com.sun.j3d.utils.compression.HuffmanNode Maven / Gradle / Ivy
Show all versions of java3d-core Show documentation
/*
* 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.
*
*/
package com.sun.j3d.utils.compression;
import java.util.Collection;
import java.util.Comparator;
/**
* Instances of this class are used as the nodes of binary trees representing
* mappings of tags to compression stream elements. Tags are descriptors
* inserted into the compression command stream that specify the encoding of
* immediately succeeding data elements.
*
* The tag assignments in such a tree are computed from the paths taken from
* the root to the leaf nodes. Each leaf node represents the particular way
* one or more compression stream elements wound up being encoded with respect
* to various combinations of data lengths, shifts, and absolute/relative
* status.
*
* Huffman's algorithm for constructing binary trees with minimal weighted
* path lengths can be used to optimize the bit lengths of the tags with
* respect to the frequency of occurrence of their associated data encodings
* in the compression stream. The weighted path length is the sum of the
* frequencies of all the leaf nodes times their path lengths to the root of
* the tree.
*
* The length of the longest tag determines the size of the table mapping tags
* to data representations. The geometry compression specification limits the
* size of the table to 64 entries, so tags cannot be longer than 6 bits. The
* depth of the tree is reduced through a process of increasing the data
* lengths of less frequently occuring nodes so they can be merged with other
* more frequent nodes.
*/
class HuffmanNode {
int tag, tagLength ;
int shift, dataLength ;
boolean absolute ;
private int frequency ;
private HuffmanNode child0, child1, mergeNode ;
private boolean merged, unmergeable, cleared ;
void clear() {
tag = -1 ;
tagLength = -1 ;
shift = -1 ;
dataLength = -1 ;
absolute = false ;
child0 = null ;
child1 = null ;
mergeNode = null ;
frequency = 0 ;
merged = false ;
unmergeable = false ;
cleared = true ;
}
HuffmanNode() {
clear() ;
}
HuffmanNode(int length, int shift, boolean absolute) {
this() ;
set(length, shift, absolute) ;
}
final void set(int length, int shift, boolean absolute) {
this.dataLength = length ;
this.shift = shift ;
this.absolute = absolute ;
this.cleared = false ;
}
final boolean cleared() {
return cleared ;
}
final void addCount() {
frequency++ ;
}
final boolean hasCount() {
return frequency > 0 ;
}
final boolean tokenEquals(HuffmanNode node) {
return
this.absolute == node.absolute &&
this.dataLength == node.dataLength &&
this.shift == node.shift ;
}
void addChildren(HuffmanNode child0, HuffmanNode child1) {
this.child0 = child0 ;
this.child1 = child1 ;
this.frequency = child0.frequency + child1.frequency ;
}
void collectLeaves(int tag, int tagLength, Collection collection) {
if (child0 == null) {
this.tag = tag ;
this.tagLength = tagLength ;
collection.add(this) ;
} else {
child0.collectLeaves((tag << 1) | 0, tagLength + 1, collection) ;
child1.collectLeaves((tag << 1) | 1, tagLength + 1, collection) ;
}
}
boolean mergeInto(HuffmanNode node) {
if (this.absolute == node.absolute) {
if (this.dataLength > node.dataLength)
node.dataLength = this.dataLength ;
if (this.shift < node.shift)
node.shift = this.shift ;
node.frequency += this.frequency ;
this.mergeNode = node ;
this.merged = true ;
return true ;
} else
return false ;
}
int incrementLength() {
if (shift > 0)
shift-- ;
else
dataLength++ ;
return dataLength - shift ;
}
final boolean merged() {
return merged ;
}
final HuffmanNode getMergeNode() {
return mergeNode ;
}
void setUnmergeable() {
unmergeable = true ;
}
final boolean unmergeable() {
return unmergeable ;
}
@Override
public String toString() {
return
"shift " + shift + " data length " + dataLength +
(absolute? " absolute " : " relative ") +
"\ntag 0x" + Integer.toHexString(tag) + " tag length " + tagLength +
"\nfrequency: " + frequency ;
}
/**
* Sorts nodes in ascending order by frequency.
*/
static class FrequencyComparator implements Comparator {
@Override
public final int compare(Object o1, Object o2) {
return ((HuffmanNode)o1).frequency - ((HuffmanNode)o2).frequency ;
}
}
/**
* Sorts nodes in descending order by tag bit length.
*/
static class TagLengthComparator implements Comparator {
@Override
public final int compare(Object o1, Object o2) {
return ((HuffmanNode)o2).tagLength - ((HuffmanNode)o1).tagLength ;
}
}
static FrequencyComparator frequencyComparator = new FrequencyComparator() ;
static TagLengthComparator tagLengthComparator = new TagLengthComparator() ;
}