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      1 /* deflate.c -- compress data using the deflation algorithm
      2  * Copyright (C) 1995-2005 Jean-loup Gailly.
      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://www.ietf.org/rfc/rfc1951.txt
     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 /* @(#) $Id$ */
     51 
     52 #include "deflate.h"
     53 
     54 const char deflate_copyright[] =
     55    " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly ";
     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  */
     66 typedef 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 
     73 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
     74 /* Compression function. Returns the block state after the call. */
     75 
     76 local void fill_window    OF((deflate_state *s));
     77 local block_state deflate_stored OF((deflate_state *s, int flush));
     78 local block_state deflate_fast   OF((deflate_state *s, int flush));
     79 #ifndef FASTEST
     80 local block_state deflate_slow   OF((deflate_state *s, int flush));
     81 #endif
     82 local void lm_init        OF((deflate_state *s));
     83 local void putShortMSB    OF((deflate_state *s, uInt b));
     84 local void flush_pending  OF((z_streamp strm));
     85 local int read_buf        OF((z_streamp strm, Bytef *buf, unsigned size));
     86 #ifndef FASTEST
     87 #ifdef ASMV
     88       void match_init OF((void)); /* asm code initialization */
     89       uInt longest_match  OF((deflate_state *s, IPos cur_match));
     90 #else
     91 local uInt longest_match  OF((deflate_state *s, IPos cur_match));
     92 #endif
     93 #endif
     94 local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
     95 
     96 #ifdef DEBUG
     97 local  void check_match OF((deflate_state *s, IPos start, IPos match,
     98                             int length));
     99 #endif
    100 
    101 /* ===========================================================================
    102  * Local data
    103  */
    104 
    105 #define NIL 0
    106 /* Tail of hash chains */
    107 
    108 #ifndef TOO_FAR
    109 #  define TOO_FAR 4096
    110 #endif
    111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
    112 
    113 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
    114 /* Minimum amount of lookahead, except at the end of the input file.
    115  * See deflate.c for comments about the MIN_MATCH+1.
    116  */
    117 
    118 /* Values for max_lazy_match, good_match and max_chain_length, depending on
    119  * the desired pack level (0..9). The values given below have been tuned to
    120  * exclude worst case performance for pathological files. Better values may be
    121  * found for specific files.
    122  */
    123 typedef struct config_s {
    124    ush good_length; /* reduce lazy search above this match length */
    125    ush max_lazy;    /* do not perform lazy search above this match length */
    126    ush nice_length; /* quit search above this match length */
    127    ush max_chain;
    128    compress_func func;
    129 } config;
    130 
    131 #ifdef FASTEST
    132 local const config configuration_table[2] = {
    133 /*      good lazy nice chain */
    134 /* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
    135 /* 1 */ {4,    4,  8,    4, deflate_fast}}; /* max speed, no lazy matches */
    136 #else
    137 local const config configuration_table[10] = {
    138 /*      good lazy nice chain */
    139 /* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
    140 /* 1 */ {4,    4,  8,    4, deflate_fast}, /* max speed, no lazy matches */
    141 /* 2 */ {4,    5, 16,    8, deflate_fast},
    142 /* 3 */ {4,    6, 32,   32, deflate_fast},
    143 
    144 /* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
    145 /* 5 */ {8,   16, 32,   32, deflate_slow},
    146 /* 6 */ {8,   16, 128, 128, deflate_slow},
    147 /* 7 */ {8,   32, 128, 256, deflate_slow},
    148 /* 8 */ {32, 128, 258, 1024, deflate_slow},
    149 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
    150 #endif
    151 
    152 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
    153  * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
    154  * meaning.
    155  */
    156 
    157 #define EQUAL 0
    158 /* result of memcmp for equal strings */
    159 
    160 #ifndef NO_DUMMY_DECL
    161 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
    162 #endif
    163 
    164 /* ===========================================================================
    165  * Update a hash value with the given input byte
    166  * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
    167  *    input characters, so that a running hash key can be computed from the
    168  *    previous key instead of complete recalculation each time.
    169  */
    170 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
    171 
    172 
    173 /* ===========================================================================
    174  * Insert string str in the dictionary and set match_head to the previous head
    175  * of the hash chain (the most recent string with same hash key). Return
    176  * the previous length of the hash chain.
    177  * If this file is compiled with -DFASTEST, the compression level is forced
    178  * to 1, and no hash chains are maintained.
    179  * IN  assertion: all calls to to INSERT_STRING are made with consecutive
    180  *    input characters and the first MIN_MATCH bytes of str are valid
    181  *    (except for the last MIN_MATCH-1 bytes of the input file).
    182  */
    183 #ifdef FASTEST
    184 #define INSERT_STRING(s, str, match_head) \
    185    (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
    186     match_head = s->head[s->ins_h], \
    187     s->head[s->ins_h] = (Pos)(str))
    188 #else
    189 #define INSERT_STRING(s, str, match_head) \
    190    (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
    191     match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
    192     s->head[s->ins_h] = (Pos)(str))
    193 #endif
    194 
    195 /* ===========================================================================
    196  * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
    197  * prev[] will be initialized on the fly.
    198  */
    199 #define CLEAR_HASH(s) \
    200     s->head[s->hash_size-1] = NIL; \
    201     zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
    202 
    203 /* ========================================================================= */
    204 int ZEXPORT deflateInit_(strm, level, version, stream_size)
    205     z_streamp strm;
    206     int level;
    207     const char *version;
    208     int stream_size;
    209 {
    210     return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
    211                          Z_DEFAULT_STRATEGY, version, stream_size);
    212     /* To do: ignore strm->next_in if we use it as window */
    213 }
    214 
    215 /* ========================================================================= */
    216 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
    217                   version, stream_size)
    218     z_streamp strm;
    219     int  level;
    220     int  method;
    221     int  windowBits;
    222     int  memLevel;
    223     int  strategy;
    224     const char *version;
    225     int stream_size;
    226 {
    227     deflate_state *s;
    228     int wrap = 1;
    229     static const char my_version[] = ZLIB_VERSION;
    230 
    231     ushf *overlay;
    232     /* We overlay pending_buf and d_buf+l_buf. This works since the average
    233      * output size for (length,distance) codes is <= 24 bits.
