605 lines
16 KiB
C#
605 lines
16 KiB
C#
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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#region Deflater Documentation
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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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#endregion Deflater Documentation
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#region Public Constants
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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 const 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 const 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 const 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 const 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 const int DEFLATED = 8;
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#endregion Public Constants
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#region Public Enum
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/// <summary>
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/// Compression Level as an enum for safer use
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/// </summary>
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public enum CompressionLevel
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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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BEST_COMPRESSION = Deflater.BEST_COMPRESSION,
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/// <summary>
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/// The worst but fastest compression level.
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/// </summary>
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BEST_SPEED = Deflater.BEST_SPEED,
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/// <summary>
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/// The default compression level.
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/// </summary>
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DEFAULT_COMPRESSION = Deflater.DEFAULT_COMPRESSION,
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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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NO_COMPRESSION = Deflater.NO_COMPRESSION,
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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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DEFLATED = Deflater.DEFLATED
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}
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#endregion Public Enum
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#region Local Constants
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private const int IS_SETDICT = 0x01;
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private const int IS_FLUSHING = 0x04;
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private const int IS_FINISHING = 0x08;
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private const int INIT_STATE = 0x00;
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private const 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 const int BUSY_STATE = 0x10;
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private const int FLUSHING_STATE = 0x14;
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private const int FINISHING_STATE = 0x1c;
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private const int FINISHED_STATE = 0x1e;
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private const int CLOSED_STATE = 0x7f;
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#endregion Local Constants
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#region Constructors
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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="level">
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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 level) : this(level, 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="level">
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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="noZlibHeaderOrFooter">
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/// true, if we should suppress the Zlib/RFC1950 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/PKZIP formats.
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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 level, bool noZlibHeaderOrFooter)
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{
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if (level == DEFAULT_COMPRESSION)
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{
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level = 6;
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}
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else if (level < NO_COMPRESSION || level > BEST_COMPRESSION)
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{
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throw new ArgumentOutOfRangeException(nameof(level));
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}
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pending = new DeflaterPending();
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engine = new DeflaterEngine(pending, noZlibHeaderOrFooter);
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this.noZlibHeaderOrFooter = noZlibHeaderOrFooter;
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SetStrategy(DeflateStrategy.Default);
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SetLevel(level);
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Reset();
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}
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#endregion Constructors
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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 = (noZlibHeaderOrFooter ? 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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{
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get
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{
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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 long TotalIn
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{
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get
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{
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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 long TotalOut
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{
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get
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{
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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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{
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get
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{
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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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{
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get
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{
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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="offset">
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/// the start of the data.
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/// </param>
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/// <param name="count">
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/// the number of data bytes of input.
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/// </param>
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/// <exception cref="System.InvalidOperationException">
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/// if the buffer was Finish()ed or if previous input is still pending.
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/// </exception>
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public void SetInput(byte[] input, int offset, int count)
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{
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if ((state & IS_FINISHING) != 0)
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{
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throw new InvalidOperationException("Finish() already called");
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}
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engine.SetInput(input, offset, count);
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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="level">
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/// the new compression level.
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/// </param>
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public void SetLevel(int level)
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{
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if (level == DEFAULT_COMPRESSION)
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{
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level = 6;
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}
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else if (level < NO_COMPRESSION || level > BEST_COMPRESSION)
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{
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throw new ArgumentOutOfRangeException(nameof(level));
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}
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if (this.level != level)
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{
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this.level = level;
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engine.SetLevel(level);
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}
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}
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/// <summary>
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/// Get current compression level
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/// </summary>
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/// <returns>Returns the current compression level</returns>
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public int GetLevel()
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{
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return level;
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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="strategy">
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/// The new compression strategy.
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/// </param>
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public void SetStrategy(DeflateStrategy strategy)
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{
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engine.Strategy = strategy;
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}
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/// <summary>
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/// Deflates the current input block with to the given array.
