// Deflater.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module. An independent module is a module which is not derived from
// or based on this library. If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
using System;
namespace ICSharpCode.SharpZipLib.Zip.Compression
{
/// <summary>
/// This is the Deflater class. The deflater class compresses input
/// with the deflate algorithm described in RFC 1951. It has several
/// compression levels and three different strategies described below.
///
/// This class is <i>not</i> thread safe. This is inherent in the API, due
/// to the split of deflate and setInput.
///
/// author of the original java version : Jochen Hoenicke
/// </summary>
public class Deflater
{
#region Deflater Documentation
/*
* The Deflater can do the following state transitions:
*
* (1) -> INIT_STATE ----> INIT_FINISHING_STATE ---.
* / | (2) (5) |
* / v (5) |
* (3)| SETDICT_STATE ---> SETDICT_FINISHING_STATE |(3)
* \ | (3) | ,--------'
* | | | (3) /
* v v (5) v v
* (1) -> BUSY_STATE ----> FINISHING_STATE
* | (6)
* v
* FINISHED_STATE
* \_____________________________________/
* | (7)
* v
* CLOSED_STATE
*
* (1) If we should produce a header we start in INIT_STATE, otherwise
* we start in BUSY_STATE.
* (2) A dictionary may be set only when we are in INIT_STATE, then
* we change the state as indicated.
* (3) Whether a dictionary is set or not, on the first call of deflate
* we change to BUSY_STATE.
* (4) -- intentionally left blank -- :)
* (5) FINISHING_STATE is entered, when flush() is called to indicate that
* there is no more INPUT. There are also states indicating, that
* the header wasn't written yet.
* (6) FINISHED_STATE is entered, when everything has been flushed to the
* internal pending output buffer.
* (7) At any time (7)
*
*/
#endregion
#region Public Constants
/// <summary>
/// The best and slowest compression level. This tries to find very
/// long and distant string repetitions.
/// </summary>
public const int BEST_COMPRESSION = 9;
/// <summary>
/// The worst but fastest compression level.
/// </summary>
public const int BEST_SPEED = 1;
/// <summary>
/// The default compression level.
/// </summary>
public const int DEFAULT_COMPRESSION = -1;
/// <summary>
/// This level won't compress at all but output uncompressed blocks.
/// </summary>
public const int NO_COMPRESSION = 0;
/// <summary>
/// The compression method. This is the only method supported so far.
/// There is no need to use this constant at all.
/// </summary>
public const int DEFLATED = 8;
#endregion
#region Local Constants
private const int IS_SETDICT = 0x01;
private const int IS_FLUSHING = 0x04;
private const int IS_FINISHING = 0x08;
private const int INIT_STATE = 0x00;
private const int SETDICT_STATE = 0x01;
// private static int INIT_FINISHING_STATE = 0x08;
// private static int SETDICT_FINISHING_STATE = 0x09;
private const int BUSY_STATE = 0x10;
private const int FLUSHING_STATE = 0x14;
private const int FINISHING_STATE = 0x1c;
private const int FINISHED_STATE = 0x1e;
private const int CLOSED_STATE = 0x7f;
#endregion
#region Constructors
/// <summary>
/// Creates a new deflater with default compression level.
/// </summary>
public Deflater() : this(DEFAULT_COMPRESSION, false)
{
}
/// <summary>
/// Creates a new deflater with given compression level.
/// </summary>
/// <param name="level">
/// the compression level, a value between NO_COMPRESSION
/// and BEST_COMPRESSION, or DEFAULT_COMPRESSION.
/// </param>
/// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
public Deflater(int level) : this(level, false)
{
}
/// <summary>
/// Creates a new deflater with given compression level.
/// </summary>
/// <param name="level">
/// the compression level, a value between NO_COMPRESSION
/// and BEST_COMPRESSION.
/// </param>
/// <param name="noZlibHeaderOrFooter">
/// true, if we should suppress the Zlib/RFC1950 header at the
/// beginning and the adler checksum at the end of the output. This is
/// useful for the GZIP/PKZIP formats.
/// </param>
/// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
public Deflater(int level, bool noZlibHeaderOrFooter)
{
if (level == DEFAULT_COMPRESSION) {
level = 6;
} else if (level < NO_COMPRESSION || level > BEST_COMPRESSION) {
throw new ArgumentOutOfRangeException("level");
}
pending = new DeflaterPending();
engine = new DeflaterEngine(pending);
this.noZlibHeaderOrFooter = noZlibHeaderOrFooter;
SetStrategy(DeflateStrategy.Default);
SetLevel(level);
Reset();
}
#endregion
/// <summary>
/// Resets the deflater. The deflater acts afterwards as if it was
/// just created with the same compression level and strategy as it
/// had before.
