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zipmark.cs
4068 lines (3654 loc) · 114 KB
/
zipmark.cs
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// zipmark.cs
// (This file is the NZipLib sources with a crude benchmark class attached -
// 2002-15-05 Dan Lewis <dihlewis@yahoo.co.uk>)
// -------------------------------------------------------------------------
//
// NZipLib source:
// Copyright (C) 2001 Mike Krueger
//
// 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.
//
// As a special exception, if you link this library with other files to
// produce an executable, this library does not by itself cause the
// resulting executable to be covered by the GNU General Public License.
// This exception does not however invalidate any other reasons why the
// executable file might be covered by the GNU General Public License.
using System;
using System.IO;
using NZlib.Streams;
using NZlib.Checksums;
using NZlib.Compression;
class ZipMark {
static int Iterations = 1000;
static int BlockSize = 1024;
public static void Main (string [] args)
{
if (args.Length == 0 || args.Length > 3) {
Console.WriteLine ("Usage: zipmark FILE [ITERATIONS] [BLOCKSIZE]");
return;
}
string filename = args [0];
FileInfo file = new FileInfo (filename);
if (!file.Exists) {
Console.WriteLine ("Couldn't find file {0}", filename);
return;
}
FileStream fs = file.OpenRead ();
byte [] raw = new byte [file.Length];
int count = fs.Read (raw, 0, (int)file.Length);
fs.Close ();
if (count != file.Length) {
Console.WriteLine ("Couldn't read file {0}", filename);
return;
}
Deflater def = new Deflater (Deflater.BEST_COMPRESSION, false);
Inflater inf = new Inflater (false);
// 1. Count deflated size
int cooked_size = Deflate (def, raw, null);
byte [] cooked = new byte [cooked_size];
// 2. Deflate & Inflate
if (args.Length > 1)
Iterations = Int32.Parse (args [1]);
if (args.Length > 2)
BlockSize = Int32.Parse (args [2]);
for (int i = 0; i < Iterations; ++ i) {
Deflate (def, raw, cooked);
Inflate (inf, cooked, raw);
}
return;
}
static int Deflate (Deflater def, byte [] src, byte [] dest)
{
bool count;
int offset, length, remain;
if (dest == null) {
dest = new byte [BlockSize];
count = true;
} else
count = false;
def.Reset ();
def.SetInput (src);
offset = 0;
while (!def.IsFinished) {
if (def.IsNeedingInput)
def.Finish ();
remain = Math.Min (dest.Length - offset, BlockSize);
if (remain == 0)
break;
length = def.Deflate (dest, offset, remain);
if (!count)
offset += length;
}
return def.TotalOut;
}
static int Inflate (Inflater inf, byte [] src, byte [] dest)
{
int offset, length, remain;
inf.Reset ();
inf.SetInput (src);
offset = 0;
while (!inf.IsNeedingInput) {
remain = Math.Min (dest.Length - offset, BlockSize);
if (remain == 0)
break;
length = inf.Inflate (dest, offset, remain);
offset += length;
}
return inf.TotalOut;
}
}
// ---------------------- NZipLib sources from here on --------------------------
namespace NZlib.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
{
/// <summary>
/// The best and slowest compression level. This tries to find very
/// long and distant string repetitions.
/// </summary>
public static int BEST_COMPRESSION = 9;
/// <summary>
/// The worst but fastest compression level.
/// </summary>
public static int BEST_SPEED = 1;
/// <summary>
/// The default compression level.
/// </summary>
public static int DEFAULT_COMPRESSION = -1;
/// <summary>
/// This level won't compress at all but output uncompressed blocks.
/// </summary>
public static int NO_COMPRESSION = 0;
/// <summary>
/// The default strategy.
/// </summary>
public static int DEFAULT_STRATEGY = 0;
/// <summary>
/// This strategy will only allow longer string repetitions. It is
/// useful for random data with a small character set.
/// </summary>
public static int FILTERED = 1;
/// <summary>
/// This strategy will not look for string repetitions at all. It
/// only encodes with Huffman trees (which means, that more common
/// characters get a smaller encoding.
/// </summary>
public static int HUFFMAN_ONLY = 2;
/// <summary>
/// The compression method. This is the only method supported so far.
/// There is no need to use this constant at all.
/// </summary>
public static int DEFLATED = 8;
/*
* 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)
*
*/
private static int IS_SETDICT = 0x01;
private static int IS_FLUSHING = 0x04;
private static int IS_FINISHING = 0x08;
private static int INIT_STATE = 0x00;
private static int SETDICT_STATE = 0x01;
// private static int INIT_FINISHING_STATE = 0x08;
// private static int SETDICT_FINISHING_STATE = 0x09;
private static int BUSY_STATE = 0x10;
private static int FLUSHING_STATE = 0x14;
private static int FINISHING_STATE = 0x1c;
private static int FINISHED_STATE = 0x1e;
private static int CLOSED_STATE = 0x7f;
/// <summary>
/// Compression level.
