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deflate.c
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00001 /* deflate.c -- compress data using the deflation algorithm
00002  * Copyright (C) 1995-2003 Jean-loup Gailly.
00003  * For conditions of distribution and use, see copyright notice in zlib.h
00004  */
00005 
00006 /*
00007  *  ALGORITHM
00008  *
00009  *      The "deflation" process depends on being able to identify portions
00010  *      of the input text which are identical to earlier input (within a
00011  *      sliding window trailing behind the input currently being processed).
00012  *
00013  *      The most straightforward technique turns out to be the fastest for
00014  *      most input files: try all possible matches and select the longest.
00015  *      The key feature of this algorithm is that insertions into the string
00016  *      dictionary are very simple and thus fast, and deletions are avoided
00017  *      completely. Insertions are performed at each input character, whereas
00018  *      string matches are performed only when the previous match ends. So it
00019  *      is preferable to spend more time in matches to allow very fast string
00020  *      insertions and avoid deletions. The matching algorithm for small
00021  *      strings is inspired from that of Rabin & Karp. A brute force approach
00022  *      is used to find longer strings when a small match has been found.
00023  *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
00024  *      (by Leonid Broukhis).
00025  *         A previous version of this file used a more sophisticated algorithm
00026  *      (by Fiala and Greene) which is guaranteed to run in linear amortized
00027  *      time, but has a larger average cost, uses more memory and is patented.
00028  *      However the F&G algorithm may be faster for some highly redundant
00029  *      files if the parameter max_chain_length (described below) is too large.
00030  *
00031  *  ACKNOWLEDGEMENTS
00032  *
00033  *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
00034  *      I found it in 'freeze' written by Leonid Broukhis.
00035  *      Thanks to many people for bug reports and testing.
00036  *
00037  *  REFERENCES
00038  *
00039  *      Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
00040  *      Available in http://www.ietf.org/rfc/rfc1951.txt
00041  *
00042  *      A description of the Rabin and Karp algorithm is given in the book
00043  *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
00044  *
00045  *      Fiala,E.R., and Greene,D.H.
00046  *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
00047  *
00048  */
00049 
00050 /* @(#) $Id$ */
00051 
00052 #include "deflate.h"
00053 
00054 const char deflate_copyright[] =
00055    " deflate 1.2.1 Copyright 1995-2003 Jean-loup Gailly ";
00056 /*
00057   If you use the zlib library in a product, an acknowledgment is welcome
00058   in the documentation of your product. If for some reason you cannot
00059   include such an acknowledgment, I would appreciate that you keep this
00060   copyright string in the executable of your product.
00061  */
00062 
00063 /* ===========================================================================
00064  *  Function prototypes.
00065  */
00066 typedef enum {
00067     need_more,      /* block not completed, need more input or more output */
00068     block_done,     /* block flush performed */
00069     finish_started, /* finish started, need only more output at next deflate */
00070     finish_done     /* finish done, accept no more input or output */
00071 } block_state;
00072 
00073 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
00074 /* Compression function. Returns the block state after the call. */
00075 
00076 local void fill_window    OF((deflate_state *s));
00077 local block_state deflate_stored OF((deflate_state *s, int flush));
00078 local block_state deflate_fast   OF((deflate_state *s, int flush));
00079 #ifndef FASTEST
00080 local block_state deflate_slow   OF((deflate_state *s, int flush));
00081 #endif
00082 local void lm_init        OF((deflate_state *s));
00083 local void putShortMSB    OF((deflate_state *s, uInt b));
00084 local void flush_pending  OF((z_streamp strm));
00085 local int read_buf        OF((z_streamp strm, Bytef *buf, unsigned size));
00086 #ifndef FASTEST
00087 #ifdef ASMV
00088       void match_init OF((void)); /* asm code initialization */
00089       uInt longest_match  OF((deflate_state *s, IPos cur_match));
00090 #else
00091 local uInt longest_match  OF((deflate_state *s, IPos cur_match));
00092 #endif
00093 #endif
00094 local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
00095 
00096 #ifdef DEBUG
00097 local  void check_match OF((deflate_state *s, IPos start, IPos match,
00098                             int length));
00099 #endif
00100 
00101 /* ===========================================================================
00102  * Local data
00103  */
00104 
00105 #define NIL 0
00106 /* Tail of hash chains */
00107 
00108 #ifndef TOO_FAR
00109 #  define TOO_FAR 4096
00110 #endif
00111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
00112 
00113 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
00114 /* Minimum amount of lookahead, except at the end of the input file.
00115  * See deflate.c for comments about the MIN_MATCH+1.
00116  */
00117 
00118 /* Values for max_lazy_match, good_match and max_chain_length, depending on
00119  * the desired pack level (0..9). The values given below have been tuned to
00120  * exclude worst case performance for pathological files. Better values may be
00121  * found for specific files.
00122  */
00123 typedef struct config_s {
00124    ush good_length; /* reduce lazy search above this match length */
00125    ush max_lazy;    /* do not perform lazy search above this match length */
00126    ush nice_length; /* quit search above this match length */
00127    ush max_chain;
00128    compress_func func;
00129 } config;
00130 
00131 #ifdef FASTEST
00132 local const config configuration_table[2] = {
00133 /*      good lazy nice chain */
00134 /* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
00135 /* 1 */ {4,    4,  8,    4, deflate_fast}}; /* max speed, no lazy matches */
00136 #else
00137 local const config configuration_table[10] = {
00138 /*      good lazy nice chain */
00139 /* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
00140 /* 1 */ {4,    4,  8,    4, deflate_fast}, /* max speed, no lazy matches */
00141 /* 2 */ {4,    5, 16,    8, deflate_fast},
00142 /* 3 */ {4,    6, 32,   32, deflate_fast},
00143 
00144 /* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
00145 /* 5 */ {8,   16, 32,   32, deflate_slow},
00146 /* 6 */ {8,   16, 128, 128, deflate_slow},
00147 /* 7 */ {8,   32, 128, 256, deflate_slow},
00148 /* 8 */ {32, 128, 258, 1024, deflate_slow},
00149 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
00150 #endif
00151 
00152 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
00153  * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
00154  * meaning.
00155  */
00156 
00157 #define EQUAL 0
00158 /* result of memcmp for equal strings */
00159 
00160 #ifndef NO_DUMMY_DECL
00161 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
00162 #endif
00163 
00164 /* ===========================================================================
00165  * Update a hash value with the given input byte
00166  * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
00167  *    input characters, so that a running hash key can be computed from the
00168  *    previous key instead of complete recalculation each time.
00169  */
00170 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
00171 
00172 
00173 /* ===========================================================================
00174  * Insert string str in the dictionary and set match_head to the previous head
00175  * of the hash chain (the most recent string with same hash key). Return
00176  * the previous length of the hash chain.