    234      */
    235 
    236     if (version == Z_NULL || version[0] != my_version[0] ||
    237         stream_size != sizeof(z_stream)) {
    238         return Z_VERSION_ERROR;
    239     }
    240     if (strm == Z_NULL) return Z_STREAM_ERROR;
    241 
    242     strm->msg = Z_NULL;
    243     if (strm->zalloc == (alloc_func)0) {
    244         strm->zalloc = zcalloc;
    245         strm->opaque = (voidpf)0;
    246     }
    247     if (strm->zfree == (free_func)0) strm->zfree = zcfree;
    248 
    249 #ifdef FASTEST
    250     if (level != 0) level = 1;
    251 #else
    252     if (level == Z_DEFAULT_COMPRESSION) level = 6;
    253 #endif
    254 
    255     if (windowBits < 0) { /* suppress zlib wrapper */
    256         wrap = 0;
    257         windowBits = -windowBits;
    258     }
    259 #ifdef GZIP
    260     else if (windowBits > 15) {
    261         wrap = 2;       /* write gzip wrapper instead */
    262         windowBits -= 16;
    263     }
    264 #endif
    265     if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
    266         windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
    267         strategy < 0 || strategy > Z_FIXED) {
    268         return Z_STREAM_ERROR;
    269     }
    270     if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */
    271     s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
    272     if (s == Z_NULL) return Z_MEM_ERROR;
    273     strm->state = (struct internal_state FAR *)s;
    274     s->strm = strm;
    275 
    276     s->wrap = wrap;
    277     s->gzhead = Z_NULL;
    278     s->w_bits = windowBits;
    279     s->w_size = 1 << s->w_bits;
    280     s->w_mask = s->w_size - 1;
    281 
    282     s->hash_bits = memLevel + 7;
    283     s->hash_size = 1 << s->hash_bits;
    284     s->hash_mask = s->hash_size - 1;
    285     s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
    286 
    287     s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
    288     s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
    289     s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
    290 
    291     s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
    292 
    293     overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
    294     s->pending_buf = (uchf *) overlay;
    295     s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
    296 
    297     if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
    298         s->pending_buf == Z_NULL) {
    299         s->status = FINISH_STATE;
    300         strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
    301         deflateEnd (strm);
    302         return Z_MEM_ERROR;
    303     }
    304     s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
    305     s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
    306 
    307     s->level = level;
    308     s->strategy = strategy;
    309     s->method = (Byte)method;
    310 
    311     return deflateReset(strm);
    312 }
    313 
    314 /* ========================================================================= */
    315 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
    316     z_streamp strm;
    317     const Bytef *dictionary;
    318     uInt  dictLength;
    319 {
    320     deflate_state *s;
    321     uInt length = dictLength;
    322     uInt n;
    323     IPos hash_head = 0;
    324 
    325     if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
    326         strm->state->wrap == 2 ||
    327         (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
    328         return Z_STREAM_ERROR;
    329 
    330     s = strm->state;
    331     if (s->wrap)
    332         strm->adler = adler32(strm->adler, dictionary, dictLength);
    333 
    334     if (length < MIN_MATCH) return Z_OK;
    335     if (length > MAX_DIST(s)) {
    336         length = MAX_DIST(s);
    337         dictionary += dictLength - length; /* use the tail of the dictionary */
    338     }
    339     zmemcpy(s->window, dictionary, length);
    340     s->strstart = length;
    341     s->block_start = (long)length;
    342 
    343     /* Insert all strings in the hash table (except for the last two bytes).
    344      * s->lookahead stays null, so s->ins_h will be recomputed at the next
    345      * call of fill_window.
    346      */
    347     s->ins_h = s->window[0];
    348     UPDATE_HASH(s, s->ins_h, s->window[1]);
    349     for (n = 0; n <= length - MIN_MATCH; n++) {
    350         INSERT_STRING(s, n, hash_head);
    351     }
    352     if (hash_head) hash_head = 0;  /* to make compiler happy */
    353     return Z_OK;
    354 }
    355 
    356 /* ========================================================================= */
    357 int ZEXPORT deflateReset (strm)
    358     z_streamp strm;
    359 {
    360     deflate_state *s;
    361 
    362     if (strm == Z_NULL || strm->state == Z_NULL ||
    363         strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
    364         return Z_STREAM_ERROR;
    365     }
    366 
    367     strm->total_in = strm->total_out = 0;
    368     strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
    369     strm->data_type = Z_UNKNOWN;
    370 
    371     s = (deflate_state *)strm->state;
    372     s->pending = 0;
    373     s->pending_out = s->pending_buf;
    374 
    375     if (s->wrap < 0) {
    376         s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
    377     }
    378     s->status = s->wrap ? INIT_STATE : BUSY_STATE;
    379     strm->adler =
    380 #ifdef GZIP
    381         s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
    382 #endif
    383         adler32(0L, Z_NULL, 0);
    384     s->last_flush = Z_NO_FLUSH;
    385 
    386     _tr_init(s);
    387     lm_init(s);
    388 
    389     return Z_OK;
    390 }
    391 
    392 /* ========================================================================= */
    393 int ZEXPORT deflateSetHeader (strm, head)
    394     z_streamp strm;
    395     gz_headerp head;
    396 {
    397     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
    398     if (strm->state->wrap != 2) return Z_STREAM_ERROR;
    399     strm->state->gzhead = head;
    400     return Z_OK;
    401 }
    402 
    403 /* ========================================================================= */
    404 int ZEXPORT deflatePrime (strm, bits, value)
    405     z_streamp strm;
    406     int bits;
    407     int value;
    408 {
    409     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
    410     strm->state->bi_valid = bits;
    411     strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
    412     return Z_OK;
    413 }
    414 
    415 /* ========================================================================= */
    416 int ZEXPORT deflateParams(strm, level, strategy)
    417     z_streamp strm;
    418     int level;
    419     int strategy;
    420 {
    421     deflate_state *s;
    422     compress_func func;
    423     int err = Z_OK;
    424 
    425     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
    426     s = strm->state;
    427 
    428 #ifdef FASTEST
    429     if (level != 0) level = 1;
    430 #else
    431     if (level == Z_DEFAULT_COMPRESSION) level = 6;
    432 #endif
    433     if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
    434         return Z_STREAM_ERROR;
    435     }
    436     func = configuration_table[s->level].func;
    437 
    438     if (func != configuration_table[level].func && strm->total_in != 0) {
    439         /* Flush the last buffer: */
    440         err = deflate(strm, Z_PARTIAL_FLUSH);
    441     }
    442     if (s->level != level) {
    443         s->level = level;
    444         s->max_lazy_match   = configuration_table[level].max_lazy;
    445         s->good_match       = configuration_table[level].good_length;
    446         s->nice_match       = configuration_table[level].nice_length;
    447         s->max_chain_length = configuration_table[level].max_chain;
    448     }
    449     s->strategy = strategy;
    450     return err;
    451 }
    452 
    453 /* ========================================================================= */
    454 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
    455     z_streamp strm;
    456     int good_length;
    457     int max_lazy;
    458     int nice_length;
    459     int max_chain;
    460 {
    461     deflate_state *s;
    462 
    463     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
    464     s = strm->state;
    465     s->good_match = good_length;
    466     s->max_lazy_match = max_lazy;
    467     s->nice_match = nice_length;
    468     s->max_chain_length = max_chain;
    469     return Z_OK;
    470 }
    471 
    472 /* =========================================================================
    473  * For the default windowBits of 15 and memLevel of 8, this function returns
    474  * a close to exact, as well as small, upper bound on the compressed size.
    475  * They are coded as constants here for a reason--if the #define's are
    476  * changed, then this function needs to be changed as well.  The return
    477  * value for 15 and 8 only works for those exact settings.
    478  *
    479  * For any setting other than those defaults for windowBits and memLevel,
    480  * the value returned is a conservative worst case for the maximum expansion
    481  * resulting from using fixed blocks instead of stored blocks, which deflate
    482  * can emit on compressed data for some combinations of the parameters.
    483  *
    484  * This function could be more sophisticated to provide closer upper bounds
    485  * for every combination of windowBits and memLevel, as well as wrap.
    486  * But even the conservative upper bound of about 14% expansion does not
    487  * seem onerous for output buffer allocation.
    488  */
    489 uLong ZEXPORT deflateBound(strm, sourceLen)
    490     z_streamp strm;
    491     uLong sourceLen;
    492 {
    493     deflate_state *s;
    494     uLong destLen;
    495 
    496     /* conservative upper bound */
    497     destLen = sourceLen +
    498               ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
    499 
    500     /* if can't get parameters, return conservative bound */
    501     if (strm == Z_NULL || strm->state == Z_NULL)
    502         return destLen;
    503 
    504     /* if not default parameters, return conservative bound */
    505     s = strm->state;
    506     if (s->w_bits != 15 || s->hash_bits != 8 + 7)
    507         return destLen;
    508 
    509     /* default settings: return tight bound for that case */
    510     return compressBound(sourceLen);
    511 }
    512 
    513 /* =========================================================================
    514  * Put a short in the pending buffer. The 16-bit value is put in MSB order.
