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/src/FreeImage/Source/ZLib/deflate.c

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   1/* deflate.c -- compress data using the deflation algorithm
   2 * Copyright (C) 1995-2012 Jean-loup Gailly and Mark Adler
   3 * For conditions of distribution and use, see copyright notice in zlib.h
   4 */
   5
   6/*
   7 *  ALGORITHM
   8 *
   9 *      The "deflation" process depends on being able to identify portions
  10 *      of the input text which are identical to earlier input (within a
  11 *      sliding window trailing behind the input currently being processed).
  12 *
  13 *      The most straightforward technique turns out to be the fastest for
  14 *      most input files: try all possible matches and select the longest.
  15 *      The key feature of this algorithm is that insertions into the string
  16 *      dictionary are very simple and thus fast, and deletions are avoided
  17 *      completely. Insertions are performed at each input character, whereas
  18 *      string matches are performed only when the previous match ends. So it
  19 *      is preferable to spend more time in matches to allow very fast string
  20 *      insertions and avoid deletions. The matching algorithm for small
  21 *      strings is inspired from that of Rabin & Karp. A brute force approach
  22 *      is used to find longer strings when a small match has been found.
  23 *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
  24 *      (by Leonid Broukhis).
  25 *         A previous version of this file used a more sophisticated algorithm
  26 *      (by Fiala and Greene) which is guaranteed to run in linear amortized
  27 *      time, but has a larger average cost, uses more memory and is patented.
  28 *      However the F&G algorithm may be faster for some highly redundant
  29 *      files if the parameter max_chain_length (described below) is too large.
  30 *
  31 *  ACKNOWLEDGEMENTS
  32 *
  33 *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
  34 *      I found it in 'freeze' written by Leonid Broukhis.
  35 *      Thanks to many people for bug reports and testing.
  36 *
  37 *  REFERENCES
  38 *
  39 *      Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
  40 *      Available in http://tools.ietf.org/html/rfc1951
  41 *
  42 *      A description of the Rabin and Karp algorithm is given in the book
  43 *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
  44 *
  45 *      Fiala,E.R., and Greene,D.H.
  46 *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
  47 *
  48 */
  49
  50/* @(#) $Id: deflate.c,v 1.8 2012/02/05 18:10:25 drolon Exp $ */
  51
  52#include "deflate.h"
  53
  54const char deflate_copyright[] =
  55   " deflate 1.2.6 Copyright 1995-2012 Jean-loup Gailly and Mark Adler ";
  56/*
  57  If you use the zlib library in a product, an acknowledgment is welcome
  58  in the documentation of your product. If for some reason you cannot
  59  include such an acknowledgment, I would appreciate that you keep this
  60  copyright string in the executable of your product.
  61 */
  62
  63/* ===========================================================================
  64 *  Function prototypes.
  65 */
  66typedef enum {
  67    need_more,      /* block not completed, need more input or more output */
  68    block_done,     /* block flush performed */
  69    finish_started, /* finish started, need only more output at next deflate */
  70    finish_done     /* finish done, accept no more input or output */
  71} block_state;
  72
  73typedef block_state (*compress_func) OF((deflate_state *s, int flush));
  74/* Compression function. Returns the block state after the call. */
  75
  76local void fill_window    OF((deflate_state *s));
  77local block_state deflate_stored OF((deflate_state *s, int flush));
  78local block_state deflate_fast   OF((deflate_state *s, int flush));
  79#ifndef FASTEST
  80local block_state deflate_slow   OF((deflate_state *s, int flush));
  81#endif
  82local block_state deflate_rle    OF((deflate_state *s, int flush));
  83local block_state deflate_huff   OF((deflate_state *s, int flush));
  84local void lm_init        OF((deflate_state *s));
  85local void putShortMSB    OF((deflate_state *s, uInt b));
  86local void flush_pending  OF((z_streamp strm));
  87local int read_buf        OF((z_streamp strm, Bytef *buf, unsigned size));
  88#ifdef ASMV
  89      void match_init OF((void)); /* asm code initialization */
  90      uInt longest_match  OF((deflate_state *s, IPos cur_match));
  91#else
  92local uInt longest_match  OF((deflate_state *s, IPos cur_match));
  93#endif
  94
  95#ifdef DEBUG
  96local  void check_match OF((deflate_state *s, IPos start, IPos match,
  97                            int length));
  98#endif
  99
 100/* ===========================================================================
 101 * Local data
 102 */
 103
 104#define NIL 0
 105/* Tail of hash chains */
 106
 107#ifndef TOO_FAR
 108#  define TOO_FAR 4096
 109#endif
 110/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
 111
 112/* Values for max_lazy_match, good_match and max_chain_length, depending on
 113 * the desired pack level (0..9). The values given below have been tuned to
 114 * exclude worst case performance for pathological files. Better values may be
 115 * found for specific files.
 116 */
 117typedef struct config_s {
 118   ush good_length; /* reduce lazy search above this match length */
 119   ush max_lazy;    /* do not perform lazy search above this match length */
 120   ush nice_length; /* quit search above this match length */
 121   ush max_chain;
 122   compress_func func;
 123} config;
 124
 125#ifdef FASTEST
 126local const config configuration_table[2] = {
 127/*      good lazy nice chain */
 128/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
 129/* 1 */ {4,    4,  8,    4, deflate_fast}}; /* max speed, no lazy matches */
 130#else
 131local const config configuration_table[10] = {
 132/*      good lazy nice chain */
 133/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
 134/* 1 */ {4,    4,  8,    4, deflate_fast}, /* max speed, no lazy matches */
 135/* 2 */ {4,    5, 16,    8, deflate_fast},
 136/* 3 */ {4,    6, 32,   32, deflate_fast},
 137
 138/* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
 139/* 5 */ {8,   16, 32,   32, deflate_slow},
 140/* 6 */ {8,   16, 128, 128, deflate_slow},
 141/* 7 */ {8,   32, 128, 256, deflate_slow},
 142/* 8 */ {32, 128, 258, 1024, deflate_slow},
 143/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
 144#endif
 145
 146/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
 147 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
 148 * meaning.
