| /* Deflater.java - Compress a data stream |
| Copyright (C) 1999, 2000, 2001, 2004, 2006 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath 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, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 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. */ |
| |
| package java.util.zip; |
| |
| import gnu.gcj.RawData; |
| |
| /** |
| * This is the Deflater class. The deflater class compresses input |
| * with the deflate algorithm described in RFC 1951. It has several |
| * compression levels and three different strategies described below. |
| * |
| * This class is <i>not</i> thread safe. This is inherent in the API, due |
| * to the split of deflate and setInput. |
| * |
| * @author Jochen Hoenicke |
| * @author Tom Tromey |
| */ |
| public class Deflater |
| { |
| /** |
| * The best and slowest compression level. This tries to find very |
| * long and distant string repetitions. |
| */ |
| public static final int BEST_COMPRESSION = 9; |
| /** |
| * The worst but fastest compression level. |
| */ |
| public static final int BEST_SPEED = 1; |
| /** |
| * The default compression level. |
| */ |
| public static final int DEFAULT_COMPRESSION = -1; |
| /** |
| * This level won't compress at all but output uncompressed blocks. |
| */ |
| public static final int NO_COMPRESSION = 0; |
| |
| /** |
| * The default strategy. |
| */ |
| public static final int DEFAULT_STRATEGY = 0; |
| /** |
| * This strategy will only allow longer string repetitions. It is |
| * useful for random data with a small character set. |
| */ |
| public static final int FILTERED = 1; |
| |
| /** |
| * This strategy will not look for string repetitions at all. It |
| * only encodes with Huffman trees (which means, that more common |
| * characters get a smaller encoding. |
| */ |
| public static final int HUFFMAN_ONLY = 2; |
| |
| /** |
| * The compression method. This is the only method supported so far. |
| * There is no need to use this constant at all. |
| */ |
| public static final int DEFLATED = 8; |
| |
| /** Compression level. */ |
| private int level; |
| |
| /** Compression strategy. */ |
| private int strategy; |
| |
| /** The zlib stream. */ |
| private RawData zstream; |
| |
| /** True if finished. */ |
| private boolean is_finished; |
| |
| /** `Flush' flag to pass to next call to deflate. */ |
| private int flush_flag; |
| |
| /** |
| * Creates a new deflater with default compression level. |
| */ |
| public Deflater() |
| { |
| this(DEFAULT_COMPRESSION, false); |
| } |
| |
| /** |
| * Creates a new deflater with given compression level. |
| * @param lvl the compression level, a value between NO_COMPRESSION |
| * and BEST_COMPRESSION, or DEFAULT_COMPRESSION. |
| * @exception IllegalArgumentException if lvl is out of range. |
| */ |
| public Deflater(int lvl) |
| { |
| this(lvl, false); |
| } |
| |
| /** |
| * Creates a new deflater with given compression level. |
| * @param lvl the compression level, a value between NO_COMPRESSION |
| * and BEST_COMPRESSION. |
| * @param nowrap true, iff we should suppress the deflate header at the |
| * beginning and the adler checksum at the end of the output. This is |
| * useful for the GZIP format. |
| * @exception IllegalArgumentException if lvl is out of range. |
| */ |
| public Deflater(int lvl, boolean noHeader) |
| { |
| this.strategy = DEFAULT_STRATEGY; |
| init(lvl, noHeader); |
| setLevel(lvl); |
| } |
| |
| private native void init(int level, boolean noHeader); |
| |
| private native void update(); |
| |
| /** |
| * Resets the deflater. The deflater acts afterwards as if it was |
| * just created with the same compression level and strategy as it |
| * had before. |
| */ |
| public native void reset(); |
| |
| /** |
| * Frees all objects allocated by the compressor. There's no |
| * reason to call this, since you can just rely on garbage |
| * collection. Exists only for compatibility against Sun's JDK, |
| * where the compressor allocates native memory. |
| * If you call any method (even reset) afterwards the behaviour is |
| * <i>undefined</i>. |
| * @deprecated Just clear all references to deflater instead. |
| */ |
| public native void end(); |
| |
| /** |
| * Gets the current adler checksum of the data that was processed so |
| * far. |
| */ |
| public native int getAdler(); |
| |
| /** |
| * Gets the number of input bytes processed so far. |
| */ |
| @Deprecated |
| public int getTotalIn() |
| { |
| return (int) getBytesRead(); |
| } |
| |
| /** |
| * Gets the number of input bytes processed so far. |
| * @since 1.5 |
| */ |
| public native long getBytesRead(); |
| |
| /** |
| * Gets the number of output bytes so far. |
| */ |
| @Deprecated |
| public int getTotalOut() |
| { |
| return (int) getBytesWritten(); |
| } |
| |
| /** |
| * Gets the number of output bytes so far. |
| * @since 1.5 |
| */ |
| public native long getBytesWritten(); |
| |
| /** |
| * Finalizes this object. |
| */ |
| protected void finalize() |
| { |
| end(); |
| } |
| |
| /** |
| * Finishes the deflater with the current input block. It is an error |
| * to give more input after this method was called. This method must |
