linux/lib/zlib_deflate/deflate.c
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   1/* +++ deflate.c */
   2/* deflate.c -- compress data using the deflation algorithm
   3 * Copyright (C) 1995-1996 Jean-loup Gailly.
   4 * For conditions of distribution and use, see copyright notice in zlib.h 
   5 */
   6
   7/*
   8 *  ALGORITHM
   9 *
  10 *      The "deflation" process depends on being able to identify portions
  11 *      of the input text which are identical to earlier input (within a
  12 *      sliding window trailing behind the input currently being processed).
  13 *
  14 *      The most straightforward technique turns out to be the fastest for
  15 *      most input files: try all possible matches and select the longest.
  16 *      The key feature of this algorithm is that insertions into the string
  17 *      dictionary are very simple and thus fast, and deletions are avoided
  18 *      completely. Insertions are performed at each input character, whereas
  19 *      string matches are performed only when the previous match ends. So it
  20 *      is preferable to spend more time in matches to allow very fast string
  21 *      insertions and avoid deletions. The matching algorithm for small
  22 *      strings is inspired from that of Rabin & Karp. A brute force approach
  23 *      is used to find longer strings when a small match has been found.
  24 *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
  25 *      (by Leonid Broukhis).
  26 *         A previous version of this file used a more sophisticated algorithm
  27 *      (by Fiala and Greene) which is guaranteed to run in linear amortized
  28 *      time, but has a larger average cost, uses more memory and is patented.
  29 *      However the F&G algorithm may be faster for some highly redundant
  30 *      files if the parameter max_chain_length (described below) is too large.
  31 *
  32 *  ACKNOWLEDGEMENTS
  33 *
  34 *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
  35 *      I found it in 'freeze' written by Leonid Broukhis.
  36 *      Thanks to many people for bug reports and testing.
  37 *
  38 *  REFERENCES
  39 *
  40 *      Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
  41 *      Available in ftp://ds.internic.net/rfc/rfc1951.txt
  42 *
  43 *      A description of the Rabin and Karp algorithm is given in the book
  44 *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
  45 *
  46 *      Fiala,E.R., and Greene,D.H.
  47 *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
  48 *
  49 */
  50
  51#include <linux/module.h>
  52#include <linux/zutil.h>
  53#include "defutil.h"
  54
  55
  56/* ===========================================================================
  57 *  Function prototypes.
  58 */
  59typedef enum {
  60    need_more,      /* block not completed, need more input or more output */
  61    block_done,     /* block flush performed */
  62    finish_started, /* finish started, need only more output at next deflate */
  63    finish_done     /* finish done, accept no more input or output */
  64} block_state;
  65
  66typedef block_state (*compress_func) (deflate_state *s, int flush);
  67/* Compression function. Returns the block state after the call. */
  68
  69static void fill_window    (deflate_state *s);
  70static block_state deflate_stored (deflate_state *s, int flush);
  71static block_state deflate_fast   (deflate_state *s, int flush);
  72static block_state deflate_slow   (deflate_state *s, int flush);
  73static void lm_init        (deflate_state *s);
  74static void putShortMSB    (deflate_state *s, uInt b);
  75static void flush_pending  (z_streamp strm);
  76static int read_buf        (z_streamp strm, Byte *buf, unsigned size);
  77static uInt longest_match  (deflate_state *s, IPos cur_match);
  78
  79#ifdef DEBUG_ZLIB
  80static  void check_match (deflate_state *s, IPos start, IPos match,
  81                         int length);
  82#endif
  83
  84/* ===========================================================================
  85 * Local data
  86 */
  87
  88#define NIL 0
  89/* Tail of hash chains */
  90
  91#ifndef TOO_FAR
  92#  define TOO_FAR 4096
  93#endif
  94/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
  95
  96#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
  97/* Minimum amount of lookahead, except at the end of the input file.
  98 * See deflate.c for comments about the MIN_MATCH+1.
  99 */
 100
 101/* Values for max_lazy_match, good_match and max_chain_length, depending on
 102 * the desired pack level (0..9). The values given below have been tuned to
 103 * exclude worst case performance for pathological files. Better values may be
 104 * found for specific files.
 105 */
 106typedef struct config_s {
 107   ush good_length; /* reduce lazy search above this match length */
 108   ush max_lazy;    /* do not perform lazy search above this match length */
 109   ush nice_length; /* quit search above this match length */
 110   ush max_chain;
 111   compress_func func;
 112} config;
 113
 114static const config configuration_table[10] = {
 115/*      good lazy nice chain */
 116/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
 117/* 1 */ {4,    4,  8,    4, deflate_fast}, /* maximum speed, no lazy matches */
 118/* 2 */ {4,    5, 16,    8, deflate_fast},
 119/* 3 */ {4,    6, 32,   32, deflate_fast},
 120
 121/* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
 122/* 5 */ {8,   16, 32,   32, deflate_slow},
 123/* 6 */ {8,   16, 128, 128, deflate_slow},
 124/* 7 */ {8,   32, 128, 256, deflate_slow},
 125/* 8 */ {32, 128, 258, 1024, deflate_slow},
 126/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* maximum compression */
 127
 128/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
 129 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
 130 * meaning.
 131 */
 132
 133#define EQUAL 0
 134/* result of memcmp for equal strings */
 135
 136/* ===========================================================================
 137 * Update a hash value with the given input byte
 138 * IN  assertion: all calls to UPDATE_HASH are made with consecutive
 139 *    input characters, so that a running hash key can be computed from the
 140 *    previous key instead of complete recalculation each time.
 141 */
 142#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
 143
 144
 145/* ===========================================================================
 146 * Insert string str in the dictionary and set match_head to the previous head
 147 * of the hash chain (the most recent string with same hash key). Return
 148 * the previous length of the hash chain.