 149 */
 150
 151#define EQUAL 0
 152/* result of memcmp for equal strings */
 153
 154#ifndef NO_DUMMY_DECL
 155struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
 156#endif
 157
 158/* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
 159#define RANK(f) (((f) << 1) - ((f) > 4 ? 9 : 0))
 160
 161/* ===========================================================================
 162 * Update a hash value with the given input byte
 163 * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
 164 *    input characters, so that a running hash key can be computed from the
 165 *    previous key instead of complete recalculation each time.
 166 */
 167#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
 168
 169
 170/* ===========================================================================
 171 * Insert string str in the dictionary and set match_head to the previous head
 172 * of the hash chain (the most recent string with same hash key). Return
 173 * the previous length of the hash chain.
 174 * If this file is compiled with -DFASTEST, the compression level is forced
 175 * to 1, and no hash chains are maintained.
 176 * IN  assertion: all calls to to INSERT_STRING are made with consecutive
 177 *    input characters and the first MIN_MATCH bytes of str are valid
 178 *    (except for the last MIN_MATCH-1 bytes of the input file).
 179 */
 180#ifdef FASTEST
 181#define INSERT_STRING(s, str, match_head) \
 182   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
 183    match_head = s->head[s->ins_h], \
 184    s->head[s->ins_h] = (Pos)(str))
 185#else
 186#define INSERT_STRING(s, str, match_head) \
 187   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
 188    match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
 189    s->head[s->ins_h] = (Pos)(str))
 190#endif
 191
 192/* ===========================================================================
 193 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
 194 * prev[] will be initialized on the fly.
 195 */
 196#define CLEAR_HASH(s) \
 197    s->head[s->hash_size-1] = NIL; \
 198    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
 199
 200/* ========================================================================= */
 201int ZEXPORT deflateInit_(strm, level, version, stream_size)
 202    z_streamp strm;
 203    int level;
 204    const char *version;
 205    int stream_size;
 206{
 207    return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
 208                         Z_DEFAULT_STRATEGY, version, stream_size);
 209    /* To do: ignore strm->next_in if we use it as window */
 210}
 211
 212/* ========================================================================= */
 213int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
 214                  version, stream_size)
 215    z_streamp strm;
 216    int  level;
 217    int  method;
 218    int  windowBits;
 219    int  memLevel;
 220    int  strategy;
 221    const char *version;
 222    int stream_size;
 223{
 224    deflate_state *s;
 225    int wrap = 1;
 226    static const char my_version[] = ZLIB_VERSION;
 227
 228    ushf *overlay;
 229    /* We overlay pending_buf and d_buf+l_buf. This works since the average
 230     * output size for (length,distance) codes is <= 24 bits.
 231     */
 232
 233    if (version == Z_NULL || version[0] != my_version[0] ||
 234        stream_size != sizeof(z_stream)) {
 235        return Z_VERSION_ERROR;
 236    }
 237    if (strm == Z_NULL) return Z_STREAM_ERROR;
 238
 239    strm->msg = Z_NULL;
 240    if (strm->zalloc == (alloc_func)0) {
 241#ifdef Z_SOLO
 242        return Z_STREAM_ERROR;
 243#else
 244        strm->zalloc = zcalloc;
 245        strm->opaque = (voidpf)0;
 246#endif
 247    }
 248    if (strm->zfree == (free_func)0)
 249#ifdef Z_SOLO
 250        return Z_STREAM_ERROR;
 251#else
 252        strm->zfree = zcfree;
 253#endif
 254
 255#ifdef FASTEST
 256    if (level != 0) level = 1;
 257#else
 258    if (level == Z_DEFAULT_COMPRESSION) level = 6;
 259#endif
 260
 261    if (windowBits < 0) { /* suppress zlib wrapper */
 262        wrap = 0;
 263        windowBits = -windowBits;
 264    }
 265#ifdef GZIP
 266    else if (windowBits > 15) {
 267        wrap = 2;       /* write gzip wrapper instead */
 268        windowBits -= 16;
 269    }
 270#endif
 271    if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
 272        windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
 273        strategy < 0 || strategy > Z_FIXED) {
 274        return Z_STREAM_ERROR;
 275    }
 276    if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */
 277    s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
 278    if (s == Z_NULL) return Z_MEM_ERROR;
 279    strm->state = (struct internal_state FAR *)s;
 280    s->strm = strm;
 281
 282    s->wrap = wrap;
 283    s->gzhead = Z_NULL;
 284    s->w_bits = windowBits;
 285    s->w_size = 1 << s->w_bits;
 286    s->w_mask = s->w_size - 1;
 287
 288    s->hash_bits = memLevel + 7;
 289    s->hash_size = 1 << s->hash_bits;
 290    s->hash_mask = s->hash_size - 1;
 291    s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
 292
 293    s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
 294    s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
 295    s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
 296
 297    s->high_water = 0;      /* nothing written to s->window yet */
 298
 299    s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
 300
 301    overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
 302    s->pending_buf = (uchf *) overlay;
 303    s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
 304
 305    if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
 306        s->pending_buf == Z_NULL) {
 307        s->status = FINISH_STATE;
 308        strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
 309        deflateEnd (strm);
 310        return Z_MEM_ERROR;
 311    }
 312    s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
 313    s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
 314
 315    s->level = level;
 316    s->strategy = strategy;
 317    s->method = (Byte)method;
 318
 319    return deflateReset(strm);
 320}
 321
 322/* ========================================================================= */
 323int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
 324    z_streamp strm;
 325    const Bytef *dictionary;
 326    uInt  dictLength;
 327{
 328    deflate_state *s;
 329    uInt str, n;
 330    int wrap;
 331    unsigned avail;
 332    unsigned char *next;
 333
 334    if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL)
 335        return Z_STREAM_ERROR;
 336    s = strm->state;
 337    wrap = s->wrap;
 338    if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
 339        return Z_STREAM_ERROR;
 340