| * be called to force all bytes to be flushed. |
| */ |
| public native void finish(); |
| |
| /** |
| * Returns true iff the stream was finished and no more output bytes |
| * are available. |
| */ |
| public synchronized boolean finished() |
| { |
| return is_finished; |
| } |
| |
| /** |
| * Returns true, if the input buffer is empty. |
| * You should then call setInput(). <br> |
| * |
| * <em>NOTE</em>: This method can also return true when the stream |
| * was finished. |
| */ |
| public native boolean needsInput(); |
| |
| /** |
| * Sets the data which should be compressed next. This should be only |
| * called when needsInput indicates that more input is needed. |
| * If you call setInput when needsInput() returns false, the |
| * previous input that is still pending will be thrown away. |
| * The given byte array should not be changed, before needsInput() returns |
| * true again. |
| * This call is equivalent to <code>setInput(input, 0, input.length)</code>. |
| * @param input the buffer containing the input data. |
| * @exception IllegalStateException if the buffer was finished() or ended(). |
| */ |
| public void setInput(byte[] input) |
| { |
| setInput(input, 0, input.length); |
| } |
| |
| /** |
| * Sets the data which should be compressed next. This should be |
| * only called when needsInput indicates that more input is needed. |
| * The given byte array should not be changed, before needsInput() returns |
| * true again. |
| * @param input the buffer containing the input data. |
| * @param off the start of the data. |
| * @param len the length of the data. |
| * @exception IllegalStateException if the buffer was finished() or ended() |
| * or if previous input is still pending. |
| */ |
| public native void setInput(byte[] input, int off, int len); |
| |
| /** |
| * Sets the compression level. There is no guarantee of the exact |
| * position of the change, but if you call this when needsInput is |
| * true the change of compression level will occur somewhere near |
| * before the end of the so far given input. |
| * @param lvl the new compression level. |
| */ |
| public synchronized void setLevel(int lvl) |
| { |
| if (lvl != -1 && (lvl < 0 || lvl > 9)) |
| throw new IllegalArgumentException(); |
| level = (lvl == -1) ? 6 : lvl; |
| update(); |
| } |
| |
| /** |
| * Sets the compression strategy. Strategy is one of |
| * DEFAULT_STRATEGY, HUFFMAN_ONLY and FILTERED. For the exact |
| * position where the strategy is changed, the same as for |
| * setLevel() applies. |
| * @param stgy the new compression strategy. |
| */ |
| public synchronized void setStrategy(int stgy) |
| { |
| if (stgy != DEFAULT_STRATEGY && stgy != FILTERED |
| && stgy != HUFFMAN_ONLY) |
| throw new IllegalArgumentException(); |
| strategy = stgy; |
| update(); |
| } |
| |
| /** |
| * Deflates the current input block to the given array. It returns |
| * the number of bytes compressed, or 0 if either |
| * needsInput() or finished() returns true or length is zero. |
| * @param output the buffer where to write the compressed data. |
| */ |
| public int deflate(byte[] output) |
| { |
| return deflate(output, 0, output.length); |
| } |
| |
| /** |
| * Deflates the current input block to the given array. It returns |
| * the number of bytes compressed, or 0 if either |
| * needsInput() or finished() returns true or length is zero. |
| * @param output the buffer where to write the compressed data. |
| * @param offset the offset into the output array. |
| * @param length the maximum number of bytes that may be written. |
| * @exception IllegalStateException if end() was called. |
| * @exception IndexOutOfBoundsException if offset and/or length |
| * don't match the array length. |
| */ |
| public native int deflate(byte[] output, int off, int len); |
| |
| /** |
| * Sets the dictionary which should be used in the deflate process. |
| * This call is equivalent to <code>setDictionary(dict, 0, |
| * dict.length)</code>. |
| * @param dict the dictionary. |
| * @exception IllegalStateException if setInput () or deflate () |
| * were already called or another dictionary was already set. |
| */ |
| public void setDictionary(byte[] dict) |
| { |
| setDictionary(dict, 0, dict.length); |
| } |
| |
| /** |
| * Sets the dictionary which should be used in the deflate process. |
| * The dictionary should be a byte array containing strings that are |
| * likely to occur in the data which should be compressed. The |
| * dictionary is not stored in the compressed output, only a |
| * checksum. To decompress the output you need to supply the same |
| * dictionary again. |
| * @param dict the dictionary. |
| * @param offset an offset into the dictionary. |
| * @param length the length of the dictionary. |
| * @exception IllegalStateException if setInput () or deflate () were |
| * already called or another dictionary was already set. |
| */ |
| public native void setDictionary(byte[] buf, int off, int len); |
| |
| // Classpath's compression library supports flushing, but we |
| // don't. So this is a no-op here. |
| void flush() |
| { |
| } |
| } |