 149 * IN  assertion: all calls to INSERT_STRING are made with consecutive
 150 *    input characters and the first MIN_MATCH bytes of str are valid
 151 *    (except for the last MIN_MATCH-1 bytes of the input file).
 152 */
 153#define INSERT_STRING(s, str, match_head) \
 154   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
 155    s->prev[(str) & s->w_mask] = match_head = s->head[s->ins_h], \
 156    s->head[s->ins_h] = (Pos)(str))
 157
 158/* ===========================================================================
 159 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
 160 * prev[] will be initialized on the fly.
 161 */
 162#define CLEAR_HASH(s) \
 163    s->head[s->hash_size-1] = NIL; \
 164    memset((char *)s->head, 0, (unsigned)(s->hash_size-1)*sizeof(*s->head));
 165
 166/* ========================================================================= */
 167int zlib_deflateInit2(
 168        z_streamp strm,
 169        int  level,
 170        int  method,
 171        int  windowBits,
 172        int  memLevel,
 173        int  strategy
 174)
 175{
 176    deflate_state *s;
 177    int noheader = 0;
 178    deflate_workspace *mem;
 179    char *next;
 180
 181    ush *overlay;
 182    /* We overlay pending_buf and d_buf+l_buf. This works since the average
 183     * output size for (length,distance) codes is <= 24 bits.
 184     */
 185
 186    if (strm == NULL) return Z_STREAM_ERROR;
 187
 188    strm->msg = NULL;
 189
 190    if (level == Z_DEFAULT_COMPRESSION) level = 6;
 191
 192    mem = (deflate_workspace *) strm->workspace;
 193
 194    if (windowBits < 0) { /* undocumented feature: suppress zlib header */
 195        noheader = 1;
 196        windowBits = -windowBits;
 197    }
 198    if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
 199        windowBits < 9 || windowBits > 15 || level < 0 || level > 9 ||
 200        strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
 201        return Z_STREAM_ERROR;
 202    }
 203
 204    /*
 205     * Direct the workspace's pointers to the chunks that were allocated
 206     * along with the deflate_workspace struct.
 207     */
 208    next = (char *) mem;
 209    next += sizeof(*mem);
 210    mem->window_memory = (Byte *) next;
 211    next += zlib_deflate_window_memsize(windowBits);
 212    mem->prev_memory = (Pos *) next;
 213    next += zlib_deflate_prev_memsize(windowBits);
 214    mem->head_memory = (Pos *) next;
 215    next += zlib_deflate_head_memsize(memLevel);
 216    mem->overlay_memory = next;
 217
 218    s = (deflate_state *) &(mem->deflate_memory);
 219    strm->state = (struct internal_state *)s;
 220    s->strm = strm;
 221
 222    s->noheader = noheader;
 223    s->w_bits = windowBits;
 224    s->w_size = 1 << s->w_bits;
 225    s->w_mask = s->w_size - 1;
 226
 227    s->hash_bits = memLevel + 7;
 228    s->hash_size = 1 << s->hash_bits;
 229    s->hash_mask = s->hash_size - 1;
 230    s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
 231
 232    s->window = (Byte *) mem->window_memory;
 233    s->prev   = (Pos *)  mem->prev_memory;
 234    s->head   = (Pos *)  mem->head_memory;
 235
 236    s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
 237
 238    overlay = (ush *) mem->overlay_memory;
 239    s->pending_buf = (uch *) overlay;
 240    s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
 241
 242    s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
 243    s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
 244
 245    s->level = level;
 246    s->strategy = strategy;
 247    s->method = (Byte)method;
 248
 249    return zlib_deflateReset(strm);
 250}
 251
 252/* ========================================================================= */
 253#if 0
 254int zlib_deflateSetDictionary(
 255        z_streamp strm,
 256        const Byte *dictionary,
 257        uInt  dictLength
 258)
 259{
 260    deflate_state *s;
 261    uInt length = dictLength;
 262    uInt n;
 263    IPos hash_head = 0;
 264
 265    if (strm == NULL || strm->state == NULL || dictionary == NULL)
 266        return Z_STREAM_ERROR;
 267
 268    s = (deflate_state *) strm->state;
 269    if (s->status != INIT_STATE) return Z_STREAM_ERROR;
 270
 271    strm->adler = zlib_adler32(strm->adler, dictionary, dictLength);
 272
 273    if (length < MIN_MATCH) return Z_OK;
 274    if (length > MAX_DIST(s)) {
 275        length = MAX_DIST(s);
 276#ifndef USE_DICT_HEAD
 277        dictionary += dictLength - length; /* use the tail of the dictionary */
 278#endif
 279    }
 280    memcpy((char *)s->window, dictionary, length);
 281    s->strstart = length;
 282    s->block_start = (long)length;
 283
 284    /* Insert all strings in the hash table (except for the last two bytes).
 285     * s->lookahead stays null, so s->ins_h will be recomputed at the next
 286     * call of fill_window.
