TimeUtils.java

/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.utils;

/**
 * Wrapper around System.nanoTime() and System.currentTimeMillis(). Use this if
 * you want to be compatible across all platforms!
 * 
 * @author mzechner
 */
public final class TimeUtils {
    /**
     * @return The current value of the system timer, in nanoseconds.
     */
    public static long nanoTime() {
        return System.nanoTime();
    }

    /**
     * @return the difference, measured in milliseconds, between the current
     *         time and midnight, January 1, 1970 UTC.
     */
    public static long millis() {
        return System.currentTimeMillis();
    }

    private static final long nanosPerMilli = 1000000;

    /**
     * Convert nanoseconds time to milliseconds
     * 
     * @param nanos
     *            must be nanoseconds
     * @return time value in milliseconds
     */
    public static long nanosToMillis(long nanos) {
        return nanos / nanosPerMilli;
    }

    /**
     * Convert milliseconds time to nanoseconds
     * 
     * @param millis
     *            must be milliseconds
     * @return time value in nanoseconds
     */
    public static long millisToNanos(long millis) {
        return millis * nanosPerMilli;
    }

    /**
     * Get the time in nanos passed since a previous time
     * 
     * @param prevTime
     *            - must be nanoseconds
     * @return - time passed since prevTime in nanoseconds
     */
    public static long timeSinceNanos(long prevTime) {
        return nanoTime() - prevTime;
    }

    /**
     * Get the time in millis passed since a previous time
     * 
     * @param prevTime
     *            - must be milliseconds
     * @return - time passed since prevTime in milliseconds
     */
    public static long timeSinceMillis(long prevTime) {
        return millis() - prevTime;
    }
}