| | | 1 | | using System; |
| | | 2 | | using ICSharpCode.SharpZipLib.Checksum; |
| | | 3 | | |
| | | 4 | | namespace ICSharpCode.SharpZipLib.Zip.Compression |
| | | 5 | | { |
| | | 6 | | /// <summary> |
| | | 7 | | /// Strategies for deflater |
| | | 8 | | /// </summary> |
| | | 9 | | public enum DeflateStrategy |
| | | 10 | | { |
| | | 11 | | /// <summary> |
| | | 12 | | /// The default strategy |
| | | 13 | | /// </summary> |
| | | 14 | | Default = 0, |
| | | 15 | | |
| | | 16 | | /// <summary> |
| | | 17 | | /// This strategy will only allow longer string repetitions. It is |
| | | 18 | | /// useful for random data with a small character set. |
| | | 19 | | /// </summary> |
| | | 20 | | Filtered = 1, |
| | | 21 | | |
| | | 22 | | |
| | | 23 | | /// <summary> |
| | | 24 | | /// This strategy will not look for string repetitions at all. It |
| | | 25 | | /// only encodes with Huffman trees (which means, that more common |
| | | 26 | | /// characters get a smaller encoding. |
| | | 27 | | /// </summary> |
| | | 28 | | HuffmanOnly = 2 |
| | | 29 | | } |
| | | 30 | | |
| | | 31 | | // DEFLATE ALGORITHM: |
| | | 32 | | // |
| | | 33 | | // The uncompressed stream is inserted into the window array. When |
| | | 34 | | // the window array is full the first half is thrown away and the |
| | | 35 | | // second half is copied to the beginning. |
| | | 36 | | // |
| | | 37 | | // The head array is a hash table. Three characters build a hash value |
| | | 38 | | // and they the value points to the corresponding index in window of |
| | | 39 | | // the last string with this hash. The prev array implements a |
| | | 40 | | // linked list of matches with the same hash: prev[index & WMASK] points |
| | | 41 | | // to the previous index with the same hash. |
| | | 42 | | // |
| | | 43 | | |
| | | 44 | | |
| | | 45 | | /// <summary> |
| | | 46 | | /// Low level compression engine for deflate algorithm which uses a 32K sliding window |
| | | 47 | | /// with secondary compression from Huffman/Shannon-Fano codes. |
| | | 48 | | /// </summary> |
| | | 49 | | public class DeflaterEngine |
| | | 50 | | { |
| | | 51 | | #region Constants |
| | | 52 | | const int TooFar = 4096; |
| | | 53 | | #endregion |
| | | 54 | | |
| | | 55 | | #region Constructors |
| | | 56 | | /// <summary> |
| | | 57 | | /// Construct instance with pending buffer |
| | | 58 | | /// </summary> |
| | | 59 | | /// <param name="pending"> |
| | | 60 | | /// Pending buffer to use |
| | | 61 | | /// </param>> |
| | 273 | 62 | | public DeflaterEngine(DeflaterPending pending) |
| | | 63 | | { |
| | 273 | 64 | | this.pending = pending; |
| | 273 | 65 | | huffman = new DeflaterHuffman(pending); |
| | 273 | 66 | | adler = new Adler32(); |
| | | 67 | | |
| | 273 | 68 | | window = new byte[2 * DeflaterConstants.WSIZE]; |
| | 273 | 69 | | head = new short[DeflaterConstants.HASH_SIZE]; |
| | 273 | 70 | | prev = new short[DeflaterConstants.WSIZE]; |
| | | 71 | | |
| | | 72 | | // We start at index 1, to avoid an implementation deficiency, that |
| | | 73 | | // we cannot build a repeat pattern at index 0. |
| | 273 | 74 | | blockStart = strstart = 1; |
| | 273 | 75 | | } |
| | | 76 | | |
| | | 77 | | #endregion |
| | | 78 | | |
| | | 79 | | /// <summary> |
| | | 80 | | /// Deflate drives actual compression of data |
| | | 81 | | /// </summary> |
| | | 82 | | /// <param name="flush">True to flush input buffers</param> |
| | | 83 | | /// <param name="finish">Finish deflation with the current input.</param> |
| | | 84 | | /// <returns>Returns true if progress has been made.</returns> |
| | | 85 | | public bool Deflate(bool flush, bool finish) |
| | | 86 | | { |
| | | 87 | | bool progress; |
| | | 88 | | do { |
| | 9140 | 89 | | FillWindow(); |
| | 9140 | 90 | | bool canFlush = flush && (inputOff == inputEnd); |
| | | 91 | | |
| | | 92 | | #if DebugDeflation |
| | | 93 | | if (DeflaterConstants.DEBUGGING) { |
| | | 94 | | Console.WriteLine("window: [" + blockStart + "," + strstart + "," |
| | | 95 | | + lookahead + "], " + compressionFunction + "," + canFlush); |
| | | 96 | | } |
| | | 97 | | #endif |
| | 9140 | 98 | | switch (compressionFunction) { |
| | | 99 | | case DeflaterConstants.DEFLATE_STORED: |
