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// 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.Silverlight.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 int 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

    }

}