    515  * IN assertion: the stream state is correct and there is enough room in
    516  * pending_buf.
    517  */
    518 local void putShortMSB (s, b)
    519     deflate_state *s;
    520     uInt b;
    521 {
    522     put_byte(s, (Byte)(b >> 8));
    523     put_byte(s, (Byte)(b & 0xff));
    524 }
    525 
    526 /* =========================================================================
    527  * Flush as much pending output as possible. All deflate() output goes
    528  * through this function so some applications may wish to modify it
    529  * to avoid allocating a large strm->next_out buffer and copying into it.
    530  * (See also read_buf()).
    531  */
    532 local void flush_pending(strm)
    533     z_streamp strm;
    534 {
    535     unsigned len = strm->state->pending;
    536 
    537     if (len > strm->avail_out) len = strm->avail_out;
    538     if (len == 0) return;
    539 
    540     zmemcpy(strm->next_out, strm->state->pending_out, len);
    541     strm->next_out  += len;
    542     strm->state->pending_out  += len;
    543     strm->total_out += len;
    544     strm->avail_out  -= len;
    545     strm->state->pending -= len;
    546     if (strm->state->pending == 0) {
    547         strm->state->pending_out = strm->state->pending_buf;
    548     }
    549 }
    550 
    551 /* ========================================================================= */
    552 int ZEXPORT deflate (strm, flush)
    553     z_streamp strm;
    554     int flush;
    555 {
    556     int old_flush; /* value of flush param for previous deflate call */
    557     deflate_state *s;
    558 
    559     if (strm == Z_NULL || strm->state == Z_NULL ||
    560         flush > Z_FINISH || flush < 0) {
    561         return Z_STREAM_ERROR;
    562     }
    563     s = strm->state;
    564 
    565     if (strm->next_out == Z_NULL ||
    566         (strm->next_in == Z_NULL && strm->avail_in != 0) ||
    567         (s->status == FINISH_STATE && flush != Z_FINISH)) {
    568         ERR_RETURN(strm, Z_STREAM_ERROR);
    569     }
    570     if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
    571 
    572     s->strm = strm; /* just in case */
    573     old_flush = s->last_flush;
    574     s->last_flush = flush;
    575 
    576     /* Write the header */
    577     if (s->status == INIT_STATE) {
    578 #ifdef GZIP
    579         if (s->wrap == 2) {
    580             strm->adler = crc32(0L, Z_NULL, 0);
    581             put_byte(s, 31);
    582             put_byte(s, 139);
    583             put_byte(s, 8);
    584             if (s->gzhead == NULL) {
    585                 put_byte(s, 0);
    586                 put_byte(s, 0);
    587                 put_byte(s, 0);
    588                 put_byte(s, 0);
    589                 put_byte(s, 0);
    590                 put_byte(s, s->level == 9 ? 2 :
    591                             (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
    592                              4 : 0));
    593                 put_byte(s, OS_CODE);
    594                 s->status = BUSY_STATE;
    595             }
    596             else {
    597                 put_byte(s, (s->gzhead->text ? 1 : 0) +
    598                             (s->gzhead->hcrc ? 2 : 0) +
    599                             (s->gzhead->extra == Z_NULL ? 0 : 4) +
    600                             (s->gzhead->name == Z_NULL ? 0 : 8) +
    601                             (s->gzhead->comment == Z_NULL ? 0 : 16)
    602                         );
    603                 put_byte(s, (Byte)(s->gzhead->time & 0xff));
    604                 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
    605                 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
    606                 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
    607                 put_byte(s, s->level == 9 ? 2 :
    608                             (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
    609                              4 : 0));
    610                 put_byte(s, s->gzhead->os & 0xff);
    611                 if (s->gzhead->extra != NULL) {
    612                     put_byte(s, s->gzhead->extra_len & 0xff);
    613                     put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
    614                 }
    615                 if (s->gzhead->hcrc)
    616                     strm->adler = crc32(strm->adler, s->pending_buf,
    617                                         s->pending);
    618                 s->gzindex = 0;
    619                 s->status = EXTRA_STATE;
    620             }
    621         }
    622         else
    623 #endif
    624         {
    625             uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
    626             uInt level_flags;
    627 
    628             if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
    629                 level_flags = 0;
    630             else if (s->level < 6)
    631                 level_flags = 1;
    632             else if (s->level == 6)
    633                 level_flags = 2;
    634             else
    635                 level_flags = 3;
    636             header |= (level_flags << 6);
    637             if (s->strstart != 0) header |= PRESET_DICT;
    638             header += 31 - (header % 31);
    639 
    640             s->status = BUSY_STATE;
    641             putShortMSB(s, header);
    642 
    643             /* Save the adler32 of the preset dictionary: */
    644             if (s->strstart != 0) {
    645                 putShortMSB(s, (uInt)(strm->adler >> 16));
    646                 putShortMSB(s, (uInt)(strm->adler & 0xffff));
    647             }
    648             strm->adler = adler32(0L, Z_NULL, 0);
    649         }
    650     }
    651 #ifdef GZIP
    652     if (s->status == EXTRA_STATE) {
    653         if (s->gzhead->extra != NULL) {
    654             uInt beg = s->pending;  /* start of bytes to update crc */
    655 
    656             while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
    657                 if (s->pending == s->pending_buf_size) {
    658                     if (s->gzhead->hcrc && s->pending > beg)
    659                         strm->adler = crc32(strm->adler, s->pending_buf + beg,
    660                                             s->pending - beg);
    661                     flush_pending(strm);
    662                     beg = s->pending;
    663                     if (s->pending == s->pending_buf_size)
    664                         break;
    665                 }
    666                 put_byte(s, s->gzhead->extra[s->gzindex]);
    667                 s->gzindex++;
    668             }
    669             if (s->gzhead->hcrc && s->pending > beg)
    670                 strm->adler = crc32(strm->adler, s->pending_buf + beg,
    671                                     s->pending - beg);
    672             if (s->gzindex == s->gzhead->extra_len) {
    673                 s->gzindex = 0;
    674                 s->status = NAME_STATE;
    675             }
    676         }
    677         else
    678             s->status = NAME_STATE;
    679     }
    680     if (s->status == NAME_STATE) {
    681         if (s->gzhead->name != NULL) {
    682             uInt beg = s->pending;  /* start of bytes to update crc */
    683             int val;
    684 
    685             do {
    686                 if (s->pending == s->pending_buf_size) {
    687                     if (s->gzhead->hcrc && s->pending > beg)
    688                         strm->adler = crc32(strm->adler, s->pending_buf + beg,
    689                                             s->pending - beg);
    690                     flush_pending(strm);
    691                     beg = s->pending;
    692                     if (s->pending == s->pending_buf_size) {
    693                         val = 1;
    694                         break;
    695                     }
    696                 }
    697                 val = s->gzhead->name[s->gzindex++];
    698                 put_byte(s, val);
    699             } while (val != 0);
    700             if (s->gzhead->hcrc && s->pending > beg)
    701                 strm->adler = crc32(strm->adler, s->pending_buf + beg,
    702                                     s->pending - beg);
    703             if (val == 0) {
    704                 s->gzindex = 0;
    705                 s->status = COMMENT_STATE;
    706             }
    707         }
    708         else
    709             s->status = COMMENT_STATE;
    710     }
    711     if (s->status == COMMENT_STATE) {
    712         if (s->gzhead->comment != NULL) {
    713             uInt beg = s->pending;  /* start of bytes to update crc */
    714             int val;
    715 
    716             do {
    717                 if (s->pending == s->pending_buf_size) {
    718                     if (s->gzhead->hcrc && s->pending > beg)
    719                         strm->adler = crc32(strm->adler, s->pending_buf + beg,
    720                                             s->pending - beg);
    721                     flush_pending(strm);
    722                     beg = s->pending;
    723                     if (s->pending == s->pending_buf_size) {
    724                         val = 1;
    725                         break;
    726                     }
    727                 }
    728                 val = s->gzhead->comment[s->gzindex++];
    729                 put_byte(s, val);
    730             } while (val != 0);
    731             if (s->gzhead->hcrc && s->pending > beg)
    732                 strm->adler = crc32(strm->adler, s->pending_buf + beg,
    733                                     s->pending - beg);
    734             if (val == 0)
    735                 s->status = HCRC_STATE;
    736         }
    737         else
    738             s->status = HCRC_STATE;
    739     }
    740     if (s->status == HCRC_STATE) {
    741         if (s->gzhead->hcrc) {
    742             if (s->pending + 2 > s->pending_buf_size)
    743                 flush_pending(strm);
    744             if (s->pending + 2 <= s->pending_buf_size) {
    745                 put_byte(s, (Byte)(strm->adler & 0xff));
    746                 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
    747                 strm->adler = crc32(0L, Z_NULL, 0);
    748                 s->status = BUSY_STATE;
    749             }
    750         }
    751         else
    752             s->status = BUSY_STATE;
    753     }
    754 #endif
    755 
    756     /* Flush as much pending output as possible */
    757     if (s->pending != 0) {
    758         flush_pending(strm);
    759         if (strm->avail_out == 0) {
    760             /* Since avail_out is 0, deflate will be called again with
    761              * more output space, but possibly with both pending and
    762              * avail_in equal to zero. There won't be anything to do,
    763              * but this is not an error situation so make sure we
    764              * return OK instead of BUF_ERROR at next call of deflate:
    765              */
    766             s->last_flush = -1;
    767             return Z_OK;
    768         }
    769 
    770     /* Make sure there is something to do and avoid duplicate consecutive
    771      * flushes. For repeated and useless calls with Z_FINISH, we keep
    772      * returning Z_STREAM_END instead of Z_BUF_ERROR.
