old-autovect-branch/libjava/java/util/zip/Inflater.java

   1 /* Inflater.java - Decompress a data stream
   2    Copyright (C) 1999, 2000, 2001, 2003  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 import gnu.gcj.RawData;
  41
  42 /* Written using on-line Java Platform 1.2 API Specification
  43  * and JCL book.
  44  * Believed complete and correct.
  45  */
  46
  47 /**
  48  * Inflater is used to decompress data that has been compressed according
  49  * to the "deflate" standard described in rfc1950.
  50  *
  51  * The usage is as following.  First you have to set some input with
  52  * <code>setInput()</code>, then inflate() it.  If inflate doesn't
  53  * inflate any bytes there may be three reasons:
  54  * <ul>
  55  * <li>needsInput() returns true because the input buffer is empty.
  56  * You have to provide more input with <code>setInput()</code>.
  57  * NOTE: needsInput() also returns true when, the stream is finished.
  58  * </li>
  59  * <li>needsDictionary() returns true, you have to provide a preset
  60  *     dictionary with <code>setDictionary()</code>.</li>
  61  * <li>finished() returns true, the inflater has finished.</li>
  62  * </ul>
  63  * Once the first output byte is produced, a dictionary will not be
  64  * needed at a later stage.
  65  *
  66  * @author John Leuner, Jochen Hoenicke
  67  * @author Tom Tromey
  68  * @date May 17, 1999
  69  * @since JDK 1.1
  70  */
  71 public class Inflater
  72 {
  73   // The zlib stream.
  74   private RawData zstream;
  75
  76   // True if finished.
  77   private boolean is_finished;
  78
  79   // True if dictionary needed.
  80   private boolean dict_needed;
  81
  82   /**
  83    * Creates a new inflater.
  84    */
  85   public Inflater ()
  86   {
  87     this (false);
  88   }
  89
  90   /**
  91    * Creates a new inflater.
  92    * @param nowrap true if no header and checksum field appears in the
  93    * stream.  This is used for GZIPed input.  For compatibility with
  94    * Sun JDK you should provide one byte of input more than needed in
  95    * this case.
  96    */
  97   public Inflater (boolean noHeader)
  98   {
  99     init (noHeader);
 100   }
 101
 102   /**
 103    * Finalizes this object.
 104    */
 105   protected void finalize ()
 106   {
 107     end ();
 108   }
 109
 110   /**
 111    * Frees all objects allocated by the inflater.  There's no reason
 112    * to call this, since you can just rely on garbage collection (even
 113    * for the Sun implementation).  Exists only for compatibility
 114    * with Sun's JDK, where the compressor allocates native memory.
 115    * If you call any method (even reset) afterwards the behaviour is
 116    * <i>undefined</i>.
 117    * @deprecated Just clear all references to inflater instead.
 118    */
 119   public native void end ();
 120
 121   /**
 122    * Returns true, if the inflater has finished.  This means, that no
 123    * input is needed and no output can be produced.
 124    */
 125   public synchronized boolean finished ()
 126   {
 127     return is_finished;
 128   }
 129
 130   /**
 131    * Gets the adler checksum.  This is either the checksum of all
 132    * uncompressed bytes returned by inflate(), or if needsDictionary()
 133    * returns true (and thus no output was yet produced) this is the
 134    * adler checksum of the expected dictionary.
 135    * @returns the adler checksum.
 136    */
 137   public native int getAdler ();
 138
 139   /**
 140    * Gets the number of unprocessed input.  Useful, if the end of the
 141    * stream is reached and you want to further process the bytes after
 142    * the deflate stream.
 143    * @return the number of bytes of the input which were not processed.
 144    */
 145   public native int getRemaining ();
 146
 147   /**
 148    * Gets the total number of processed compressed input bytes.
 149    * @return the total number of bytes of processed input bytes.
 150    */
 151   public native int getTotalIn ();
 152
 153   /**
 154    * Gets the total number of output bytes returned by inflate().
 155    * @return the total number of output bytes.
