// InflaterDynHeader.cs
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// Copyright (C) 2001 Mike Krueger
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//
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// This file was translated from java, it was part of the GNU Classpath
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// Copyright (C) 2001 Free Software Foundation, Inc.
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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//
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// Linking this library statically or dynamically with other modules is
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// making a combined work based on this library. Thus, the terms and
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// conditions of the GNU General Public License cover the whole
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// combination.
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//
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// As a special exception, the copyright holders of this library give you
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// permission to link this library with independent modules to produce an
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// executable, regardless of the license terms of these independent
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// modules, and to copy and distribute the resulting executable under
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// terms of your choice, provided that you also meet, for each linked
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// independent module, the terms and conditions of the license of that
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// module. An independent module is a module which is not derived from
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// or based on this library. If you modify this library, you may extend
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// this exception to your version of the library, but you are not
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// obligated to do so. If you do not wish to do so, delete this
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// exception statement from your version.
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using System;
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using ICSharpCode.SharpZipLib.Zip.Compression.Streams;
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namespace ICSharpCode.SharpZipLib.Zip.Compression
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{
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class InflaterDynHeader
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{
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#region Constants
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const int LNUM = 0;
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const int DNUM = 1;
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const int BLNUM = 2;
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const int BLLENS = 3;
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const int LENS = 4;
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const int REPS = 5;
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static readonly int[] repMin = { 3, 3, 11 };
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static readonly int[] repBits = { 2, 3, 7 };
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static readonly int[] BL_ORDER =
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{ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
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#endregion
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#region Constructors
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public InflaterDynHeader()
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{
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}
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#endregion
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public bool Decode(StreamManipulator input)
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{
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decode_loop:
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for (;;) {
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switch (mode) {
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case LNUM:
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lnum = input.PeekBits(5);
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if (lnum < 0) {
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return false;
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}
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lnum += 257;
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input.DropBits(5);
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// System.err.println("LNUM: "+lnum);
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mode = DNUM;
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goto case DNUM; // fall through
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case DNUM:
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dnum = input.PeekBits(5);
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if (dnum < 0) {
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return false;
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}
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dnum++;
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input.DropBits(5);
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// System.err.println("DNUM: "+dnum);
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num = lnum+dnum;
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litdistLens = new byte[num];
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mode = BLNUM;
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goto case BLNUM; // fall through
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case BLNUM:
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blnum = input.PeekBits(4);
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if (blnum < 0) {
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return false;
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}
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blnum += 4;
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input.DropBits(4);
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blLens = new byte[19];
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ptr = 0;
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// System.err.println("BLNUM: "+blnum);
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mode = BLLENS;
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goto case BLLENS; // fall through
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case BLLENS:
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while (ptr < blnum) {
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int len = input.PeekBits(3);
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if (len < 0) {
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return false;
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}
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input.DropBits(3);
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// System.err.println("blLens["+BL_ORDER[ptr]+"]: "+len);
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blLens[BL_ORDER[ptr]] = (byte) len;
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ptr++;
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}
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blTree = new InflaterHuffmanTree(blLens);
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blLens = null;
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ptr = 0;
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mode = LENS;
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goto case LENS; // fall through
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case LENS:
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{
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int symbol;
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while (((symbol = blTree.GetSymbol(input)) & ~15) == 0) {
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/* Normal case: symbol in [0..15] */
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// System.err.println("litdistLens["+ptr+"]: "+symbol);
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litdistLens[ptr++] = lastLen = (byte)symbol;
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if (ptr == num) {
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/* Finished */
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return true;
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}
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}
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/* need more input ? */
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if (symbol < 0) {
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return false;
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}
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/* otherwise repeat code */
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if (symbol >= 17) {
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/* repeat zero */
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// System.err.println("repeating zero");
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lastLen = 0;
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} else {
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if (ptr == 0) {
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throw new SharpZipBaseException();
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}
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}
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repSymbol = symbol-16;
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}
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mode = REPS;
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goto case REPS; // fall through
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case REPS:
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{
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int bits = repBits[repSymbol];
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int count = input.PeekBits(bits);
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if (count < 0) {
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return false;
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}
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input.DropBits(bits);
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count += repMin[repSymbol];
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// System.err.println("litdistLens repeated: "+count);
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if (ptr + count > num) {
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throw new SharpZipBaseException();
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}
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while (count-- > 0) {
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litdistLens[ptr++] = lastLen;
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}
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if (ptr == num) {
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/* Finished */
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return true;
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}
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}
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mode = LENS;
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goto decode_loop;
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}
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}
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}
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public InflaterHuffmanTree BuildLitLenTree()
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{
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byte[] litlenLens = new byte[lnum];
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Array.Copy(litdistLens, 0, litlenLens, 0, lnum);
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return new InflaterHuffmanTree(litlenLens);
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}
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public InflaterHuffmanTree BuildDistTree()
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{
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byte[] distLens = new byte[dnum];
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Array.Copy(litdistLens, lnum, distLens, 0, dnum);
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return new InflaterHuffmanTree(distLens);
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}
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#region Instance Fields
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byte[] blLens;
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byte[] litdistLens;
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InflaterHuffmanTree blTree;
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/// <summary>
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/// The current decode mode
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/// </summary>
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int mode;
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int lnum, dnum, blnum, num;
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int repSymbol;
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byte lastLen;
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int ptr;
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#endregion
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}
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}
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