 341    /* when using zlib wrappers, compute Adler-32 for provided dictionary */
 342    if (wrap == 1)
 343        strm->adler = adler32(strm->adler, dictionary, dictLength);
 344    s->wrap = 0;                    /* avoid computing Adler-32 in read_buf */
 345
 346    /* if dictionary would fill window, just replace the history */
 347    if (dictLength >= s->w_size) {
 348        if (wrap == 0) {            /* already empty otherwise */
 349            CLEAR_HASH(s);
 350            s->strstart = 0;
 351            s->block_start = 0L;
 352            s->insert = 0;
 353        }
 354        dictionary += dictLength - s->w_size;  /* use the tail */
 355        dictLength = s->w_size;
 356    }
 357
 358    /* insert dictionary into window and hash */
 359    avail = strm->avail_in;
 360    next = strm->next_in;
 361    strm->avail_in = dictLength;
 362    strm->next_in = (Bytef *)dictionary;
 363    fill_window(s);
 364    while (s->lookahead >= MIN_MATCH) {
 365        str = s->strstart;
 366        n = s->lookahead - (MIN_MATCH-1);
 367        do {
 368            UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
 369#ifndef FASTEST
 370            s->prev[str & s->w_mask] = s->head[s->ins_h];
 371#endif
 372            s->head[s->ins_h] = (Pos)str;
 373            str++;
 374        } while (--n);
 375        s->strstart = str;
 376        s->lookahead = MIN_MATCH-1;
 377        fill_window(s);
 378    }
 379    s->strstart += s->lookahead;
 380    s->block_start = (long)s->strstart;
 381    s->insert = s->lookahead;
 382    s->lookahead = 0;
 383    s->match_length = s->prev_length = MIN_MATCH-1;
 384    s->match_available = 0;
 385    strm->next_in = next;
 386    strm->avail_in = avail;
 387    s->wrap = wrap;
 388    return Z_OK;
 389}
 390
 391/* ========================================================================= */
 392int ZEXPORT deflateResetKeep (strm)
 393    z_streamp strm;
 394{
 395    deflate_state *s;
 396
 397    if (strm == Z_NULL || strm->state == Z_NULL ||
 398        strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
 399        return Z_STREAM_ERROR;
 400    }
 401
 402    strm->total_in = strm->total_out = 0;
 403    strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
 404    strm->data_type = Z_UNKNOWN;
 405
 406    s = (deflate_state *)strm->state;
 407    s->pending = 0;
 408    s->pending_out = s->pending_buf;
 409
 410    if (s->wrap < 0) {
 411        s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
 412    }
 413    s->status = s->wrap ? INIT_STATE : BUSY_STATE;
 414    strm->adler =
 415#ifdef GZIP
 416        s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
 417#endif
 418        adler32(0L, Z_NULL, 0);
 419    s->last_flush = Z_NO_FLUSH;
 420
 421    _tr_init(s);
 422
 423    return Z_OK;
 424}
 425
 426/* ========================================================================= */
 427int ZEXPORT deflateReset (strm)
 428    z_streamp strm;
 429{
 430    int ret;
 431
 432    ret = deflateResetKeep(strm);
 433    if (ret == Z_OK)
 434        lm_init(strm->state);
 435    return ret;
 436}
 437
 438/* ========================================================================= */
 439int ZEXPORT deflateSetHeader (strm, head)
 440    z_streamp strm;
 441    gz_headerp head;
 442{
 443    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
 444    if (strm->state->wrap != 2) return Z_STREAM_ERROR;
 445    strm->state->gzhead = head;
 446    return Z_OK;
 447}
 448
 449/* ========================================================================= */
 450int ZEXPORT deflatePending (strm, pending, bits)
 451    unsigned *pending;
 452    int *bits;
 453    z_streamp strm;
 454{
 455    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
 456    if (pending != Z_NULL)
 457        *pending = strm->state->pending;
 458    if (bits != Z_NULL)
 459        *bits = strm->state->bi_valid;
 460    return Z_OK;
 461}
 462
 463/* ========================================================================= */
 464int ZEXPORT deflatePrime (strm, bits, value)
 465    z_streamp strm;
 466    int bits;
 467    int value;
 468{
 469    deflate_state *s;
 470    int put;
 471
 472    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
 473    s = strm->state;
 474    if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
 475        return Z_BUF_ERROR;
 476    do {
 477        put = Buf_size - s->bi_valid;
 478        if (put > bits)
 479            put = bits;
 480        s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
 481        s->bi_valid += put;
 482        _tr_flush_bits(s);
 483        value >>= put;
 484        bits -= put;
 485    } while (bits);
 486    return Z_OK;
 487}
 488
 489/* ========================================================================= */
 490int ZEXPORT deflateParams(strm, level, strategy)
 491    z_streamp strm;
 492    int level;
 493    int strategy;
 494{
 495    deflate_state *s;
 496    compress_func func;
 497    int err = Z_OK;
 498
 499    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
 500    s = strm->state;
 501
 502#ifdef FASTEST
 503    if (level != 0) level = 1;
 504#else
 505    if (level == Z_DEFAULT_COMPRESSION) level = 6;
 506#endif
 507    if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
 508        return Z_STREAM_ERROR;
 509    }
 510    func = configuration_table[s->level].func;
 511
 512    if ((strategy != s->strategy || func != configuration_table[level].func) &&
 513        strm->total_in != 0) {
 514        /* Flush the last buffer: */
 515        err = deflate(strm, Z_BLOCK);
 516    }
 517    if (s->level != level) {
 518        s->level = level;
 519        s->max_lazy_match   = configuration_table[level].max_lazy;
 520        s->good_match       = configuration_table[level].good_length;
 521        s->nice_match       = configuration_table[level].nice_length;
 522        s->max_chain_length = configuration_table[level].max_chain;
 523    }
 524    s->strategy = strategy;
 525    return err;
 526}
 527
 528/* ========================================================================= */
 529int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
 530    z_streamp strm;
 531    int good_length;
 532    int max_lazy;
 533    int nice_length;
 534    int max_chain;
 535{
 536    deflate_state *s;
 537
 538    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
 539    s = strm->state;
 540    s->good_match = good_length;
 541    s->max_lazy_match = max_lazy;
 542    s->nice_match = nice_length;
 543    s->max_chain_length = max_chain;
 544    return Z_OK;
 545}
 546
 547/* =========================================================================
 548 * For the default windowBits of 15 and memLevel of 8, this function returns
 549 * a close to exact, as well as small, upper bound on the compressed size.
