gomp-20050608-branch/libjava/classpath/java/util/zip/InflaterDynHeader.java

   1 /* java.util.zip.InflaterDynHeader
   2    Copyright (C) 2001 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package java.util.zip;
  39
  40 class InflaterDynHeader
  41 {
  42   private static final int LNUM   = 0;
  43   private static final int DNUM   = 1;
  44   private static final int BLNUM  = 2;
  45   private static final int BLLENS = 3;
  46   private static final int LENS   = 4;
  47   private static final int REPS   = 5;
  48
  49   private static final int repMin[]  = { 3, 3, 11 };
  50   private static final int repBits[] = { 2, 3,  7 };
  51
  52
  53   private byte[] blLens;
  54   private byte[] litdistLens;
  55
  56   private InflaterHuffmanTree blTree;
  57
  58   private int mode;
  59   private int lnum, dnum, blnum, num;
  60   private int repSymbol;
  61   private byte lastLen;
  62   private int ptr;
  63
  64   private static final int[] BL_ORDER =
  65   { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
  66
  67   public InflaterDynHeader()
  68   {
  69   }
  70
  71   public boolean decode(StreamManipulator input) throws DataFormatException
  72   {
  73   decode_loop:
  74     for (;;)
  75       {
  76         switch (mode)
  77           {
  78           case LNUM:
  79             lnum = input.peekBits(5);
  80             if (lnum < 0)
  81               return false;
  82             lnum += 257;
  83             input.dropBits(5);
  84 //          System.err.println("LNUM: "+lnum);
  85             mode = DNUM;
  86             /* fall through */
  87           case DNUM:
  88             dnum = input.peekBits(5);
  89             if (dnum < 0)
  90               return false;
  91             dnum++;
  92             input.dropBits(5);
  93 //          System.err.println("DNUM: "+dnum);
  94             num = lnum+dnum;
  95             litdistLens = new byte[num];
  96             mode = BLNUM;
  97             /* fall through */
  98           case BLNUM:
  99             blnum = input.peekBits(4);
 100             if (blnum < 0)
 101               return false;
 102             blnum += 4;
 103             input.dropBits(4);
 104             blLens = new byte[19];
 105             ptr = 0;
 106 //          System.err.println("BLNUM: "+blnum);
 107             mode = BLLENS;
 108             /* fall through */
 109           case BLLENS:
 110             while (ptr < blnum)
 111               {
 112                 int len = input.peekBits(3);
 113                 if (len < 0)
 114                   return false;
 115                 input.dropBits(3);
 116 //              System.err.println("blLens["+BL_ORDER[ptr]+"]: "+len);
 117                 blLens[BL_ORDER[ptr]] = (byte) len;
 118                 ptr++;
 119               }
 120             blTree = new InflaterHuffmanTree(blLens);
 121             blLens = null;
 122             ptr = 0;
 123             mode = LENS;
 124             /* fall through */
 125           case LENS:
 126             {
 127               int symbol;
 128               while (((symbol = blTree.getSymbol(input)) & ~15) == 0)
 129                 {
 130                   /* Normal case: symbol in [0..15] */
 131
 132 //                System.err.println("litdistLens["+ptr+"]: "+symbol);
 133                   litdistLens[ptr++] = lastLen = (byte) symbol;
 134
 135                   if (ptr == num)
 136                     {
 137                       /* Finished */
 138                       return true;
 139                     }
 140                 }
 141
 142               /* need more input ? */
 143               if (symbol < 0)
 144                 return false;
 145
 146               /* otherwise repeat code */
 147               if (symbol >= 17)
 148                 {
 149                   /* repeat zero */
 150 //                System.err.println("repeating zero");
 151                   lastLen = 0;
 152                 }
 153               else
 154                 {
 155                   if (ptr == 0)
 156                     throw new DataFormatException();
 157                 }
 158               repSymbol = symbol-16;
 159               mode = REPS;
 160             }
 161             /* fall through */
 162
 163           case REPS:
 164             {
 165               int bits = repBits[repSymbol];
 166               int count = input.peekBits(bits);
 167               if (count < 0)
 168                 return false;
 169               input.dropBits(bits);
 170               count += repMin[repSymbol];
 171 //            System.err.println("litdistLens repeated: "+count);
 172
 173               if (ptr + count > num)
 174                 throw new DataFormatException();
 175               while (count-- > 0)
 176                 litdistLens[ptr++] = lastLen;
 177
 178               if (ptr == num)
 179                 {
 180                   /* Finished */
 181                   return true;
 182                 }
 183             }
 184             mode = LENS;
 185             continue decode_loop;
 186           }
 187       }
 188   }
 189
 190   public InflaterHuffmanTree buildLitLenTree() throws DataFormatException
 191   {
 192     byte[] litlenLens = new byte[lnum];
 193     System.arraycopy(litdistLens, 0, litlenLens, 0, lnum);
 194     return new InflaterHuffmanTree(litlenLens);
 195   }
 196
 197   public InflaterHuffmanTree buildDistTree() throws DataFormatException
 198   {
 199     byte[] distLens = new byte[dnum];
 200     System.arraycopy(litdistLens, lnum, distLens, 0, dnum);
 201     return new InflaterHuffmanTree(distLens);
 202   }
 203 }