    773      */
    774     } else if (strm->avail_in == 0 && flush <= old_flush &&
    775                flush != Z_FINISH) {
    776         ERR_RETURN(strm, Z_BUF_ERROR);
    777     }
    778 
    779     /* User must not provide more input after the first FINISH: */
    780     if (s->status == FINISH_STATE && strm->avail_in != 0) {
    781         ERR_RETURN(strm, Z_BUF_ERROR);
    782     }
    783 
    784     /* Start a new block or continue the current one.
    785      */
    786     if (strm->avail_in != 0 || s->lookahead != 0 ||
    787         (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
    788         block_state bstate;
    789 
    790         bstate = (*(configuration_table[s->level].func))(s, flush);
    791 
    792         if (bstate == finish_started || bstate == finish_done) {
    793             s->status = FINISH_STATE;
    794         }
    795         if (bstate == need_more || bstate == finish_started) {
    796             if (strm->avail_out == 0) {
    797                 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
    798             }
    799             return Z_OK;
    800             /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
    801              * of deflate should use the same flush parameter to make sure
    802              * that the flush is complete. So we don't have to output an
    803              * empty block here, this will be done at next call. This also
    804              * ensures that for a very small output buffer, we emit at most
    805              * one empty block.
    806              */
    807         }
    808         if (bstate == block_done) {
    809             if (flush == Z_PARTIAL_FLUSH) {
    810                 _tr_align(s);
    811             } else { /* FULL_FLUSH or SYNC_FLUSH */
    812                 _tr_stored_block(s, (char*)0, 0L, 0);
    813                 /* For a full flush, this empty block will be recognized
    814                  * as a special marker by inflate_sync().
    815                  */
    816                 if (flush == Z_FULL_FLUSH) {
    817                     CLEAR_HASH(s);             /* forget history */
    818                 }
    819             }
    820             flush_pending(strm);
    821             if (strm->avail_out == 0) {
    822               s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
    823               return Z_OK;
    824             }
    825         }
    826     }
    827     Assert(strm->avail_out > 0, "bug2");
    828 
    829     if (flush != Z_FINISH) return Z_OK;
    830     if (s->wrap <= 0) return Z_STREAM_END;
    831 
    832     /* Write the trailer */
    833 #ifdef GZIP
    834     if (s->wrap == 2) {
    835         put_byte(s, (Byte)(strm->adler & 0xff));
    836         put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
    837         put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
    838         put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
    839         put_byte(s, (Byte)(strm->total_in & 0xff));
    840         put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
    841         put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
    842         put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
    843     }
    844     else
    845 #endif
    846     {
    847         putShortMSB(s, (uInt)(strm->adler >> 16));
    848         putShortMSB(s, (uInt)(strm->adler & 0xffff));
    849     }
    850     flush_pending(strm);
    851     /* If avail_out is zero, the application will call deflate again
    852      * to flush the rest.
    853      */
    854     if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
    855     return s->pending != 0 ? Z_OK : Z_STREAM_END;
    856 }
    857 
    858 /* ========================================================================= */
    859 int ZEXPORT deflateEnd (strm)
    860     z_streamp strm;
    861 {
    862     int status;
    863 
    864     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
    865 
    866     status = strm->state->status;
    867     if (status != INIT_STATE &&
    868         status != EXTRA_STATE &&
    869         status != NAME_STATE &&
    870         status != COMMENT_STATE &&
    871         status != HCRC_STATE &&
    872         status != BUSY_STATE &&
    873         status != FINISH_STATE) {
    874       return Z_STREAM_ERROR;
    875     }
    876 
    877     /* Deallocate in reverse order of allocations: */
    878     TRY_FREE(strm, strm->state->pending_buf);
    879     TRY_FREE(strm, strm->state->head);
    880     TRY_FREE(strm, strm->state->prev);
    881     TRY_FREE(strm, strm->state->window);
    882 
    883     ZFREE(strm, strm->state);
    884     strm->state = Z_NULL;
    885 
    886     return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
    887 }
    888 
    889 /* =========================================================================
    890  * Copy the source state to the destination state.
    891  * To simplify the source, this is not supported for 16-bit MSDOS (which
    892  * doesn't have enough memory anyway to duplicate compression states).
    893  */
    894 int ZEXPORT deflateCopy (dest, source)
    895     z_streamp dest;
    896     z_streamp source;
    897 {
    898 #ifdef MAXSEG_64K
    899     return Z_STREAM_ERROR;
    900 #else
    901     deflate_state *ds;
    902     deflate_state *ss;
    903     ushf *overlay;
    904 
    905 
    906     if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
    907         return Z_STREAM_ERROR;
    908     }
    909 
    910     ss = source->state;
    911 
    912     zmemcpy(dest, source, sizeof(z_stream));
    913 
    914     ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
    915     if (ds == Z_NULL) return Z_MEM_ERROR;
    916     dest->state = (struct internal_state FAR *) ds;
    917     zmemcpy(ds, ss, sizeof(deflate_state));
    918     ds->strm = dest;
    919 
    920     ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
    921     ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
    922     ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
    923     overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
    924     ds->pending_buf = (uchf *) overlay;
    925 
    926     if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
    927         ds->pending_buf == Z_NULL) {
    928         deflateEnd (dest);
    929         return Z_MEM_ERROR;
    930     }
    931     /* following zmemcpy do not work for 16-bit MSDOS */
    932     zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
    933     zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
    934     zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
    935     zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
    936 
    937     ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
    938     ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
    939     ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
    940 
    941     ds->l_desc.dyn_tree = ds->dyn_ltree;
    942     ds->d_desc.dyn_tree = ds->dyn_dtree;
    943     ds->bl_desc.dyn_tree = ds->bl_tree;
    944 
    945     return Z_OK;
    946 #endif /* MAXSEG_64K */
    947 }
    948 
    949 /* ===========================================================================
    950  * Read a new buffer from the current input stream, update the adler32
    951  * and total number of bytes read.  All deflate() input goes through
    952  * this function so some applications may wish to modify it to avoid
    953  * allocating a large strm->next_in buffer and copying from it.