 550 * They are coded as constants here for a reason--if the #define's are
 551 * changed, then this function needs to be changed as well.  The return
 552 * value for 15 and 8 only works for those exact settings.
 553 *
 554 * For any setting other than those defaults for windowBits and memLevel,
 555 * the value returned is a conservative worst case for the maximum expansion
 556 * resulting from using fixed blocks instead of stored blocks, which deflate
 557 * can emit on compressed data for some combinations of the parameters.
 558 *
 559 * This function could be more sophisticated to provide closer upper bounds for
 560 * every combination of windowBits and memLevel.  But even the conservative
 561 * upper bound of about 14% expansion does not seem onerous for output buffer
 562 * allocation.
 563 */
 564uLong ZEXPORT deflateBound(strm, sourceLen)
 565    z_streamp strm;
 566    uLong sourceLen;
 567{
 568    deflate_state *s;
 569    uLong complen, wraplen;
 570    Bytef *str;
 571
 572    /* conservative upper bound for compressed data */
 573    complen = sourceLen +
 574              ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
 575
 576    /* if can't get parameters, return conservative bound plus zlib wrapper */
 577    if (strm == Z_NULL || strm->state == Z_NULL)
 578        return complen + 6;
 579
 580    /* compute wrapper length */
 581    s = strm->state;
 582    switch (s->wrap) {
 583    case 0:                                 /* raw deflate */
 584        wraplen = 0;
 585        break;
 586    case 1:                                 /* zlib wrapper */
 587        wraplen = 6 + (s->strstart ? 4 : 0);
 588        break;
 589    case 2:                                 /* gzip wrapper */
 590        wraplen = 18;
 591        if (s->gzhead != Z_NULL) {          /* user-supplied gzip header */
 592            if (s->gzhead->extra != Z_NULL)
 593                wraplen += 2 + s->gzhead->extra_len;
 594            str = s->gzhead->name;
 595            if (str != Z_NULL)
 596                do {
 597                    wraplen++;
 598                } while (*str++);
 599            str = s->gzhead->comment;
 600            if (str != Z_NULL)
 601                do {
 602                    wraplen++;
 603                } while (*str++);
 604            if (s->gzhead->hcrc)
 605                wraplen += 2;
 606        }
 607        break;
 608    default:                                /* for compiler happiness */
 609        wraplen = 6;
 610    }
 611
 612    /* if not default parameters, return conservative bound */
 613    if (s->w_bits != 15 || s->hash_bits != 8 + 7)
 614        return complen + wraplen;
 615
 616    /* default settings: return tight bound for that case */
 617    return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
 618           (sourceLen >> 25) + 13 - 6 + wraplen;
 619}
 620
 621/* =========================================================================
 622 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
 623 * IN assertion: the stream state is correct and there is enough room in
 624 * pending_buf.
 625 */
 626local void putShortMSB (s, b)
 627    deflate_state *s;
 628    uInt b;
 629{
 630    put_byte(s, (Byte)(b >> 8));
 631    put_byte(s, (Byte)(b & 0xff));
 632}
 633
 634/* =========================================================================
 635 * Flush as much pending output as possible. All deflate() output goes
 636 * through this function so some applications may wish to modify it
 637 * to avoid allocating a large strm->next_out buffer and copying into it.
 638 * (See also read_buf()).
 639 */
 640local void flush_pending(strm)
 641    z_streamp strm;
 642{
 643    unsigned len;
 644    deflate_state *s = strm->state;
 645
 646    _tr_flush_bits(s);
 647    len = s->pending;
 648    if (len > strm->avail_out) len = strm->avail_out;
 649    if (len == 0) return;
 650
 651    zmemcpy(strm->next_out, s->pending_out, len);
 652    strm->next_out  += len;
 653    s->pending_out  += len;
 654    strm->total_out += len;
 655    strm->avail_out  -= len;
 656    s->pending -= len;
 657    if (s->pending == 0) {
 658        s->pending_out = s->pending_buf;
 659    }
 660}
 661
 662/* ========================================================================= */
 663int ZEXPORT deflate (strm, flush)
 664    z_streamp strm;
 665    int flush;
 666{
 667    int old_flush; /* value of flush param for previous deflate call */
 668    deflate_state *s;
 669
 670    if (strm == Z_NULL || strm->state == Z_NULL ||
 671        flush > Z_BLOCK || flush < 0) {
 672        return Z_STREAM_ERROR;
 673    }
 674    s = strm->state;
 675
 676    if (strm->next_out == Z_NULL ||
 677        (strm->next_in == Z_NULL && strm->avail_in != 0) ||
 678        (s->status == FINISH_STATE && flush != Z_FINISH)) {
 679        ERR_RETURN(strm, Z_STREAM_ERROR);
 680    }
 681    if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
 682
 683    s->strm = strm; /* just in case */
 684    old_flush = s->last_flush;
 685    s->last_flush = flush;
 686
 687    /* Write the header */
 688    if (s->status == INIT_STATE) {
 689#ifdef GZIP
 690        if (s->wrap == 2) {
 691            strm->adler = crc32(0L, Z_NULL, 0);
 692            put_byte(s, 31);
 693            put_byte(s, 139);
 694            put_byte(s, 8);
 695            if (s->gzhead == Z_NULL) {
 696                put_byte(s, 0);
 697                put_byte(s, 0);
 698                put_byte(s, 0);
 699                put_byte(s, 0);
 700                put_byte(s, 0);
 701                put_byte(s, s->level == 9 ? 2 :
 702                            (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
 703                             4 : 0));
 704                put_byte(s, OS_CODE);
 705                s->status = BUSY_STATE;
 706            }
 707            else {
 708                put_byte(s, (s->gzhead->text ? 1 : 0) +
 709                            (s->gzhead->hcrc ? 2 : 0) +
 710                            (s->gzhead->extra == Z_NULL ? 0 : 4) +
 711                            (s->gzhead->name == Z_NULL ? 0 : 8) +
 712                            (s->gzhead->comment == Z_NULL ? 0 : 16)
 713                        );
 714                put_byte(s, (Byte)(s->gzhead->time & 0xff));
 715                put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
 716                put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
 717                put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
 718                put_byte(s, s->level == 9 ? 2 :
 719                            (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
 720                             4 : 0));
 721                put_byte(s, s->gzhead->os & 0xff);