 287     */
 288    s->ins_h = s->window[0];
 289    UPDATE_HASH(s, s->ins_h, s->window[1]);
 290    for (n = 0; n <= length - MIN_MATCH; n++) {
 291        INSERT_STRING(s, n, hash_head);
 292    }
 293    if (hash_head) hash_head = 0;  /* to make compiler happy */
 294    return Z_OK;
 295}
 296#endif  /*  0  */
 297
 298/* ========================================================================= */
 299int zlib_deflateReset(
 300        z_streamp strm
 301)
 302{
 303    deflate_state *s;
 304    
 305    if (strm == NULL || strm->state == NULL)
 306        return Z_STREAM_ERROR;
 307
 308    strm->total_in = strm->total_out = 0;
 309    strm->msg = NULL;
 310    strm->data_type = Z_UNKNOWN;
 311
 312    s = (deflate_state *)strm->state;
 313    s->pending = 0;
 314    s->pending_out = s->pending_buf;
 315
 316    if (s->noheader < 0) {
 317        s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
 318    }
 319    s->status = s->noheader ? BUSY_STATE : INIT_STATE;
 320    strm->adler = 1;
 321    s->last_flush = Z_NO_FLUSH;
 322
 323    zlib_tr_init(s);
 324    lm_init(s);
 325
 326    return Z_OK;
 327}
 328
 329/* ========================================================================= */
 330#if 0
 331int zlib_deflateParams(
 332        z_streamp strm,
 333        int level,
 334        int strategy
 335)
 336{
 337    deflate_state *s;
 338    compress_func func;
 339    int err = Z_OK;
 340
 341    if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
 342    s = (deflate_state *) strm->state;
 343
 344    if (level == Z_DEFAULT_COMPRESSION) {
 345        level = 6;
 346    }
 347    if (level < 0 || level > 9 || strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
 348        return Z_STREAM_ERROR;
 349    }
 350    func = configuration_table[s->level].func;
 351
 352    if (func != configuration_table[level].func && strm->total_in != 0) {
 353        /* Flush the last buffer: */
 354        err = zlib_deflate(strm, Z_PARTIAL_FLUSH);
 355    }
 356    if (s->level != level) {
 357        s->level = level;
 358        s->max_lazy_match   = configuration_table[level].max_lazy;
 359        s->good_match       = configuration_table[level].good_length;
 360        s->nice_match       = configuration_table[level].nice_length;
 361        s->max_chain_length = configuration_table[level].max_chain;
 362    }
 363    s->strategy = strategy;
 364    return err;
 365}
 366#endif  /*  0  */
 367
 368/* =========================================================================
 369 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
 370 * IN assertion: the stream state is correct and there is enough room in
 371 * pending_buf.
 372 */
 373static void putShortMSB(
 374        deflate_state *s,
 375        uInt b
 376)
 377{
 378    put_byte(s, (Byte)(b >> 8));
 379    put_byte(s, (Byte)(b & 0xff));
 380}   
 381
 382/* =========================================================================
 383 * Flush as much pending output as possible. All deflate() output goes
 384 * through this function so some applications may wish to modify it
 385 * to avoid allocating a large strm->next_out buffer and copying into it.
 386 * (See also read_buf()).
 387 */
 388static void flush_pending(
 389        z_streamp strm
 390)
 391{
 392    deflate_state *s = (deflate_state *) strm->state;
 393    unsigned len = s->pending;
 394
 395    if (len > strm->avail_out) len = strm->avail_out;
 396    if (len == 0) return;
 397
 398    if (strm->next_out != NULL) {
 399        memcpy(strm->next_out, s->pending_out, len);
 400        strm->next_out += len;
 401    }
 402    s->pending_out += len;
 403    strm->total_out += len;
 404    strm->avail_out  -= len;
 405    s->pending -= len;
 406    if (s->pending == 0) {
 407        s->pending_out = s->pending_buf;
 408    }
 409}
 410
 411/* ========================================================================= */
 412int zlib_deflate(
 413        z_streamp strm,
 414        int flush
 415)
 416{
 417    int old_flush; /* value of flush param for previous deflate call */
 418    deflate_state *s;
 419
 420    if (strm == NULL || strm->state == NULL ||
 421        flush > Z_FINISH || flush < 0) {
 422        return Z_STREAM_ERROR;
 423    }
 424    s = (deflate_state *) strm->state;
 425
 426    if ((strm->next_in == NULL && strm->avail_in != 0) ||
 427        (s->status == FINISH_STATE && flush != Z_FINISH)) {
 428        return Z_STREAM_ERROR;
 429    }
 430    if (strm->avail_out == 0) return Z_BUF_ERROR;
 431
 432    s->strm = strm; /* just in case */
 433    old_flush = s->last_flush;
 434    s->last_flush = flush;
 435
 436    /* Write the zlib header */
 437    if (s->status == INIT_STATE) {
 438
 439        uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
 440        uInt level_flags = (s->level-1) >> 1;
 441
 442        if (level_flags > 3) level_flags = 3;
 443        header |= (level_flags << 6);
 444        if (s->strstart != 0) header |= PRESET_DICT;
 445        header += 31 - (header % 31);
 446
 447        s->status = BUSY_STATE;
 448        putShortMSB(s, header);
 449
 450        /* Save the adler32 of the preset dictionary: */
 451        if (s->strstart != 0) {
 452            putShortMSB(s, (uInt)(strm->adler >> 16));
 453            putShortMSB(s, (uInt)(strm->adler & 0xffff));
 454        }
 455        strm->adler = 1L;
 456    }
 457
 458    /* Flush as much pending output as possible */
 459    if (s->pending != 0) {
 460        flush_pending(strm);
 461        if (strm->avail_out == 0) {
 462            /* Since avail_out is 0, deflate will be called again with
 463             * more output space, but possibly with both pending and
 464             * avail_in equal to zero. There won't be anything to do,
 465             * but this is not an error situation so make sure we
 466             * return OK instead of BUF_ERROR at next call of deflate:
 467             */
 468            s->last_flush = -1;
 469            return Z_OK;
 470        }
 471
 472    /* Make sure there is something to do and avoid duplicate consecutive
 473     * flushes. For repeated and useless calls with Z_FINISH, we keep
 474     * returning Z_STREAM_END instead of Z_BUFF_ERROR.