| | 1373 | 100 | | progress = DeflateStored(canFlush, finish); |
| | 1373 | 101 | | break; |
| | | 102 | | case DeflaterConstants.DEFLATE_FAST: |
| | 3236 | 103 | | progress = DeflateFast(canFlush, finish); |
| | 3236 | 104 | | break; |
| | | 105 | | case DeflaterConstants.DEFLATE_SLOW: |
| | 4531 | 106 | | progress = DeflateSlow(canFlush, finish); |
| | 4531 | 107 | | break; |
| | | 108 | | default: |
| | 0 | 109 | | throw new InvalidOperationException("unknown compressionFunction"); |
| | | 110 | | } |
| | 9140 | 111 | | } while (pending.IsFlushed && progress); // repeat while we have no pending output and progress was made |
| | 4878 | 112 | | return progress; |
| | | 113 | | } |
| | | 114 | | |
| | | 115 | | /// <summary> |
| | | 116 | | /// Sets input data to be deflated. Should only be called when <code>NeedsInput()</code> |
| | | 117 | | /// returns true |
| | | 118 | | /// </summary> |
| | | 119 | | /// <param name="buffer">The buffer containing input data.</param> |
| | | 120 | | /// <param name="offset">The offset of the first byte of data.</param> |
| | | 121 | | /// <param name="count">The number of bytes of data to use as input.</param> |
| | | 122 | | public void SetInput(byte[] buffer, int offset, int count) |
| | | 123 | | { |
| | 4479 | 124 | | if (buffer == null) { |
| | 0 | 125 | | throw new ArgumentNullException(nameof(buffer)); |
| | | 126 | | } |
| | | 127 | | |
| | 4479 | 128 | | if (offset < 0) { |
| | 0 | 129 | | throw new ArgumentOutOfRangeException(nameof(offset)); |
| | | 130 | | } |
| | | 131 | | |
| | 4479 | 132 | | if (count < 0) { |
| | 0 | 133 | | throw new ArgumentOutOfRangeException(nameof(count)); |
| | | 134 | | } |
| | | 135 | | |
| | 4479 | 136 | | if (inputOff < inputEnd) { |
| | 0 | 137 | | throw new InvalidOperationException("Old input was not completely processed"); |
| | | 138 | | } |
| | | 139 | | |
| | 4479 | 140 | | int end = offset + count; |
| | | 141 | | |
| | | 142 | | /* We want to throw an ArrayIndexOutOfBoundsException early. The |
| | | 143 | | * check is very tricky: it also handles integer wrap around. |
| | | 144 | | */ |
| | 4479 | 145 | | if ((offset > end) || (end > buffer.Length)) { |
| | 0 | 146 | | throw new ArgumentOutOfRangeException(nameof(count)); |
| | | 147 | | } |
| | | 148 | | |
| | 4479 | 149 | | inputBuf = buffer; |
| | 4479 | 150 | | inputOff = offset; |
| | 4479 | 151 | | inputEnd = end; |
| | 4479 | 152 | | } |
| | | 153 | | |
| | | 154 | | /// <summary> |
| | | 155 | | /// Determines if more <see cref="SetInput">input</see> is needed. |
| | | 156 | | /// </summary> |
| | | 157 | | /// <returns>Return true if input is needed via <see cref="SetInput">SetInput</see></returns> |
| | | 158 | | public bool NeedsInput() |
| | | 159 | | { |
| | 16258 | 160 | | return (inputEnd == inputOff); |
| | | 161 | | } |
| | | 162 | | |
| | | 163 | | /// <summary> |
| | | 164 | | /// Set compression dictionary |
| | | 165 | | /// </summary> |
| | | 166 | | /// <param name="buffer">The buffer containing the dictionary data</param> |
| | | 167 | | /// <param name="offset">The offset in the buffer for the first byte of data</param> |
| | | 168 | | /// <param name="length">The length of the dictionary data.</param> |
| | | 169 | | public void SetDictionary(byte[] buffer, int offset, int length) |
| | | 170 | | { |
| | | 171 | | #if DebugDeflation |
| | | 172 | | if (DeflaterConstants.DEBUGGING && (strstart != 1) ) |
| | | 173 | | { |
| | | 174 | | throw new InvalidOperationException("strstart not 1"); |
| | | 175 | | } |
| | | 176 | | #endif |
| | 0 | 177 | | adler.Update(buffer, offset, length); |
| | 0 | 178 | | if (length < DeflaterConstants.MIN_MATCH) { |
| | 0 | 179 | | return; |
| | | 180 | | } |
| | | 181 | | |
| | 0 | 182 | | if (length > DeflaterConstants.MAX_DIST) { |
| | 0 | 183 | | offset += length - DeflaterConstants.MAX_DIST; |
| | 0 | 184 | | length = DeflaterConstants.MAX_DIST; |
| | | 185 | | } |
| | | 186 | | |
| | 0 | 187 | | System.Array.Copy(buffer, offset, window, strstart, length); |
| | | 188 | | |
| | 0 | 189 | | UpdateHash(); |
| | 0 | 190 | | --length; |
| | 0 | 191 | | while (--length > 0) { |
| | 0 | 192 | | InsertString(); |
| | 0 | 193 | | strstart++; |
| | | 194 | | } |
