/**
* Copyright (c) 2013, Institute of Information Systems (Sven Groppe and contributors of LUPOSDATE), University of Luebeck
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
* disclaimer.
* - Redistributions 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 the University of Luebeck nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package lupos.compression.huffman;
import java.io.IOException;
import java.io.InputStream;
import lupos.compression.bitstream.BitInputStream;
import lupos.compression.huffman.tree.Node;
/**
* The block-wise huffman input stream for reading in a huffman encoded stream.
* In comparison to the adaptive huffman tree, we choose a block-wise encoding scheme due to performance reasons.
* In the block-wise encoding scheme, each block contains a huffman tree and a huffman tree is valid (and is not changed) for a complete block.
*/
public class HuffmanInputStream extends InputStream {
/**
* the underlying bit input stream
*/
protected final BitInputStream in;
/**
* the current position in the block (necessary to detect when to read in a new huffman tree)
*/
protected int current = 0;
/**
* the root of the current huffman tree
*/
protected Node rootOfHuffmanTree;
/**
* Constructor
* @param in the underlying bit input stream from which for each block the huffman tree is read and the huffman encoded block
*/
public HuffmanInputStream(final BitInputStream in){
this.in = in;
}
/**
* Constructor
* @param in the underlying input stream, from which a bit input stream is created and from which for each block the huffman tree is read and the huffman encoded block
*/
public HuffmanInputStream(final InputStream in){
this.in = new BitInputStream(in);
}
@Override
public int read() throws IOException {
if(this.current == 0){
// initialization or next block
// => read in huffman tree
this.rootOfHuffmanTree = Node.readInHuffmanTree(this.in);
}
// get next symbol
final int result = this.rootOfHuffmanTree.getSymbol(this.in);
this.current++;
if(this.current==HuffmanOutputStream.blocksize){
// is one block finished?
this.current = 0;
}
return result;
}
@Override
public void close() throws IOException {
// close underlying bit input stream...
this.in.close();
}
}