 475     */
 476    } else if (strm->avail_in == 0 && flush <= old_flush &&
 477               flush != Z_FINISH) {
 478        return Z_BUF_ERROR;
 479    }
 480
 481    /* User must not provide more input after the first FINISH: */
 482    if (s->status == FINISH_STATE && strm->avail_in != 0) {
 483        return Z_BUF_ERROR;
 484    }
 485
 486    /* Start a new block or continue the current one.
 487     */
 488    if (strm->avail_in != 0 || s->lookahead != 0 ||
 489        (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
 490        block_state bstate;
 491
 492        bstate = (*(configuration_table[s->level].func))(s, flush);
 493
 494        if (bstate == finish_started || bstate == finish_done) {
 495            s->status = FINISH_STATE;
 496        }
 497        if (bstate == need_more || bstate == finish_started) {
 498            if (strm->avail_out == 0) {
 499                s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
 500            }
 501            return Z_OK;
 502            /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
 503             * of deflate should use the same flush parameter to make sure
 504             * that the flush is complete. So we don't have to output an
 505             * empty block here, this will be done at next call. This also
 506             * ensures that for a very small output buffer, we emit at most
 507             * one empty block.
 508             */
 509        }
 510        if (bstate == block_done) {
 511            if (flush == Z_PARTIAL_FLUSH) {
 512                zlib_tr_align(s);
 513            } else if (flush == Z_PACKET_FLUSH) {
 514                /* Output just the 3-bit `stored' block type value,
 515                   but not a zero length. */
 516                zlib_tr_stored_type_only(s);
 517            } else { /* FULL_FLUSH or SYNC_FLUSH */
 518                zlib_tr_stored_block(s, (char*)0, 0L, 0);
 519                /* For a full flush, this empty block will be recognized
 520                 * as a special marker by inflate_sync().
 521                 */
 522                if (flush == Z_FULL_FLUSH) {
 523                    CLEAR_HASH(s);             /* forget history */
 524                }
 525            }
 526            flush_pending(strm);
 527            if (strm->avail_out == 0) {
 528              s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
 529              return Z_OK;
 530            }
 531        }
 532    }
 533    Assert(strm->avail_out > 0, "bug2");
 534
 535    if (flush != Z_FINISH) return Z_OK;
 536    if (s->noheader) return Z_STREAM_END;
 537
 538    /* Write the zlib trailer (adler32) */
 539    putShortMSB(s, (uInt)(strm->adler >> 16));
 540    putShortMSB(s, (uInt)(strm->adler & 0xffff));
 541    flush_pending(strm);
 542    /* If avail_out is zero, the application will call deflate again
 543     * to flush the rest.
 544     */
 545    s->noheader = -1; /* write the trailer only once! */
 546    return s->pending != 0 ? Z_OK : Z_STREAM_END;
 547}
 548
 549/* ========================================================================= */
 550int zlib_deflateEnd(
 551        z_streamp strm
 552)
 553{
 554    int status;
 555    deflate_state *s;
 556
 557    if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
 558    s = (deflate_state *) strm->state;
 559
 560    status = s->status;
 561    if (status != INIT_STATE && status != BUSY_STATE &&
 562        status != FINISH_STATE) {
 563      return Z_STREAM_ERROR;
 564    }
 565
 566    strm->state = NULL;
 567
 568    return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
 569}
 570
 571/* =========================================================================
 572 * Copy the source state to the destination state.
 573 */
 574#if 0
 575int zlib_deflateCopy (
 576        z_streamp dest,
 577        z_streamp source
 578)
 579{
 580#ifdef MAXSEG_64K
 581    return Z_STREAM_ERROR;
 582#else
 583    deflate_state *ds;
 584    deflate_state *ss;
 585    ush *overlay;
 586    deflate_workspace *mem;
 587
 588
 589    if (source == NULL || dest == NULL || source->state == NULL) {
 590        return Z_STREAM_ERROR;
 591    }
 592
 593    ss = (deflate_state *) source->state;
 594
 595    *dest = *source;
 596
 597    mem = (deflate_workspace *) dest->workspace;
 598
 599    ds = &(mem->deflate_memory);
 600
 601    dest->state = (struct internal_state *) ds;
 602    *ds = *ss;
 603    ds->strm = dest;
 604
 605    ds->window = (Byte *) mem->window_memory;
 606    ds->prev   = (Pos *)  mem->prev_memory;
 607    ds->head   = (Pos *)  mem->head_memory;
 608    overlay = (ush *) mem->overlay_memory;
 609    ds->pending_buf = (uch *) overlay;
 610
 611    memcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
 612    memcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
 613    memcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
 614    memcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
 615
 616    ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
 617    ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
 618    ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
 619
 620    ds->l_desc.dyn_tree = ds->dyn_ltree;
 621    ds->d_desc.dyn_tree = ds->dyn_dtree;
 622    ds->bl_desc.dyn_tree = ds->bl_tree;
 623
 624    return Z_OK;
 625#endif
 626}
 627#endif  /*  0  */
 628
 629/* ===========================================================================
 630 * Read a new buffer from the current input stream, update the adler32
 631 * and total number of bytes read.  All deflate() input goes through
 632 * this function so some applications may wish to modify it to avoid
 633 * allocating a large strm->next_in buffer and copying from it.
 634 * (See also flush_pending()).