00177  * If this file is compiled with -DFASTEST, the compression level is forced
00178  * to 1, and no hash chains are maintained.
00179  * IN  assertion: all calls to to INSERT_STRING are made with consecutive
00180  *    input characters and the first MIN_MATCH bytes of str are valid
00181  *    (except for the last MIN_MATCH-1 bytes of the input file).
00182  */
00183 #ifdef FASTEST
00184 #define INSERT_STRING(s, str, match_head) \
00185    (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
00186     match_head = s->head[s->ins_h], \
00187     s->head[s->ins_h] = (Pos)(str))
00188 #else
00189 #define INSERT_STRING(s, str, match_head) \
00190    (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
00191     match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
00192     s->head[s->ins_h] = (Pos)(str))
00193 #endif
00194 
00195 /* ===========================================================================
00196  * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
00197  * prev[] will be initialized on the fly.
00198  */
00199 #define CLEAR_HASH(s) \
00200     s->head[s->hash_size-1] = NIL; \
00201     zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
00202 
00203 /* ========================================================================= */
00204 int ZEXPORT deflateInit_(strm, level, version, stream_size)
00205     z_streamp strm;
00206     int level;
00207     const char *version;
00208     int stream_size;
00209 {
00210     return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
00211                          Z_DEFAULT_STRATEGY, version, stream_size);
00212     /* To do: ignore strm->next_in if we use it as window */
00213 }
00214 
00215 /* ========================================================================= */
00216 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
00217                   version, stream_size)
00218     z_streamp strm;
00219     int  level;
00220     int  method;
00221     int  windowBits;
00222     int  memLevel;
00223     int  strategy;
00224     const char *version;
00225     int stream_size;
00226 {
00227     deflate_state *s;
00228     int wrap = 1;
00229     static const char my_version[] = ZLIB_VERSION;
00230 
00231     ushf *overlay;
00232     /* We overlay pending_buf and d_buf+l_buf. This works since the average
00233      * output size for (length,distance) codes is <= 24 bits.
00234      */
00235 
00236     if (version == Z_NULL || version[0] != my_version[0] ||
00237         stream_size != sizeof(z_stream)) {
00238         return Z_VERSION_ERROR;
00239     }
00240     if (strm == Z_NULL) return Z_STREAM_ERROR;
00241 
00242     strm->msg = Z_NULL;
00243     if (strm->zalloc == (alloc_func)0) {
00244         strm->zalloc = zcalloc;
00245         strm->opaque = (voidpf)0;
00246     }
00247     if (strm->zfree == (free_func)0) strm->zfree = zcfree;
00248 
00249 #ifdef FASTEST
00250     if (level != 0) level = 1;
00251 #else
00252     if (level == Z_DEFAULT_COMPRESSION) level = 6;
00253 #endif
00254 
00255     if (windowBits < 0) { /* suppress zlib wrapper */
00256         wrap = 0;
00257         windowBits = -windowBits;
00258     }
00259 #ifdef GZIP
00260     else if (windowBits > 15) {
00261         wrap = 2;       /* write gzip wrapper instead */
00262         windowBits -= 16;
00263     }
00264 #endif
00265     if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
00266         windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
00267         strategy < 0 || strategy > Z_RLE) {
00268         return Z_STREAM_ERROR;
00269     }
00270     if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */
00271     s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
00272     if (s == Z_NULL) return Z_MEM_ERROR;
00273     strm->state = (struct internal_state FAR *)s;
00274     s->strm = strm;
00275 
00276     s->wrap = wrap;
00277     s->w_bits = windowBits;
00278     s->w_size = 1 << s->w_bits;
00279     s->w_mask = s->w_size - 1;
00280 
00281     s->hash_bits = memLevel + 7;
00282     s->hash_size = 1 << s->hash_bits;
00283     s->hash_mask = s->hash_size - 1;
00284     s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
00285 
00286     s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
00287     s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
00288     s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
00289 
00290     s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
00291 
00292     overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
00293     s->pending_buf = (uchf *) overlay;
00294     s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
00295 
00296     if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
00297         s->pending_buf == Z_NULL) {
00298         s->status = FINISH_STATE;
00299         strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
00300         deflateEnd (strm);
00301         return Z_MEM_ERROR;
00302     }
00303     s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
00304     s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
00305 
00306     s->level = level;
00307     s->strategy = strategy;
00308     s->method = (Byte)method;
00309 
00310     return deflateReset(strm);
00311 }
00312 
00313 /* ========================================================================= */
00314 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
00315     z_streamp strm;
00316     const Bytef *dictionary;
00317     uInt  dictLength;
00318 {
00319     deflate_state *s;
00320     uInt length = dictLength;
00321     uInt n;
00322     IPos hash_head = 0;
00323 
00324     if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
00325         strm->state->wrap == 2 ||
00326         (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
00327         return Z_STREAM_ERROR;
00328 
00329     s = strm->state;
00330     if (s->wrap)
00331         strm->adler = adler32(strm->adler, dictionary, dictLength);
00332 
00333     if (length < MIN_MATCH) return Z_OK;
00334     if (length > MAX_DIST(s)) {
00335         length = MAX_DIST(s);
00336 #ifndef USE_DICT_HEAD
00337         dictionary += dictLength - length; /* use the tail of the dictionary */
00338 #endif
00339     }
00340     zmemcpy(s->window, dictionary, length);
00341     s->strstart = length;
00342     s->block_start = (long)length;
00343 
00344     /* Insert all strings in the hash table (except for the last two bytes).
00345      * s->lookahead stays null, so s->ins_h will be recomputed at the next
00346      * call of fill_window.
