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/* Copyright (c) 2014, David A. Clunie DBA Pixelmed Publishing. All rights reserved. */
package com.pixelmed.codec.jpeg;
import java.util.Map;
/**
* <p>A JPEG DHT Marker Segment.</p>
*
* @author dclunie
*/
public class MarkerSegmentDHT {
private static final String identString = "@(#) $Header: /userland/cvs/codec/com/pixelmed/codec/jpeg/MarkerSegmentDHT.java,v 1.2 2014/03/21 21:46:20 dclunie Exp $";
private int nTables;
private int[] TableClass;
private int[] HuffmanTableIdentifier;
private int[][] nHuffmanCodesOfLengthI;
private int[][][] ValueOfHuffmanCodeIJ;
public MarkerSegmentDHT(byte[] b,int length) throws Exception {
TableClass = new int [4];
HuffmanTableIdentifier = new int [4];
nHuffmanCodesOfLengthI = new int [4][];
ValueOfHuffmanCodeIJ = new int [4][][];
nTables=0;
int offset=0;
while (length > 0) {
if (nTables >= 4) {
throw new Exception("Only 4 tables are permitted");
}
TableClass[nTables] = Utilities.extract8(b,offset) >> 4;
HuffmanTableIdentifier[nTables] = Utilities.extract8(b,offset) & 0x0f;
++offset; --length;
nHuffmanCodesOfLengthI[nTables] = new int[16];
for (int i=0; i<16; ++i) {
nHuffmanCodesOfLengthI[nTables][i] = Utilities.extract8(b,offset);
++offset; --length;
}
ValueOfHuffmanCodeIJ[nTables] = new int[16][];
for (int i=0; i<16; ++i) {
ValueOfHuffmanCodeIJ[nTables][i] = new int[nHuffmanCodesOfLengthI[nTables][i]];
for (int j=0; j<nHuffmanCodesOfLengthI[nTables][i]; ++j) {
ValueOfHuffmanCodeIJ[nTables][i][j] = Utilities.extract8(b,offset);
++offset; --length;
}
}
++nTables;
}
}
public void addToMapByClassAndIdentifier(Map<String,HuffmanTable> htByClassAndIdentifer) {
for (int t=0; t<nTables; ++t) {
int cl = TableClass[t];
int id = HuffmanTableIdentifier[t];
String key = Integer.toString(cl) + "+" + Integer.toString(id);
htByClassAndIdentifer.put(key,new HuffmanTable(cl,id,nHuffmanCodesOfLengthI[t],ValueOfHuffmanCodeIJ[t]));
}
}
public String toString() {
StringBuffer buf = new StringBuffer();
buf.append("\n\tDHT:\n");
for (int t=0; t<nTables; ++t) {
buf.append("\t\t TableClass = " +TableClass[t]+"\n");
buf.append("\t\t HuffmanTableIdentifier = "+HuffmanTableIdentifier[t]+"\n");
for (int i=0; i<16; ++i) {
buf.append("\t\t\t nHuffmanCodesOfLength "+i+" = "+nHuffmanCodesOfLengthI[t][i]+"\n");
for (int j=0; j<nHuffmanCodesOfLengthI[t][i];++j) {
buf.append("\t\t\t\t ValueOfHuffmanCode "+j+" = "+ValueOfHuffmanCodeIJ[t][i][j]+"\n");
}
}
}
return buf.toString();
}
}
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