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/*
* $RCSfile$
*
* Copyright (c) 2007 Sun Microsystems, Inc. All rights reserved.
*
* Use is subject to license terms.
*
* $Revision$
* $Date$
* $State$
*/
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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