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/// </summary>
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/// <param name="output">
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/// The buffer where compressed data is stored
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/// </param>
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/// <returns>
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/// The number of compressed bytes added to the output, or 0 if either
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/// IsNeedingInput() or IsFinished returns true or length is zero.
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/// </returns>
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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.
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/// </summary>
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/// <param name="output">
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/// Buffer to store the compressed data.
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/// </param>
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/// <param name="offset">
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/// 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 stored.
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/// </param>
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/// <returns>
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/// The number of compressed bytes added to the output, or 0 if either
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/// needsInput() or finished() returns true or length is zero.
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/// </returns>
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/// <exception cref="System.InvalidOperationException">
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/// If Finish() was previously called.
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/// </exception>
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/// <exception cref="System.ArgumentOutOfRangeException">
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/// If offset 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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{
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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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{
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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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{
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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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{
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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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{
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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 (; ; )
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{
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int count = pending.Flush(output, offset, length);
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offset += count;
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totalOut += count;
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length -= count;
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if (length == 0 || state == FINISHED_STATE)
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{
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break;
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}
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if (!engine.Deflate((state & IS_FLUSHING) != 0, (state & IS_FINISHING) != 0))
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{
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switch (state)
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{
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case BUSY_STATE:
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// We need more input now
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return origLength - length;
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case FLUSHING_STATE:
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if (level != NO_COMPRESSION)
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{
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/* We have to supply some lookahead. 8 bit lookahead
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* is needed by the zlib inflater, and we must fill
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* the next byte, so that all bits are flushed.
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*/
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int neededbits = 8 + ((-pending.BitCount) & 7);
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while (neededbits > 0)
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{
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/* write a static tree block consisting solely of
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* an EOF:
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*/
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pending.WriteBits(2, 10);
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neededbits -= 10;
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}
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}
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state = BUSY_STATE;
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break;
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case FINISHING_STATE:
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pending.AlignToByte();
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// Compressed data is complete. Write footer information if required.
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if (!noZlibHeaderOrFooter)
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{
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int adler = engine.Adler;
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pending.WriteShortMSB(adler >> 16);
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pending.WriteShortMSB(adler & 0xffff);
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}
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state = FINISHED_STATE;
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break;
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}
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}
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}
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return origLength - length;
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}
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/// <summary>
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/// Sets the dictionary which should be used in the deflate process.
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/// This call is equivalent to <code>setDictionary(dict, 0, dict.Length)</code>.
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/// </summary>
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/// <param name="dictionary">
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/// the dictionary.
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/// </param>
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/// <exception cref="System.InvalidOperationException">
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/// if SetInput () or Deflate () were already called or another dictionary was already set.
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/// </exception>
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public void SetDictionary(byte[] dictionary)
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{
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SetDictionary(dictionary, 0, dictionary.Length);
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}
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/// <summary>
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/// Sets the dictionary which should be used in the deflate process.
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/// The dictionary is a byte array containing strings that are
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/// likely to occur in the data which should be compressed. The
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/// dictionary is not stored in the compressed output, only a
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/// checksum. To decompress the output you need to supply the same
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/// dictionary again.
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/// </summary>
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/// <param name="dictionary">
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/// The dictionary data
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/// </param>
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/// <param name="index">
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/// The index where dictionary information commences.
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/// </param>
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/// <param name="count">
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/// The number of bytes in the dictionary.
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/// </param>
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/// <exception cref="System.InvalidOperationException">
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/// If SetInput () or Deflate() were already called or another dictionary was already set.
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/// </exception>
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public void SetDictionary(byte[] dictionary, int index, int count)
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{
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if (state != INIT_STATE)
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{
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throw new InvalidOperationException();
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}
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state = SETDICT_STATE;
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engine.SetDictionary(dictionary, index, count);
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}
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#region Instance Fields
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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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/// If true no Zlib/RFC1950 headers or footers are generated
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/// </summary>
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private bool noZlibHeaderOrFooter;
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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 long 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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#endregion Instance Fields
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}
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}
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