/// </summary>
public void Reset()
{
state = (noZlibHeaderOrFooter ? BUSY_STATE : INIT_STATE);
totalOut = 0;
pending.Reset();
engine.Reset();
}
/// <summary>
/// Gets the current adler checksum of the data that was processed so far.
/// </summary>
public int Adler {
get {
return engine.Adler;
}
}
/// <summary>
/// Gets the number of input bytes processed so far.
/// </summary>
public long TotalIn {
get {
return engine.TotalIn;
}
}
/// <summary>
/// Gets the number of output bytes so far.
/// </summary>
public long TotalOut {
get {
return totalOut;
}
}
/// <summary>
/// Flushes the current input block. Further calls to deflate() will
/// produce enough output to inflate everything in the current input
/// block. This is not part of Sun's JDK so I have made it package
/// private. It is used by DeflaterOutputStream to implement
/// flush().
/// </summary>
public void Flush()
{
state |= IS_FLUSHING;
}
/// <summary>
/// Finishes the deflater with the current input block. It is an error
/// to give more input after this method was called. This method must
/// be called to force all bytes to be flushed.
/// </summary>
public void Finish()
{
state |= (IS_FLUSHING | IS_FINISHING);
}
/// <summary>
/// Returns true if the stream was finished and no more output bytes
/// are available.
/// </summary>
public bool IsFinished {
get {
return (state == FINISHED_STATE) && pending.IsFlushed;
}
}
/// <summary>
/// Returns true, if the input buffer is empty.
/// You should then call setInput().
/// NOTE: This method can also return true when the stream
/// was finished.
/// </summary>
public bool IsNeedingInput {
get {
return engine.NeedsInput();
}
}
/// <summary>
/// Sets the data which should be compressed next. This should be only
/// called when needsInput indicates that more input is needed.
/// If you call setInput when needsInput() returns false, the
/// previous input that is still pending will be thrown away.
/// The given byte array should not be changed, before needsInput() returns
/// true again.
/// This call is equivalent to <code>setInput(input, 0, input.length)</code>.
/// </summary>
/// <param name="input">
/// the buffer containing the input data.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if the buffer was finished() or ended().
/// </exception>
public void SetInput(byte[] input)
{
SetInput(input, 0, input.Length);
}
/// <summary>
/// Sets the data which should be compressed next. This should be
/// only called when needsInput indicates that more input is needed.
/// The given byte array should not be changed, before needsInput() returns
/// true again.
/// </summary>
/// <param name="input">
/// the buffer containing the input data.
/// </param>
/// <param name="offset">
/// the start of the data.
/// </param>
/// <param name="count">
/// the number of data bytes of input.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if the buffer was Finish()ed or if previous input is still pending.
/// </exception>
public void SetInput(byte[] input, int offset, int count)
{
if ((state & IS_FINISHING) != 0) {
throw new InvalidOperationException("Finish() already called");
}
engine.SetInput(input, offset, count);
}
/// <summary>
/// Sets the compression level. There is no guarantee of the exact
/// position of the change, but if you call this when needsInput is
/// true the change of compression level will occur somewhere near
/// before the end of the so far given input.
/// </summary>
/// <param name="level">
/// the new compression level.
/// </param>
public void SetLevel(int level)
{
if (level == DEFAULT_COMPRESSION) {
level = 6;
} else if (level < NO_COMPRESSION || level > BEST_COMPRESSION) {
throw new ArgumentOutOfRangeException("level");
}
if (this.level != level) {
this.level = level;
engine.SetLevel(level);
}
}
/// <summary>
/// Get current compression level
/// </summary>
/// <returns>Returns the current compression level</returns>
public int GetLevel() {
return level;
}
/// <summary>
/// Sets the compression strategy. Strategy is one of
/// DEFAULT_STRATEGY, HUFFMAN_ONLY and FILTERED. For the exact
/// position where the strategy is changed, the same as for
/// SetLevel() applies.
/// </summary>
/// <param name="strategy">
/// The new compression strategy.
/// </param>
public void SetStrategy(DeflateStrategy strategy)
{
engine.Strategy = strategy;
}
/// <summary>
/// Deflates the current input block with to the given array.
/// </summary>
/// <param name="output">
/// The buffer where compressed data is stored
/// </param>
/// <returns>
/// The number of compressed bytes added to the output, or 0 if either
/// IsNeedingInput() or IsFinished returns true or length is zero.
/// </returns>
public int Deflate(byte[] output)
{
return Deflate(output, 0, output.Length);
}
/// <summary>
/// Deflates the current input block to the given array.
/// </summary>
/// <param name="output">
/// Buffer to store the compressed data.
