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97 lines
2.6 KiB
V
97 lines
2.6 KiB
V
// Copyright (c) 2019-2023 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module time
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// unix returns a time struct from Unix time.
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pub fn unix(abs i64) Time {
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// Split into day and time
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mut day_offset := abs / seconds_per_day
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if abs % seconds_per_day < 0 {
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// Compensate for round towards zero on integers as we want floored instead
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day_offset--
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}
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year, month, day := calculate_date_from_offset(day_offset)
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hr, min, sec := calculate_time_from_offset(abs % seconds_per_day)
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return Time{
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year: year
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month: month
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day: day
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hour: hr
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minute: min
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second: sec
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unix: abs
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}
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}
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// unix2 returns a time struct from Unix time and microsecond value
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pub fn unix2(abs i64, microsecond int) Time {
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// Split into day and time
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mut day_offset := abs / seconds_per_day
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if abs % seconds_per_day < 0 {
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// Compensate for round towards zero on integers as we want floored instead
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day_offset--
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}
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year, month, day := calculate_date_from_offset(day_offset)
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hr, min, sec := calculate_time_from_offset(abs % seconds_per_day)
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return Time{
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year: year
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month: month
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day: day
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hour: hr
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minute: min
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second: sec
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microsecond: microsecond
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unix: abs
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}
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}
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fn calculate_date_from_offset(day_offset_ i64) (int, int, int) {
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mut day_offset := day_offset_
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// source: http://howardhinnant.github.io/date_algorithms.html#civil_from_days
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// shift from 1970-01-01 to 0000-03-01
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day_offset += 719468 // int(days_per_400_years * 1970 / 400 - (28+31))
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mut era := 0
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if day_offset >= 0 {
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era = int(day_offset / days_per_400_years)
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} else {
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era = int((day_offset - days_per_400_years - 1) / days_per_400_years)
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}
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// doe(day of era) [0, 146096]
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doe := day_offset - era * days_per_400_years
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// yoe(year of era) [0, 399]
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yoe := (doe - doe / (days_per_4_years - 1) + doe / days_per_100_years - doe / (days_per_400_years - 1)) / days_in_year
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// year number
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mut y := int(yoe + era * 400)
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// doy (day of year), with year beginning Mar 1 [0, 365]
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doy := doe - (days_in_year * yoe + yoe / 4 - yoe / 100)
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mp := (5 * doy + 2) / 153
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d := int(doy - (153 * mp + 2) / 5 + 1)
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mut m := int(mp)
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if mp < 10 {
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m += 3
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} else {
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m -= 9
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}
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if m <= 2 {
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y += 1
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}
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return y, m, d
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}
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fn calculate_time_from_offset(second_offset_ i64) (int, int, int) {
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mut second_offset := second_offset_
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if second_offset < 0 {
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second_offset += seconds_per_day
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}
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hour_ := second_offset / seconds_per_hour
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second_offset %= seconds_per_hour
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min := second_offset / seconds_per_minute
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second_offset %= seconds_per_minute
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return int(hour_), int(min), int(second_offset)
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}
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