// InflaterDynHeader.cs // Copyright (C) 2001 Mike Krueger // // This file was translated from java, it was part of the GNU Classpath // Copyright (C) 2001 Free Software Foundation, Inc. // // This program is free software; you can redistribute it and/or // modify it under the terms of the GNU General Public License // as published by the Free Software Foundation; either version 2 // of the License, or (at your option) any later version. // // This program 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 for more details. // // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. // // Linking this library statically or dynamically with other modules is // making a combined work based on this library. Thus, the terms and // conditions of the GNU General Public License cover the whole // combination. // // As a special exception, the copyright holders of this library give you // permission to link this library with independent modules to produce an // executable, regardless of the license terms of these independent // modules, and to copy and distribute the resulting executable under // terms of your choice, provided that you also meet, for each linked // independent module, the terms and conditions of the license of that // module. An independent module is a module which is not derived from // or based on this library. If you modify this library, you may extend // this exception to your version of the library, but you are not // obligated to do so. If you do not wish to do so, delete this // exception statement from your version. using System; using ICSharpCode.SharpZipLib.Zip.Compression.Streams; namespace ICSharpCode.SharpZipLib.Zip.Compression { class InflaterDynHeader { const int LNUM = 0; const int DNUM = 1; const int BLNUM = 2; const int BLLENS = 3; const int LENS = 4; const int REPS = 5; static readonly int[] repMin = { 3, 3, 11 }; static readonly int[] repBits = { 2, 3, 7 }; byte[] blLens; byte[] litdistLens; InflaterHuffmanTree blTree; int mode; int lnum, dnum, blnum, num; int repSymbol; byte lastLen; int ptr; static readonly int[] BL_ORDER = { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 }; public InflaterDynHeader() { } public bool Decode(StreamManipulator input) { decode_loop: for (;;) { switch (mode) { case LNUM: lnum = input.PeekBits(5); if (lnum < 0) { return false; } lnum += 257; input.DropBits(5); // System.err.println("LNUM: "+lnum); mode = DNUM; goto case DNUM; // fall through case DNUM: dnum = input.PeekBits(5); if (dnum < 0) { return false; } dnum++; input.DropBits(5); // System.err.println("DNUM: "+dnum); num = lnum+dnum; litdistLens = new byte[num]; mode = BLNUM; goto case BLNUM; // fall through case BLNUM: blnum = input.PeekBits(4); if (blnum < 0) { return false; } blnum += 4; input.DropBits(4); blLens = new byte[19]; ptr = 0; // System.err.println("BLNUM: "+blnum); mode = BLLENS; goto case BLLENS; // fall through case BLLENS: while (ptr < blnum) { int len = input.PeekBits(3); if (len < 0) { return false; } input.DropBits(3); // System.err.println("blLens["+BL_ORDER[ptr]+"]: "+len); blLens[BL_ORDER[ptr]] = (byte) len; ptr++; } blTree = new InflaterHuffmanTree(blLens); blLens = null; ptr = 0; mode = LENS; goto case LENS; // fall through case LENS: { int symbol; while (((symbol = blTree.GetSymbol(input)) & ~15) == 0) { /* Normal case: symbol in [0..15] */ // System.err.println("litdistLens["+ptr+"]: "+symbol); litdistLens[ptr++] = lastLen = (byte)symbol; if (ptr == num) { /* Finished */ return true; } } /* need more input ? */ if (symbol < 0) { return false; } /* otherwise repeat code */ if (symbol >= 17) { /* repeat zero */ // System.err.println("repeating zero"); lastLen = 0; } else { if (ptr == 0) { throw new Exception(); } } repSymbol = symbol-16; } mode = REPS; goto case REPS; // fall through case REPS: { int bits = repBits[repSymbol]; int count = input.PeekBits(bits); if (count < 0) { return false; } input.DropBits(bits); count += repMin[repSymbol]; // System.err.println("litdistLens repeated: "+count); if (ptr + count > num) { throw new Exception(); } while (count-- > 0) { litdistLens[ptr++] = lastLen; } if (ptr == num) { /* Finished */ return true; } } mode = LENS; goto decode_loop; } } } public InflaterHuffmanTree BuildLitLenTree() { byte[] litlenLens = new byte[lnum]; Array.Copy(litdistLens, 0, litlenLens, 0, lnum); return new InflaterHuffmanTree(litlenLens); } public InflaterHuffmanTree BuildDistTree() { byte[] distLens = new byte[dnum]; Array.Copy(litdistLens, lnum, distLens, 0, dnum); return new InflaterHuffmanTree(distLens); } } }