| | 0 | 195 | | strstart += 2; |
| | 0 | 196 | | blockStart = strstart; |
| | 0 | 197 | | } |
| | | 198 | | |
| | | 199 | | /// <summary> |
| | | 200 | | /// Reset internal state |
| | | 201 | | /// </summary> |
| | | 202 | | public void Reset() |
| | | 203 | | { |
| | 392 | 204 | | huffman.Reset(); |
| | 392 | 205 | | adler.Reset(); |
| | 392 | 206 | | blockStart = strstart = 1; |
| | 392 | 207 | | lookahead = 0; |
| | 392 | 208 | | totalIn = 0; |
| | 392 | 209 | | prevAvailable = false; |
| | 392 | 210 | | matchLen = DeflaterConstants.MIN_MATCH - 1; |
| | | 211 | | |
| | 25690896 | 212 | | for (int i = 0; i < DeflaterConstants.HASH_SIZE; i++) { |
| | 12845056 | 213 | | head[i] = 0; |
| | | 214 | | } |
| | | 215 | | |
| | 25690896 | 216 | | for (int i = 0; i < DeflaterConstants.WSIZE; i++) { |
| | 12845056 | 217 | | prev[i] = 0; |
| | | 218 | | } |
| | 392 | 219 | | } |
| | | 220 | | |
| | | 221 | | /// <summary> |
| | | 222 | | /// Reset Adler checksum |
| | | 223 | | /// </summary> |
| | | 224 | | public void ResetAdler() |
| | | 225 | | { |
| | 0 | 226 | | adler.Reset(); |
| | 0 | 227 | | } |
| | | 228 | | |
| | | 229 | | /// <summary> |
| | | 230 | | /// Get current value of Adler checksum |
| | | 231 | | /// </summary> |
| | | 232 | | public int Adler { |
| | | 233 | | get { |
| | 14 | 234 | | return unchecked((int)adler.Value); |
| | | 235 | | } |
| | | 236 | | } |
| | | 237 | | |
| | | 238 | | /// <summary> |
| | | 239 | | /// Total data processed |
| | | 240 | | /// </summary> |
| | | 241 | | public long TotalIn { |
| | | 242 | | get { |
| | 9 | 243 | | return totalIn; |
| | | 244 | | } |
| | | 245 | | } |
| | | 246 | | |
| | | 247 | | /// <summary> |
| | | 248 | | /// Get/set the <see cref="DeflateStrategy">deflate strategy</see> |
| | | 249 | | /// </summary> |
| | | 250 | | public DeflateStrategy Strategy { |
| | | 251 | | get { |
| | 0 | 252 | | return strategy; |
| | | 253 | | } |
| | | 254 | | set { |
| | 273 | 255 | | strategy = value; |
| | 273 | 256 | | } |
| | | 257 | | } |
| | | 258 | | |
| | | 259 | | /// <summary> |
| | | 260 | | /// Set the deflate level (0-9) |
| | | 261 | | /// </summary> |
| | | 262 | | /// <param name="level">The value to set the level to.</param> |
| | | 263 | | public void SetLevel(int level) |
| | | 264 | | { |
| | 327 | 265 | | if ((level < 0) || (level > 9)) { |
| | 0 | 266 | | throw new ArgumentOutOfRangeException(nameof(level)); |
| | | 267 | | } |
| | | 268 | | |
| | 327 | 269 | | goodLength = DeflaterConstants.GOOD_LENGTH[level]; |
| | 327 | 270 | | max_lazy = DeflaterConstants.MAX_LAZY[level]; |
| | 327 | 271 | | niceLength = DeflaterConstants.NICE_LENGTH[level]; |
| | 327 | 272 | | max_chain = DeflaterConstants.MAX_CHAIN[level]; |
| | | 273 | | |
| | 327 | 274 | | if (DeflaterConstants.COMPR_FUNC[level] != compressionFunction) { |
| | | 275 | | |
| | | 276 | | #if DebugDeflation |
| | | 277 | | if (DeflaterConstants.DEBUGGING) { |
| | | 278 | | Console.WriteLine("Change from " + compressionFunction + " to " |
| | | 279 | | + DeflaterConstants.COMPR_FUNC[level]); |
| | | 280 | | } |
| | | 281 | | #endif |
| | 309 | 282 | | switch (compressionFunction) { |
| | | 283 | | case DeflaterConstants.DEFLATE_STORED: |
| | 272 | 284 | | if (strstart > blockStart) { |
| | 0 | 285 | | huffman.FlushStoredBlock(window, blockStart, |
| | 0 | 286 | | strstart - blockStart, false); |
| | 0 | 287 | | blockStart = strstart; |
| | | 288 | | } |
| | 272 | 289 | | UpdateHash(); |
| | 272 | 290 | | break; |
| | | 291 | | |
| | | 292 | | case DeflaterConstants.DEFLATE_FAST: |
| | 6 | 293 | | if (strstart > blockStart) { |
| | 0 | 294 | | huffman.FlushBlock(window, blockStart, strstart - blockStart, |
| | 0 | 295 | | false); |
| | 0 | 296 | | blockStart = strstart; |
| | | 297 | | } |
| | 0 | 298 | | break; |
| | | 299 | | |
| | | 300 | | case DeflaterConstants.DEFLATE_SLOW: |
| | 31 | 301 | | if (prevAvailable) { |
| | 0 | 302 | | huffman.TallyLit(window[strstart - 1] & 0xff); |
| | | 303 | | } |
| | 31 | 304 | | if (strstart > blockStart) { |
| | 0 | 305 | | huffman.FlushBlock(window, blockStart, strstart - blockStart, false); |
| | 0 | 306 | | blockStart = strstart; |
| | | 307 | | } |
| | 31 | 308 | | prevAvailable = false; |