    954  * (See also flush_pending()).
    955  */
    956 local int read_buf(strm, buf, size)
    957     z_streamp strm;
    958     Bytef *buf;
    959     unsigned size;
    960 {
    961     unsigned len = strm->avail_in;
    962 
    963     if (len > size) len = size;
    964     if (len == 0) return 0;
    965 
    966     strm->avail_in  -= len;
    967 
    968     if (strm->state->wrap == 1) {
    969         strm->adler = adler32(strm->adler, strm->next_in, len);
    970     }
    971 #ifdef GZIP
    972     else if (strm->state->wrap == 2) {
    973         strm->adler = crc32(strm->adler, strm->next_in, len);
    974     }
    975 #endif
    976     zmemcpy(buf, strm->next_in, len);
    977     strm->next_in  += len;
    978     strm->total_in += len;
    979 
    980     return (int)len;
    981 }
    982 
    983 /* ===========================================================================
    984  * Initialize the "longest match" routines for a new zlib stream
    985  */
    986 local void lm_init (s)
    987     deflate_state *s;
    988 {
    989     s->window_size = (ulg)2L*s->w_size;
    990 
    991     CLEAR_HASH(s);
    992 
    993     /* Set the default configuration parameters:
    994      */
    995     s->max_lazy_match   = configuration_table[s->level].max_lazy;
    996     s->good_match       = configuration_table[s->level].good_length;
    997     s->nice_match       = configuration_table[s->level].nice_length;
    998     s->max_chain_length = configuration_table[s->level].max_chain;
    999 
   1000     s->strstart = 0;
   1001     s->block_start = 0L;
   1002     s->lookahead = 0;
   1003     s->match_length = s->prev_length = MIN_MATCH-1;
   1004     s->match_available = 0;
   1005     s->ins_h = 0;
   1006 #ifndef FASTEST
   1007 #ifdef ASMV
   1008     match_init(); /* initialize the asm code */
   1009 #endif
   1010 #endif
   1011 }
   1012 
   1013 #ifndef FASTEST
   1014 /* ===========================================================================
   1015  * Set match_start to the longest match starting at the given string and
   1016  * return its length. Matches shorter or equal to prev_length are discarded,
   1017  * in which case the result is equal to prev_length and match_start is
   1018  * garbage.
   1019  * IN assertions: cur_match is the head of the hash chain for the current
   1020  *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
   1021  * OUT assertion: the match length is not greater than s->lookahead.
   1022  */
   1023 #ifndef ASMV
   1024 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
   1025  * match.S. The code will be functionally equivalent.
   1026  */
   1027 local uInt longest_match(s, cur_match)
   1028     deflate_state *s;
   1029     IPos cur_match;                             /* current match */
   1030 {
   1031     unsigned chain_length = s->max_chain_length;/* max hash chain length */
   1032     register Bytef *scan = s->window + s->strstart; /* current string */
   1033     register Bytef *match;                       /* matched string */
   1034     register int len;                           /* length of current match */
   1035     int best_len = s->prev_length;              /* best match length so far */
   1036     int nice_match = s->nice_match;             /* stop if match long enough */
   1037     IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
   1038         s->strstart - (IPos)MAX_DIST(s) : NIL;
   1039     /* Stop when cur_match becomes <= limit. To simplify the code,
   1040      * we prevent matches with the string of window index 0.
   1041      */
   1042     Posf *prev = s->prev;
   1043     uInt wmask = s->w_mask;
   1044 
   1045 #ifdef UNALIGNED_OK
   1046     /* Compare two bytes at a time. Note: this is not always beneficial.
   1047      * Try with and without -DUNALIGNED_OK to check.
   1048      */
   1049     register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
   1050     register ush scan_start = *(ushf*)scan;
   1051     register ush scan_end   = *(ushf*)(scan+best_len-1);
   1052 #else
   1053     register Bytef *strend = s->window + s->strstart + MAX_MATCH;
   1054     register Byte scan_end1  = scan[best_len-1];
   1055     register Byte scan_end   = scan[best_len];
   1056 #endif
   1057 
   1058     /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
   1059      * It is easy to get rid of this optimization if necessary.
   1060      */
   1061     Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
   1062 
   1063     /* Do not waste too much time if we already have a good match: */
   1064     if (s->prev_length >= s->good_match) {
   1065         chain_length >>= 2;
   1066     }
   1067     /* Do not look for matches beyond the end of the input. This is necessary
   1068      * to make deflate deterministic.
   1069      */
   1070     if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
   1071 
   1072     Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
   1073 
   1074     do {
   1075         Assert(cur_match < s->strstart, "no future");
   1076         match = s->window + cur_match;
   1077 
   1078         /* Skip to next match if the match length cannot increase
   1079          * or if the match length is less than 2.  Note that the checks below
   1080          * for insufficient lookahead only occur occasionally for performance
   1081          * reasons.  Therefore uninitialized memory will be accessed, and
   1082          * conditional jumps will be made that depend on those values.
   1083          * However the length of the match is limited to the lookahead, so
   1084          * the output of deflate is not affected by the uninitialized values.
   1085          */
   1086 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
   1087         /* This code assumes sizeof(unsigned short) == 2. Do not use
   1088          * UNALIGNED_OK if your compiler uses a different size.
   1089          */
   1090         if (*(ushf*)(match+best_len-1) != scan_end ||
   1091             *(ushf*)match != scan_start) continue;
   1092 
   1093         /* It is not necessary to compare scan[2] and match[2] since they are
   1094          * always equal when the other bytes match, given that the hash keys
   1095          * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
   1096          * strstart+3, +5, ... up to strstart+257. We check for insufficient
   1097          * lookahead only every 4th comparison; the 128th check will be made
   1098          * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
   1099          * necessary to put more guard bytes at the end of the window, or
   1100          * to check more often for insufficient lookahead.
   1101          */
   1102         Assert(scan[2] == match[2], "scan[2]?");
   1103         scan++, match++;
   1104         do {
   1105         } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
   1106                  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
   1107                  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
   1108                  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
   1109                  scan < strend);
   1110         /* The funny "do {}" generates better code on most compilers */
   1111 
   1112         /* Here, scan <= window+strstart+257 */
   1113         Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
   1114         if (*scan == *match) scan++;
   1115 
   1116         len = (MAX_MATCH - 1) - (int)(strend-scan);
   1117         scan = strend - (MAX_MATCH-1);
   1118 
   1119 #else /* UNALIGNED_OK */
   1120 
   1121         if (match[best_len]   != scan_end  ||
   1122             match[best_len-1] != scan_end1 ||
   1123             *match            != *scan     ||
   1124             *++match          != scan[1])      continue;
   1125 
   1126         /* The check at best_len-1 can be removed because it will be made
   1127          * again later. (This heuristic is not always a win.)
   1128          * It is not necessary to compare scan[2] and match[2] since they
   1129          * are always equal when the other bytes match, given that
   1130          * the hash keys are equal and that HASH_BITS >= 8.
   1131          */
   1132         scan += 2, match++;
   1133         Assert(*scan == *match, "match[2]?");
   1134 
   1135         /* We check for insufficient lookahead only every 8th comparison;
   1136          * the 256th check will be made at strstart+258.