00347      */
00348     s->ins_h = s->window[0];
00349     UPDATE_HASH(s, s->ins_h, s->window[1]);
00350     for (n = 0; n <= length - MIN_MATCH; n++) {
00351         INSERT_STRING(s, n, hash_head);
00352     }
00353     if (hash_head) hash_head = 0;  /* to make compiler happy */
00354     return Z_OK;
00355 }
00356 
00357 /* ========================================================================= */
00358 int ZEXPORT deflateReset (strm)
00359     z_streamp strm;
00360 {
00361     deflate_state *s;
00362 
00363     if (strm == Z_NULL || strm->state == Z_NULL ||
00364         strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
00365         return Z_STREAM_ERROR;
00366     }
00367 
00368     strm->total_in = strm->total_out = 0;
00369     strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
00370     strm->data_type = Z_UNKNOWN;
00371 
00372     s = (deflate_state *)strm->state;
00373     s->pending = 0;
00374     s->pending_out = s->pending_buf;
00375 
00376     if (s->wrap < 0) {
00377         s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
00378     }
00379     s->status = s->wrap ? INIT_STATE : BUSY_STATE;
00380     strm->adler =
00381 #ifdef GZIP
00382         s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
00383 #endif
00384         adler32(0L, Z_NULL, 0);
00385     s->last_flush = Z_NO_FLUSH;
00386 
00387     _tr_init(s);
00388     lm_init(s);
00389 
00390     return Z_OK;
00391 }
00392 
00393 /* ========================================================================= */
00394 int ZEXPORT deflatePrime (strm, bits, value)
00395     z_streamp strm;
00396     int bits;
00397     int value;
00398 {
00399     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
00400     strm->state->bi_valid = bits;
00401     strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
00402     return Z_OK;
00403 }
00404 
00405 /* ========================================================================= */
00406 int ZEXPORT deflateParams(strm, level, strategy)
00407     z_streamp strm;
00408     int level;
00409     int strategy;
00410 {
00411     deflate_state *s;
00412     compress_func func;
00413     int err = Z_OK;
00414 
00415     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
00416     s = strm->state;
00417 
00418 #ifdef FASTEST
00419     if (level != 0) level = 1;
00420 #else
00421     if (level == Z_DEFAULT_COMPRESSION) level = 6;
00422 #endif
00423     if (level < 0 || level > 9 || strategy < 0 || strategy > Z_RLE) {
00424         return Z_STREAM_ERROR;
00425     }
00426     func = configuration_table[s->level].func;
00427 
00428     if (func != configuration_table[level].func && strm->total_in != 0) {
00429         /* Flush the last buffer: */
00430         err = deflate(strm, Z_PARTIAL_FLUSH);
00431     }
00432     if (s->level != level) {
00433         s->level = level;
00434         s->max_lazy_match   = configuration_table[level].max_lazy;
00435         s->good_match       = configuration_table[level].good_length;
00436         s->nice_match       = configuration_table[level].nice_length;
00437         s->max_chain_length = configuration_table[level].max_chain;
00438     }
00439     s->strategy = strategy;
00440     return err;
00441 }
00442 
00443 /* =========================================================================
00444  * For the default windowBits of 15 and memLevel of 8, this function returns
00445  * a close to exact, as well as small, upper bound on the compressed size.
00446  * They are coded as constants here for a reason--if the #define's are
00447  * changed, then this function needs to be changed as well.  The return
00448  * value for 15 and 8 only works for those exact settings.
00449  *
00450  * For any setting other than those defaults for windowBits and memLevel,
00451  * the value returned is a conservative worst case for the maximum expansion
00452  * resulting from using fixed blocks instead of stored blocks, which deflate
00453  * can emit on compressed data for some combinations of the parameters.
00454  *
00455  * This function could be more sophisticated to provide closer upper bounds
00456  * for every combination of windowBits and memLevel, as well as wrap.
00457  * But even the conservative upper bound of about 14% expansion does not
00458  * seem onerous for output buffer allocation.
00459  */
00460 uLong ZEXPORT deflateBound(strm, sourceLen)
00461     z_streamp strm;
00462     uLong sourceLen;
00463 {
00464     deflate_state *s;
00465     uLong destLen;
00466 
00467     /* conservative upper bound */
00468     destLen = sourceLen +
00469               ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
00470 
00471     /* if can't get parameters, return conservative bound */
00472     if (strm == Z_NULL || strm->state == Z_NULL)
00473         return destLen;
00474 
00475     /* if not default parameters, return conservative bound */
00476     s = strm->state;
00477     if (s->w_bits != 15 || s->hash_bits != 8 + 7)
00478         return destLen;
00479 
00480     /* default settings: return tight bound for that case */
00481     return compressBound(sourceLen);
00482 }
00483 
00484 /* =========================================================================
00485  * Put a short in the pending buffer. The 16-bit value is put in MSB order.
00486  * IN assertion: the stream state is correct and there is enough room in
00487  * pending_buf.
00488  */
00489 local void putShortMSB (s, b)
00490     deflate_state *s;
00491     uInt b;
00492 {
00493     put_byte(s, (Byte)(b >> 8));
00494     put_byte(s, (Byte)(b & 0xff));
00495 }
00496 
00497 /* =========================================================================
00498  * Flush as much pending output as possible. All deflate() output goes
00499  * through this function so some applications may wish to modify it
00500  * to avoid allocating a large strm->next_out buffer and copying into it.
00501  * (See also read_buf()).
00502  */
00503 local void flush_pending(strm)
00504     z_streamp strm;
00505 {
00506     unsigned len = strm->state->pending;
00507 
00508     if (len > strm->avail_out) len = strm->avail_out;
00509     if (len == 0) return;
00510 
00511     zmemcpy(strm->next_out, strm->state->pending_out, len);
00512     strm->next_out  += len;
00513     strm->state->pending_out  += len;
00514     strm->total_out += len;
00515     strm->avail_out  -= len;
00516     strm->state->pending -= len;
00517     if (strm->state->pending == 0) {
00518         strm->state->pending_out = strm->state->pending_buf;
00519     }
00520 }
00521 
00522 /* ========================================================================= */
00523 int ZEXPORT deflate (strm, flush)
00524     z_streamp strm;
00525     int flush;
00526 {
00527     int old_flush; /* value of flush param for previous deflate call */
00528     deflate_state *s;
00529 
00530     if (strm == Z_NULL || strm->state == Z_NULL ||
00531         flush > Z_FINISH || flush < 0) {
00532         return Z_STREAM_ERROR;
00533     }
00534     s = strm->state;
00535 
00536     if (strm->next_out == Z_NULL ||
00537         (strm->next_in == Z_NULL && strm->avail_in != 0) ||
00538         (s->status == FINISH_STATE && flush != Z_FINISH)) {
00539         ERR_RETURN(strm, Z_STREAM_ERROR);
00540     }
00541     if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
00542 
00543     s->strm = strm; /* just in case */
00544     old_flush = s->last_flush;
00545     s->last_flush = flush;
00546 
00547     /* Write the header */
00548     if (s->status == INIT_STATE) {
00549 #ifdef GZIP
00550         if (s->wrap == 2) {
00551             put_byte(s, 31);
00552             put_byte(s, 139);
00553             put_byte(s, 8);
00554             put_byte(s, 0);
00555             put_byte(s, 0);
00556             put_byte(s, 0);
00557             put_byte(s, 0);
00558             put_byte(s, 0);
00559             put_byte(s, s->level == 9 ? 2 :
00560                         (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
00561                          4 : 0));
00562             put_byte(s, 255);
00563             s->status = BUSY_STATE;
00564             strm->adler = crc32(0L, Z_NULL, 0);
00565         }
00566         else
00567 #endif
00568         {
00569             uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
00570             uInt level_flags;
00571 
00572             if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
00573                 level_flags = 0;
00574             else if (s->level < 6)
00575                 level_flags = 1;
00576             else if (s->level == 6)
00577                 level_flags = 2;
00578             else
00579                 level_flags = 3;
00580             header |= (level_flags << 6);
00581             if (s->strstart != 0) header |= PRESET_DICT;
00582             header += 31 - (header % 31);
00583 
00584             s->status = BUSY_STATE;
00585             putShortMSB(s, header);
00586 
00587             /* Save the adler32 of the preset dictionary: */
00588             if (s->strstart != 0) {
00589                 putShortMSB(s, (uInt)(strm->adler >> 16));
00590                 putShortMSB(s, (uInt)(strm->adler & 0xffff));
00591             }
00592             strm->adler = adler32(0L, Z_NULL, 0);
00593         }
00594     }
00595 
00596     /* Flush as much pending output as possible */
00597     if (s->pending != 0) {
00598         flush_pending(strm);
00599         if (strm->avail_out == 0) {
00600             /* Since avail_out is 0, deflate will be called again with
00601              * more output space, but possibly with both pending and
00602              * avail_in equal to zero. There won't be anything to do,
00603              * but this is not an error situation so make sure we
00604              * return OK instead of BUF_ERROR at next call of deflate:
00605              */
00606             s->last_flush = -1;
00607             return Z_OK;
00608         }
00609 
00610     /* Make sure there is something to do and avoid duplicate consecutive
00611      * flushes. For repeated and useless calls with Z_FINISH, we keep
00612      * returning Z_STREAM_END instead of Z_BUF_ERROR.