| | 31 | 309 | | matchLen = DeflaterConstants.MIN_MATCH - 1; |
| | | 310 | | break; |
| | | 311 | | } |
| | 309 | 312 | | compressionFunction = DeflaterConstants.COMPR_FUNC[level]; |
| | | 313 | | } |
| | 327 | 314 | | } |
| | | 315 | | |
| | | 316 | | /// <summary> |
| | | 317 | | /// Fill the window |
| | | 318 | | /// </summary> |
| | | 319 | | public void FillWindow() |
| | | 320 | | { |
| | | 321 | | /* If the window is almost full and there is insufficient lookahead, |
| | | 322 | | * move the upper half to the lower one to make room in the upper half. |
| | | 323 | | */ |
| | 9140 | 324 | | if (strstart >= DeflaterConstants.WSIZE + DeflaterConstants.MAX_DIST) { |
| | 20 | 325 | | SlideWindow(); |
| | | 326 | | } |
| | | 327 | | |
| | | 328 | | /* If there is not enough lookahead, but still some input left, |
| | | 329 | | * read in the input |
| | | 330 | | */ |
| | 13659 | 331 | | while (lookahead < DeflaterConstants.MIN_LOOKAHEAD && inputOff < inputEnd) { |
| | 4519 | 332 | | int more = 2 * DeflaterConstants.WSIZE - lookahead - strstart; |
| | | 333 | | |
| | 4519 | 334 | | if (more > inputEnd - inputOff) { |
| | 4479 | 335 | | more = inputEnd - inputOff; |
| | | 336 | | } |
| | | 337 | | |
| | 4519 | 338 | | System.Array.Copy(inputBuf, inputOff, window, strstart + lookahead, more); |
| | 4519 | 339 | | adler.Update(inputBuf, inputOff, more); |
| | | 340 | | |
| | 4519 | 341 | | inputOff += more; |
| | 4519 | 342 | | totalIn += more; |
| | 4519 | 343 | | lookahead += more; |
| | | 344 | | } |
| | | 345 | | |
| | 9140 | 346 | | if (lookahead >= DeflaterConstants.MIN_MATCH) { |
| | 8381 | 347 | | UpdateHash(); |
| | | 348 | | } |
| | 9140 | 349 | | } |
| | | 350 | | |
| | | 351 | | void UpdateHash() |
| | | 352 | | { |
| | | 353 | | /* |
| | | 354 | | if (DEBUGGING) { |
| | | 355 | | Console.WriteLine("updateHash: "+strstart); |
| | | 356 | | } |
| | | 357 | | */ |
| | 8653 | 358 | | ins_h = (window[strstart] << DeflaterConstants.HASH_SHIFT) ^ window[strstart + 1]; |
| | 8653 | 359 | | } |
| | | 360 | | |
| | | 361 | | /// <summary> |
| | | 362 | | /// Inserts the current string in the head hash and returns the previous |
| | | 363 | | /// value for this hash. |
| | | 364 | | /// </summary> |
| | | 365 | | /// <returns>The previous hash value</returns> |
| | | 366 | | int InsertString() |
| | | 367 | | { |
| | | 368 | | short match; |
| | 3625693 | 369 | | int hash = ((ins_h << DeflaterConstants.HASH_SHIFT) ^ window[strstart + (DeflaterConstants.MIN_MATCH - 1)]) & Defl |
| | | 370 | | |
| | | 371 | | #if DebugDeflation |
| | | 372 | | if (DeflaterConstants.DEBUGGING) |
| | | 373 | | { |
| | | 374 | | if (hash != (((window[strstart] << (2*HASH_SHIFT)) ^ |
| | | 375 | | (window[strstart + 1] << HASH_SHIFT) ^ |
| | | 376 | | (window[strstart + 2])) & HASH_MASK)) { |
| | | 377 | | throw new SharpZipBaseException("hash inconsistent: " + hash + "/" |
| | | 378 | | +window[strstart] + "," |
| | | 379 | | +window[strstart + 1] + "," |
| | | 380 | | +window[strstart + 2] + "," + HASH_SHIFT); |
| | | 381 | | } |
| | | 382 | | } |
| | | 383 | | #endif |
| | 3625693 | 384 | | prev[strstart & DeflaterConstants.WMASK] = match = head[hash]; |
| | 3625693 | 385 | | head[hash] = unchecked((short)strstart); |
| | 3625693 | 386 | | ins_h = hash; |
| | 3625693 | 387 | | return match & 0xffff; |
| | | 388 | | } |
| | | 389 | | |
| | | 390 | | void SlideWindow() |
| | | 391 | | { |
| | 40 | 392 | | Array.Copy(window, DeflaterConstants.WSIZE, window, 0, DeflaterConstants.WSIZE); |
| | 40 | 393 | | matchStart -= DeflaterConstants.WSIZE; |
| | 40 | 394 | | strstart -= DeflaterConstants.WSIZE; |
| | 40 | 395 | | blockStart -= DeflaterConstants.WSIZE; |
| | | 396 | | |
| | | 397 | | // Slide the hash table (could be avoided with 32 bit values |
| | | 398 | | // at the expense of memory usage). |
| | 2621520 | 399 | | for (int i = 0; i < DeflaterConstants.HASH_SIZE; ++i) { |
| | 1310720 | 400 | | int m = head[i] & 0xffff; |
| | 1310720 | 401 | | head[i] = (short)(m >= DeflaterConstants.WSIZE ? (m - DeflaterConstants.WSIZE) : 0); |
| | | 402 | | } |
| | | 403 | | |
| | | 404 | | // Slide the prev table. |
| | 2621520 | 405 | | for (int i = 0; i < DeflaterConstants.WSIZE; i++) { |