   1137          */
   1138         do {
   1139         } while (*++scan == *++match && *++scan == *++match &&
   1140                  *++scan == *++match && *++scan == *++match &&
   1141                  *++scan == *++match && *++scan == *++match &&
   1142                  *++scan == *++match && *++scan == *++match &&
   1143                  scan < strend);
   1144 
   1145         Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
   1146 
   1147         len = MAX_MATCH - (int)(strend - scan);
   1148         scan = strend - MAX_MATCH;
   1149 
   1150 #endif /* UNALIGNED_OK */
   1151 
   1152         if (len > best_len) {
   1153             s->match_start = cur_match;
   1154             best_len = len;
   1155             if (len >= nice_match) break;
   1156 #ifdef UNALIGNED_OK
   1157             scan_end = *(ushf*)(scan+best_len-1);
   1158 #else
   1159             scan_end1  = scan[best_len-1];
   1160             scan_end   = scan[best_len];
   1161 #endif
   1162         }
   1163     } while ((cur_match = prev[cur_match & wmask]) > limit
   1164              && --chain_length != 0);
   1165 
   1166     if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
   1167     return s->lookahead;
   1168 }
   1169 #endif /* ASMV */
   1170 #endif /* FASTEST */
   1171 
   1172 /* ---------------------------------------------------------------------------
   1173  * Optimized version for level == 1 or strategy == Z_RLE only
   1174  */
   1175 local uInt longest_match_fast(s, cur_match)
   1176     deflate_state *s;
   1177     IPos cur_match;                             /* current match */
   1178 {
   1179     register Bytef *scan = s->window + s->strstart; /* current string */
   1180     register Bytef *match;                       /* matched string */
   1181     register int len;                           /* length of current match */
   1182     register Bytef *strend = s->window + s->strstart + MAX_MATCH;
   1183 
   1184     /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
   1185      * It is easy to get rid of this optimization if necessary.
   1186      */
   1187     Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
   1188 
   1189     Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
   1190 
   1191     Assert(cur_match < s->strstart, "no future");
   1192 
   1193     match = s->window + cur_match;
   1194 
   1195     /* Return failure if the match length is less than 2:
   1196      */
   1197     if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
   1198 
   1199     /* The check at best_len-1 can be removed because it will be made
   1200      * again later. (This heuristic is not always a win.)
   1201      * It is not necessary to compare scan[2] and match[2] since they
   1202      * are always equal when the other bytes match, given that
   1203      * the hash keys are equal and that HASH_BITS >= 8.
   1204      */
   1205     scan += 2, match += 2;
   1206     Assert(*scan == *match, "match[2]?");
   1207 
   1208     /* We check for insufficient lookahead only every 8th comparison;
   1209      * the 256th check will be made at strstart+258.
   1210      */
   1211     do {
   1212     } while (*++scan == *++match && *++scan == *++match &&
   1213              *++scan == *++match && *++scan == *++match &&
   1214              *++scan == *++match && *++scan == *++match &&
   1215              *++scan == *++match && *++scan == *++match &&
   1216              scan < strend);
   1217 
   1218     Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
   1219 
   1220     len = MAX_MATCH - (int)(strend - scan);
   1221 
   1222     if (len < MIN_MATCH) return MIN_MATCH - 1;
   1223 
   1224     s->match_start = cur_match;
   1225     return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
   1226 }
   1227 
   1228 #ifdef DEBUG
   1229 /* ===========================================================================
   1230  * Check that the match at match_start is indeed a match.
   1231  */
   1232 local void check_match(s, start, match, length)
   1233     deflate_state *s;
   1234     IPos start, match;
   1235     int length;
   1236 {
   1237     /* check that the match is indeed a match */
   1238     if (zmemcmp(s->window + match,
   1239                 s->window + start, length) != EQUAL) {
   1240         fprintf(stderr, " start %u, match %u, length %d\n",
   1241                 start, match, length);
   1242         do {
   1243             fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
   1244         } while (--length != 0);
   1245         z_error("invalid match");
   1246     }
   1247     if (z_verbose > 1) {
   1248         fprintf(stderr,"\\[%d,%d]", start-match, length);
   1249         do { putc(s->window[start++], stderr); } while (--length != 0);
   1250     }
   1251 }
   1252 #else
   1253 #  define check_match(s, start, match, length)
   1254 #endif /* DEBUG */
   1255 
   1256 /* ===========================================================================
   1257  * Fill the window when the lookahead becomes insufficient.
   1258  * Updates strstart and lookahead.
   1259  *
   1260  * IN assertion: lookahead < MIN_LOOKAHEAD
   1261  * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
   1262  *    At least one byte has been read, or avail_in == 0; reads are
   1263  *    performed for at least two bytes (required for the zip translate_eol
   1264  *    option -- not supported here).
   1265  */
   1266 local void fill_window(s)
   1267     deflate_state *s;
   1268 {
   1269     register unsigned n, m;
   1270     register Posf *p;
   1271     unsigned more;    /* Amount of free space at the end of the window. */
   1272     uInt wsize = s->w_size;
   1273 
   1274     do {
   1275         more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
   1276 
   1277         /* Deal with !@#$% 64K limit: */
   1278         if (sizeof(int) <= 2) {
   1279             if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
   1280                 more = wsize;
   1281 
   1282             } else if (more == (unsigned)(-1)) {
   1283                 /* Very unlikely, but possible on 16 bit machine if
   1284                  * strstart == 0 && lookahead == 1 (input done a byte at time)
   1285                  */
   1286                 more--;
   1287             }
   1288         }
   1289 
   1290         /* If the window is almost full and there is insufficient lookahead,
   1291          * move the upper half to the lower one to make room in the upper half.
   1292          */
   1293         if (s->strstart >= wsize+MAX_DIST(s)) {
   1294 
   1295             zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
   1296             s->match_start -= wsize;
   1297             s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
   1298             s->block_start -= (long) wsize;
   1299 
   1300             /* Slide the hash table (could be avoided with 32 bit values
   1301                at the expense of memory usage). We slide even when level == 0
   1302                to keep the hash table consistent if we switch back to level > 0
   1303                later. (Using level 0 permanently is not an optimal usage of
   1304                zlib, so we don't care about this pathological case.)
   1305              */
   1306             /* %%% avoid this when Z_RLE */
   1307             n = s->hash_size;
   1308             p = &s->head[n];
   1309             do {
   1310                 m = *--p;
   1311                 *p = (Pos)(m >= wsize ? m-wsize : NIL);
   1312             } while (--n);
   1313 
   1314             n = wsize;
   1315 #ifndef FASTEST
   1316             p = &s->prev[n];
   1317             do {
   1318                 m = *--p;
   1319                 *p = (Pos)(m >= wsize ? m-wsize : NIL);
   1320                 /* If n is not on any hash chain, prev[n] is garbage but
   1321                  * its value will never be used.
   1322                  */
   1323             } while (--n);
   1324 #endif
   1325             more += wsize;
   1326         }
   1327         if (s->strm->avail_in == 0) return;
   1328 
   1329         /* If there was no sliding:
   1330          *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
   1331          *    more == window_size - lookahead - strstart
   1332          * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
   1333          * => more >= window_size - 2*WSIZE + 2
   1334          * In the BIG_MEM or MMAP case (not yet supported),
   1335          *   window_size == input_size + MIN_LOOKAHEAD  &&
   1336          *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
   1337          * Otherwise, window_size == 2*WSIZE so more >= 2.
   1338          * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
   1339          */
   1340         Assert(more >= 2, "more < 2");
   1341 
   1342         n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
   1343         s->lookahead += n;
   1344 
   1345         /* Initialize the hash value now that we have some input: */
   1346         if (s->lookahead >= MIN_MATCH) {
   1347             s->ins_h = s->window[s->strstart];
   1348             UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
   1349 #if MIN_MATCH != 3
   1350             Call UPDATE_HASH() MIN_MATCH-3 more times
   1351 #endif
   1352         }
   1353         /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
   1354          * but this is not important since only literal bytes will be emitted.