/// </summary>
private int level;
/// <summary>
/// should we include a header.
/// </summary>
private bool noHeader;
// /// <summary>
// /// Compression strategy.
// /// </summary>
// private int strategy;
/// <summary>
/// The current state.
/// </summary>
private int state;
/// <summary>
/// The total bytes of output written.
/// </summary>
private int totalOut;
/// <summary>
/// The pending output.
/// </summary>
private DeflaterPending pending;
/// <summary>
/// The deflater engine.
/// </summary>
private DeflaterEngine engine;
/// <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="lvl">
/// 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 lvl) : this(lvl, false)
{
}
/// <summary>
/// Creates a new deflater with given compression level.
/// </summary>
/// <param name="lvl">
/// the compression level, a value between NO_COMPRESSION
/// and BEST_COMPRESSION.
/// </param>
/// <param name="nowrap">
/// true, if we should suppress the deflate header at the
/// beginning and the adler checksum at the end of the output. This is
/// useful for the GZIP format.
/// </param>
/// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
public Deflater(int lvl, bool nowrap)
{
if (lvl == DEFAULT_COMPRESSION) {
lvl = 6;
} else if (lvl < NO_COMPRESSION || lvl > BEST_COMPRESSION) {
throw new ArgumentOutOfRangeException("lvl");
}
pending = new DeflaterPending();
engine = new DeflaterEngine(pending);
this.noHeader = nowrap;
SetStrategy(DEFAULT_STRATEGY);
SetLevel(lvl);
Reset();
}
/// <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 = (noHeader ? BUSY_STATE : INIT_STATE);
totalOut = 0;
pending.Reset();
engine.Reset();
}
/// <summary>
/// Gets the current adler checksum of the data that was processed so far.
/// </summary>
public int Adler {
get {
return engine.Adler;
}
}
/// <summary>
/// Gets the number of input bytes processed so far.
/// </summary>
public int TotalIn {
get {
return engine.TotalIn;
}
}
/// <summary>
/// Gets the number of output bytes so far.
/// </summary>
public int 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="off">
/// the start of the data.
/// </param>
/// <param name="len">
/// the length of the data.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if the buffer was finished() or ended() or if previous input is still pending.
/// </exception>
public void SetInput(byte[] input, int off, int len)
{
if ((state & IS_FINISHING) != 0) {
throw new InvalidOperationException("finish()/end() already called");
}
engine.SetInput(input, off, len);
}
/// <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="lvl">
/// the new compression level.
/// </param>
public void SetLevel(int lvl)
{
if (lvl == DEFAULT_COMPRESSION) {
lvl = 6;
} else if (lvl < NO_COMPRESSION || lvl > BEST_COMPRESSION) {
throw new ArgumentOutOfRangeException("lvl");
}
if (level != lvl) {
level = lvl;
engine.SetLevel(lvl);
}
}
/// <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="stgy">
/// the new compression strategy.
/// </param>
public void SetStrategy(int stgy)
{
if (stgy != DEFAULT_STRATEGY && stgy != FILTERED && stgy != HUFFMAN_ONLY) {
throw new Exception();
}
engine.Strategy = stgy;
}
/// <summary>
/// Deflates the current input block to the given array. It returns
/// the number of bytes compressed, or 0 if either
/// needsInput() or finished() returns true or length is zero.
/// </summary>
/// <param name="output">
/// the buffer where to write the compressed data.
/// </param>
public int Deflate(byte[] output)
{
return Deflate(output, 0, output.Length);
}
/// <summary>
/// Deflates the current input block to the given array. It returns
/// the number of bytes compressed, or 0 if either
/// needsInput() or finished() returns true or length is zero.
/// </summary>
/// <param name="output">
/// the buffer where to write the compressed data.
/// </param>
/// <param name="offset">
/// the offset into the output array.
/// </param>
/// <param name="length">
/// the maximum number of bytes that may be written.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if end() was called.
/// </exception>
/// <exception cref="System.ArgumentOutOfRangeException">
/// if offset and/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
* 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);
}
}
}
namespace NZlib.Compression {
/// <summary>
/// This class contains constants used for the deflater.
