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543 lines
17 KiB
C#
543 lines
17 KiB
C#
![]() |
// Deflater.cs
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// Copyright (C) 2001 Mike Krueger
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//
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// This file was translated from java, it was part of the GNU Classpath
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// Copyright (C) 2001 Free Software Foundation, Inc.
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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//
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// Linking this library statically or dynamically with other modules is
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// making a combined work based on this library. Thus, the terms and
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// conditions of the GNU General Public License cover the whole
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// combination.
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//
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// As a special exception, the copyright holders of this library give you
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// permission to link this library with independent modules to produce an
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// executable, regardless of the license terms of these independent
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// modules, and to copy and distribute the resulting executable under
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// terms of your choice, provided that you also meet, for each linked
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// independent module, the terms and conditions of the license of that
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// module. An independent module is a module which is not derived from
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// or based on this library. If you modify this library, you may extend
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// this exception to your version of the library, but you are not
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// obligated to do so. If you do not wish to do so, delete this
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// exception statement from your version.
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using System;
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namespace ICSharpCode.SharpZipLib.Zip.Compression
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{
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/// <summary>
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/// This is the Deflater class. The deflater class compresses input
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/// with the deflate algorithm described in RFC 1951. It has several
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/// compression levels and three different strategies described below.
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///
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/// This class is <i>not</i> thread safe. This is inherent in the API, due
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/// to the split of deflate and setInput.
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///
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/// author of the original java version : Jochen Hoenicke
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/// </summary>
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public class Deflater
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{
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/// <summary>
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/// The best and slowest compression level. This tries to find very
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/// long and distant string repetitions.
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/// </summary>
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public static int BEST_COMPRESSION = 9;
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/// <summary>
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/// The worst but fastest compression level.
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/// </summary>
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public static int BEST_SPEED = 1;
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/// <summary>
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/// The default compression level.
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/// </summary>
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public static int DEFAULT_COMPRESSION = -1;
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/// <summary>
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/// This level won't compress at all but output uncompressed blocks.
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/// </summary>
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public static int NO_COMPRESSION = 0;
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/// <summary>
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/// The compression method. This is the only method supported so far.
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/// There is no need to use this constant at all.
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/// </summary>
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public static int DEFLATED = 8;
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/*
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* The Deflater can do the following state transitions:
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*
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* (1) -> INIT_STATE ----> INIT_FINISHING_STATE ---.
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* / | (2) (5) |
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* / v (5) |
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* (3)| SETDICT_STATE ---> SETDICT_FINISHING_STATE |(3)
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* \ | (3) | ,-------'
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* | | | (3) /
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* v v (5) v v
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* (1) -> BUSY_STATE ----> FINISHING_STATE
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* | (6)
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* v
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* FINISHED_STATE
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* \_____________________________________/
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* | (7)
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* v
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* CLOSED_STATE
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*
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* (1) If we should produce a header we start in INIT_STATE, otherwise
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* we start in BUSY_STATE.
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* (2) A dictionary may be set only when we are in INIT_STATE, then
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* we change the state as indicated.
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* (3) Whether a dictionary is set or not, on the first call of deflate
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* we change to BUSY_STATE.
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* (4) -- intentionally left blank -- :)
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* (5) FINISHING_STATE is entered, when flush() is called to indicate that
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* there is no more INPUT. There are also states indicating, that
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* the header wasn't written yet.
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* (6) FINISHED_STATE is entered, when everything has been flushed to the
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* internal pending output buffer.
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* (7) At any time (7)
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*
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*/
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private static int IS_SETDICT = 0x01;
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private static int IS_FLUSHING = 0x04;
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private static int IS_FINISHING = 0x08;
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private static int INIT_STATE = 0x00;
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private static int SETDICT_STATE = 0x01;
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// private static int INIT_FINISHING_STATE = 0x08;
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// private static int SETDICT_FINISHING_STATE = 0x09;
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private static int BUSY_STATE = 0x10;
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private static int FLUSHING_STATE = 0x14;
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private static int FINISHING_STATE = 0x1c;
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private static int FINISHED_STATE = 0x1e;
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private static int CLOSED_STATE = 0x7f;
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/// <summary>
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/// Compression level.
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/// </summary>
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private int level;
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/// <summary>
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/// should we include a header.
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/// </summary>
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private bool noHeader;
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// /// <summary>
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// /// Compression strategy.
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// /// </summary>
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// private int strategy;
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/// <summary>
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/// The current state.
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/// </summary>
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private int state;
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/// <summary>
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/// The total bytes of output written.
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/// </summary>
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private int totalOut;
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/// <summary>
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/// The pending output.
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/// </summary>
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private DeflaterPending pending;
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/// <summary>
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/// The deflater engine.