| | 1310720 | 406 | | int m = prev[i] & 0xffff; |
| | 1310720 | 407 | | prev[i] = (short)(m >= DeflaterConstants.WSIZE ? (m - DeflaterConstants.WSIZE) : 0); |
| | | 408 | | } |
| | 40 | 409 | | } |
| | | 410 | | |
| | | 411 | | /// <summary> |
| | | 412 | | /// Find the best (longest) string in the window matching the |
| | | 413 | | /// string starting at strstart. |
| | | 414 | | /// |
| | | 415 | | /// Preconditions: |
| | | 416 | | /// <code> |
| | | 417 | | /// strstart + DeflaterConstants.MAX_MATCH <= window.length.</code> |
| | | 418 | | /// </summary> |
| | | 419 | | /// <param name="curMatch"></param> |
| | | 420 | | /// <returns>True if a match greater than the minimum length is found</returns> |
| | | 421 | | bool FindLongestMatch(int curMatch) |
| | | 422 | | { |
| | 1801927 | 423 | | int chainLength = this.max_chain; |
| | 1801927 | 424 | | int niceLength = this.niceLength; |
| | 1801927 | 425 | | short[] prev = this.prev; |
| | 1801927 | 426 | | int scan = this.strstart; |
| | | 427 | | int match; |
| | 1801927 | 428 | | int best_end = this.strstart + matchLen; |
| | 1801927 | 429 | | int best_len = Math.Max(matchLen, DeflaterConstants.MIN_MATCH - 1); |
| | | 430 | | |
| | 1801927 | 431 | | int limit = Math.Max(strstart - DeflaterConstants.MAX_DIST, 0); |
| | | 432 | | |
| | 1801927 | 433 | | int strend = strstart + DeflaterConstants.MAX_MATCH - 1; |
| | 1801927 | 434 | | byte scan_end1 = window[best_end - 1]; |
| | 1801927 | 435 | | byte scan_end = window[best_end]; |
| | | 436 | | |
| | | 437 | | // Do not waste too much time if we already have a good match: |
| | 1801927 | 438 | | if (best_len >= this.goodLength) { |
| | 66 | 439 | | chainLength >>= 2; |
| | | 440 | | } |
| | | 441 | | |
| | | 442 | | /* Do not look for matches beyond the end of the input. This is necessary |
| | | 443 | | * to make deflate deterministic. |
| | | 444 | | */ |
| | 1801927 | 445 | | if (niceLength > lookahead) { |
| | 3257 | 446 | | niceLength = lookahead; |
| | | 447 | | } |
| | | 448 | | |
| | | 449 | | #if DebugDeflation |
| | | 450 | | |
| | | 451 | | if (DeflaterConstants.DEBUGGING && (strstart > 2 * DeflaterConstants.WSIZE - DeflaterConstants.MIN_LOOKAHEAD)) |
| | | 452 | | { |
| | | 453 | | throw new InvalidOperationException("need lookahead"); |
| | | 454 | | } |
| | | 455 | | #endif |
| | | 456 | | |
| | | 457 | | do { |
| | | 458 | | |
| | | 459 | | #if DebugDeflation |
| | | 460 | | |
| | | 461 | | if (DeflaterConstants.DEBUGGING && (curMatch >= strstart) ) |
| | | 462 | | { |
| | | 463 | | throw new InvalidOperationException("no future"); |
| | | 464 | | } |
| | | 465 | | #endif |
| | 2700341 | 466 | | if (window[curMatch + best_len] != scan_end || |
| | 2700341 | 467 | | window[curMatch + best_len - 1] != scan_end1 || |
| | 2700341 | 468 | | window[curMatch] != window[scan] || |
| | 2700341 | 469 | | window[curMatch + 1] != window[scan + 1]) { |
| | | 470 | | continue; |
| | | 471 | | } |
| | | 472 | | |
| | 5274 | 473 | | match = curMatch + 2; |
| | 5274 | 474 | | scan += 2; |
| | | 475 | | |
| | | 476 | | /* We check for insufficient lookahead only every 8th comparison; |
| | | 477 | | * the 256th check will be made at strstart + 258. |
| | | 478 | | */ |
| | 9174 | 479 | | while ( |
| | 9174 | 480 | | window[++scan] == window[++match] && |
| | 9174 | 481 | | window[++scan] == window[++match] && |
| | 9174 | 482 | | window[++scan] == window[++match] && |
| | 9174 | 483 | | window[++scan] == window[++match] && |
| | 9174 | 484 | | window[++scan] == window[++match] && |
| | 9174 | 485 | | window[++scan] == window[++match] && |
| | 9174 | 486 | | window[++scan] == window[++match] && |
| | 9174 | 487 | | window[++scan] == window[++match] && |
| | 9174 | 488 | | (scan < strend)) { |
| | | 489 | | // Do nothing |
| | | 490 | | } |
| | | 491 | | |
| | 5274 | 492 | | if (scan > best_end) { |
| | | 493 | | #if DebugDeflation |
| | | 494 | | if (DeflaterConstants.DEBUGGING && (ins_h == 0) ) |
| | | 495 | | Console.Error.WriteLine("Found match: " + curMatch + "-" + (scan - strstart)); |
| | | 496 | | #endif |
| | 5212 | 497 | | matchStart = curMatch; |
| | 5212 | 498 | | best_end = scan; |
| | 5212 | 499 | | best_len = scan - strstart; |