 635 */
 636static int read_buf(
 637        z_streamp strm,
 638        Byte *buf,
 639        unsigned size
 640)
 641{
 642    unsigned len = strm->avail_in;
 643
 644    if (len > size) len = size;
 645    if (len == 0) return 0;
 646
 647    strm->avail_in  -= len;
 648
 649    if (!((deflate_state *)(strm->state))->noheader) {
 650        strm->adler = zlib_adler32(strm->adler, strm->next_in, len);
 651    }
 652    memcpy(buf, strm->next_in, len);
 653    strm->next_in  += len;
 654    strm->total_in += len;
 655
 656    return (int)len;
 657}
 658
 659/* ===========================================================================
 660 * Initialize the "longest match" routines for a new zlib stream
 661 */
 662static void lm_init(
 663        deflate_state *s
 664)
 665{
 666    s->window_size = (ulg)2L*s->w_size;
 667
 668    CLEAR_HASH(s);
 669
 670    /* Set the default configuration parameters:
 671     */
 672    s->max_lazy_match   = configuration_table[s->level].max_lazy;
 673    s->good_match       = configuration_table[s->level].good_length;
 674    s->nice_match       = configuration_table[s->level].nice_length;
 675    s->max_chain_length = configuration_table[s->level].max_chain;
 676
 677    s->strstart = 0;
 678    s->block_start = 0L;
 679    s->lookahead = 0;
 680    s->match_length = s->prev_length = MIN_MATCH-1;
 681    s->match_available = 0;
 682    s->ins_h = 0;
 683}
 684
 685/* ===========================================================================
 686 * Set match_start to the longest match starting at the given string and
 687 * return its length. Matches shorter or equal to prev_length are discarded,
 688 * in which case the result is equal to prev_length and match_start is
 689 * garbage.
 690 * IN assertions: cur_match is the head of the hash chain for the current
 691 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
 692 * OUT assertion: the match length is not greater than s->lookahead.
 693 */
 694/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
 695 * match.S. The code will be functionally equivalent.
 696 */
 697static uInt longest_match(
 698        deflate_state *s,
 699        IPos cur_match                  /* current match */
 700)
 701{
 702    unsigned chain_length = s->max_chain_length;/* max hash chain length */
 703    register Byte *scan = s->window + s->strstart; /* current string */
 704    register Byte *match;                       /* matched string */
 705    register int len;                           /* length of current match */
 706    int best_len = s->prev_length;              /* best match length so far */
 707    int nice_match = s->nice_match;             /* stop if match long enough */
 708    IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
 709        s->strstart - (IPos)MAX_DIST(s) : NIL;
 710    /* Stop when cur_match becomes <= limit. To simplify the code,
 711     * we prevent matches with the string of window index 0.
 712     */
 713    Pos *prev = s->prev;
 714    uInt wmask = s->w_mask;
 715
 716#ifdef UNALIGNED_OK
 717    /* Compare two bytes at a time. Note: this is not always beneficial.
 718     * Try with and without -DUNALIGNED_OK to check.
 719     */
 720    register Byte *strend = s->window + s->strstart + MAX_MATCH - 1;
 721    register ush scan_start = *(ush*)scan;
 722    register ush scan_end   = *(ush*)(scan+best_len-1);
 723#else
 724    register Byte *strend = s->window + s->strstart + MAX_MATCH;
 725    register Byte scan_end1  = scan[best_len-1];
 726    register Byte scan_end   = scan[best_len];
 727#endif
 728
 729    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
 730     * It is easy to get rid of this optimization if necessary.
 731     */
 732    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
 733
 734    /* Do not waste too much time if we already have a good match: */
 735    if (s->prev_length >= s->good_match) {
 736        chain_length >>= 2;
 737    }
 738    /* Do not look for matches beyond the end of the input. This is necessary
 739     * to make deflate deterministic.
 740     */
 741    if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
 742
 743    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
 744
 745    do {
 746        Assert(cur_match < s->strstart, "no future");
 747        match = s->window + cur_match;
 748
 749        /* Skip to next match if the match length cannot increase
 750         * or if the match length is less than 2:
 751         */
 752#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
 753        /* This code assumes sizeof(unsigned short) == 2. Do not use
 754         * UNALIGNED_OK if your compiler uses a different size.
 755         */
 756        if (*(ush*)(match+best_len-1) != scan_end ||
 757            *(ush*)match != scan_start) continue;
 758
 759        /* It is not necessary to compare scan[2] and match[2] since they are
 760         * always equal when the other bytes match, given that the hash keys
 761         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
 762         * strstart+3, +5, ... up to strstart+257. We check for insufficient
 763         * lookahead only every 4th comparison; the 128th check will be made
 764         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
 765         * necessary to put more guard bytes at the end of the window, or
 766         * to check more often for insufficient lookahead.
 767         */
 768        Assert(scan[2] == match[2], "scan[2]?");
 769        scan++, match++;
 770        do {
 771        } while (*(ush*)(scan+=2) == *(ush*)(match+=2) &&
 772                 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
 773                 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
 774                 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
 775                 scan < strend);
 776        /* The funny "do {}" generates better code on most compilers */
 777
 778        /* Here, scan <= window+strstart+257 */
 779        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
 780        if (*scan == *match) scan++;
 781
 782        len = (MAX_MATCH - 1) - (int)(strend-scan);
 783        scan = strend - (MAX_MATCH-1);
 784
 785#else /* UNALIGNED_OK */
 786
 787        if (match[best_len]   != scan_end  ||
 788            match[best_len-1] != scan_end1 ||
 789            *match            != *scan     ||
 790            *++match          != scan[1])      continue;
 791
 792        /* The check at best_len-1 can be removed because it will be made
 793         * again later. (This heuristic is not always a win.)
 794         * It is not necessary to compare scan[2] and match[2] since they
 795         * are always equal when the other bytes match, given that
 796         * the hash keys are equal and that HASH_BITS >= 8.
 797         */
 798        scan += 2, match++;
 799        Assert(*scan == *match, "match[2]?");
 800
 801        /* We check for insufficient lookahead only every 8th comparison;
 802         * the 256th check will be made at strstart+258.