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/// </summary>
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private DeflaterEngine engine;
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/// <summary>
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/// Creates a new deflater with default compression level.
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/// </summary>
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public Deflater() : this(DEFAULT_COMPRESSION, false)
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{
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}
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/// <summary>
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/// Creates a new deflater with given compression level.
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/// </summary>
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/// <param name="lvl">
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/// the compression level, a value between NO_COMPRESSION
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/// and BEST_COMPRESSION, or DEFAULT_COMPRESSION.
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/// </param>
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/// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
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public Deflater(int lvl) : this(lvl, false)
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{
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}
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/// <summary>
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/// Creates a new deflater with given compression level.
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/// </summary>
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/// <param name="lvl">
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/// the compression level, a value between NO_COMPRESSION
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/// and BEST_COMPRESSION.
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/// </param>
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/// <param name="nowrap">
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/// true, if we should suppress the deflate header at the
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/// beginning and the adler checksum at the end of the output. This is
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/// useful for the GZIP format.
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/// </param>
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/// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
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public Deflater(int lvl, bool nowrap)
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{
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if (lvl == DEFAULT_COMPRESSION) {
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lvl = 6;
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} else if (lvl < NO_COMPRESSION || lvl > BEST_COMPRESSION) {
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throw new ArgumentOutOfRangeException("lvl");
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}
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pending = new DeflaterPending();
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engine = new DeflaterEngine(pending);
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this.noHeader = nowrap;
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SetStrategy(DeflateStrategy.Default);
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SetLevel(lvl);
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Reset();
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}
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/// <summary>
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/// Resets the deflater. The deflater acts afterwards as if it was
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/// just created with the same compression level and strategy as it
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/// had before.
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/// </summary>
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public void Reset()
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{
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state = (noHeader ? BUSY_STATE : INIT_STATE);
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totalOut = 0;
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pending.Reset();
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engine.Reset();
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}
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/// <summary>
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/// Gets the current adler checksum of the data that was processed so far.
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/// </summary>
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public int Adler {
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get {
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return engine.Adler;
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}
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}
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/// <summary>
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/// Gets the number of input bytes processed so far.
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/// </summary>
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public int TotalIn {
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get {
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return engine.TotalIn;
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}
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}
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/// <summary>
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/// Gets the number of output bytes so far.
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/// </summary>
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public int TotalOut {
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get {
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return totalOut;
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}
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}
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/// <summary>
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/// Flushes the current input block. Further calls to deflate() will
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/// produce enough output to inflate everything in the current input
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/// block. This is not part of Sun's JDK so I have made it package
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/// private. It is used by DeflaterOutputStream to implement
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/// flush().
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/// </summary>
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public void Flush()
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{
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state |= IS_FLUSHING;
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}
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/// <summary>
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/// Finishes the deflater with the current input block. It is an error
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/// to give more input after this method was called. This method must
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/// be called to force all bytes to be flushed.
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/// </summary>
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public void Finish()
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{
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state |= IS_FLUSHING | IS_FINISHING;
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}
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/// <summary>
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/// Returns true if the stream was finished and no more output bytes
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/// are available.
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/// </summary>
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public bool IsFinished {
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get {
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return state == FINISHED_STATE && pending.IsFlushed;
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}
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}
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/// <summary>
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/// Returns true, if the input buffer is empty.
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/// You should then call setInput().
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/// NOTE: This method can also return true when the stream
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/// was finished.
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/// </summary>
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public bool IsNeedingInput {
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get {
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return engine.NeedsInput();
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}
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}
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/// <summary>
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/// Sets the data which should be compressed next. This should be only
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/// called when needsInput indicates that more input is needed.
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/// If you call setInput when needsInput() returns false, the
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/// previous input that is still pending will be thrown away.
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/// The given byte array should not be changed, before needsInput() returns
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/// true again.
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/// This call is equivalent to <code>setInput(input, 0, input.length)</code>.
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/// </summary>
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/// <param name="input">
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/// the buffer containing the input data.
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/// </param>
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/// <exception cref="System.InvalidOperationException">
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/// if the buffer was finished() or ended().
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/// </exception>
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public void SetInput(byte[] input)
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{
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SetInput(input, 0, input.Length);
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}
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/// <summary>
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/// Sets the data which should be compressed next. This should be
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/// only called when needsInput indicates that more input is needed.
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/// The given byte array should not be changed, before needsInput() returns
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/// true again.
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/// </summary>
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/// <param name="input">
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/// the buffer containing the input data.
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/// </param>
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/// <param name="off">
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/// the start of the data.
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/// </param>
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/// <param name="len">
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/// the length of the data.
