DAYS_PER_4Y; + + remyears = remdays / 365; + if (remyears == 4) remyears--; + remdays -= remyears * 365; + + leap = !remyears && (q_cycles || !c_cycles); + yday = remdays + 31 + 28 + leap; + if (yday >= 365+leap) yday -= 365+leap; + + years = remyears + 4*q_cycles + 100*c_cycles + 400*qc_cycles; + + for (months=0; days_in_month[months] <= remdays; months++) + remdays -= days_in_month[months]; + + years += 2000; + + months += 2; + if (months >= 12) { + months -=12; + years++; + } + + if (years < 2020 || years > 2083) return retval; + retval.unit.year = years - WATCH_RTC_REFERENCE_YEAR; + retval.unit.month = months + 1; + retval.unit.day = remdays + 1; + + retval.unit.hour = remsecs / 3600; + retval.unit.minute = remsecs / 60 % 60; + retval.unit.second = remsecs % 60; + + return retval; +} + float watch_utility_thermistor_temperature(uint16_t value, bool highside, float b_coefficient, float nominal_temperature, float nominal_resistance, float series_resistance) { float reading = (float)value; diff --git a/watch-library/watch/watch_utility.h b/watch-library/watch/watch_utility.h index 5374fb1c..0a8f2b13 100644 --- a/watch-library/watch/watch_utility.h +++ b/watch-library/watch/watch_utility.h @@ -60,6 +60,16 @@ uint32_t watch_utility_convert_to_unix_time(uint16_t year, uint8_t month, uint8_ */ uint32_t watch_utility_date_time_to_unix_time(watch_date_time date_time, uint32_t utc_offset); +/** @brief Returns the UNIX time (seconds since 1970) for a given watch_date_time struct. + * @param timestamp The UNIX timestamp that you wish to convert. + * @param utc_offset The number of seconds that you wish date_time to be offset from UTC. + * @return A watch_date_time for the given UNIX timestamp and UTC offset, or if outside the range that + * watch_date_time can represent, a watch_date_time with all fields set to 0. + * @note Adapted from MIT-licensed code from musl, Copyright © 2005-2014 Rich Felker, et al.: + * https://github.com/esmil/musl/blob/1cc81f5cb0df2b66a795ff0c26d7bbc4d16e13c6/src/time/__secs_to_tm.c + */ +watch_date_time watch_utility_date_time_from_unix_time(uint32_t timestamp, uint32_t utc_offset); + /** @brief Returns a temperature in degrees Celsius for a given thermistor voltage divider circuit. * @param value The raw analog reading from the thermistor pin (0-65535) * @param highside True if the thermistor is connected to VCC and the series resistor is connected |