 803         */
 804        do {
 805        } while (*++scan == *++match && *++scan == *++match &&
 806                 *++scan == *++match && *++scan == *++match &&
 807                 *++scan == *++match && *++scan == *++match &&
 808                 *++scan == *++match && *++scan == *++match &&
 809                 scan < strend);
 810
 811        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
 812
 813        len = MAX_MATCH - (int)(strend - scan);
 814        scan = strend - MAX_MATCH;
 815
 816#endif /* UNALIGNED_OK */
 817
 818        if (len > best_len) {
 819            s->match_start = cur_match;
 820            best_len = len;
 821            if (len >= nice_match) break;
 822#ifdef UNALIGNED_OK
 823            scan_end = *(ush*)(scan+best_len-1);
 824#else
 825            scan_end1  = scan[best_len-1];
 826            scan_end   = scan[best_len];
 827#endif
 828        }
 829    } while ((cur_match = prev[cur_match & wmask]) > limit
 830             && --chain_length != 0);
 831
 832    if ((uInt)best_len <= s->lookahead) return best_len;
 833    return s->lookahead;
 834}
 835
 836#ifdef DEBUG_ZLIB
 837/* ===========================================================================
 838 * Check that the match at match_start is indeed a match.
 839 */
 840static void check_match(
 841        deflate_state *s,
 842        IPos start,
 843        IPos match,
 844        int length
 845)
 846{
 847    /* check that the match is indeed a match */
 848    if (memcmp((char *)s->window + match,
 849                (char *)s->window + start, length) != EQUAL) {
 850        fprintf(stderr, " start %u, match %u, length %d\n",
 851                start, match, length);
 852        do {
 853            fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
 854        } while (--length != 0);
 855        z_error("invalid match");
 856    }
 857    if (z_verbose > 1) {
 858        fprintf(stderr,"\\[%d,%d]", start-match, length);
 859        do { putc(s->window[start++], stderr); } while (--length != 0);
 860    }
 861}
 862#else
 863#  define check_match(s, start, match, length)
 864#endif
 865
 866/* ===========================================================================
 867 * Fill the window when the lookahead becomes insufficient.
 868 * Updates strstart and lookahead.
 869 *
 870 * IN assertion: lookahead < MIN_LOOKAHEAD
 871 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
 872 *    At least one byte has been read, or avail_in == 0; reads are
 873 *    performed for at least two bytes (required for the zip translate_eol
 874 *    option -- not supported here).
 875 */
 876static void fill_window(
 877        deflate_state *s
 878)
 879{
 880    register unsigned n, m;
 881    register Pos *p;
 882    unsigned more;    /* Amount of free space at the end of the window. */
 883    uInt wsize = s->w_size;
 884
 885    do {
 886        more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
 887
 888        /* Deal with !@#$% 64K limit: */
 889        if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
 890            more = wsize;
 891
 892        } else if (more == (unsigned)(-1)) {
 893            /* Very unlikely, but possible on 16 bit machine if strstart == 0
 894             * and lookahead == 1 (input done one byte at time)
 895             */
 896            more--;
 897
 898        /* If the window is almost full and there is insufficient lookahead,
 899         * move the upper half to the lower one to make room in the upper half.
 900         */
 901        } else if (s->strstart >= wsize+MAX_DIST(s)) {
 902
 903            memcpy((char *)s->window, (char *)s->window+wsize,
 904                   (unsigned)wsize);
 905            s->match_start -= wsize;
 906            s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
 907            s->block_start -= (long) wsize;
 908
 909            /* Slide the hash table (could be avoided with 32 bit values
 910               at the expense of memory usage). We slide even when level == 0
 911               to keep the hash table consistent if we switch back to level > 0
 912               later. (Using level 0 permanently is not an optimal usage of
 913               zlib, so we don't care about this pathological case.)
 914             */
 915            n = s->hash_size;
 916            p = &s->head[n];
 917            do {
 918                m = *--p;
 919                *p = (Pos)(m >= wsize ? m-wsize : NIL);
 920            } while (--n);
 921
 922            n = wsize;
 923            p = &s->prev[n];
 924            do {
 925                m = *--p;
 926                *p = (Pos)(m >= wsize ? m-wsize : NIL);
 927                /* If n is not on any hash chain, prev[n] is garbage but
 928                 * its value will never be used.
 929                 */
 930            } while (--n);
 931            more += wsize;
 932        }
 933        if (s->strm->avail_in == 0) return;
 934
 935        /* If there was no sliding:
 936         *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
 937         *    more == window_size - lookahead - strstart
 938         * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
 939         * => more >= window_size - 2*WSIZE + 2
 940         * In the BIG_MEM or MMAP case (not yet supported),
 941         *   window_size == input_size + MIN_LOOKAHEAD  &&
 942         *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
 943         * Otherwise, window_size == 2*WSIZE so more >= 2.
 944         * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
 945         */
 946        Assert(more >= 2, "more < 2");
 947
 948        n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
 949        s->lookahead += n;
 950
 951        /* Initialize the hash value now that we have some input: */
 952        if (s->lookahead >= MIN_MATCH) {
 953            s->ins_h = s->window[s->strstart];
 954            UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
 955#if MIN_MATCH != 3
 956            Call UPDATE_HASH() MIN_MATCH-3 more times
 957#endif
 958        }
 959        /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
 960         * but this is not important since only literal bytes will be emitted.
 961         */
 962
 963    } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
 964}
 965
 966/* ===========================================================================
 967 * Flush the current block, with given end-of-file flag.
 968 * IN assertion: strstart is set to the end of the current match.