/// </summary>
public class DeflaterConstants
{
public const bool DEBUGGING = false;
public const int STORED_BLOCK = 0;
public const int STATIC_TREES = 1;
public const int DYN_TREES = 2;
public const int PRESET_DICT = 0x20;
public const int DEFAULT_MEM_LEVEL = 8;
public const int MAX_MATCH = 258;
public const int MIN_MATCH = 3;
public const int MAX_WBITS = 15;
public const int WSIZE = 1 << MAX_WBITS;
public const int WMASK = WSIZE - 1;
public const int HASH_BITS = DEFAULT_MEM_LEVEL + 7;
public const int HASH_SIZE = 1 << HASH_BITS;
public const int HASH_MASK = HASH_SIZE - 1;
public const int HASH_SHIFT = (HASH_BITS + MIN_MATCH - 1) / MIN_MATCH;
public const int MIN_LOOKAHEAD = MAX_MATCH + MIN_MATCH + 1;
public const int MAX_DIST = WSIZE - MIN_LOOKAHEAD;
public const int PENDING_BUF_SIZE = 1 << (DEFAULT_MEM_LEVEL + 8);
public static int MAX_BLOCK_SIZE = Math.Min(65535, PENDING_BUF_SIZE-5);
public const int DEFLATE_STORED = 0;
public const int DEFLATE_FAST = 1;
public const int DEFLATE_SLOW = 2;
public static int[] GOOD_LENGTH = { 0, 4, 4, 4, 4, 8, 8, 8, 32, 32 };
public static int[] MAX_LAZY = { 0, 4, 5, 6, 4,16, 16, 32, 128, 258 };
public static int[] NICE_LENGTH = { 0, 8,16,32,16,32,128,128, 258, 258 };
public static int[] MAX_CHAIN = { 0, 4, 8,32,16,32,128,256,1024,4096 };
public static int[] COMPR_FUNC = { 0, 1, 1, 1, 1, 2, 2, 2, 2, 2 };
}
}
namespace NZlib.Compression {
public class DeflaterEngine : DeflaterConstants
{
private static int TOO_FAR = 4096;
private int ins_h;
// private byte[] buffer;
private short[] head;
private short[] prev;
private int matchStart, matchLen;
private bool prevAvailable;
private int blockStart;
private int strstart, lookahead;
private byte[] window;
private int strategy, max_chain, max_lazy, niceLength, goodLength;
/// <summary>
/// The current compression function.
/// </summary>
private int comprFunc;
/// <summary>
/// The input data for compression.
/// </summary>
private byte[] inputBuf;
/// <summary>
/// The total bytes of input read.
/// </summary>
private int totalIn;
/// <summary>
/// The offset into inputBuf, where input data starts.
/// </summary>
private int inputOff;
/// <summary>
/// The end offset of the input data.
/// </summary>
private int inputEnd;
private DeflaterPending pending;
private DeflaterHuffman huffman;
/// <summary>
/// The adler checksum
/// </summary>
private Adler32 adler;
public DeflaterEngine(DeflaterPending pending)
{
this.pending = pending;
huffman = new DeflaterHuffman(pending);
adler = new Adler32();
window = new byte[2*WSIZE];
head = new short[HASH_SIZE];
prev = new short[WSIZE];
/* We start at index 1, to avoid a implementation deficiency, that
* we cannot build a repeat pattern at index 0.
*/
blockStart = strstart = 1;
}
public void Reset()
{
huffman.Reset();
adler.Reset();
blockStart = strstart = 1;
lookahead = 0;
totalIn = 0;
prevAvailable = false;
matchLen = MIN_MATCH - 1;
for (int i = 0; i < HASH_SIZE; i++) {
head[i] = 0;
}
for (int i = 0; i < WSIZE; i++) {
prev[i] = 0;
}
}
public void ResetAdler()
{
adler.Reset();
}
public int Adler {
get {
return (int)adler.Value;
}
}
public int TotalIn {
get {
return totalIn;
}
}
public int Strategy {
get {
return strategy;
}
set {
strategy = value;
}
}
public void SetLevel(int lvl)
{
goodLength = DeflaterConstants.GOOD_LENGTH[lvl];
max_lazy = DeflaterConstants.MAX_LAZY[lvl];
niceLength = DeflaterConstants.NICE_LENGTH[lvl];
max_chain = DeflaterConstants.MAX_CHAIN[lvl];
if (DeflaterConstants.COMPR_FUNC[lvl] != comprFunc) {
// if (DeflaterConstants.DEBUGGING) {
// Console.WriteLine("Change from "+comprFunc +" to "
// + DeflaterConstants.COMPR_FUNC[lvl]);
// }
switch (comprFunc) {
case DEFLATE_STORED:
if (strstart > blockStart) {
huffman.FlushStoredBlock(window, blockStart,
strstart - blockStart, false);