| | | 500 | | |
| | 5212 | 501 | | if (best_len >= niceLength) { |
| | | 502 | | break; |
| | | 503 | | } |
| | | 504 | | |
| | 5136 | 505 | | scan_end1 = window[best_end - 1]; |
| | 5136 | 506 | | scan_end = window[best_end]; |
| | | 507 | | } |
| | 5198 | 508 | | scan = strstart; |
| | 2700265 | 509 | | } while ((curMatch = (prev[curMatch & DeflaterConstants.WMASK] & 0xffff)) > limit && --chainLength != 0); |
| | | 510 | | |
| | 1801927 | 511 | | matchLen = Math.Min(best_len, lookahead); |
| | 1801927 | 512 | | return matchLen >= DeflaterConstants.MIN_MATCH; |
| | | 513 | | } |
| | | 514 | | |
| | | 515 | | bool DeflateStored(bool flush, bool finish) |
| | | 516 | | { |
| | 1373 | 517 | | if (!flush && (lookahead == 0)) { |
| | 676 | 518 | | return false; |
| | | 519 | | } |
| | | 520 | | |
| | 697 | 521 | | strstart += lookahead; |
| | 697 | 522 | | lookahead = 0; |
| | | 523 | | |
| | 697 | 524 | | int storedLength = strstart - blockStart; |
| | | 525 | | |
| | 697 | 526 | | if ((storedLength >= DeflaterConstants.MAX_BLOCK_SIZE) || // Block is full |
| | 697 | 527 | | (blockStart < DeflaterConstants.WSIZE && storedLength >= DeflaterConstants.MAX_DIST) || // Block may move out |
| | 697 | 528 | | flush) { |
| | 21 | 529 | | bool lastBlock = finish; |
| | 21 | 530 | | if (storedLength > DeflaterConstants.MAX_BLOCK_SIZE) { |
| | 2 | 531 | | storedLength = DeflaterConstants.MAX_BLOCK_SIZE; |
| | 2 | 532 | | lastBlock = false; |
| | | 533 | | } |
| | | 534 | | |
| | | 535 | | #if DebugDeflation |
| | | 536 | | if (DeflaterConstants.DEBUGGING) |
| | | 537 | | { |
| | | 538 | | Console.WriteLine("storedBlock[" + storedLength + "," + lastBlock + "]"); |
| | | 539 | | } |
| | | 540 | | #endif |
| | | 541 | | |
| | 21 | 542 | | huffman.FlushStoredBlock(window, blockStart, storedLength, lastBlock); |
| | 21 | 543 | | blockStart += storedLength; |
| | 21 | 544 | | return !lastBlock; |
| | | 545 | | } |
| | 676 | 546 | | return true; |
| | | 547 | | } |
| | | 548 | | |
| | | 549 | | bool DeflateFast(bool flush, bool finish) |
| | | 550 | | { |
| | 3236 | 551 | | if (lookahead < DeflaterConstants.MIN_LOOKAHEAD && !flush) { |
| | 1526 | 552 | | return false; |
| | | 553 | | } |
| | | 554 | | |
| | 1597843 | 555 | | while (lookahead >= DeflaterConstants.MIN_LOOKAHEAD || flush) { |
| | 1596259 | 556 | | if (lookahead == 0) { |
| | | 557 | | // We are flushing everything |
| | 30 | 558 | | huffman.FlushBlock(window, blockStart, strstart - blockStart, finish); |
| | 30 | 559 | | blockStart = strstart; |
| | 30 | 560 | | return false; |
| | | 561 | | } |
| | | 562 | | |
| | 1596229 | 563 | | if (strstart > 2 * DeflaterConstants.WSIZE - DeflaterConstants.MIN_LOOKAHEAD) { |
| | | 564 | | /* slide window, as FindLongestMatch needs this. |
| | | 565 | | * This should only happen when flushing and the window |
| | | 566 | | * is almost full. |
| | | 567 | | */ |
| | 0 | 568 | | SlideWindow(); |
| | | 569 | | } |
| | | 570 | | |
| | | 571 | | int hashHead; |
| | 1596229 | 572 | | if (lookahead >= DeflaterConstants.MIN_MATCH && |
| | 1596229 | 573 | | (hashHead = InsertString()) != 0 && |
| | 1596229 | 574 | | strategy != DeflateStrategy.HuffmanOnly && |
| | 1596229 | 575 | | strstart - hashHead <= DeflaterConstants.MAX_DIST && |
| | 1596229 | 576 | | FindLongestMatch(hashHead)) { |
| | | 577 | | // longestMatch sets matchStart and matchLen |
| | | 578 | | #if DebugDeflation |
| | | 579 | | if (DeflaterConstants.DEBUGGING) |
| | | 580 | | { |
| | | 581 | | for (int i = 0 ; i < matchLen; i++) { |
| | | 582 | | if (window[strstart + i] != window[matchStart + i]) { |
| | | 583 | | throw new SharpZipBaseException("Match failure"); |
| | | 584 | | } |
| | | 585 | | } |
| | | 586 | | } |
| | | 587 | | #endif |
| | | 588 | | |
| | 2203 | 589 | | bool full = huffman.TallyDist(strstart - matchStart, matchLen); |
| | | 590 | | |
| | 2203 | 591 | | lookahead -= matchLen; |
| | 2203 | 592 | | if (matchLen <= max_lazy && lookahead >= DeflaterConstants.MIN_MATCH) { |
| | 6608 | 593 | | while (--matchLen > 0) { |
| | 4408 | 594 | | ++strstart; |
| | 4408 | 595 | | InsertString(); |
| | | 596 | | } |
| | 2200 | 597 | | ++strstart; |
| | 2200 | 598 | | } else { |
| | 3 | 599 | | strstart += matchLen; |