 969 */
 970#define FLUSH_BLOCK_ONLY(s, eof) { \
 971   zlib_tr_flush_block(s, (s->block_start >= 0L ? \
 972                   (char *)&s->window[(unsigned)s->block_start] : \
 973                   NULL), \
 974                (ulg)((long)s->strstart - s->block_start), \
 975                (eof)); \
 976   s->block_start = s->strstart; \
 977   flush_pending(s->strm); \
 978   Tracev((stderr,"[FLUSH]")); \
 979}
 980
 981/* Same but force premature exit if necessary. */
 982#define FLUSH_BLOCK(s, eof) { \
 983   FLUSH_BLOCK_ONLY(s, eof); \
 984   if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
 985}
 986
 987/* ===========================================================================
 988 * Copy without compression as much as possible from the input stream, return
 989 * the current block state.
 990 * This function does not insert new strings in the dictionary since
 991 * uncompressible data is probably not useful. This function is used
 992 * only for the level=0 compression option.
 993 * NOTE: this function should be optimized to avoid extra copying from
 994 * window to pending_buf.
 995 */
 996static block_state deflate_stored(
 997        deflate_state *s,
 998        int flush
 999)
1000{
1001    /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1002     * to pending_buf_size, and each stored block has a 5 byte header:
1003     */
1004    ulg max_block_size = 0xffff;
1005    ulg max_start;
1006
1007    if (max_block_size > s->pending_buf_size - 5) {
1008        max_block_size = s->pending_buf_size - 5;
1009    }
1010
1011    /* Copy as much as possible from input to output: */
1012    for (;;) {
1013        /* Fill the window as much as possible: */
1014        if (s->lookahead <= 1) {
1015
1016            Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1017                   s->block_start >= (long)s->w_size, "slide too late");
1018
1019            fill_window(s);
1020            if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1021
1022            if (s->lookahead == 0) break; /* flush the current block */
1023        }
1024        Assert(s->block_start >= 0L, "block gone");
1025
1026        s->strstart += s->lookahead;
1027        s->lookahead = 0;
1028
1029        /* Emit a stored block if pending_buf will be full: */
1030        max_start = s->block_start + max_block_size;
1031        if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1032            /* strstart == 0 is possible when wraparound on 16-bit machine */
1033            s->lookahead = (uInt)(s->strstart - max_start);
1034            s->strstart = (uInt)max_start;
1035            FLUSH_BLOCK(s, 0);
1036        }
1037        /* Flush if we may have to slide, otherwise block_start may become
1038         * negative and the data will be gone:
1039         */
1040        if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1041            FLUSH_BLOCK(s, 0);
1042        }
1043    }
1044    FLUSH_BLOCK(s, flush == Z_FINISH);
1045    return flush == Z_FINISH ? finish_done : block_done;
1046}
1047
1048/* ===========================================================================
1049 * Compress as much as possible from the input stream, return the current
1050 * block state.
1051 * This function does not perform lazy evaluation of matches and inserts
1052 * new strings in the dictionary only for unmatched strings or for short
1053 * matches. It is used only for the fast compression options.
1054 */
1055static block_state deflate_fast(
1056        deflate_state *s,
1057        int flush
1058)
1059{
1060    IPos hash_head = NIL; /* head of the hash chain */
1061    int bflush;           /* set if current block must be flushed */
1062
1063    for (;;) {
1064        /* Make sure that we always have enough lookahead, except
1065         * at the end of the input file. We need MAX_MATCH bytes
1066         * for the next match, plus MIN_MATCH bytes to insert the
1067         * string following the next match.
1068         */
1069        if (s->lookahead < MIN_LOOKAHEAD) {
1070            fill_window(s);
1071            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1072                return need_more;
1073            }
1074            if (s->lookahead == 0) break; /* flush the current block */
1075        }
1076
1077        /* Insert the string window[strstart .. strstart+2] in the
1078         * dictionary, and set hash_head to the head of the hash chain:
1079         */
1080        if (s->lookahead >= MIN_MATCH) {
1081            INSERT_STRING(s, s->strstart, hash_head);
1082        }
1083
1084        /* Find the longest match, discarding those <= prev_length.
1085         * At this point we have always match_length < MIN_MATCH
1086         */
1087        if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1088            /* To simplify the code, we prevent matches with the string
1089             * of window index 0 (in particular we have to avoid a match
1090             * of the string with itself at the start of the input file).
1091             */
1092            if (s->strategy != Z_HUFFMAN_ONLY) {
1093                s->match_length = longest_match (s, hash_head);
1094            }
1095            /* longest_match() sets match_start */
1096        }
1097        if (s->match_length >= MIN_MATCH) {
1098            check_match(s, s->strstart, s->match_start, s->match_length);
1099
1100            bflush = zlib_tr_tally(s, s->strstart - s->match_start,
1101                               s->match_length - MIN_MATCH);
1102
1103            s->lookahead -= s->match_length;
1104
1105            /* Insert new strings in the hash table only if the match length
1106             * is not too large. This saves time but degrades compression.
1107             */
1108            if (s->match_length <= s->max_insert_length &&
1109                s->lookahead >= MIN_MATCH) {
1110                s->match_length--; /* string at strstart already in hash table */
1111                do {
1112                    s->strstart++;
1113                    INSERT_STRING(s, s->strstart, hash_head);
1114                    /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1115                     * always MIN_MATCH bytes ahead.
1116                     */
1117                } while (--s->match_length != 0);
1118                s->strstart++; 
1119            } else {
1120                s->strstart += s->match_length;
1121                s->match_length = 0;
1122                s->ins_h = s->window[s->strstart];
1123                UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1124#if MIN_MATCH != 3
1125                Call UPDATE_HASH() MIN_MATCH-3 more times
1126#endif
1127                /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1128                 * matter since it will be recomputed at next deflate call.