   1355          */
   1356 
   1357     } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
   1358 }
   1359 
   1360 /* ===========================================================================
   1361  * Flush the current block, with given end-of-file flag.
   1362  * IN assertion: strstart is set to the end of the current match.
   1363  */
   1364 #define FLUSH_BLOCK_ONLY(s, eof) { \
   1365    _tr_flush_block(s, (s->block_start >= 0L ? \
   1366                    (charf *)&s->window[(unsigned)s->block_start] : \
   1367                    (charf *)Z_NULL), \
   1368                 (ulg)((long)s->strstart - s->block_start), \
   1369                 (eof)); \
   1370    s->block_start = s->strstart; \
   1371    flush_pending(s->strm); \
   1372    Tracev((stderr,"[FLUSH]")); \
   1373 }
   1374 
   1375 /* Same but force premature exit if necessary. */
   1376 #define FLUSH_BLOCK(s, eof) { \
   1377    FLUSH_BLOCK_ONLY(s, eof); \
   1378    if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
   1379 }
   1380 
   1381 /* ===========================================================================
   1382  * Copy without compression as much as possible from the input stream, return
   1383  * the current block state.
   1384  * This function does not insert new strings in the dictionary since
   1385  * uncompressible data is probably not useful. This function is used
   1386  * only for the level=0 compression option.
   1387  * NOTE: this function should be optimized to avoid extra copying from
   1388  * window to pending_buf.
   1389  */
   1390 local block_state deflate_stored(s, flush)
   1391     deflate_state *s;
   1392     int flush;
   1393 {
   1394     /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
   1395      * to pending_buf_size, and each stored block has a 5 byte header:
   1396      */
   1397     ulg max_block_size = 0xffff;
   1398     ulg max_start;
   1399 
   1400     if (max_block_size > s->pending_buf_size - 5) {
   1401         max_block_size = s->pending_buf_size - 5;
   1402     }
   1403 
   1404     /* Copy as much as possible from input to output: */
   1405     for (;;) {
   1406         /* Fill the window as much as possible: */
   1407         if (s->lookahead <= 1) {
   1408 
   1409             Assert(s->strstart < s->w_size+MAX_DIST(s) ||
   1410                    s->block_start >= (long)s->w_size, "slide too late");
   1411 
   1412             fill_window(s);
   1413             if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
   1414 
   1415             if (s->lookahead == 0) break; /* flush the current block */
   1416         }
   1417         Assert(s->block_start >= 0L, "block gone");
   1418 
   1419         s->strstart += s->lookahead;
   1420         s->lookahead = 0;
   1421 
   1422         /* Emit a stored block if pending_buf will be full: */
   1423         max_start = s->block_start + max_block_size;
   1424         if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
   1425             /* strstart == 0 is possible when wraparound on 16-bit machine */
   1426             s->lookahead = (uInt)(s->strstart - max_start);
   1427             s->strstart = (uInt)max_start;
   1428             FLUSH_BLOCK(s, 0);
   1429         }
   1430         /* Flush if we may have to slide, otherwise block_start may become
   1431          * negative and the data will be gone:
   1432          */
   1433         if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
   1434             FLUSH_BLOCK(s, 0);
   1435         }
   1436     }
   1437     FLUSH_BLOCK(s, flush == Z_FINISH);
   1438     return flush == Z_FINISH ? finish_done : block_done;
   1439 }
   1440 
   1441 /* ===========================================================================
   1442  * Compress as much as possible from the input stream, return the current
   1443  * block state.
   1444  * This function does not perform lazy evaluation of matches and inserts
   1445  * new strings in the dictionary only for unmatched strings or for short
   1446  * matches. It is used only for the fast compression options.
   1447  */
   1448 local block_state deflate_fast(s, flush)
   1449     deflate_state *s;
   1450     int flush;
   1451 {
   1452     IPos hash_head = NIL; /* head of the hash chain */
   1453     int bflush;           /* set if current block must be flushed */
   1454 
   1455     for (;;) {
   1456         /* Make sure that we always have enough lookahead, except
   1457          * at the end of the input file. We need MAX_MATCH bytes
   1458          * for the next match, plus MIN_MATCH bytes to insert the
   1459          * string following the next match.
   1460          */
   1461         if (s->lookahead < MIN_LOOKAHEAD) {
   1462             fill_window(s);
   1463             if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
   1464                 return need_more;
   1465             }
   1466             if (s->lookahead == 0) break; /* flush the current block */
   1467         }
   1468 
   1469         /* Insert the string window[strstart .. strstart+2] in the
   1470          * dictionary, and set hash_head to the head of the hash chain:
   1471          */
   1472         if (s->lookahead >= MIN_MATCH) {
   1473             INSERT_STRING(s, s->strstart, hash_head);
   1474         }
   1475 
   1476         /* Find the longest match, discarding those <= prev_length.
   1477          * At this point we have always match_length < MIN_MATCH
   1478          */
   1479         if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
   1480             /* To simplify the code, we prevent matches with the string
   1481              * of window index 0 (in particular we have to avoid a match
   1482              * of the string with itself at the start of the input file).
   1483              */
   1484 #ifdef FASTEST
   1485             if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) ||
   1486                 (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
   1487                 s->match_length = longest_match_fast (s, hash_head);
   1488             }
   1489 #else
   1490             if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
   1491                 s->match_length = longest_match (s, hash_head);
   1492             } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
   1493                 s->match_length = longest_match_fast (s, hash_head);
   1494             }
   1495 #endif
   1496             /* longest_match() or longest_match_fast() sets match_start */
   1497         }
   1498         if (s->match_length >= MIN_MATCH) {
   1499             check_match(s, s->strstart, s->match_start, s->match_length);
   1500 
   1501             _tr_tally_dist(s, s->strstart - s->match_start,
   1502                            s->match_length - MIN_MATCH, bflush);
   1503 
   1504             s->lookahead -= s->match_length;
   1505 
   1506             /* Insert new strings in the hash table only if the match length
   1507              * is not too large. This saves time but degrades compression.
   1508              */
   1509 #ifndef FASTEST
   1510             if (s->match_length <= s->max_insert_length &&
   1511                 s->lookahead >= MIN_MATCH) {
   1512                 s->match_length--; /* string at strstart already in table */
   1513                 do {
   1514                     s->strstart++;
   1515                     INSERT_STRING(s, s->strstart, hash_head);
   1516                     /* strstart never exceeds WSIZE-MAX_MATCH, so there are
   1517                      * always MIN_MATCH bytes ahead.
   1518                      */
   1519                 } while (--s->match_length != 0);
   1520                 s->strstart++;
   1521             } else
   1522 #endif
   1523             {
   1524                 s->strstart += s->match_length;
   1525                 s->match_length = 0;
   1526                 s->ins_h = s->window[s->strstart];
   1527                 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
   1528 #if MIN_MATCH != 3
   1529                 Call UPDATE_HASH() MIN_MATCH-3 more times
   1530 #endif
   1531                 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
   1532                  * matter since it will be recomputed at next deflate call.
   1533                  */
   1534             }
   1535         } else {
   1536             /* No match, output a literal byte */
   1537             Tracevv((stderr,"%c", s->window[s->strstart]));
   1538             _tr_tally_lit (s, s->window[s->strstart], bflush);
   1539             s->lookahead--;
   1540             s->strstart++;
   1541         }
   1542         if (bflush) FLUSH_BLOCK(s, 0);
   1543     }
   1544     FLUSH_BLOCK(s, flush == Z_FINISH);
   1545     return flush == Z_FINISH ? finish_done : block_done;
   1546 }
   1547 
   1548 #ifndef FASTEST
   1549 /* ===========================================================================
   1550  * Same as above, but achieves better compression. We use a lazy
   1551  * evaluation for matches: a match is finally adopted only if there is
   1552  * no better match at the next window position.