 722                if (s->gzhead->extra != Z_NULL) {
 723                    put_byte(s, s->gzhead->extra_len & 0xff);
 724                    put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
 725                }
 726                if (s->gzhead->hcrc)
 727                    strm->adler = crc32(strm->adler, s->pending_buf,
 728                                        s->pending);
 729                s->gzindex = 0;
 730                s->status = EXTRA_STATE;
 731            }
 732        }
 733        else
 734#endif
 735        {
 736            uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
 737            uInt level_flags;
 738
 739            if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
 740                level_flags = 0;
 741            else if (s->level < 6)
 742                level_flags = 1;
 743            else if (s->level == 6)
 744                level_flags = 2;
 745            else
 746                level_flags = 3;
 747            header |= (level_flags << 6);
 748            if (s->strstart != 0) header |= PRESET_DICT;
 749            header += 31 - (header % 31);
 750
 751            s->status = BUSY_STATE;
 752            putShortMSB(s, header);
 753
 754            /* Save the adler32 of the preset dictionary: */
 755            if (s->strstart != 0) {
 756                putShortMSB(s, (uInt)(strm->adler >> 16));
 757                putShortMSB(s, (uInt)(strm->adler & 0xffff));
 758            }
 759            strm->adler = adler32(0L, Z_NULL, 0);
 760        }
 761    }
 762#ifdef GZIP
 763    if (s->status == EXTRA_STATE) {
 764        if (s->gzhead->extra != Z_NULL) {
 765            uInt beg = s->pending;  /* start of bytes to update crc */
 766
 767            while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
 768                if (s->pending == s->pending_buf_size) {
 769                    if (s->gzhead->hcrc && s->pending > beg)
 770                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
 771                                            s->pending - beg);
 772                    flush_pending(strm);
 773                    beg = s->pending;
 774                    if (s->pending == s->pending_buf_size)
 775                        break;
 776                }
 777                put_byte(s, s->gzhead->extra[s->gzindex]);
 778                s->gzindex++;
 779            }
 780            if (s->gzhead->hcrc && s->pending > beg)
 781                strm->adler = crc32(strm->adler, s->pending_buf + beg,
 782                                    s->pending - beg);
 783            if (s->gzindex == s->gzhead->extra_len) {
 784                s->gzindex = 0;
 785                s->status = NAME_STATE;
 786            }
 787        }
 788        else
 789            s->status = NAME_STATE;
 790    }
 791    if (s->status == NAME_STATE) {
 792        if (s->gzhead->name != Z_NULL) {
 793            uInt beg = s->pending;  /* start of bytes to update crc */
 794            int val;
 795
 796            do {
 797                if (s->pending == s->pending_buf_size) {
 798                    if (s->gzhead->hcrc && s->pending > beg)
 799                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
 800                                            s->pending - beg);
 801                    flush_pending(strm);
 802                    beg = s->pending;
 803                    if (s->pending == s->pending_buf_size) {
 804                        val = 1;
 805                        break;
 806                    }
 807                }
 808                val = s->gzhead->name[s->gzindex++];
 809                put_byte(s, val);
 810            } while (val != 0);
 811            if (s->gzhead->hcrc && s->pending > beg)
 812                strm->adler = crc32(strm->adler, s->pending_buf + beg,
 813                                    s->pending - beg);
 814            if (val == 0) {
 815                s->gzindex = 0;
 816                s->status = COMMENT_STATE;
 817            }
 818        }
 819        else
 820            s->status = COMMENT_STATE;
 821    }
 822    if (s->status == COMMENT_STATE) {
 823        if (s->gzhead->comment != Z_NULL) {
 824            uInt beg = s->pending;  /* start of bytes to update crc */
 825            int val;
 826
 827            do {
 828                if (s->pending == s->pending_buf_size) {
 829                    if (s->gzhead->hcrc && s->pending > beg)
 830                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
 831                                            s->pending - beg);
 832                    flush_pending(strm);
 833                    beg = s->pending;
 834                    if (s->pending == s->pending_buf_size) {
 835                        val = 1;
 836                        break;
 837                    }
 838                }
 839                val = s->gzhead->comment[s->gzindex++];
 840                put_byte(s, val);
 841            } while (val != 0);
 842            if (s->gzhead->hcrc && s->pending > beg)
 843                strm->adler = crc32(strm->adler, s->pending_buf + beg,
 844                                    s->pending - beg);
 845            if (val == 0)
 846                s->status = HCRC_STATE;
 847        }
 848        else
 849            s->status = HCRC_STATE;
 850    }
 851    if (s->status == HCRC_STATE) {
 852        if (s->gzhead->hcrc) {
 853            if (s->pending + 2 > s->pending_buf_size)
 854                flush_pending(strm);
 855            if (s->pending + 2 <= s->pending_buf_size) {
 856                put_byte(s, (Byte)(strm->adler & 0xff));
 857                put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
 858                strm->adler = crc32(0L, Z_NULL, 0);
 859                s->status = BUSY_STATE;
 860            }
 861        }
 862        else
 863            s->status = BUSY_STATE;
 864    }
 865#endif
 866
 867    /* Flush as much pending output as possible */
 868    if (s->pending != 0) {
 869        flush_pending(strm);
 870        if (strm->avail_out == 0) {
 871            /* Since avail_out is 0, deflate will be called again with
 872             * more output space, but possibly with both pending and
 873             * avail_in equal to zero. There won't be anything to do,
 874             * but this is not an error situation so make sure we
 875             * return OK instead of BUF_ERROR at next call of deflate:
 876             */
 877            s->last_flush = -1;
 878            return Z_OK;
 879        }
 880
 881    /* Make sure there is something to do and avoid duplicate consecutive
 882     * flushes. For repeated and useless calls with Z_FINISH, we keep
 883     * returning Z_STREAM_END instead of Z_BUF_ERROR.
