1 files changed, 44 insertions, 0 deletions
diff --git a/src/javax/media/j3d/J3dHash.java b/src/javax/media/j3d/J3dHash.java
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+++ b/src/javax/media/j3d/J3dHash.java
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+/*
+ * Copyright 2013 Harvey Harrison <[email protected]>
+ *
+ * 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).
+ */
+package javax.media.j3d;
+
+/**
+ * A Utility class wrapping the approach used to hash double values in Java3D
+ */
+class J3dHash {
+
+// prevent an instance from actually being created
+private J3dHash() {}
+
+/**
+ * Mix the given double into the provided long hash.
+ */
+static final long mixDoubleBits(long hash, double d) {
+	hash *= 31L;
+	// Treat 0.0d and -0.0d the same (all zero bits)
+	if (d == 0.0d)
+		return hash;
+
+	return hash + Double.doubleToLongBits(d);
+}
+
+/**
+ * Return an integer hash from a long by mixing it with itself.
+ */
+static final int finish(long hash) {
+	return (int)(hash ^ (hash >> 32));
+}
+}