blockStart = strstart;
}
UpdateHash();
break;
case DEFLATE_FAST:
if (strstart > blockStart) {
huffman.FlushBlock(window, blockStart, strstart - blockStart,
false);
blockStart = strstart;
}
break;
case DEFLATE_SLOW:
if (prevAvailable) {
huffman.TallyLit(window[strstart-1] & 0xff);
}
if (strstart > blockStart) {
huffman.FlushBlock(window, blockStart, strstart - blockStart,
false);
blockStart = strstart;
}
prevAvailable = false;
matchLen = MIN_MATCH - 1;
break;
}
comprFunc = COMPR_FUNC[lvl];
}
}
private void UpdateHash()
{
// if (DEBUGGING) {
// Console.WriteLine("updateHash: "+strstart);
// }
ins_h = (window[strstart] << HASH_SHIFT) ^ window[strstart + 1];
}
private int InsertString()
{
short match;
int hash = ((ins_h << HASH_SHIFT) ^ window[strstart + (MIN_MATCH -1)]) & HASH_MASK;
// if (DEBUGGING) {
// if (hash != (((window[strstart] << (2*HASH_SHIFT)) ^
// (window[strstart + 1] << HASH_SHIFT) ^
// (window[strstart + 2])) & HASH_MASK)) {
// throw new Exception("hash inconsistent: "+hash+"/"
// +window[strstart]+","
// +window[strstart+1]+","
// +window[strstart+2]+","+HASH_SHIFT);
// }
// }
prev[strstart & WMASK] = match = head[hash];
head[hash] = (short)strstart;
ins_h = hash;
return match & 0xffff;
}
public void FillWindow()
{
while (lookahead < DeflaterConstants.MIN_LOOKAHEAD && inputOff < inputEnd) {
int more = 2*WSIZE - lookahead - strstart;
/* If the window is almost full and there is insufficient lookahead,
* move the upper half to the lower one to make room in the upper half.
*/
if (strstart >= WSIZE + MAX_DIST) {
System.Array.Copy(window, WSIZE, window, 0, WSIZE);
matchStart -= WSIZE;
strstart -= WSIZE;
blockStart -= WSIZE;
/* Slide the hash table (could be avoided with 32 bit values
* at the expense of memory usage).
*/
for (int i = 0; i < HASH_SIZE; i++) {
int m = head[i];
head[i] = m >= WSIZE ? (short) (m - WSIZE) : (short)0;
}
more += WSIZE;
}
if (more > inputEnd - inputOff) {
more = inputEnd - inputOff;
}
System.Array.Copy(inputBuf, inputOff, window, strstart + lookahead, more);
adler.Update(inputBuf, inputOff, more);
inputOff += more;
totalIn += more;
lookahead += more;
if (lookahead >= MIN_MATCH) {
UpdateHash();
}
}
}
private bool FindLongestMatch(int curMatch)
{
int chainLength = this.max_chain;
int niceLength = this.niceLength;
short[] prev = this.prev;
int scan = this.strstart;
int match;
int best_end = this.strstart + matchLen;
int best_len = Math.Max(matchLen, MIN_MATCH - 1);
int limit = Math.Max(strstart - MAX_DIST, 0);
int strend = strstart + MAX_MATCH - 1;
byte scan_end1 = window[best_end - 1];
byte scan_end = window[best_end];
/* Do not waste too much time if we already have a good match: */
if (best_len >= this.goodLength) {
chainLength >>= 2;
}
/* Do not look for matches beyond the end of the input. This is necessary
* to make deflate deterministic.
*/
if (niceLength > lookahead) {
niceLength = lookahead;
}
if (DeflaterConstants.DEBUGGING && strstart > 2*WSIZE - MIN_LOOKAHEAD) {
throw new InvalidOperationException("need lookahead");
}
do {
if (DeflaterConstants.DEBUGGING && curMatch >= strstart) {
throw new InvalidOperationException("future match");
}
if (window[curMatch + best_len] != scan_end ||
window[curMatch + best_len - 1] != scan_end1 ||
window[curMatch] != window[scan] ||
window[curMatch+1] != window[scan + 1]) {
continue;
}
match = curMatch + 2;
scan += 2;
/* We check for insufficient lookahead only every 8th comparison;
* the 256th check will be made at strstart+258.
*/
while (window[++scan] == window[++match] &&
window[++scan] == window[++match] &&
window[++scan] == window[++match] &&
window[++scan] == window[++match] &&
window[++scan] == window[++match] &&
window[++scan] == window[++match] &&
window[++scan] == window[++match] &&
window[++scan] == window[++match] && scan < strend) ;