 884     */
 885    } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
 886               flush != Z_FINISH) {
 887        ERR_RETURN(strm, Z_BUF_ERROR);
 888    }
 889
 890    /* User must not provide more input after the first FINISH: */
 891    if (s->status == FINISH_STATE && strm->avail_in != 0) {
 892        ERR_RETURN(strm, Z_BUF_ERROR);
 893    }
 894
 895    /* Start a new block or continue the current one.
 896     */
 897    if (strm->avail_in != 0 || s->lookahead != 0 ||
 898        (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
 899        block_state bstate;
 900
 901        bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
 902                    (s->strategy == Z_RLE ? deflate_rle(s, flush) :
 903                        (*(configuration_table[s->level].func))(s, flush));
 904
 905        if (bstate == finish_started || bstate == finish_done) {
 906            s->status = FINISH_STATE;
 907        }
 908        if (bstate == need_more || bstate == finish_started) {
 909            if (strm->avail_out == 0) {
 910                s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
 911            }
 912            return Z_OK;
 913            /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
 914             * of deflate should use the same flush parameter to make sure
 915             * that the flush is complete. So we don't have to output an
 916             * empty block here, this will be done at next call. This also
 917             * ensures that for a very small output buffer, we emit at most
 918             * one empty block.
 919             */
 920        }
 921        if (bstate == block_done) {
 922            if (flush == Z_PARTIAL_FLUSH) {
 923                _tr_align(s);
 924            } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
 925                _tr_stored_block(s, (char*)0, 0L, 0);
 926                /* For a full flush, this empty block will be recognized
 927                 * as a special marker by inflate_sync().
 928                 */
 929                if (flush == Z_FULL_FLUSH) {
 930                    CLEAR_HASH(s);             /* forget history */
 931                    if (s->lookahead == 0) {
 932                        s->strstart = 0;
 933                        s->block_start = 0L;
 934                        s->insert = 0;
 935                    }
 936                }
 937            }
 938            flush_pending(strm);
 939            if (strm->avail_out == 0) {
 940              s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
 941              return Z_OK;
 942            }
 943        }
 944    }
 945    Assert(strm->avail_out > 0, "bug2");
 946
 947    if (flush != Z_FINISH) return Z_OK;
 948    if (s->wrap <= 0) return Z_STREAM_END;
 949
 950    /* Write the trailer */
 951#ifdef GZIP
 952    if (s->wrap == 2) {
 953        put_byte(s, (Byte)(strm->adler & 0xff));
 954        put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
 955        put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
 956        put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
 957        put_byte(s, (Byte)(strm->total_in & 0xff));
 958        put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
 959        put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
 960        put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
 961    }
 962    else
 963#endif
 964    {
 965        putShortMSB(s, (uInt)(strm->adler >> 16));
 966        putShortMSB(s, (uInt)(strm->adler & 0xffff));
 967    }
 968    flush_pending(strm);
 969    /* If avail_out is zero, the application will call deflate again
 970     * to flush the rest.
 971     */
 972    if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
 973    return s->pending != 0 ? Z_OK : Z_STREAM_END;
 974}
 975
 976/* ========================================================================= */
 977int ZEXPORT deflateEnd (strm)
 978    z_streamp strm;
 979{
 980    int status;
 981
 982    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
 983
 984    status = strm->state->status;
 985    if (status != INIT_STATE &&
 986        status != EXTRA_STATE &&
 987        status != NAME_STATE &&
 988        status != COMMENT_STATE &&
 989        status != HCRC_STATE &&
 990        status != BUSY_STATE &&
 991        status != FINISH_STATE) {
 992      return Z_STREAM_ERROR;
 993    }
 994
 995    /* Deallocate in reverse order of allocations: */
 996    TRY_FREE(strm, strm->state->pending_buf);
 997    TRY_FREE(strm, strm->state->head);
 998    TRY_FREE(strm, strm->state->prev);
 999    TRY_FREE(strm, strm->state->window);
1000
1001    ZFREE(strm, strm->state);
1002    strm->state = Z_NULL;
1003
1004    return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1005}
1006
1007/* =========================================================================
1008 * Copy the source state to the destination state.
1009 * To simplify the source, this is not supported for 16-bit MSDOS (which
1010 * doesn't have enough memory anyway to duplicate compression states).
1011 */
1012int ZEXPORT deflateCopy (dest, source)
1013    z_streamp dest;
1014    z_streamp source;
1015{
1016#ifdef MAXSEG_64K
1017    return Z_STREAM_ERROR;
1018#else
1019    deflate_state *ds;
1020    deflate_state *ss;
1021    ushf *overlay;
1022
1023
1024    if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
1025        return Z_STREAM_ERROR;
1026    }
1027
1028    ss = source->state;
1029
1030    zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1031
1032    ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1033    if (ds == Z_NULL) return Z_MEM_ERROR;
1034    dest->state = (struct internal_state FAR *) ds;
1035    zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1036    ds->strm = dest;
1037
1038    ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1039    ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
1040    ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
1041    overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1042    ds->pending_buf = (uchf *) overlay;
1043
1044    if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1045        ds->pending_buf == Z_NULL) {
1046        deflateEnd (dest);
1047        return Z_MEM_ERROR;
1048    }
1049    /* following zmemcpy do not work for 16-bit MSDOS */
1050    zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1051    zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1052    zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1053    zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1054
1055    ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1056    ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1057    ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1058
1059    ds->l_desc.dyn_tree = ds->dyn_ltree;
1060    ds->d_desc.dyn_tree = ds->dyn_dtree;
1061    ds->bl_desc.dyn_tree = ds->bl_tree;
1062
1063    return Z_OK;
1064#endif /* MAXSEG_64K */
1065}
1066
1067/* ===========================================================================
1068 * Read a new buffer from the current input stream, update the adler32
1069 * and total number of bytes read.  All deflate() input goes through
1070 * this function so some applications may wish to modify it to avoid
1071 * allocating a large strm->next_in buffer and copying from it.