00613      */
00614     } else if (strm->avail_in == 0 && flush <= old_flush &&
00615                flush != Z_FINISH) {
00616         ERR_RETURN(strm, Z_BUF_ERROR);
00617     }
00618 
00619     /* User must not provide more input after the first FINISH: */
00620     if (s->status == FINISH_STATE && strm->avail_in != 0) {
00621         ERR_RETURN(strm, Z_BUF_ERROR);
00622     }
00623 
00624     /* Start a new block or continue the current one.
00625      */
00626     if (strm->avail_in != 0 || s->lookahead != 0 ||
00627         (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
00628         block_state bstate;
00629 
00630         bstate = (*(configuration_table[s->level].func))(s, flush);
00631 
00632         if (bstate == finish_started || bstate == finish_done) {
00633             s->status = FINISH_STATE;
00634         }
00635         if (bstate == need_more || bstate == finish_started) {
00636             if (strm->avail_out == 0) {
00637                 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
00638             }
00639             return Z_OK;
00640             /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
00641              * of deflate should use the same flush parameter to make sure
00642              * that the flush is complete. So we don't have to output an
00643              * empty block here, this will be done at next call. This also
00644              * ensures that for a very small output buffer, we emit at most
00645              * one empty block.
00646              */
00647         }
00648         if (bstate == block_done) {
00649             if (flush == Z_PARTIAL_FLUSH) {
00650                 _tr_align(s);
00651             } else { /* FULL_FLUSH or SYNC_FLUSH */
00652                 _tr_stored_block(s, (char*)0, 0L, 0);
00653                 /* For a full flush, this empty block will be recognized
00654                  * as a special marker by inflate_sync().
00655                  */
00656                 if (flush == Z_FULL_FLUSH) {
00657                     CLEAR_HASH(s);             /* forget history */
00658                 }
00659             }
00660             flush_pending(strm);
00661             if (strm->avail_out == 0) {
00662               s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
00663               return Z_OK;
00664             }
00665         }
00666     }
00667     Assert(strm->avail_out > 0, "bug2");
00668 
00669     if (flush != Z_FINISH) return Z_OK;
00670     if (s->wrap <= 0) return Z_STREAM_END;
00671 
00672     /* Write the trailer */
00673 #ifdef GZIP
00674     if (s->wrap == 2) {
00675         put_byte(s, (Byte)(strm->adler & 0xff));
00676         put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
00677         put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
00678         put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
00679         put_byte(s, (Byte)(strm->total_in & 0xff));
00680         put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
00681         put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
00682         put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
00683     }
00684     else
00685 #endif
00686     {
00687         putShortMSB(s, (uInt)(strm->adler >> 16));
00688         putShortMSB(s, (uInt)(strm->adler & 0xffff));
00689     }
00690     flush_pending(strm);
00691     /* If avail_out is zero, the application will call deflate again
00692      * to flush the rest.
00693      */
00694     if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
00695     return s->pending != 0 ? Z_OK : Z_STREAM_END;
00696 }
00697 
00698 /* ========================================================================= */
00699 int ZEXPORT deflateEnd (strm)
00700     z_streamp strm;
00701 {
00702     int status;
00703 
00704     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
00705 
00706     status = strm->state->status;
00707     if (status != INIT_STATE && status != BUSY_STATE &&
00708         status != FINISH_STATE) {
00709       return Z_STREAM_ERROR;
00710     }
00711 
00712     /* Deallocate in reverse order of allocations: */
00713     TRY_FREE(strm, strm->state->pending_buf);
00714     TRY_FREE(strm, strm->state->head);
00715     TRY_FREE(strm, strm->state->prev);
00716     TRY_FREE(strm, strm->state->window);
00717 
00718     ZFREE(strm, strm->state);
00719     strm->state = Z_NULL;
00720 
00721     return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
00722 }
00723 
00724 /* =========================================================================
00725  * Copy the source state to the destination state.
00726  * To simplify the source, this is not supported for 16-bit MSDOS (which
00727  * doesn't have enough memory anyway to duplicate compression states).
00728  */
00729 int ZEXPORT deflateCopy (dest, source)
00730     z_streamp dest;
00731     z_streamp source;
00732 {
00733 #ifdef MAXSEG_64K
00734     return Z_STREAM_ERROR;
00735 #else
00736     deflate_state *ds;
00737     deflate_state *ss;
00738     ushf *overlay;
00739 
00740 
00741     if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
00742         return Z_STREAM_ERROR;
00743     }
00744 
00745     ss = source->state;
00746 
00747     *dest = *source;
00748 
00749     ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
00750     if (ds == Z_NULL) return Z_MEM_ERROR;
00751     dest->state = (struct internal_state FAR *) ds;
00752     *ds = *ss;
00753     ds->strm = dest;
00754 
00755     ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
00756     ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
00757     ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
00758     overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
00759     ds->pending_buf = (uchf *) overlay;
00760 
00761     if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
00762         ds->pending_buf == Z_NULL) {
00763         deflateEnd (dest);
00764         return Z_MEM_ERROR;
00765     }
00766     /* following zmemcpy do not work for 16-bit MSDOS */
00767     zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
00768     zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
00769     zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
00770     zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
00771 
00772     ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
00773     ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
00774     ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
00775 
00776     ds->l_desc.dyn_tree = ds->dyn_ltree;
00777     ds->d_desc.dyn_tree = ds->dyn_dtree;
00778     ds->bl_desc.dyn_tree = ds->bl_tree;
00779 
00780     return Z_OK;
00781 #endif /* MAXSEG_64K */
00782 }
00783 
00784 /* ===========================================================================
00785  * Read a new buffer from the current input stream, update the adler32
00786  * and total number of bytes read.  All deflate() input goes through
00787  * this function so some applications may wish to modify it to avoid
00788  * allocating a large strm->next_in buffer and copying from it.
