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Diffstat (limited to 'libjava/classpath/java/util/zip/Deflater.java')
| -rw-r--r-- | libjava/classpath/java/util/zip/Deflater.java | 520 |
1 files changed, 520 insertions, 0 deletions
diff --git a/libjava/classpath/java/util/zip/Deflater.java b/libjava/classpath/java/util/zip/Deflater.java new file mode 100644 index 0000000..7bc1a19 --- /dev/null +++ b/libjava/classpath/java/util/zip/Deflater.java @@ -0,0 +1,520 @@ +/* Deflater.java - Compress a data stream + Copyright (C) 1999, 2000, 2001, 2004 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; + +/** + * 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; + + /* + * The Deflater can do the following state transitions: + * + * (1) -> INIT_STATE ----> INIT_FINISHING_STATE ---. + * / | (2) (5) | + * / v (5) | + * (3)| SETDICT_STATE ---> SETDICT_FINISHING_STATE |(3) + * \ | (3) | ,-------' + * | | | (3) / + * v v (5) v v + * (1) -> BUSY_STATE ----> FINISHING_STATE + * | (6) + * v + * FINISHED_STATE + * \_____________________________________/ + * | (7) + * v + * CLOSED_STATE + * + * (1) If we should produce a header we start in INIT_STATE, otherwise + * we start in BUSY_STATE. + * (2) A dictionary may be set only when we are in INIT_STATE, then + * we change the state as indicated. + * (3) Whether a dictionary is set or not, on the first call of deflate + * we change to BUSY_STATE. + * (4) -- intentionally left blank -- :) + * (5) FINISHING_STATE is entered, when flush() is called to indicate that + * there is no more INPUT. There are also states indicating, that + * the header wasn't written yet. + * (6) FINISHED_STATE is entered, when everything has been flushed to the + * internal pending output buffer. + * (7) At any time (7) + * + */ + + private static final int IS_SETDICT = 0x01; + private static final int IS_FLUSHING = 0x04; + private static final int IS_FINISHING = 0x08; + + private static final int INIT_STATE = 0x00; + private static final int SETDICT_STATE = 0x01; + private static final int INIT_FINISHING_STATE = 0x08; + private static final int SETDICT_FINISHING_STATE = 0x09; + private static final int BUSY_STATE = 0x10; + private static final int FLUSHING_STATE = 0x14; + private static final int FINISHING_STATE = 0x1c; + private static final int FINISHED_STATE = 0x1e; + private static final int CLOSED_STATE = 0x7f; + + /** Compression level. */ + private int level; + + /** should we include a header. */ + private boolean noHeader; + + /** The current state. */ + private int state; + + /** The total bytes of output written. */ + private int totalOut; + + /** The pending output. */ + private DeflaterPending pending; + + /** The deflater engine. */ + private DeflaterEngine engine; + + /** + * 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 nowrap) + { + if (lvl == DEFAULT_COMPRESSION) + lvl = 6; + else if (lvl < NO_COMPRESSION || lvl > BEST_COMPRESSION) + throw new IllegalArgumentException(); + + pending = new DeflaterPending(); + engine = new DeflaterEngine(pending); + this.noHeader = nowrap; + setStrategy(DEFAULT_STRATEGY); + setLevel(lvl); + reset(); + } + + /** + * 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 void reset() + { + state = (noHeader ? BUSY_STATE : INIT_STATE); + totalOut = 0; + pending.reset(); + engine.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 void end() + { + engine = null; + pending = null; + state = CLOSED_STATE; + } + + /** + * Gets the current adler checksum of the data that was processed so + * far. + */ + public int getAdler() + { + return engine.getAdler(); + } + + /** + * Gets the number of input bytes processed so far. + */ + public int getTotalIn() + { + return engine.getTotalIn(); + } + + /** + * Gets the number of output bytes so far. + */ + public int getTotalOut() + { + return totalOut; + } + + /** + * Finalizes this object. + */ + protected void finalize() + { + /* Exists solely for