root/trunk/Updater/ICSharpCode.SharpZipLib/Zip/Compression/Deflater.cs @ 597

// Deflater.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
//
// 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;

namespace ICSharpCode.SharpZipLib.Zip.Compression
{
        
        /// <summary>
        /// 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 of the original java version : Jochen Hoenicke
        /// </summary>
        public class Deflater
        {
                #region Deflater Documentation
                /*
                * 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)
                *
                */
                #endregion
                #region Public Constants
                /// <summary>
                /// The best and slowest compression level.  This tries to find very
                /// long and distant string repetitions.
                /// </summary>
                public const  int BEST_COMPRESSION = 9;
                
                /// <summary>
                /// The worst but fastest compression level.
                /// </summary>
                public const  int BEST_SPEED = 1;
                
                /// <summary>
                /// The default compression level.
                /// </summary>
                public const  int DEFAULT_COMPRESSION = -1;
                
                /// <summary>
                /// This level won't compress at all but output uncompressed blocks.
                /// </summary>
                public const  int NO_COMPRESSION = 0;
                                
                /// <summary>
                /// The compression method.  This is the only method supported so far.
                /// There is no need to use this constant at all.
                /// </summary>
                public const  int DEFLATED = 8;
                #endregion
                #region Local Constants
                private const  int IS_SETDICT              = 0x01;
                private const  int IS_FLUSHING             = 0x04;
                private const  int IS_FINISHING            = 0x08;
                
                private const  int INIT_STATE              = 0x00;
                private const  int SETDICT_STATE           = 0x01;
                //              private static  int INIT_FINISHING_STATE    = 0x08;
                //              private static  int SETDICT_FINISHING_STATE = 0x09;
                private const  int BUSY_STATE              = 0x10;
                private const  int FLUSHING_STATE          = 0x14;
                private const  int FINISHING_STATE         = 0x1c;
                private const  int FINISHED_STATE          = 0x1e;
                private const  int CLOSED_STATE            = 0x7f;
                #endregion
                #region Constructors
                /// <summary>
                /// Creates a new deflater with default compression level.
                /// </summary>
                public Deflater() : this(DEFAULT_COMPRESSION, false)
                {
                        
                }
                
                /// <summary>
                /// Creates a new deflater with given compression level.
                /// </summary>
                /// <param name="level">
                /// the compression level, a value between NO_COMPRESSION
                /// and BEST_COMPRESSION, or DEFAULT_COMPRESSION.
                /// </param>
                /// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
                public Deflater(int level) : this(level, false)
                {
                        
                }
                
                /// <summary>
                /// Creates a new deflater with given compression level.
                /// </summary>
                /// <param name="level">
                /// the compression level, a value between NO_COMPRESSION
                /// and BEST_COMPRESSION.
                /// </param>
                /// <param name="noZlibHeaderOrFooter">
                /// true, if we should suppress the Zlib/RFC1950 header at the
                /// beginning and the adler checksum at the end of the output.  This is
                /// useful for the GZIP/PKZIP formats.
                /// </param>
                /// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
                public Deflater(int level, bool noZlibHeaderOrFooter)
                {
                        if (level == DEFAULT_COMPRESSION) {
                                level = 6;
                        } else if (level < NO_COMPRESSION || level > BEST_COMPRESSION) {
                                throw new ArgumentOutOfRangeException("level");
                        }
                        
                        pending = new DeflaterPending();
                        engine = new DeflaterEngine(pending);
                        this.noZlibHeaderOrFooter = noZlibHeaderOrFooter;
                        SetStrategy(DeflateStrategy.Default);
                        SetLevel(level);
                        Reset();
                }
                #endregion
                
                /// <summary>
                /// Resets the deflater.  The deflater acts afterwards as if it was
                /// just created with the same compression level and strategy as it
                /// had before.
                /// </summary>
                public void Reset()
                {
                        state = (noZlibHeaderOrFooter ? BUSY_STATE : INIT_STATE);
                        totalOut = 0;
                        pending.Reset();
                        engine.Reset();
                }
                
                /// <summary>
                /// Gets the current adler checksum of the data that was processed so far.
                /// </summary>
                public int Adler {
                        get {
                                return engine.Adler;
                        }
                }
                
                /// <summary>
                /// Gets the number of input bytes processed so far.
                /// </summary>
                public long TotalIn {
                        get {
                                return engine.TotalIn;
                        }
                }
                
                /// <summary>
                /// Gets the number of output bytes so far.
                /// </summary>
                public long TotalOut {
                        get {
                                return totalOut;
                        }
                }
                
                /// <summary>
                /// 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().
                /// </summary>
                public void Flush() 
                {
                        state |= IS_FLUSHING;
                }
                
                /// <summary>
                /// 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.
                /// </summary>
                public void Finish() 
                {
                        state |= (IS_FLUSHING | IS_FINISHING);
                }
                
                /// <summary>
                /// Returns true if the stream was finished and no more output bytes
                /// are available.
                /// </summary>
                public bool IsFinished {
                        get {
                                return (state == FINISHED_STATE) && pending.IsFlushed;
                        }
                }
                
                /// <summary>
                /// Returns true, if the input buffer is empty.
                /// You should then call setInput(). 
                /// NOTE: This method can also return true when the stream
                /// was finished.
                /// </summary>
                public bool IsNeedingInput {
                        get {
                                return engine.NeedsInput();
                        }
                }
                
                /// <summary>
                /// 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>.
                /// </summary>
                /// <param name="input">
                /// the buffer containing the input data.
                /// </param>
                /// <exception cref="System.InvalidOperationException">
                /// if the buffer was finished() or ended().
                /// </exception>
                public void SetInput(byte[] input)
                {
                        SetInput(input, 0, input.Length);
                }
                
