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/*
* $RCSfile$
*
* Copyright (c) 2007 Sun Microsystems, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistribution of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistribution in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any
* kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
* WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
* EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL
* NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
* USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR
* ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
* CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
* REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
* INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or
* intended for use in the design, construction, operation or
* maintenance of any nuclear facility.
*
* $Revision$
* $Date$
* $State$
*/
package com.sun.j3d.internal;
/**
* Utility class used when computing the hash code for
* objects containing float or double values. This fixes Issue 36.
*/
public class HashCodeUtil {
/**
* Returns the representation of the specified floating-point
* value according to the IEEE 754 floating-point "single format"
* bit layout, after first mapping -0.0 to 0.0. This method is
* identical to Float.floatToIntBits(float) except that an integer
* value of 0 is returned for a floating-point value of
* -0.0f. This is done for the purpose of computing a hash code
* that satisfies the contract of hashCode() and equals(). The
* equals() method in some Java 3D classes does a pair-wise
* "==" test on each floating-point field in the class. Since
* 0.0f == -0.0f returns true, we must also return the
* same hash code for two objects, one of which has a field with a
* value of -0.0f and the other of which has a cooresponding field
* with a value of 0.0f.
*
* @param f an input floating-point number
* @return the integer bits representing that floating-point
* number, after first mapping -0.0f to 0.0f
*/
public static int floatToIntBits(float f) {
// Check for +0 or -0
if (f == 0.0f) {
return 0;
}
else {
return Float.floatToIntBits(f);
}
}
/**
* Returns the representation of the specified floating-point
* value according to the IEEE 754 floating-point "double format"
* bit layout, after first mapping -0.0 to 0.0. This method is
* identical to Double.doubleToLongBits(double) except that an
* integer value of 0L is returned for a floating-point value of
* -0.0. This is done for the purpose of computing a hash code
* that satisfies the contract of hashCode() and equals(). The
* equals() method in some Java 3D classes does a pair-wise
* "==" test on each floating-point field in the class. Since
* 0.0 == -0.0 returns true, we must also return the
* same hash code for two objects, one of which has a field with a
* value of -0.0 and the other of which has a cooresponding field
* with a value of 0.0.
*
* @param d an input double precision floating-point number
* @return the integer bits representing that floating-point
* number, after first mapping -0.0f to 0.0f
*/
public static long doubleToLongBits(double d) {
// Check for +0 or -0
if (d == 0.0) {
return 0L;
}
else {
return Double.doubleToLongBits(d);
}
}
/**
* Do not construct an instance of this class.
*/
private HashCodeUtil() {
}
}
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