1072 * (See also flush_pending()).
1073 */
1074local int read_buf(strm, buf, size)
1075    z_streamp strm;
1076    Bytef *buf;
1077    unsigned size;
1078{
1079    unsigned len = strm->avail_in;
1080
1081    if (len > size) len = size;
1082    if (len == 0) return 0;
1083
1084    strm->avail_in  -= len;
1085
1086    zmemcpy(buf, strm->next_in, len);
1087    if (strm->state->wrap == 1) {
1088        strm->adler = adler32(strm->adler, buf, len);
1089    }
1090#ifdef GZIP
1091    else if (strm->state->wrap == 2) {
1092        strm->adler = crc32(strm->adler, buf, len);
1093    }
1094#endif
1095    strm->next_in  += len;
1096    strm->total_in += len;
1097
1098    return (int)len;
1099}
1100
1101/* ===========================================================================
1102 * Initialize the "longest match" routines for a new zlib stream
1103 */
1104local void lm_init (s)
1105    deflate_state *s;
1106{
1107    s->window_size = (ulg)2L*s->w_size;
1108
1109    CLEAR_HASH(s);
1110
1111    /* Set the default configuration parameters:
1112     */
1113    s->max_lazy_match   = configuration_table[s->level].max_lazy;
1114    s->good_match       = configuration_table[s->level].good_length;
1115    s->nice_match       = configuration_table[s->level].nice_length;
1116    s->max_chain_length = configuration_table[s->level].max_chain;
1117
1118    s->strstart = 0;
1119    s->block_start = 0L;
1120    s->lookahead = 0;
1121    s->insert = 0;
1122    s->match_length = s->prev_length = MIN_MATCH-1;
1123    s->match_available = 0;
1124    s->ins_h = 0;
1125#ifndef FASTEST
1126#ifdef ASMV
1127    match_init(); /* initialize the asm code */
1128#endif
1129#endif
1130}
1131
1132#ifndef FASTEST
1133/* ===========================================================================
1134 * Set match_start to the longest match starting at the given string and
1135 * return its length. Matches shorter or equal to prev_length are discarded,
1136 * in which case the result is equal to prev_length and match_start is
1137 * garbage.
1138 * IN assertions: cur_match is the head of the hash chain for the current
1139 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1140 * OUT assertion: the match length is not greater than s->lookahead.
1141 */
1142#ifndef ASMV
1143/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1144 * match.S. The code will be functionally equivalent.
1145 */
1146local uInt longest_match(s, cur_match)
1147    deflate_state *s;
1148    IPos cur_match;                             /* current match */
1149{
1150    unsigned chain_length = s->max_chain_length;/* max hash chain length */
1151    register Bytef *scan = s->window + s->strstart; /* current string */
1152    register Bytef *match;                       /* matched string */
1153    register int len;                           /* length of current match */
1154    int best_len = s->prev_length;              /* best match length so far */
1155    int nice_match = s->nice_match;             /* stop if match long enough */
1156    IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1157        s->strstart - (IPos)MAX_DIST(s) : NIL;
1158    /* Stop when cur_match becomes <= limit. To simplify the code,
1159     * we prevent matches with the string of window index 0.
1160     */
1161    Posf *prev = s->prev;
1162    uInt wmask = s->w_mask;
1163
1164#ifdef UNALIGNED_OK
1165    /* Compare two bytes at a time. Note: this is not always beneficial.
1166     * Try with and without -DUNALIGNED_OK to check.
1167     */
1168    register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1169    register ush scan_start = *(ushf*)scan;
1170    register ush scan_end   = *(ushf*)(scan+best_len-1);
1171#else
1172    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1173    register Byte scan_end1  = scan[best_len-1];
1174    register Byte scan_end   = scan[best_len];
1175#endif
1176
1177    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1178     * It is easy to get rid of this optimization if necessary.
1179     */
1180    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1181
1182    /* Do not waste too much time if we already have a good match: */
1183    if (s->prev_length >= s->good_match) {
1184        chain_length >>= 2;
1185    }
1186    /* Do not look for matches beyond the end of the input. This is necessary
1187     * to make deflate deterministic.
1188     */
1189    if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1190
1191    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1192
1193    do {
1194        Assert(cur_match < s->strstart, "no future");
1195        match = s->window + cur_match;
1196
1197        /* Skip to next match if the match length cannot increase
1198         * or if the match length is less than 2.  Note that the checks below
1199         * for insufficient lookahead only occur occasionally for performance
1200         * reasons.  Therefore uninitialized memory will be accessed, and
1201         * conditional jumps will be made that depend on those values.
1202         * However the length of the match is limited to the lookahead, so
1203         * the output of deflate is not affected by the uninitialized values.
1204         */
1205#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1206        /* This code assumes sizeof(unsigned short) == 2. Do not use
1207         * UNALIGNED_OK if your compiler uses a different size.
1208         */
1209        if (*(ushf*)(match+best_len-1) != scan_end ||
1210            *(ushf*)match != scan_start) continue;
1211
1212        /* It is not necessary to compare scan[2] and match[2] since they are
1213         * always equal when the other bytes match, given that the hash keys
1214         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1215         * strstart+3, +5, ... up to strstart+257. We check for insufficient
1216         * lookahead only every 4th comparison; the 128th check will be made
1217         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1218         * necessary to put more guard bytes at the end of the window, or
1219         * to check more often for insufficient lookahead.