                /// <summary>
                /// 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.
                /// </summary>
                /// <param name="input">
                /// the buffer containing the input data.
                /// </param>
                /// <param name="offset">
                /// the start of the data.
                /// </param>
                /// <param name="count">
                /// the number of data bytes of input.
                /// </param>
                /// <exception cref="System.InvalidOperationException">
                /// if the buffer was Finish()ed or if previous input is still pending.
                /// </exception>
                public void SetInput(byte[] input, int offset, int count)
                {
                        if ((state & IS_FINISHING) != 0) {
                                throw new InvalidOperationException("Finish() already called");
                        }
                        engine.SetInput(input, offset, count);
                }
                
                /// <summary>
                /// 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.
                /// </summary>
                /// <param name="level">
                /// the new compression level.
                /// </param>
                public void SetLevel(int level)
                {
                        if (level == DEFAULT_COMPRESSION) {
                                level = 6;
                        } else if (level < NO_COMPRESSION || level > BEST_COMPRESSION) {
                                throw new ArgumentOutOfRangeException("level");
                        }
                        
                        if (this.level != level) {
                                this.level = level;
                                engine.SetLevel(level);
                        }
                }
                
                /// <summary>
                /// Get current compression level
                /// </summary>
                /// <returns>Returns the current compression level</returns>
                public int GetLevel() {
                        return level;
                }
                
                /// <summary>
                /// 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.
                /// </summary>
                /// <param name="strategy">
                /// The new compression strategy.
                /// </param>
                public void SetStrategy(DeflateStrategy strategy)
                {
                        engine.Strategy = strategy;
                }
                
                /// <summary>
                /// Deflates the current input block with to the given array.
                /// </summary>
                /// <param name="output">
                /// The buffer where compressed data is stored
                /// </param>
                /// <returns>
                /// The number of compressed bytes added to the output, or 0 if either
                /// IsNeedingInput() or IsFinished returns true or length is zero.
                /// </returns>
                public int Deflate(byte[] output)
                {
                        return Deflate(output, 0, output.Length);
                }
                
                /// <summary>
                /// Deflates the current input block to the given array.
                /// </summary>
                /// <param name="output">
                /// Buffer to store the compressed data.
                /// </param>
                /// <param name="offset">
                /// Offset into the output array.
                /// </param>
                /// <param name="length">
                /// The maximum number of bytes that may be stored.
                /// </param>
                /// <returns>
                /// The number of compressed bytes added to the output, or 0 if either
                /// needsInput() or finished() returns true or length is zero.
                /// </returns>
                /// <exception cref="System.InvalidOperationException">
                /// If Finish() was previously called.
                /// </exception>
                /// <exception cref="System.ArgumentOutOfRangeException">
                /// If offset or length don't match the array length.
                /// </exception>
                public int Deflate(byte[] output, int offset, int length)
                {
                        int origLength = length;
                        
                        if (state == CLOSED_STATE) {
                                throw new InvalidOperationException("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.Adler;
                                        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
                                                         * is needed by the zlib inflater, and we must fill
                                                         * the next byte, so that all bits are flushed.
                                                         */
                                                        int neededbits = 8 + ((-pending.BitCount) & 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();

                                                // Compressed data is complete.  Write footer information if required.
                                                if (!noZlibHeaderOrFooter) {
                                                        int adler = engine.Adler;
                                                        pending.WriteShortMSB(adler >> 16);
                                                        pending.WriteShortMSB(adler & 0xffff);
                                                }
                                                state = FINISHED_STATE;
                                        }
                                }
                        }
                        return origLength - length;
                }
                
                /// <summary>
                /// Sets the dictionary which should be used in the deflate process.
                /// This call is equivalent to <code>setDictionary(dict, 0, dict.Length)</code>.
                /// </summary>
                /// <param name="dictionary">
                /// the dictionary.
                /// </param>
                /// <exception cref="System.InvalidOperationException">
                /// if SetInput () or Deflate () were already called or another dictionary was already set.
                /// </exception>
                public void SetDictionary(byte[] dictionary)
                {
                        SetDictionary(dictionary, 0, dictionary.Length);
                }
                
                /// <summary>
                /// Sets the dictionary which should be used in the deflate process.
                /// The dictionary is 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.
                /// </summary>
                /// <param name="dictionary">
                /// The dictionary data
                /// </param>
                /// <param name="index">
                /// The index where dictionary information commences.
                /// </param>
                /// <param name="count">
                /// The number of bytes in the dictionary.
                /// </param>
                /// <exception cref="System.InvalidOperationException">
                /// If SetInput () or Deflate() were already called or another dictionary was already set.
                /// </exception>
                public void SetDictionary(byte[] dictionary, int index, int count)
                {
                        if (state != INIT_STATE) {
                                throw new InvalidOperationException();
                        }
                        
                        state = SETDICT_STATE;
                        engine.SetDictionary(dictionary, index, count);
                }

                #region Instance Fields
                /// <summary>
                /// Compression level.
                /// </summary>
                int level;
                
                /// <summary>
                /// If true no Zlib/RFC1950 headers or footers are generated
                /// </summary>
                bool noZlibHeaderOrFooter;
                
                /// <summary>
                /// The current state.
                /// </summary>
                int state;
                
                /// <summary>
                /// The total bytes of output written.
                /// </summary>
                long totalOut;
                
                /// <summary>
                /// The pending output.
                /// </summary>
                DeflaterPending pending;
                
                /// <summary>
                /// The deflater engine.
                /// </summary>
                DeflaterEngine engine;
                #endregion
        }
}