00789  * (See also flush_pending()).
00790  */
00791 local int read_buf(strm, buf, size)
00792     z_streamp strm;
00793     Bytef *buf;
00794     unsigned size;
00795 {
00796     unsigned len = strm->avail_in;
00797 
00798     if (len > size) len = size;
00799     if (len == 0) return 0;
00800 
00801     strm->avail_in  -= len;
00802 
00803     if (strm->state->wrap == 1) {
00804         strm->adler = adler32(strm->adler, strm->next_in, len);
00805     }
00806 #ifdef GZIP
00807     else if (strm->state->wrap == 2) {
00808         strm->adler = crc32(strm->adler, strm->next_in, len);
00809     }
00810 #endif
00811     zmemcpy(buf, strm->next_in, len);
00812     strm->next_in  += len;
00813     strm->total_in += len;
00814 
00815     return (int)len;
00816 }
00817 
00818 /* ===========================================================================
00819  * Initialize the "longest match" routines for a new zlib stream
00820  */
00821 local void lm_init (s)
00822     deflate_state *s;
00823 {
00824     s->window_size = (ulg)2L*s->w_size;
00825 
00826     CLEAR_HASH(s);
00827 
00828     /* Set the default configuration parameters:
00829      */
00830     s->max_lazy_match   = configuration_table[s->level].max_lazy;
00831     s->good_match       = configuration_table[s->level].good_length;
00832     s->nice_match       = configuration_table[s->level].nice_length;
00833     s->max_chain_length = configuration_table[s->level].max_chain;
00834 
00835     s->strstart = 0;
00836     s->block_start = 0L;
00837     s->lookahead = 0;
00838     s->match_length = s->prev_length = MIN_MATCH-1;
00839     s->match_available = 0;
00840     s->ins_h = 0;
00841 #ifdef ASMV
00842     match_init(); /* initialize the asm code */
00843 #endif
00844 }
00845 
00846 #ifndef FASTEST
00847 /* ===========================================================================
00848  * Set match_start to the longest match starting at the given string and
00849  * return its length. Matches shorter or equal to prev_length are discarded,
00850  * in which case the result is equal to prev_length and match_start is
00851  * garbage.
00852  * IN assertions: cur_match is the head of the hash chain for the current
00853  *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
00854  * OUT assertion: the match length is not greater than s->lookahead.
00855  */
00856 #ifndef ASMV
00857 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
00858  * match.S. The code will be functionally equivalent.
00859  */
00860 local uInt longest_match(s, cur_match)
00861     deflate_state *s;
00862     IPos cur_match;                             /* current match */
00863 {
00864     unsigned chain_length = s->max_chain_length;/* max hash chain length */
00865     register Bytef *scan = s->window + s->strstart; /* current string */
00866     register Bytef *match;                       /* matched string */
00867     register int len;                           /* length of current match */
00868     int best_len = s->prev_length;              /* best match length so far */
00869     int nice_match = s->nice_match;             /* stop if match long enough */
00870     IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
00871         s->strstart - (IPos)MAX_DIST(s) : NIL;
00872     /* Stop when cur_match becomes <= limit. To simplify the code,
00873      * we prevent matches with the string of window index 0.
00874      */
00875     Posf *prev = s->prev;
00876     uInt wmask = s->w_mask;
00877 
00878 #ifdef UNALIGNED_OK
00879     /* Compare two bytes at a time. Note: this is not always beneficial.
00880      * Try with and without -DUNALIGNED_OK to check.
00881      */
00882     register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
00883     register ush scan_start = *(ushf*)scan;
00884     register ush scan_end   = *(ushf*)(scan+best_len-1);
00885 #else
00886     register Bytef *strend = s->window + s->strstart + MAX_MATCH;
00887     register Byte scan_end1  = scan[best_len-1];
00888     register Byte scan_end   = scan[best_len];
00889 #endif
00890 
00891     /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
00892      * It is easy to get rid of this optimization if necessary.
00893      */
00894     Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
00895 
00896     /* Do not waste too much time if we already have a good match: */
00897     if (s->prev_length >= s->good_match) {
00898         chain_length >>= 2;
00899     }
00900     /* Do not look for matches beyond the end of the input. This is necessary
00901      * to make deflate deterministic.
00902      */
00903     if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
00904 
00905     Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
00906 
00907     do {
00908         Assert(cur_match < s->strstart, "no future");
00909         match = s->window + cur_match;
00910 
00911         /* Skip to next match if the match length cannot increase
00912          * or if the match length is less than 2:
00913          */
00914 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
00915         /* This code assumes sizeof(unsigned short) == 2. Do not use
00916          * UNALIGNED_OK if your compiler uses a different size.
00917          */
00918         if (*(ushf*)(match+best_len-1) != scan_end ||
00919             *(ushf*)match != scan_start) continue;
00920 
00921         /* It is not necessary to compare scan[2] and match[2] since they are
00922          * always equal when the other bytes match, given that the hash keys
00923          * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
00924          * strstart+3, +5, ... up to strstart+257. We check for insufficient
00925          * lookahead only every 4th comparison; the 128th check will be made
00926          * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
00927          * necessary to put more guard bytes at the end of the window, or
00928          * to check more often for insufficient lookahead.
00929          */
00930         Assert(scan[2] == match[2], "scan[2]?");
00931         scan++, match++;
00932         do {
00933         } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
00934                  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
00935                  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
00936                  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
00937                  scan < strend);
00938         /* The funny "do {}" generates better code on most compilers */
00939 
00940         /* Here, scan <= window+strstart+257 */
00941         Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
00942         if (*scan == *match) scan++;
00943 
00944         len = (MAX_MATCH - 1) - (int)(strend-scan);
00945         scan = strend - (MAX_MATCH-1);
00946 
00947 #else /* UNALIGNED_OK */
00948 
00949         if (match[best_len]   != scan_end  ||
00950             match[best_len-1] != scan_end1 ||
00951             *match            != *scan     ||
00952             *++match          != scan[1])      continue;
00953 
00954         /* The check at best_len-1 can be removed because it will be made
00955          * again later. (This heuristic is not always a win.)