| | 3 | 600 | | if (lookahead >= DeflaterConstants.MIN_MATCH - 1) { |
| | 0 | 601 | | UpdateHash(); |
| | | 602 | | } |
| | | 603 | | } |
| | 2203 | 604 | | matchLen = DeflaterConstants.MIN_MATCH - 1; |
| | 2203 | 605 | | if (!full) { |
| | 2203 | 606 | | continue; |
| | | 607 | | } |
| | | 608 | | } else { |
| | | 609 | | // No match found |
| | 1594026 | 610 | | huffman.TallyLit(window[strstart] & 0xff); |
| | 1594026 | 611 | | ++strstart; |
| | 1594026 | 612 | | --lookahead; |
| | | 613 | | } |
| | | 614 | | |
| | 1594026 | 615 | | if (huffman.IsFull()) { |
| | 96 | 616 | | bool lastBlock = finish && (lookahead == 0); |
| | 96 | 617 | | huffman.FlushBlock(window, blockStart, strstart - blockStart, lastBlock); |
| | 96 | 618 | | blockStart = strstart; |
| | 96 | 619 | | return !lastBlock; |
| | | 620 | | } |
| | | 621 | | } |
| | 1584 | 622 | | return true; |
| | | 623 | | } |
| | | 624 | | |
| | | 625 | | bool DeflateSlow(bool flush, bool finish) |
| | | 626 | | { |
| | 4531 | 627 | | if (lookahead < DeflaterConstants.MIN_LOOKAHEAD && !flush) { |
| | 2145 | 628 | | return false; |
| | | 629 | | } |
| | | 630 | | |
| | 2011632 | 631 | | while (lookahead >= DeflaterConstants.MIN_LOOKAHEAD || flush) { |
| | 2009630 | 632 | | if (lookahead == 0) { |
| | 264 | 633 | | if (prevAvailable) { |
| | 205 | 634 | | huffman.TallyLit(window[strstart - 1] & 0xff); |
| | | 635 | | } |
| | 264 | 636 | | prevAvailable = false; |
| | | 637 | | |
| | | 638 | | // We are flushing everything |
| | | 639 | | #if DebugDeflation |
| | | 640 | | if (DeflaterConstants.DEBUGGING && !flush) |
| | | 641 | | { |
| | | 642 | | throw new SharpZipBaseException("Not flushing, but no lookahead"); |
| | | 643 | | } |
| | | 644 | | #endif |
| | 264 | 645 | | huffman.FlushBlock(window, blockStart, strstart - blockStart, |
| | 264 | 646 | | finish); |
| | 264 | 647 | | blockStart = strstart; |
| | 264 | 648 | | return false; |
| | | 649 | | } |
| | | 650 | | |
| | 2009366 | 651 | | if (strstart >= 2 * DeflaterConstants.WSIZE - DeflaterConstants.MIN_LOOKAHEAD) { |
| | | 652 | | /* slide window, as FindLongestMatch needs this. |
| | | 653 | | * This should only happen when flushing and the window |
| | | 654 | | * is almost full. |
| | | 655 | | */ |
| | 20 | 656 | | SlideWindow(); |
| | | 657 | | } |
| | | 658 | | |
| | 2009366 | 659 | | int prevMatch = matchStart; |
| | 2009366 | 660 | | int prevLen = matchLen; |
| | 2009366 | 661 | | if (lookahead >= DeflaterConstants.MIN_MATCH) { |
| | | 662 | | |
| | 2008972 | 663 | | int hashHead = InsertString(); |
| | | 664 | | |
| | 2008972 | 665 | | if (strategy != DeflateStrategy.HuffmanOnly && |
| | 2008972 | 666 | | hashHead != 0 && |
| | 2008972 | 667 | | strstart - hashHead <= DeflaterConstants.MAX_DIST && |
| | 2008972 | 668 | | FindLongestMatch(hashHead)) { |
| | | 669 | | |
| | | 670 | | // longestMatch sets matchStart and matchLen |
| | | 671 | | |
| | | 672 | | // Discard match if too small and too far away |
| | 3376 | 673 | | if (matchLen <= 5 && (strategy == DeflateStrategy.Filtered || (matchLen == DeflaterConstants.MIN_MATCH && st |
| | 2383 | 674 | | matchLen = DeflaterConstants.MIN_MATCH - 1; |
| | | 675 | | } |
| | | 676 | | } |
| | | 677 | | } |
| | | 678 | | |
| | | 679 | | // previous match was better |
| | 2009366 | 680 | | if ((prevLen >= DeflaterConstants.MIN_MATCH) && (matchLen <= prevLen)) { |
| | | 681 | | #if DebugDeflation |
| | | 682 | | if (DeflaterConstants.DEBUGGING) |
| | | 683 | | { |
| | | 684 | | for (int i = 0 ; i < matchLen; i++) { |
| | | 685 | | if (window[strstart-1+i] != window[prevMatch + i]) |
| | | 686 | | throw new SharpZipBaseException(); |
| | | 687 | | } |
| | | 688 | | } |
| | | 689 | | #endif |
| | 625 | 690 | | huffman.TallyDist(strstart - 1 - prevMatch, prevLen); |
| | 625 | 691 | | prevLen -= 2; |
| | | 692 | | do { |
| | 16197 | 693 | | strstart++; |
| | 16197 | 694 | | lookahead--; |
| | 16197 | 695 | | if (lookahead >= DeflaterConstants.MIN_MATCH) { |
| | 16135 | 696 | | InsertString(); |
| | | 697 | | } |
| | 16197 | 698 | | } while (--prevLen > 0); |
| | | 699 | | |
| | 625 | 700 | | strstart++; |
| | 625 | 701 | | lookahead--; |
| | 625 | 702 | | prevAvailable = false; |