 156    */
 157   public native int getTotalOut ();
 158
 159   /**
 160    * Inflates the compressed stream to the output buffer.  If this
 161    * returns 0, you should check, whether needsDictionary(),
 162    * needsInput() or finished() returns true, to determine why no
 163    * further output is produced.
 164    * @param buffer the output buffer.
 165    * @return the number of bytes written to the buffer, 0 if no further
 166    * output can be produced.
 167    * @exception DataFormatException if deflated stream is invalid.
 168    * @exception IllegalArgumentException if buf has length 0.
 169    */
 170   public int inflate (byte[] buf) throws DataFormatException
 171   {
 172     return inflate (buf, 0, buf.length);
 173   }
 174
 175   /**
 176    * Inflates the compressed stream to the output buffer.  If this
 177    * returns 0, you should check, whether needsDictionary(),
 178    * needsInput() or finished() returns true, to determine why no
 179    * further output is produced.
 180    * @param buffer the output buffer.
 181    * @param off the offset into buffer where the output should start.
 182    * @param len the maximum length of the output.
 183    * @return the number of bytes written to the buffer, 0 if no further
 184    * output can be produced.
 185    * @exception DataFormatException if deflated stream is invalid.
 186    * @exception IndexOutOfBoundsException if the off and/or len are wrong.
 187    */
 188   public native int inflate (byte[] buf, int off, int len)
 189     throws DataFormatException;
 190
 191   private native void init (boolean noHeader);
 192
 193   /**
 194    * Returns true, if a preset dictionary is needed to inflate the input.
 195    */
 196   public synchronized boolean needsDictionary ()
 197   {
 198     return dict_needed;
 199   }
 200
 201   /**
 202    * Returns true, if the input buffer is empty.
 203    * You should then call setInput(). <br>
 204    *
 205    * <em>NOTE</em>: This method also returns true when the stream is finished.
 206    */
 207   public synchronized boolean needsInput ()
 208   {
 209     return getRemaining () == 0;
 210   }
 211
 212   /**
 213    * Resets the inflater so that a new stream can be decompressed.  All
 214    * pending input and output will be discarded.
 215    */
 216   public native void reset ();
 217
 218   /**
 219    * Sets the preset dictionary.  This should only be called, if
 220    * needsDictionary() returns true and it should set the same
 221    * dictionary, that was used for deflating.  The getAdler()
 222    * function returns the checksum of the dictionary needed.
 223    * @param buffer the dictionary.
 224    * @exception IllegalStateException if no dictionary is needed.
 225    * @exception IllegalArgumentException if the dictionary checksum is
 226    * wrong.
 227    */
 228   public void setDictionary (byte[] buf)
 229   {
 230     setDictionary (buf, 0, buf.length);
 231   }
 232
 233   /**
 234    * Sets the preset dictionary.  This should only be called, if
 235    * needsDictionary() returns true and it should set the same
 236    * dictionary, that was used for deflating.  The getAdler()
 237    * function returns the checksum of the dictionary needed.
 238    * @param buffer the dictionary.
 239    * @param off the offset into buffer where the dictionary starts.
 240    * @param len the length of the dictionary.
 241    * @exception IllegalStateException if no dictionary is needed.
 242    * @exception IllegalArgumentException if the dictionary checksum is
 243    * wrong.
 244    * @exception IndexOutOfBoundsException if the off and/or len are wrong.
 245    */
 246   public native void setDictionary (byte[] buf, int off, int len);
 247
 248   /**
 249    * Sets the input.  This should only be called, if needsInput()
 250    * returns true.
 251    * @param buffer the input.
 252    * @exception IllegalStateException if no input is needed.
 253    */
 254   public void setInput (byte[] buf)
 255   {
 256     setInput (buf, 0, buf.length);
 257   }
 258
 259   /**
 260    * Sets the input.  This should only be called, if needsInput()
 261    * returns true.
 262    * @param buffer the input.
 263    * @param off the offset into buffer where the input starts.
 264    * @param len the length of the input.
 265    * @exception IllegalStateException if no input is needed.
 266    * @exception IndexOutOfBoundsException if the off and/or len are wrong.
 267    */
 268   public native void setInput (byte[] buf, int off, int len);
 269 }