00956          * It is not necessary to compare scan[2] and match[2] since they
00957          * are always equal when the other bytes match, given that
00958          * the hash keys are equal and that HASH_BITS >= 8.
00959          */
00960         scan += 2, match++;
00961         Assert(*scan == *match, "match[2]?");
00962 
00963         /* We check for insufficient lookahead only every 8th comparison;
00964          * the 256th check will be made at strstart+258.
00965          */
00966         do {
00967         } while (*++scan == *++match && *++scan == *++match &&
00968                  *++scan == *++match && *++scan == *++match &&
00969                  *++scan == *++match && *++scan == *++match &&
00970                  *++scan == *++match && *++scan == *++match &&
00971                  scan < strend);
00972 
00973         Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
00974 
00975         len = MAX_MATCH - (int)(strend - scan);
00976         scan = strend - MAX_MATCH;
00977 
00978 #endif /* UNALIGNED_OK */
00979 
00980         if (len > best_len) {
00981             s->match_start = cur_match;
00982             best_len = len;
00983             if (len >= nice_match) break;
00984 #ifdef UNALIGNED_OK
00985             scan_end = *(ushf*)(scan+best_len-1);
00986 #else
00987             scan_end1  = scan[best_len-1];
00988             scan_end   = scan[best_len];
00989 #endif
00990         }
00991     } while ((cur_match = prev[cur_match & wmask]) > limit
00992              && --chain_length != 0);
00993 
00994     if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
00995     return s->lookahead;
00996 }
00997 #endif /* ASMV */
00998 #endif /* FASTEST */
00999 
01000 /* ---------------------------------------------------------------------------
01001  * Optimized version for level == 1 or strategy == Z_RLE only
01002  */
01003 local uInt longest_match_fast(s, cur_match)
01004     deflate_state *s;
01005     IPos cur_match;                             /* current match */
01006 {
01007     register Bytef *scan = s->window + s->strstart; /* current string */
01008     register Bytef *match;                       /* matched string */
01009     register int len;                           /* length of current match */
01010     register Bytef *strend = s->window + s->strstart + MAX_MATCH;
01011 
01012     /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
01013      * It is easy to get rid of this optimization if necessary.
01014      */
01015     Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
01016 
01017     Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
01018 
01019     Assert(cur_match < s->strstart, "no future");
01020 
01021     match = s->window + cur_match;
01022 
01023     /* Return failure if the match length is less than 2:
01024      */
01025     if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
01026 
01027     /* The check at best_len-1 can be removed because it will be made
01028      * again later. (This heuristic is not always a win.)
01029      * It is not necessary to compare scan[2] and match[2] since they
01030      * are always equal when the other bytes match, given that
01031      * the hash keys are equal and that HASH_BITS >= 8.
01032      */
01033     scan += 2, match += 2;
01034     Assert(*scan == *match, "match[2]?");
01035 
01036     /* We check for insufficient lookahead only every 8th comparison;
01037      * the 256th check will be made at strstart+258.
01038      */
01039     do {
01040     } while (*++scan == *++match && *++scan == *++match &&
01041              *++scan == *++match && *++scan == *++match &&
01042              *++scan == *++match && *++scan == *++match &&
01043              *++scan == *++match && *++scan == *++match &&
01044              scan < strend);
01045 
01046     Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
01047 
01048     len = MAX_MATCH - (int)(strend - scan);
01049 
01050     if (len < MIN_MATCH) return MIN_MATCH - 1;
01051 
01052     s->match_start = cur_match;
01053     return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
01054 }
01055 
01056 #ifdef DEBUG
01057 /* ===========================================================================
01058  * Check that the match at match_start is indeed a match.
01059  */
01060 local void check_match(s, start, match, length)
01061     deflate_state *s;
01062     IPos start, match;
01063     int length;
01064 {
01065     /* check that the match is indeed a match */
01066     if (zmemcmp(s->window + match,
01067                 s->window + start, length) != EQUAL) {
01068         fprintf(stderr, " start %u, match %u, length %d\n",
01069                 start, match, length);
01070         do {
01071             fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
01072         } while (--length != 0);
01073         z_error("invalid match");
01074     }
01075     if (z_verbose > 1) {
01076         fprintf(stderr,"\\[%d,%d]", start-match, length);
01077         do { putc(s->window[start++], stderr); } while (--length != 0);
01078     }
01079 }
01080 #else
01081 #  define check_match(s, start, match, length)
01082 #endif /* DEBUG */
01083 
01084 /* ===========================================================================
01085  * Fill the window when the lookahead becomes insufficient.
01086  * Updates strstart and lookahead.
01087  *
01088  * IN assertion: lookahead < MIN_LOOKAHEAD
01089  * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
01090  *    At least one byte has been read, or avail_in == 0; reads are
01091  *    performed for at least two bytes (required for the zip translate_eol
01092  *    option -- not supported here).
01093  */
01094 local void fill_window(s)
01095     deflate_state *s;
01096 {
01097     register unsigned n, m;
01098     register Posf *p;
01099     unsigned more;    /* Amount of free space at the end of the window. */
01100     uInt wsize = s->w_size;
01101 
01102     do {
01103         more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
01104 
01105         /* Deal with !@#$% 64K limit: */
01106         if (sizeof(int) <= 2) {
01107             if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
01108                 more = wsize;
01109 
01110             } else if (more == (unsigned)(-1)) {
01111                 /* Very unlikely, but possible on 16 bit machine if
01112                  * strstart == 0 && lookahead == 1 (input done a byte at time)
01113                  */
01114                 more--;
01115             }
01116         }
01117 
01118         /* If the window is almost full and there is insufficient lookahead,
01119          * move the upper half to the lower one to make room in the upper half.
01120          */
01121         if (s->strstart >= wsize+MAX_DIST(s)) {
01122 
01123             zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
01124             s->match_start -= wsize;
01125             s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
01126             s->block_start -= (long) wsize;
01127 
01128             /* Slide the hash table (could be avoided with 32 bit values
01129                at the expense of memory usage). We slide even when level == 0
01130                to keep the hash table consistent if we switch back to level > 0
01131                later. (Using level 0 permanently is not an optimal usage of
01132                zlib, so we don't care about this pathological case.)
01133              */
01134             n = s->hash_size;
01135             p = &s->head[n];
01136             do {
01137                 m = *--p;
01138                 *p = (Pos)(m >= wsize ? m-wsize : NIL);
01139             } while (--n);
01140 
01141             n = wsize;
01142 #ifndef FASTEST
01143             p = &s->prev[n];
01144             do {
01145                 m = *--p;
01146                 *p = (Pos)(m >= wsize ? m-wsize : NIL);
01147                 /* If n is not on any hash chain, prev[n] is garbage but
01148                  * its value will never be used.
