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/*
* $RCSfile$
*
* Copyright 2004-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code 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 General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
* $Revision$
* $Date$
* $State$
*/
package javax.vecmath;
/**
* Utility vecmath class used when computing the hash code for vecmath
* objects containing float or double values. This fixes Issue 36.
*/
class VecMathUtil {
/**
* 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 each vecmath class does a pair-wise "=="
* test on each floating-point field in the class (e.g., x, y, and
* z for a Tuple3f). 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
*/
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 each vecmath class does a pair-wise "=="
* test on each floating-point field in the class (e.g., x, y, and
* z for a Tuple3d). 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
*/
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 VecMathUtil() {
}
}
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