1220         */
1221        Assert(scan[2] == match[2], "scan[2]?");
1222        scan++, match++;
1223        do {
1224        } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1225                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1226                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1227                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1228                 scan < strend);
1229        /* The funny "do {}" generates better code on most compilers */
1230
1231        /* Here, scan <= window+strstart+257 */
1232        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1233        if (*scan == *match) scan++;
1234
1235        len = (MAX_MATCH - 1) - (int)(strend-scan);
1236        scan = strend - (MAX_MATCH-1);
1237
1238#else /* UNALIGNED_OK */
1239
1240        if (match[best_len]   != scan_end  ||
1241            match[best_len-1] != scan_end1 ||
1242            *match            != *scan     ||
1243            *++match          != scan[1])      continue;
1244
1245        /* The check at best_len-1 can be removed because it will be made
1246         * again later. (This heuristic is not always a win.)
1247         * It is not necessary to compare scan[2] and match[2] since they
1248         * are always equal when the other bytes match, given that
1249         * the hash keys are equal and that HASH_BITS >= 8.
1250         */
1251        scan += 2, match++;
1252        Assert(*scan == *match, "match[2]?");
1253
1254        /* We check for insufficient lookahead only every 8th comparison;
1255         * the 256th check will be made at strstart+258.
1256         */
1257        do {
1258        } while (*++scan == *++match && *++scan == *++match &&
1259                 *++scan == *++match && *++scan == *++match &&
1260                 *++scan == *++match && *++scan == *++match &&
1261                 *++scan == *++match && *++scan == *++match &&
1262                 scan < strend);
1263
1264        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1265
1266        len = MAX_MATCH - (int)(strend - scan);
1267        scan = strend - MAX_MATCH;
1268
1269#endif /* UNALIGNED_OK */
1270
1271        if (len > best_len) {
1272            s->match_start = cur_match;
1273            best_len = len;
1274            if (len >= nice_match) break;
1275#ifdef UNALIGNED_OK
1276            scan_end = *(ushf*)(scan+best_len-1);
1277#else
1278            scan_end1  = scan[best_len-1];
1279            scan_end   = scan[best_len];
1280#endif
1281        }
1282    } while ((cur_match = prev[cur_match & wmask]) > limit
1283             && --chain_length != 0);
1284
1285    if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1286    return s->lookahead;
1287}
1288#endif /* ASMV */
1289
1290#else /* FASTEST */
1291
1292/* ---------------------------------------------------------------------------
1293 * Optimized version for FASTEST only
1294 */
1295local uInt longest_match(s, cur_match)
1296    deflate_state *s;
1297    IPos cur_match;                             /* current match */
1298{
1299    register Bytef *scan = s->window + s->strstart; /* current string */
1300    register Bytef *match;                       /* matched string */
1301    register int len;                           /* length of current match */
1302    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1303
1304    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1305     * It is easy to get rid of this optimization if necessary.
1306     */
1307    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1308
1309    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1310
1311    Assert(cur_match < s->strstart, "no future");
1312
1313    match = s->window + cur_match;
1314
1315    /* Return failure if the match length is less than 2:
1316     */
1317    if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1318
1319    /* The check at best_len-1 can be removed because it will be made
1320     * again later. (This heuristic is not always a win.)
1321     * It is not necessary to compare scan[2] and match[2] since they
1322     * are always equal when the other bytes match, given that
1323     * the hash keys are equal and that HASH_BITS >= 8.
1324     */
1325    scan += 2, match += 2;
1326    Assert(*scan == *match, "match[2]?");
1327
1328    /* We check for insufficient lookahead only every 8th comparison;
1329     * the 256th check will be made at strstart+258.
1330     */
1331    do {
1332    } while (*++scan == *++match && *++scan == *++match &&
1333             *++scan == *++match && *++scan == *++match &&
1334             *++scan == *++match && *++scan == *++match &&
1335             *++scan == *++match && *++scan == *++match &&
1336             scan < strend);
1337
1338    Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1339
1340    len = MAX_MATCH - (int)(strend - scan);
1341
1342    if (len < MIN_MATCH) return MIN_MATCH - 1;
1343
1344    s->match_start = cur_match;
1345    return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1346}
1347
1348#endif /* FASTEST */
1349
1350#ifdef DEBUG
1351/* ===========================================================================
1352 * Check that the match at match_start is indeed a match.
1353 */
1354local void check_match(s, start, match, length)
1355    deflate_state *s;
1356    IPos start, match;
1357    int length;
1358{
1359    /* check that the match is indeed a match */
1360    if (zmemcmp(s->window + match,
1361                s->window + start, length) != EQUAL) {
1362        fprintf(stderr, " start %u, match %u, length %d\n",
1363                start, match, length);
1364        do {
1365            fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1366        } while (--length != 0);
1367        z_error("invalid match");
1368    }
1369    if (z_verbose > 1) {
1370        fprintf(stderr,"\\[%d,%d]", start-match, length);
1371        do { putc(s->window[start++], stderr); } while (--length != 0);
1372    }
1373}
1374#else
1375#  define check_match(s, start, match, length)
1376#endif /* DEBUG */
1377
1378/* ===========================================================================
1379 * Fill the window when the lookahead becomes insufficient.
1380 * Updates strstart and lookahead.
1381 *
1382 * IN assertion: lookahead < MIN_LOOKAHEAD
1383 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1384 *    At least one byte has been read, or avail_in == 0; reads are
1385 *    performed for at least two bytes (required for the zip translate_eol
1386 *    option -- not supported here).
1387 */
1388local void fill_window(s)
1389    deflate_state *s;
1390{
1391    register unsigned n, m;
1392    register Posf *p;
1393    unsigned more;    /* Amount of free space at the end of the window. */
1394    uInt wsize = s->w_size;
1395
1396    Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1397
1398    do {
1399        more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1400
1401        /* Deal with !@#$% 64K limit: */
1402        if (sizeof(int) <= 2) {
1403            if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1404      

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