01149                  */
01150             } while (--n);
01151 #endif
01152             more += wsize;
01153         }
01154         if (s->strm->avail_in == 0) return;
01155 
01156         /* If there was no sliding:
01157          *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
01158          *    more == window_size - lookahead - strstart
01159          * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
01160          * => more >= window_size - 2*WSIZE + 2
01161          * In the BIG_MEM or MMAP case (not yet supported),
01162          *   window_size == input_size + MIN_LOOKAHEAD  &&
01163          *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
01164          * Otherwise, window_size == 2*WSIZE so more >= 2.
01165          * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
01166          */
01167         Assert(more >= 2, "more < 2");
01168 
01169         n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
01170         s->lookahead += n;
01171 
01172         /* Initialize the hash value now that we have some input: */
01173         if (s->lookahead >= MIN_MATCH) {
01174             s->ins_h = s->window[s->strstart];
01175             UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
01176 #if MIN_MATCH != 3
01177             Call UPDATE_HASH() MIN_MATCH-3 more times
01178 #endif
01179         }
01180         /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
01181          * but this is not important since only literal bytes will be emitted.
01182          */
01183 
01184     } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
01185 }
01186 
01187 /* ===========================================================================
01188  * Flush the current block, with given end-of-file flag.
01189  * IN assertion: strstart is set to the end of the current match.
01190  */
01191 #define FLUSH_BLOCK_ONLY(s, eof) { \
01192    _tr_flush_block(s, (s->block_start >= 0L ? \
01193                    (charf *)&s->window[(unsigned)s->block_start] : \
01194                    (charf *)Z_NULL), \
01195                 (ulg)((long)s->strstart - s->block_start), \
01196                 (eof)); \
01197    s->block_start = s->strstart; \
01198    flush_pending(s->strm); \
01199    Tracev((stderr,"[FLUSH]")); \
01200 }
01201 
01202 /* Same but force premature exit if necessary. */
01203 #define FLUSH_BLOCK(s, eof) { \
01204    FLUSH_BLOCK_ONLY(s, eof); \
01205    if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
01206 }
01207 
01208 /* ===========================================================================
01209  * Copy without compression as much as possible from the input stream, return
01210  * the current block state.
01211  * This function does not insert new strings in the dictionary since
01212  * uncompressible data is probably not useful. This function is used
01213  * only for the level=0 compression option.
01214  * NOTE: this function should be optimized to avoid extra copying from
01215  * window to pending_buf.
01216  */
01217 local block_state deflate_stored(s, flush)
01218     deflate_state *s;
01219     int flush;
01220 {
01221     /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
01222      * to pending_buf_size, and each stored block has a 5 byte header:
01223      */
01224     ulg max_block_size = 0xffff;
01225     ulg max_start;
01226 
01227     if (max_block_size > s->pending_buf_size - 5) {
01228         max_block_size = s->pending_buf_size - 5;
01229     }
01230 
01231     /* Copy as much as possible from input to output: */
01232     for (;;) {
01233         /* Fill the window as much as possible: */
01234         if (s->lookahead <= 1) {
01235 
01236             Assert(s->strstart < s->w_size+MAX_DIST(s) ||
01237                    s->block_start >= (long)s->w_size, "slide too late");
01238 
01239             fill_window(s);
01240             if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
01241 
01242             if (s->lookahead == 0) break; /* flush the current block */
01243         }
01244         Assert(s->block_start >= 0L, "block gone");
01245 
01246         s->strstart += s->lookahead;
01247         s->lookahead = 0;
01248 
01249         /* Emit a stored block if pending_buf will be full: */
01250         max_start = s->block_start + max_block_size;
01251         if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
01252             /* strstart == 0 is possible when wraparound on 16-bit machine */
01253             s->lookahead = (uInt)(s->strstart - max_start);
01254             s->strstart = (uInt)max_start;
01255             FLUSH_BLOCK(s, 0);
01256         }
01257         /* Flush if we may have to slide, otherwise block_start may become
01258          * negative and the data will be gone:
01259          */
01260         if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
01261             FLUSH_BLOCK(s, 0);
01262         }
01263     }
01264     FLUSH_BLOCK(s, flush == Z_FINISH);
01265     return flush == Z_FINISH ? finish_done : block_done;
01266 }
01267 
01268 /* ===========================================================================
01269  * Compress as much as possible from the input stream, return the current
01270  * block state.
01271  * This function does not perform lazy evaluation of matches and inserts
01272  * new strings in the dictionary only for unmatched strings or for short
01273  * matches. It is used only for the fast compression options.
01274  */
01275 local block_state deflate_fast(s, flush)
01276     deflate_state *s;
01277     int flush;
01278 {
01279     IPos hash_head = NIL; /* head of the hash chain */
01280     int bflush;           /* set if current block must be flushed */
01281 
01282     for (;;) {
01283         /* Make sure that we always have enough lookahead, except
01284          * at the end of the input file. We need MAX_MATCH bytes
01285          * for the next match, plus MIN_MATCH bytes to insert the
01286          * string following the next match.
01287          */
01288         if (s->lookahead < MIN_LOOKAHEAD) {
01289             fill_window(s);
01290             if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
01291                 return need_more;
01292             }
01293             if (s->lookahead == 0) break; /* flush the current block */
01294         }
01295 
01296         /* Insert the string window[strstart .. strstart+2] in the
01297          * dictionary, and set hash_head to the head of the hash chain:
01298          */
01299         if (s->lookahead >= MIN_MATCH) {
01300             INSERT_STRING(s, s->strstart, hash_head);
01301         }
01302 
01303         /* Find the longest match, discarding those <= prev_length.
01304          * At this point we have always match_length < MIN_MATCH
01305          */
01306         if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
01307             /* To simplify the code, we prevent matches with the string
01308              * of window index 0 (in particular we have to avoid a match
01309              * of the string with itself at the start of the input file).
01310              */
01311 #ifdef FASTEST
01312             if ((s->strategy < Z_HUFFMAN_ONLY) ||
01313                 (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
01314                 s->match_length = longest_match_fast (s, hash_head);
01315             }
01316 #else
01317             if (s->strategy < Z_HUFFMAN_ONLY) {
01318                 s->match_length = longest_match (s, hash_head);
01319             } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
01320                 s->match_length = longest_match_fast (s, hash_head);
01321             }
01322 #endif
01323             /* longest_match() or longest_match_fast() sets match_start */
01324         }
01325         if (s->match_length >= MIN_MATCH) {
01326             check_match(s, s->strstart, s->match_start, s->match_length);
01327 
01328             _tr_tally_dist(s, s->strstart - s->match_start,
01329                            s->match_length - MIN_MATCH, bflush);
01330 
01331             s->lookahead -= s->match_length;
01332 
01333             /* Insert new strings in the hash table only if the match length
01334              * is not too large. This saves time but degrades compression.