1129                 */
1130            }
1131        } else {
1132            /* No match, output a literal byte */
1133            Tracevv((stderr,"%c", s->window[s->strstart]));
1134            bflush = zlib_tr_tally (s, 0, s->window[s->strstart]);
1135            s->lookahead--;
1136            s->strstart++; 
1137        }
1138        if (bflush) FLUSH_BLOCK(s, 0);
1139    }
1140    FLUSH_BLOCK(s, flush == Z_FINISH);
1141    return flush == Z_FINISH ? finish_done : block_done;
1142}
1143
1144/* ===========================================================================
1145 * Same as above, but achieves better compression. We use a lazy
1146 * evaluation for matches: a match is finally adopted only if there is
1147 * no better match at the next window position.
1148 */
1149static block_state deflate_slow(
1150        deflate_state *s,
1151        int flush
1152)
1153{
1154    IPos hash_head = NIL;    /* head of hash chain */
1155    int bflush;              /* set if current block must be flushed */
1156
1157    /* Process the input block. */
1158    for (;;) {
1159        /* Make sure that we always have enough lookahead, except
1160         * at the end of the input file. We need MAX_MATCH bytes
1161         * for the next match, plus MIN_MATCH bytes to insert the
1162         * string following the next match.
1163         */
1164        if (s->lookahead < MIN_LOOKAHEAD) {
1165            fill_window(s);
1166            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1167                return need_more;
1168            }
1169            if (s->lookahead == 0) break; /* flush the current block */
1170        }
1171
1172        /* Insert the string window[strstart .. strstart+2] in the
1173         * dictionary, and set hash_head to the head of the hash chain:
1174         */
1175        if (s->lookahead >= MIN_MATCH) {
1176            INSERT_STRING(s, s->strstart, hash_head);
1177        }
1178
1179        /* Find the longest match, discarding those <= prev_length.
1180         */
1181        s->prev_length = s->match_length, s->prev_match = s->match_start;
1182        s->match_length = MIN_MATCH-1;
1183
1184        if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1185            s->strstart - hash_head <= MAX_DIST(s)) {
1186            /* To simplify the code, we prevent matches with the string
1187             * of window index 0 (in particular we have to avoid a match
1188             * of the string with itself at the start of the input file).
1189             */
1190            if (s->strategy != Z_HUFFMAN_ONLY) {
1191                s->match_length = longest_match (s, hash_head);
1192            }
1193            /* longest_match() sets match_start */
1194
1195            if (s->match_length <= 5 && (s->strategy == Z_FILTERED ||
1196                 (s->match_length == MIN_MATCH &&
1197                  s->strstart - s->match_start > TOO_FAR))) {
1198
1199                /* If prev_match is also MIN_MATCH, match_start is garbage
1200                 * but we will ignore the current match anyway.
1201                 */
1202                s->match_length = MIN_MATCH-1;
1203            }
1204        }
1205        /* If there was a match at the previous step and the current
1206         * match is not better, output the previous match:
1207         */
1208        if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1209            uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1210            /* Do not insert strings in hash table beyond this. */
1211
1212            check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1213
1214            bflush = zlib_tr_tally(s, s->strstart -1 - s->prev_match,
1215                                   s->prev_length - MIN_MATCH);
1216
1217            /* Insert in hash table all strings up to the end of the match.
1218             * strstart-1 and strstart are already inserted. If there is not
1219             * enough lookahead, the last two strings are not inserted in
1220             * the hash table.
1221             */
1222            s->lookahead -= s->prev_length-1;
1223            s->prev_length -= 2;
1224            do {
1225                if (++s->strstart <= max_insert) {
1226                    INSERT_STRING(s, s->strstart, hash_head);
1227                }
1228            } while (--s->prev_length != 0);
1229            s->match_available = 0;
1230            s->match_length = MIN_MATCH-1;
1231            s->strstart++;
1232
1233            if (bflush) FLUSH_BLOCK(s, 0);
1234
1235        } else if (s->match_available) {
1236            /* If there was no match at the previous position, output a
1237             * single literal. If there was a match but the current match
1238             * is longer, truncate the previous match to a single literal.
1239             */
1240            Tracevv((stderr,"%c", s->window[s->strstart-1]));
1241            if (zlib_tr_tally (s, 0, s->window[s->strstart-1])) {
1242                FLUSH_BLOCK_ONLY(s, 0);
1243            }
1244            s->strstart++;
1245            s->lookahead--;
1246            if (s->strm->avail_out == 0) return need_more;
1247        } else {
1248            /* There is no previous match to compare with, wait for
1249             * the next step to decide.
1250             */
1251            s->match_available = 1;
1252            s->strstart++;
1253            s->lookahead--;
1254        }
1255    }
1256    Assert (flush != Z_NO_FLUSH, "no flush?");
1257    if (s->match_available) {
1258        Tracevv((stderr,"%c", s->window[s->strstart-1]));
1259        zlib_tr_tally (s, 0, s->window[s->strstart-1]);
1260        s->match_available = 0;
1261    }
1262    FLUSH_BLOCK(s, flush == Z_FINISH);
1263    return flush == Z_FINISH ? finish_done : block_done;
1264}
1265
1266int zlib_deflate_workspacesize(int windowBits, int memLevel)
1267{
1268    if (windowBits < 0) /* undocumented feature: suppress zlib header */
1269        windowBits = -windowBits;
1270
1271    /* Since the return value is typically passed to vmalloc() unchecked... */
1272    BUG_ON(memLevel < 1 || memLevel > MAX_MEM_LEVEL || windowBits < 9 ||
1273                                                        windowBits > 15);
1274
1275    return sizeof(deflate_workspace)
1276        + zlib_deflate_window_memsize(windowBits)
1277        + zlib_deflate_prev_memsize(windowBits)
1278        + zlib_deflate_head_memsize(memLevel)
1279        + zlib_deflate_overlay_memsize(memLevel);
1280}
1281
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