/*
* -----------------------------------------------------------------------
* Copyright © 2013-2014 Meno Hochschild, <http://www.menodata.de/>
* -----------------------------------------------------------------------
* This file (SI.java) is part of project Time4J.
*
* Time4J is free software: You can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 2.1 of the License, or
* (at your option) any later version.
*
* Time4J is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Time4J. If not, see <http://www.gnu.org/licenses/>.
* -----------------------------------------------------------------------
*/
package net.time4j;
import net.time4j.base.MathUtils;
import net.time4j.engine.ChronoUnit;
import net.time4j.scale.TimeScale;
/**
* <p>Defines the SI-second as the duration of 9,192,631,770 periods of the
* radiation corresponding to the transition between the two hyperfine levels
* of the ground state of the caesium 133 atom. </p>
*
* <p>SI-seconds were first officially defined in 1967 so that any reference
* before that date are meaningless. Time4J supports SI-seconds first with
* the start of UTC epoch <strong>1972-01-01</strong> because especially the
* class {@code Moment} stores everything before 1972 in mean solar
* seconds. </p>
*
* @author Meno Hochschild
*/
/*[deutsch]
* <p>Definiert die SI-Sekunde als das 9.192.631.770-fache der Periodendauer
* der dem Übergang zwischen den beiden Hyperfeinstrukturniveaus des
* Grundzustands von Atomen des Nuklids Cäsium-133 entsprechenden
* Strahlung. </p>
*
* <p>SI-Sekunden wurden erst 1967 definiert, so daß jede Referenz
* auf sie vor diesem Jahr gegenstandslos sind. Time4J unterstützt
* aber das Rechnen damit ab der UTC-Epoche <strong>1972-01-01</strong>, weil
* insbesondere die Klasse {@code Moment} alles davor in mittleren
* Sonnensekunden speichert. </p>
*
* @author Meno Hochschild
*/
public enum SI
implements ChronoUnit {
//~ Statische Felder/Initialisierungen --------------------------------
SECONDS(1.0),
NANOSECONDS(1.0 / 1000000000);
//~ Instanzvariablen --------------------------------------------------
private final double length;
//~ Konstruktoren -----------------------------------------------------
private SI(double length) {
this.length = length;
}
//~ Methoden ----------------------------------------------------------
/**
* <p>Calculates the time distance between given time points
* in SI-units. </p>
*
* @param start start time point
* @param end end time point
* @return count of SI-units between start and end
* @throws UnsupportedOperationException if any time point is before 1972
*/
/*[deutsch]
* <p>Berechnet den zeitlichen Abstand zwischen den angegebenen Zeitpunkten
* in SI-Einheiten. </p>
*
* @param start Startzeitpunkt
* @param end Endzeitpunkt
* @return Anzahl der SI-Einheiten zwischen Start und Ende
* @throws UnsupportedOperationException wenn ein Zeitpunkt vor 1972 ist
*/
public long between(
Moment start,
Moment end
) {
Moment.check1972(start);
Moment.check1972(end);
switch (this) {
case SECONDS:
long delta = (
end.getElapsedTime(TimeScale.UTC)
- start.getElapsedTime(TimeScale.UTC));
if (delta < 0) {
if (end.getNanosecond() > start.getNanosecond()) {
delta++;
}
} else if (delta > 0) {
if (end.getNanosecond() < start.getNanosecond()) {
delta--;
}
}
return delta;
case NANOSECONDS:
return MathUtils.safeAdd(
MathUtils.safeMultiply(
MathUtils.safeSubtract(
end.getElapsedTime(TimeScale.UTC),
start.getElapsedTime(TimeScale.UTC)
),
1000000000
),
end.getNanosecond() - start.getNanosecond()
);
default:
throw new UnsupportedOperationException();
}
}
@Override
public double getLength() {
return this.length;
}
@Override
public boolean isCalendrical() {
return false;
}
}