com.flowpowered.math.HashFunctions Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of flow-math Show documentation
Immutable math library for Java with a focus on games and computer graphics.
The newest version!
/*
 * This file is part of Flow Math, licensed under the MIT License (MIT).
 *
 * Copyright (c) 2013 Flow Powered 
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
/* Copyright (c) 1999 CERN - European Organization for Nuclear Research.
 *
 * Permission to use, copy, modify, distribute and sell this software and
 * its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and that
 * both that copyright notice and this permission notice appear in
 * supporting documentation. CERN makes no representations about the
 * suitability of this software for any purpose. It is provided "as is"
 * without expressed or implied warranty.
 */
package com.flowpowered.math;

/**
 * Provides various hash functions.
 *
 * @author [email protected]
 * @version 1.0, 09/24/99
 */
public final class HashFunctions {
    /**
     * Returns a hashcode for the specified value.
     *
     * @return a hash code value for the specified value.
     */
    public static int hash(double value) {
        assert !Double.isNaN(value) : "Values of NaN are not supported.";

        long bits = Double.doubleToLongBits(value);
        return (int) (bits ^ (bits >>> 32));
        //return (int) Double.doubleToLongBits(value*663608941.737);
        // This avoids excessive hashCollisions in the case values are of the form (1.0, 2.0, 3.0, ...)
    }

    /**
     * Returns a hashcode for the specified value.
     *
     * @return a hash code value for the specified value.
     */
    public static int hash(float value) {
        assert !Float.isNaN(value) : "Values of NaN are not supported.";

        return Float.floatToIntBits(value * 663608941.737f);
        // This avoids excessive hashCollisions in the case values are of the form (1.0, 2.0, 3.0, ...)
    }

    /**
     * Returns a hashcode for the specified value.
     *
     * @return a hash code value for the specified value.
     */
    public static int hash(int value) {
        return value;
    }

    /**
     * Returns a hashcode for the specified value.
     *
     * @return a hash code value for the specified value.
     */
    public static int hash(long value) {
        return ((int) (value ^ (value >>> 32)));
    }

    /**
     * Returns a hashcode for the specified object.
     *
     * @return a hash code value for the specified object.
     */
    public static int hash(Object object) {
        return object == null ? 0 : object.hashCode();
    }

    /**
     * In profiling, it has been found to be faster to have our own local implementation of "ceil" rather than to call to {@link Math#ceil(double)}.
     */
    public static int fastCeil(float v) {
        int possible_result = (int) v;
        if (v - possible_result > 0) {
            possible_result++;
        }
        return possible_result;
    }
}