/// </param>
/// <param name="offset">
/// Offset into the output array.
/// </param>
/// <param name="length">
/// The maximum number of bytes that may be stored.
/// </param>
/// <returns>
/// The number of compressed bytes added to the output, or 0 if either
/// needsInput() or finished() returns true or length is zero.
/// </returns>
/// <exception cref="System.InvalidOperationException">
/// If Finish() was previously called.
/// </exception>
/// <exception cref="System.ArgumentOutOfRangeException">
/// If offset or length don't match the array length.
/// </exception>
public int Deflate(byte[] output, int offset, int length)
{
int origLength = length;
if (state == CLOSED_STATE) {
throw new InvalidOperationException("Deflater closed");
}
if (state < BUSY_STATE) {
// output header
int header = (DEFLATED +
((DeflaterConstants.MAX_WBITS - 8) << 4)) << 8;
int level_flags = (level - 1) >> 1;
if (level_flags < 0 || level_flags > 3) {
level_flags = 3;
}
header |= level_flags << 6;
if ((state & IS_SETDICT) != 0) {
// Dictionary was set
header |= DeflaterConstants.PRESET_DICT;
}
header += 31 - (header % 31);
pending.WriteShortMSB(header);
if ((state & IS_SETDICT) != 0) {
int chksum = engine.Adler;
engine.ResetAdler();
pending.WriteShortMSB(chksum >> 16);
pending.WriteShortMSB(chksum & 0xffff);
}
state = BUSY_STATE | (state & (IS_FLUSHING | IS_FINISHING));
}
for (;;) {
int count = pending.Flush(output, offset, length);
offset += count;
totalOut += count;
length -= count;
if (length == 0 || state == FINISHED_STATE) {
break;
}
if (!engine.Deflate((state & IS_FLUSHING) != 0, (state & IS_FINISHING) != 0)) {
if (state == BUSY_STATE) {
// We need more input now
return origLength - length;
} else if (state == FLUSHING_STATE) {
if (level != NO_COMPRESSION) {
/* We have to supply some lookahead. 8 bit lookahead
* is needed by the zlib inflater, and we must fill
* the next byte, so that all bits are flushed.
*/
int neededbits = 8 + ((-pending.BitCount) & 7);
while (neededbits > 0) {
/* write a static tree block consisting solely of
* an EOF:
*/
pending.WriteBits(2, 10);
neededbits -= 10;
}
}
state = BUSY_STATE;
} else if (state == FINISHING_STATE) {
pending.AlignToByte();
// Compressed data is complete. Write footer information if required.
if (!noZlibHeaderOrFooter) {
int adler = engine.Adler;
pending.WriteShortMSB(adler >> 16);
pending.WriteShortMSB(adler & 0xffff);
}
state = FINISHED_STATE;
}
}
}
return origLength - length;
}
/// <summary>
/// Sets the dictionary which should be used in the deflate process.
/// This call is equivalent to <code>setDictionary(dict, 0, dict.Length)</code>.
/// </summary>
/// <param name="dictionary">
/// the dictionary.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if SetInput () or Deflate () were already called or another dictionary was already set.
/// </exception>
public void SetDictionary(byte[] dictionary)
{
SetDictionary(dictionary, 0, dictionary.Length);
}
/// <summary>
/// Sets the dictionary which should be used in the deflate process.
/// The dictionary is a byte array containing strings that are
/// likely to occur in the data which should be compressed. The
/// dictionary is not stored in the compressed output, only a
/// checksum. To decompress the output you need to supply the same
/// dictionary again.
/// </summary>
/// <param name="dictionary">
/// The dictionary data
/// </param>
/// <param name="index">
/// The index where dictionary information commences.
/// </param>
/// <param name="count">
/// The number of bytes in the dictionary.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// If SetInput () or Deflate() were already called or another dictionary was already set.
/// </exception>
public void SetDictionary(byte[] dictionary, int index, int count)
{
if (state != INIT_STATE) {
throw new InvalidOperationException();
}
state = SETDICT_STATE;
engine.SetDictionary(dictionary, index, count);
}
#region Instance Fields
/// <summary>
/// Compression level.
/// </summary>
int level;
/// <summary>
/// If true no Zlib/RFC1950 headers or footers are generated
/// </summary>
bool noZlibHeaderOrFooter;
/// <summary>
/// The current state.
/// </summary>
int state;
/// <summary>
/// The total bytes of output written.
/// </summary>
long totalOut;
/// <summary>
/// The pending output.
/// </summary>
DeflaterPending pending;
/// <summary>
/// The deflater engine.
/// </summary>
DeflaterEngine engine;
#endregion
}
}
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