01335              */
01336 #ifndef FASTEST
01337             if (s->match_length <= s->max_insert_length &&
01338                 s->lookahead >= MIN_MATCH) {
01339                 s->match_length--; /* string at strstart already in table */
01340                 do {
01341                     s->strstart++;
01342                     INSERT_STRING(s, s->strstart, hash_head);
01343                     /* strstart never exceeds WSIZE-MAX_MATCH, so there are
01344                      * always MIN_MATCH bytes ahead.
01345                      */
01346                 } while (--s->match_length != 0);
01347                 s->strstart++;
01348             } else
01349 #endif
01350             {
01351                 s->strstart += s->match_length;
01352                 s->match_length = 0;
01353                 s->ins_h = s->window[s->strstart];
01354                 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
01355 #if MIN_MATCH != 3
01356                 Call UPDATE_HASH() MIN_MATCH-3 more times
01357 #endif
01358                 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
01359                  * matter since it will be recomputed at next deflate call.
01360                  */
01361             }
01362         } else {
01363             /* No match, output a literal byte */
01364             Tracevv((stderr,"%c", s->window[s->strstart]));
01365             _tr_tally_lit (s, s->window[s->strstart], bflush);
01366             s->lookahead--;
01367             s->strstart++;
01368         }
01369         if (bflush) FLUSH_BLOCK(s, 0);
01370     }
01371     FLUSH_BLOCK(s, flush == Z_FINISH);
01372     return flush == Z_FINISH ? finish_done : block_done;
01373 }
01374 
01375 #ifndef FASTEST
01376 /* ===========================================================================
01377  * Same as above, but achieves better compression. We use a lazy
01378  * evaluation for matches: a match is finally adopted only if there is
01379  * no better match at the next window position.
01380  */
01381 local block_state deflate_slow(s, flush)
01382     deflate_state *s;
01383     int flush;
01384 {
01385     IPos hash_head = NIL;    /* head of hash chain */
01386     int bflush;              /* set if current block must be flushed */
01387 
01388     /* Process the input block. */
01389     for (;;) {
01390         /* Make sure that we always have enough lookahead, except
01391          * at the end of the input file. We need MAX_MATCH bytes
01392          * for the next match, plus MIN_MATCH bytes to insert the
01393          * string following the next match.
01394          */
01395         if (s->lookahead < MIN_LOOKAHEAD) {
01396             fill_window(s);
01397             if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
01398                 return need_more;
01399             }
01400             if (s->lookahead == 0) break; /* flush the current block */
01401         }
01402 
01403         /* Insert the string window[strstart .. strstart+2] in the
01404          * dictionary, and set hash_head to the head of the hash chain:
01405          */
01406         if (s->lookahead >= MIN_MATCH) {
01407             INSERT_STRING(s, s->strstart, hash_head);
01408         }
01409 
01410         /* Find the longest match, discarding those <= prev_length.
01411          */
01412         s->prev_length = s->match_length, s->prev_match = s->match_start;
01413         s->match_length = MIN_MATCH-1;
01414 
01415         if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
01416             s->strstart - hash_head <= MAX_DIST(s)) {
01417             /* To simplify the code, we prevent matches with the string
01418              * of window index 0 (in particular we have to avoid a match
01419              * of the string with itself at the start of the input file).
01420              */
01421             if (s->strategy < Z_HUFFMAN_ONLY) {
01422                 s->match_length = longest_match (s, hash_head);
01423             } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
01424                 s->match_length = longest_match_fast (s, hash_head);
01425             }
01426             /* longest_match() or longest_match_fast() sets match_start */
01427 
01428             if (s->match_length <= 5 && (s->strategy == Z_FILTERED
01429 #if TOO_FAR <= 32767
01430                 || (s->match_length == MIN_MATCH &&
01431                     s->strstart - s->match_start > TOO_FAR)
01432 #endif
01433                 )) {
01434 
01435                 /* If prev_match is also MIN_MATCH, match_start is garbage
01436                  * but we will ignore the current match anyway.
01437                  */
01438                 s->match_length = MIN_MATCH-1;
01439             }
01440         }
01441         /* If there was a match at the previous step and the current
01442          * match is not better, output the previous match:
01443          */
01444         if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
01445             uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
01446             /* Do not insert strings in hash table beyond this. */
01447 
01448             check_match(s, s->strstart-1, s->prev_match, s->prev_length);
01449 
01450             _tr_tally_dist(s, s->strstart -1 - s->prev_match,
01451                            s->prev_length - MIN_MATCH, bflush);
01452 
01453             /* Insert in hash table all strings up to the end of the match.
01454              * strstart-1 and strstart are already inserted. If there is not
01455              * enough lookahead, the last two strings are not inserted in
01456              * the hash table.
01457              */
01458             s->lookahead -= s->prev_length-1;
01459             s->prev_length -= 2;
01460             do {
01461                 if (++s->strstart <= max_insert) {
01462                     INSERT_STRING(s, s->strstart, hash_head);
01463                 }
01464             } while (--s->prev_length != 0);
01465             s->match_available = 0;
01466             s->match_length = MIN_MATCH-1;
01467             s->strstart++;
01468 
01469             if (bflush) FLUSH_BLOCK(s, 0);
01470 
01471         } else if (s->match_available) {
01472             /* If there was no match at the previous position, output a
01473              * single literal. If there was a match but the current match
01474              * is longer, truncate the previous match to a single literal.
01475              */
01476             Tracevv((stderr,"%c", s->window[s->strstart-1]));
01477             _tr_tally_lit(s, s->window[s->strstart-1], bflush);
01478             if (bflush) {
01479                 FLUSH_BLOCK_ONLY(s, 0);
01480             }
01481             s->strstart++;
01482             s->lookahead--;
01483             if (s->strm->avail_out == 0) return need_more;
01484         } else {
01485             /* There is no previous match to compare with, wait for
01486              * the next step to decide.
01487              */
01488             s->match_available = 1;
01489             s->strstart++;
01490             s->lookahead--;
01491         }
01492     }
01493     Assert (flush != Z_NO_FLUSH, "no flush?");
01494     if (s->match_available) {
01495         Tracevv((stderr,"%c", s->window[s->strstart-1]));
01496         _tr_tally_lit(s, s->window[s->strstart-1], bflush);
01497         s->match_available = 0;
01498     }
01499     FLUSH_BLOCK(s, flush == Z_FINISH);
01500     return flush == Z_FINISH ? finish_done : block_done;
01501 }
01502 #endif /* FASTEST */