compatibility. We don't have any native state. */ + } + + /** + * Flushes the current input block. Further calls to deflate() will + * produce enough output to inflate everything in the current input + * block. This is not part of Sun's JDK so I have made it package + * private. It is used by DeflaterOutputStream to implement + * flush(). + */ + void flush() { + state |= IS_FLUSHING; + } + + /** + * 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 void finish() { + state |= IS_FLUSHING | IS_FINISHING; + } + + /** + * Returns true iff the stream was finished and no more output bytes + * are available. + */ + public boolean finished() + { + return state == FINISHED_STATE && pending.isFlushed(); + } + + /** + * 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 boolean needsInput() + { + return engine.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 void setInput(byte[] input, int off, int len) + { + if ((state & IS_FINISHING) != 0) + throw new IllegalStateException("finish()/end() already called"); + engine.setInput(input, off, 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 void setLevel(int lvl) + { + if (lvl == DEFAULT_COMPRESSION) + lvl = 6; + else if (lvl < NO_COMPRESSION || lvl > BEST_COMPRESSION) + throw new IllegalArgumentException(); + + + if (level != lvl) + { + level = lvl; + engine.setLevel(lvl); + } + } + + /** + * 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 void setStrategy(int stgy) + { + if (stgy != DEFAULT_STRATEGY && stgy != FILTERED + && stgy != HUFFMAN_ONLY) + throw new IllegalArgumentException(); + engine.setStrategy(stgy); + } + + /** + * 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 int deflate(byte[] output, int offset, int length) + { + int origLength = length; + + if (state == CLOSED_STATE) + throw new IllegalStateException("Deflater closed"); + + if (state < BUSY_STATE) + { + /* output header */ + int header = (DEFLATED + + ((DeflaterConstants.MAX_WBITS - 8) << 4)) << 8; + int level_flags = (level - 1) >> 1; + if (level_flags < 0 || level_flags > 3) + level_flags = 3; + header |= level_flags << 6; + if ((state & IS_SETDICT) != 0) + /* Dictionary was set */ + header |= DeflaterConstants.PRESET_DICT; + header += 31 - (header % 31); + + pending.writeShortMSB(header); + if ((state & IS_SETDICT) != 0) + { + int chksum = engine.getAdler(); + engine.resetAdler(); + pending.writeShortMSB(chksum >> 16); + pending.writeShortMSB(chksum & 0xffff); + } + + state = BUSY_STATE | (state & (IS_FLUSHING | IS_FINISHING)); + } + + for (;;) + { + int count = pending.flush(output, offset, length); + offset += count; + totalOut += count; + length -= count; + if (length == 0 || state == FINISHED_STATE) + break; + + if (!engine.deflate((state & IS_FLUSHING) != 0, + (state & IS_FINISHING) != 0)) + { + if (state == BUSY_STATE) + /* We need more input now */ + return origLength - length; + else if (state == FLUSHING_STATE) + { + if (level != NO_COMPRESSION) + { + /* We have to supply some lookahead. 8 bit lookahead + * are needed by the zlib inflater, and we must fill + * the next byte, so that all bits are flushed. + */ + int neededbits = 8 + ((-pending.getBitCount()) & 7); + while (neededbits > 0) + { + /* write a static tree block consisting solely of + * an EOF: + */ + pending.writeBits(2, 10); + neededbits -= 10; + } + } + state = BUSY_STATE; + } + else if (state == FINISHING_STATE) + { + pending.alignToByte(); + /* We have completed the stream */ + if (!noHeader) + { + int adler = engine.getAdler(); + pending.writeShortMSB(adler >> 16); + pending.writeShortMSB(adler & 0xffff); + } + state = FINISHED_STATE; + } + } + } + + return origLength - length; + } + + /** + * 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 void setDictionary(byte[] dict, int offset, int length) + { + if (state != INIT_STATE) + throw new IllegalStateException(); + + state = SETDICT_STATE; + engine.setDictionary(dict, offset, length); + } +} |