| | 625 | 703 | | matchLen = DeflaterConstants.MIN_MATCH - 1; |
| | 625 | 704 | | } else { |
| | 2008741 | 705 | | if (prevAvailable) { |
| | 2007911 | 706 | | huffman.TallyLit(window[strstart - 1] & 0xff); |
| | | 707 | | } |
| | 2008741 | 708 | | prevAvailable = true; |
| | 2008741 | 709 | | strstart++; |
| | 2008741 | 710 | | lookahead--; |
| | | 711 | | } |
| | | 712 | | |
| | 2009366 | 713 | | if (huffman.IsFull()) { |
| | 120 | 714 | | int len = strstart - blockStart; |
| | 120 | 715 | | if (prevAvailable) { |
| | 120 | 716 | | len--; |
| | | 717 | | } |
| | 120 | 718 | | bool lastBlock = (finish && (lookahead == 0) && !prevAvailable); |
| | 120 | 719 | | huffman.FlushBlock(window, blockStart, len, lastBlock); |
| | 120 | 720 | | blockStart += len; |
| | 120 | 721 | | return !lastBlock; |
| | | 722 | | } |
| | | 723 | | } |
| | 2002 | 724 | | return true; |
| | | 725 | | } |
| | | 726 | | |
| | | 727 | | #region Instance Fields |
| | | 728 | | |
| | | 729 | | // Hash index of string to be inserted |
| | | 730 | | int ins_h; |
| | | 731 | | |
| | | 732 | | /// <summary> |
| | | 733 | | /// Hashtable, hashing three characters to an index for window, so |
| | | 734 | | /// that window[index]..window[index+2] have this hash code. |
| | | 735 | | /// Note that the array should really be unsigned short, so you need |
| | | 736 | | /// to and the values with 0xffff. |
| | | 737 | | /// </summary> |
| | | 738 | | short[] head; |
| | | 739 | | |
| | | 740 | | /// <summary> |
| | | 741 | | /// <code>prev[index & WMASK]</code> points to the previous index that has the |
| | | 742 | | /// same hash code as the string starting at index. This way |
| | | 743 | | /// entries with the same hash code are in a linked list. |
| | | 744 | | /// Note that the array should really be unsigned short, so you need |
| | | 745 | | /// to and the values with 0xffff. |
| | | 746 | | /// </summary> |
| | | 747 | | short[] prev; |
| | | 748 | | |
| | | 749 | | int matchStart; |
| | | 750 | | // Length of best match |
| | | 751 | | int matchLen; |
| | | 752 | | // Set if previous match exists |
| | | 753 | | bool prevAvailable; |
| | | 754 | | int blockStart; |
| | | 755 | | |
| | | 756 | | /// <summary> |
| | | 757 | | /// Points to the current character in the window. |
| | | 758 | | /// </summary> |
| | | 759 | | int strstart; |
| | | 760 | | |
| | | 761 | | /// <summary> |
| | | 762 | | /// lookahead is the number of characters starting at strstart in |
| | | 763 | | /// window that are valid. |
| | | 764 | | /// So window[strstart] until window[strstart+lookahead-1] are valid |
| | | 765 | | /// characters. |
| | | 766 | | /// </summary> |
| | | 767 | | int lookahead; |
| | | 768 | | |
| | | 769 | | /// <summary> |
| | | 770 | | /// This array contains the part of the uncompressed stream that |
| | | 771 | | /// is of relevance. The current character is indexed by strstart. |
| | | 772 | | /// </summary> |
| | | 773 | | byte[] window; |
| | | 774 | | |
| | | 775 | | DeflateStrategy strategy; |
| | | 776 | | int max_chain, max_lazy, niceLength, goodLength; |
| | | 777 | | |
| | | 778 | | /// <summary> |
| | | 779 | | /// The current compression function. |
| | | 780 | | /// </summary> |
| | | 781 | | int compressionFunction; |
| | | 782 | | |
| | | 783 | | /// <summary> |
| | | 784 | | /// The input data for compression. |
| | | 785 | | /// </summary> |
| | | 786 | | byte[] inputBuf; |
| | | 787 | | |
| | | 788 | | /// <summary> |
| | | 789 | | /// The total bytes of input read. |
| | | 790 | | /// </summary> |
| | | 791 | | long totalIn; |
| | | 792 | | |
| | | 793 | | /// <summary> |
| | | 794 | | /// The offset into inputBuf, where input data starts. |
| | | 795 | | /// </summary> |
| | | 796 | | int inputOff; |
| | | 797 | | |
| | | 798 | | /// <summary> |
| | | 799 | | /// The end offset of the input data. |
| | | 800 | | /// </summary> |
| | | 801 | | int inputEnd; |
| | | 802 | | |
| | | 803 | | DeflaterPending pending; |
| | | 804 | | DeflaterHuffman huffman; |
| | | 805 | | |
| | | 806 | | /// <summary> |
| | | 807 | | /// The adler checksum |
| | | 808 | | /// </summary> |
| | | 809 | | Adler32 adler; |
| | | 810 | | #endregion |
| | | 811 | | } |
| | | 812 | | } |