Time.java

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package org.ros.message;

/**
 * ROS Time representation. Time and Time are primitive types in ROS. ROS
 * represents each as two 32-bit integers: seconds and nanoseconds since epoch.
 *
 * @see "http://www.ros.org/wiki/msg"
 *
 * @author Jason Wolfe
 * @author kwc@willowgarage.com (Ken Conley)
 */
public class Time implements Comparable<Time> {

  public int secs;
  public int nsecs;

  public Time() {
    secs = 0;
    nsecs = 0;
  }

  public Time(int secs, int nsecs) {
    this.secs = secs;
    this.nsecs = nsecs;
    normalize();
  }

  public Time(double secs) {
    this.secs = (int) secs;
    this.nsecs = (int) ((secs - this.secs) * 1000000000);
    normalize();
  }

  public Time(Time t) {
    this.secs = t.secs;
    this.nsecs = t.nsecs;
  }

  public Time add(Duration d) {
    return new Time(secs + d.secs, nsecs + d.nsecs);
  }

  public Time subtract(Duration d) {
    return new Time(secs - d.secs, nsecs - d.nsecs);
  }

  public Duration subtract(Time t) {
    return new Duration(secs - t.secs, nsecs - t.nsecs);
  }

  public static Time fromMillis(long timeInMillis) {
    int secs = (int) (timeInMillis / 1000);
    int nsecs = (int) (timeInMillis % 1000) * 1000000;
    return new Time(secs, nsecs);
  }

  public static Time fromNano(long timeInNs) {
    int secs = (int) (timeInNs / 1000000000);
    int nsecs = (int) (timeInNs % 1000000000);
    return new Time(secs, nsecs);
  }

  @Override
  public String toString() {
    return secs + ":" + nsecs;
  }

  public double toSeconds() {
    return totalNsecs() / 1e9;
  }

  public long totalNsecs() {
    return ((long) secs) * 1000000000 + nsecs;
  }

  public boolean isZero() {
    return totalNsecs() == 0;
  }

  public void normalize() {
    while (nsecs < 0) {
      nsecs += 1000000000;
      secs -= 1;
    }
    while (nsecs >= 1000000000) {
      nsecs -= 1000000000;
      secs += 1;
    }
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + nsecs;
    result = prime * result + secs;
    return result;
  }

  /**
   * Check for equality between {@link Time} objects.
   * <p>
   * This method does not normalize {@link Time} representations, so fields must
   * match exactly.
   */
  @Override
  public boolean equals(Object obj) {
    if (this == obj)
      return true;
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    Time other = (Time) obj;
    if (nsecs != other.nsecs)
      return false;
    if (secs != other.secs)
      return false;
    return true;
  }

  @Override
  public int compareTo(Time t) {
    if ((secs > t.secs) || ((secs == t.secs) && nsecs > t.nsecs)) {
      return 1;
    }
    if ((secs == t.secs) && (nsecs == t.nsecs)) {
      return 0;
    }
    return -1;
  }
}