   1553  */
   1554 local block_state deflate_slow(s, flush)
   1555     deflate_state *s;
   1556     int flush;
   1557 {
   1558     IPos hash_head = NIL;    /* head of hash chain */
   1559     int bflush;              /* set if current block must be flushed */
   1560 
   1561     /* Process the input block. */
   1562     for (;;) {
   1563         /* Make sure that we always have enough lookahead, except
   1564          * at the end of the input file. We need MAX_MATCH bytes
   1565          * for the next match, plus MIN_MATCH bytes to insert the
   1566          * string following the next match.
   1567          */
   1568         if (s->lookahead < MIN_LOOKAHEAD) {
   1569             fill_window(s);
   1570             if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
   1571                 return need_more;
   1572             }
   1573             if (s->lookahead == 0) break; /* flush the current block */
   1574         }
   1575 
   1576         /* Insert the string window[strstart .. strstart+2] in the
   1577          * dictionary, and set hash_head to the head of the hash chain:
   1578          */
   1579         if (s->lookahead >= MIN_MATCH) {
   1580             INSERT_STRING(s, s->strstart, hash_head);
   1581         }
   1582 
   1583         /* Find the longest match, discarding those <= prev_length.
   1584          */
   1585         s->prev_length = s->match_length, s->prev_match = s->match_start;
   1586         s->match_length = MIN_MATCH-1;
   1587 
   1588         if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
   1589             s->strstart - hash_head <= MAX_DIST(s)) {
   1590             /* To simplify the code, we prevent matches with the string
   1591              * of window index 0 (in particular we have to avoid a match
   1592              * of the string with itself at the start of the input file).
   1593              */
   1594             if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
   1595                 s->match_length = longest_match (s, hash_head);
   1596             } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
   1597                 s->match_length = longest_match_fast (s, hash_head);
   1598             }
   1599             /* longest_match() or longest_match_fast() sets match_start */
   1600 
   1601             if (s->match_length <= 5 && (s->strategy == Z_FILTERED
   1602 #if TOO_FAR <= 32767
   1603                 || (s->match_length == MIN_MATCH &&
   1604                     s->strstart - s->match_start > TOO_FAR)
   1605 #endif
   1606                 )) {
   1607 
   1608                 /* If prev_match is also MIN_MATCH, match_start is garbage
   1609                  * but we will ignore the current match anyway.
   1610                  */
   1611                 s->match_length = MIN_MATCH-1;
   1612             }
   1613         }
   1614         /* If there was a match at the previous step and the current
   1615          * match is not better, output the previous match:
   1616          */
   1617         if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
   1618             uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
   1619             /* Do not insert strings in hash table beyond this. */
   1620 
   1621             check_match(s, s->strstart-1, s->prev_match, s->prev_length);
   1622 
   1623             _tr_tally_dist(s, s->strstart -1 - s->prev_match,
   1624                            s->prev_length - MIN_MATCH, bflush);
   1625 
   1626             /* Insert in hash table all strings up to the end of the match.
   1627              * strstart-1 and strstart are already inserted. If there is not
   1628              * enough lookahead, the last two strings are not inserted in
   1629              * the hash table.
   1630              */
   1631             s->lookahead -= s->prev_length-1;
   1632             s->prev_length -= 2;
   1633             do {
   1634                 if (++s->strstart <= max_insert) {
   1635                     INSERT_STRING(s, s->strstart, hash_head);
   1636                 }
   1637             } while (--s->prev_length != 0);
   1638             s->match_available = 0;
   1639             s->match_length = MIN_MATCH-1;
   1640             s->strstart++;
   1641 
   1642             if (bflush) FLUSH_BLOCK(s, 0);
   1643 
   1644         } else if (s->match_available) {
   1645             /* If there was no match at the previous position, output a
   1646              * single literal. If there was a match but the current match
   1647              * is longer, truncate the previous match to a single literal.
   1648              */
   1649             Tracevv((stderr,"%c", s->window[s->strstart-1]));
   1650             _tr_tally_lit(s, s->window[s->strstart-1], bflush);
   1651             if (bflush) {
   1652                 FLUSH_BLOCK_ONLY(s, 0);
   1653             }
   1654             s->strstart++;
   1655             s->lookahead--;
   1656             if (s->strm->avail_out == 0) return need_more;
   1657         } else {
   1658             /* There is no previous match to compare with, wait for
   1659              * the next step to decide.
   1660              */
   1661             s->match_available = 1;
   1662             s->strstart++;
   1663             s->lookahead--;
   1664         }
   1665     }
   1666     Assert (flush != Z_NO_FLUSH, "no flush?");
   1667     if (s->match_available) {
   1668         Tracevv((stderr,"%c", s->window[s->strstart-1]));
   1669         _tr_tally_lit(s, s->window[s->strstart-1], bflush);
   1670         s->match_available = 0;
   1671     }
   1672     FLUSH_BLOCK(s, flush == Z_FINISH);
   1673     return flush == Z_FINISH ? finish_done : block_done;
   1674 }
   1675 #endif /* FASTEST */
   1676 
   1677 #if 0
   1678 /* ===========================================================================
   1679  * For Z_RLE, simply look for runs of bytes, generate matches only of distance
   1680  * one.  Do not maintain a hash table.  (It will be regenerated if this run of
   1681  * deflate switches away from Z_RLE.)
   1682  */
   1683 local block_state deflate_rle(s, flush)
   1684     deflate_state *s;
   1685     int flush;
   1686 {
   1687     int bflush;         /* set if current block must be flushed */
   1688     uInt run;           /* length of run */
   1689     uInt max;           /* maximum length of run */
   1690     uInt prev;          /* byte at distance one to match */
   1691     Bytef *scan;        /* scan for end of run */
   1692 
   1693     for (;;) {
   1694         /* Make sure that we always have enough lookahead, except
   1695          * at the end of the input file. We need MAX_MATCH bytes
   1696          * for the longest encodable run.
   1697          */
   1698         if (s->lookahead < MAX_MATCH) {
   1699             fill_window(s);
   1700             if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {
   1701                 return need_more;
   1702             }
   1703             if (s->lookahead == 0) break; /* flush the current block */
   1704         }
   1705 
   1706         /* See how many times the previous byte repeats */
   1707         run = 0;
   1708         if (s->strstart > 0) {      /* if there is a previous byte, that is */
   1709             max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH;
   1710             scan = s->window + s->strstart - 1;
   1711             prev = *scan++;
   1712             do {
   1713                 if (*scan++ != prev)
   1714                     break;
   1715             } while (++run < max);
   1716         }
   1717 
   1718         /* Emit match if have run of MIN_MATCH or longer, else emit literal */
   1719         if (run >= MIN_MATCH) {
   1720             check_match(s, s->strstart, s->strstart - 1, run);
   1721             _tr_tally_dist(s, 1, run - MIN_MATCH, bflush);
   1722             s->lookahead -= run;
   1723             s->strstart += run;
   1724         } else {
   1725             /* No match, output a literal byte */
   1726             Tracevv((stderr,"%c", s->window[s->strstart]));
   1727             _tr_tally_lit (s, s->window[s->strstart], bflush);
   1728             s->lookahead--;
   1729             s->strstart++;
   1730         }
   1731         if (bflush) FLUSH_BLOCK(s, 0);
   1732     }
   1733     FLUSH_BLOCK(s, flush == Z_FINISH);
   1734     return flush == Z_FINISH ? finish_done : block_done;
   1735 }
   1736 #endif
   1737