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/// </param>
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/// <exception cref="System.InvalidOperationException">
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/// if the buffer was finished() or ended() or if previous input is still pending.
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/// </exception>
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public void SetInput(byte[] input, int off, int len)
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{
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if ((state & IS_FINISHING) != 0) {
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throw new InvalidOperationException("finish()/end() already called");
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}
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engine.SetInput(input, off, len);
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}
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/// <summary>
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/// Sets the compression level. There is no guarantee of the exact
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/// position of the change, but if you call this when needsInput is
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/// true the change of compression level will occur somewhere near
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/// before the end of the so far given input.
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/// </summary>
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/// <param name="lvl">
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/// the new compression level.
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/// </param>
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public void SetLevel(int lvl)
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{
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if (lvl == DEFAULT_COMPRESSION) {
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lvl = 6;
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} else if (lvl < NO_COMPRESSION || lvl > BEST_COMPRESSION) {
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throw new ArgumentOutOfRangeException("lvl");
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}
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if (level != lvl) {
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level = lvl;
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engine.SetLevel(lvl);
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}
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}
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/// <summary>
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/// Sets the compression strategy. Strategy is one of
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/// DEFAULT_STRATEGY, HUFFMAN_ONLY and FILTERED. For the exact
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/// position where the strategy is changed, the same as for
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/// setLevel() applies.
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/// </summary>
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/// <param name="stgy">
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/// the new compression strategy.
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/// </param>
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public void SetStrategy(DeflateStrategy stgy)
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{
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engine.Strategy = stgy;
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}
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/// <summary>
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/// Deflates the current input block to the given array. It returns
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/// the number of bytes compressed, or 0 if either
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/// needsInput() or finished() returns true or length is zero.
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/// </summary>
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/// <param name="output">
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/// the buffer where to write the compressed data.
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/// </param>
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public int Deflate(byte[] output)
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{
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return Deflate(output, 0, output.Length);
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}
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/// <summary>
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/// Deflates the current input block to the given array. It returns
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/// the number of bytes compressed, or 0 if either
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/// needsInput() or finished() returns true or length is zero.
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/// </summary>
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/// <param name="output">
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/// the buffer where to write the compressed data.
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/// </param>
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/// <param name="offset">
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/// the offset into the output array.
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/// </param>
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/// <param name="length">
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/// the maximum number of bytes that may be written.
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/// </param>
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/// <exception cref="System.InvalidOperationException">
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/// if end() was called.
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/// </exception>
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/// <exception cref="System.ArgumentOutOfRangeException">
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/// if offset and/or length don't match the array length.
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/// </exception>
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public int Deflate(byte[] output, int offset, int length)
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{
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int origLength = length;
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if (state == CLOSED_STATE) {
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throw new InvalidOperationException("Deflater closed");
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}
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if (state < BUSY_STATE) {
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/* output header */
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int header = (DEFLATED +
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((DeflaterConstants.MAX_WBITS - 8) << 4)) << 8;
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int level_flags = (level - 1) >> 1;
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if (level_flags < 0 || level_flags > 3) {
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level_flags = 3;
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}
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header |= level_flags << 6;
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if ((state & IS_SETDICT) != 0) {
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/* Dictionary was set */
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header |= DeflaterConstants.PRESET_DICT;
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}
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header += 31 - (header % 31);
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pending.WriteShortMSB(header);
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if ((state & IS_SETDICT) != 0) {
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int chksum = engine.Adler;
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engine.ResetAdler();
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pending.WriteShortMSB(chksum >> 16);
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pending.WriteShortMSB(chksum & 0xffff);
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}
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state = BUSY_STATE | (state & (IS_FLUSHING | IS_FINISHING));
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}
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|
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.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();
|
||
|
/* We have completed the stream */
|
||
|
if (!noHeader) {
|
||
|
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="dict">
|
||
|
/// 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[] dict)
|
||
|
{
|
||
|
SetDictionary(dict, 0, dict.Length);
|
||
|
}
|
||
|
|
||
|
/// <summary>
|
||
|
/// 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.
|
||
|
/// </summary>
|
||
|
/// <param name="dict">
|
||
|
/// the dictionary.
|
||
|
/// </param>
|
||
|
/// <param name="offset">
|
||
|
/// an offset into the dictionary.
|
||
|
/// </param>
|
||
|
/// <param name="length">
|
||
|
/// the length of 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[] dict, int offset, int length)
|
||
|
{
|
||
|
if (state != INIT_STATE) {
|
||
|
throw new InvalidOperationException();
|
||
|
}
|
||
|
|
||
|
state = SETDICT_STATE;
|
||
|
engine.SetDictionary(dict, offset, length);
|
||
|
}
|
||
|
}
|
||
|
}
|