root/tools/packfi2/deflate.c

DEFINITIONS

1. deflateInit_
2. deflateInit2_
3. deflateSetDictionary
4. deflateReset
5. deflateSetHeader
6. deflatePrime
7. deflateParams
8. deflateTune
9. deflateBound
10. putShortMSB
11. flush_pending
12. deflate
13. deflateEnd
14. deflateCopy
15. read_buf
16. lm_init
17. longest_match
18. longest_match_fast
19. check_match
20. fill_window
21. deflate_stored
22. deflate_fast
23. deflate_slow
24. deflate_rle

   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  */
   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  */
  50 /* @(#) $Id$ */
  52 #include "deflate.h"
  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  */
  63 /* ===========================================================================

  64  *  Function prototypes.

  65  */
  66 typedef enum {
need_more,      /* block not completed, need more input or more output */
block_done,     /* block flush performed */
finish_started, /* finish started, need only more output at next deflate */
finish_done     /* finish done, accept no more input or output */
  71 } block_state;
  73 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
  74 /* Compression function. Returns the block state after the call. */
local void fill_window    OF((deflate_state *s));
local block_state deflate_stored OF((deflate_state *s, int flush));
local block_state deflate_fast   OF((deflate_state *s, int flush));
  79 #ifndef FASTEST
local block_state deflate_slow   OF((deflate_state *s, int flush));
  81 #endif
local void lm_init        OF((deflate_state *s));
local void putShortMSB    OF((deflate_state *s, uInt b));
local void flush_pending  OF((z_streamp strm));
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 */
uInt longest_match  OF((deflate_state *s, IPos cur_match));
  90 #else
local uInt longest_match  OF((deflate_state *s, IPos cur_match));
  92 #endif
  93 #endif
local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
  96 #ifdef DEBUG
local  void check_match OF((deflate_state *s, IPos start, IPos match,
  98                             int length));
  99 #endif
 101 /* ===========================================================================

 102  * Local data

 103  */
 105 #define NIL 0
 106 /* Tail of hash chains */
 108 #ifndef TOO_FAR
 109 #  define TOO_FAR 4096
 110 #endif
 111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
 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  */
 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 {
ush good_length; /* reduce lazy search above this match length */
ush max_lazy;    /* do not perform lazy search above this match length */
ush nice_length; /* quit search above this match length */
ush max_chain;
compress_func func;
 129 } config;
 131 #ifdef FASTEST
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
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},
 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
 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  */
 157 #define EQUAL 0
 158 /* result of memcmp for equal strings */
 160 #ifndef NO_DUMMY_DECL
 161 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
 162 #endif
 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)
 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)]), \
match_head = s->head[s->ins_h], \
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)]), \
match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
s->head[s->ins_h] = (Pos)(str))
 193 #endif
 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) \
s->head[s->hash_size-1] = NIL; \
zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
 203 /* ========================================================================= */
 204 int ZEXPORT deflateInit_(strm, level, version, stream_size)
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,
Z_DEFAULT_STRATEGY, version, stream_size);
 212     /* To do: ignore strm->next_in if we use it as window */
 213 }
 215 /* ========================================================================= */
 216 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
version, stream_size)
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 {
deflate_state *s;
 228     int wrap = 1;
 229     static const char my_version[] = ZLIB_VERSION;
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      */
 236     if (version == Z_NULL || version[0] != my_version[0] ||
stream_size != sizeof(z_stream)) {
 238         return Z_VERSION_ERROR;
 239     }
 240     if (strm == Z_NULL) return Z_STREAM_ERROR;
strm->msg = Z_NULL;
 243     if (strm->zalloc == (alloc_func)0) {
strm->zalloc = zcalloc;
strm->opaque = (voidpf)0;
 246     }
 247     if (strm->zfree == (free_func)0) strm->zfree = zcfree;
 249 #ifdef FASTEST
 250     if (level != 0) level = 1;
 251 #else
 252     if (level == Z_DEFAULT_COMPRESSION) level = 6;
 253 #endif
 255     if (windowBits < 0) { /* suppress zlib wrapper */
wrap = 0;
windowBits = -windowBits;
 258     }
 259 #ifdef GZIP
 260     else if (windowBits > 15) {
wrap = 2;       /* write gzip wrapper instead */
windowBits -= 16;
 263     }
 264 #endif
 265     if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
strategy < 0 || strategy > Z_FIXED) {
 268         return Z_STREAM_ERROR;
 269     }
 270     if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */
s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
 272     if (s == Z_NULL) return Z_MEM_ERROR;
strm->state = (struct internal_state FAR *)s;
s->strm = strm;
s->wrap = wrap;
s->gzhead = Z_NULL;
s->w_bits = windowBits;
s->w_size = 1 << s->w_bits;
s->w_mask = s->w_size - 1;
s->hash_bits = memLevel + 7;
s->hash_size = 1 << s->hash_bits;
s->hash_mask = s->hash_size - 1;
s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
s->pending_buf = (uchf *) overlay;
s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
 297     if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
s->pending_buf == Z_NULL) {
s->status = FINISH_STATE;
strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
deflateEnd (strm);
 302         return Z_MEM_ERROR;
 303     }
s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
s->level = level;
s->strategy = strategy;
s->method = (Byte)method;
 311     return deflateReset(strm);
 312 }
 314 /* ========================================================================= */
 315 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
z_streamp strm;
 317     const Bytef *dictionary;
uInt  dictLength;
 319 {
deflate_state *s;
uInt length = dictLength;
uInt n;
IPos hash_head = 0;
 325     if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
strm->state->wrap == 2 ||
 327         (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
 328         return Z_STREAM_ERROR;
s = strm->state;
 331     if (s->wrap)
strm->adler = adler32(strm->adler, dictionary, dictLength);
 334     if (length < MIN_MATCH) return Z_OK;
 335     if (length > MAX_DIST(s)) {
length = MAX_DIST(s);
dictionary += dictLength - length; /* use the tail of the dictionary */
 338     }
zmemcpy(s->window, dictionary, length);
s->strstart = length;
s->block_start = (long)length;
 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      */
s->ins_h = s->window[0];
UPDATE_HASH(s, s->ins_h, s->window[1]);
 349     for (n = 0; n <= length - MIN_MATCH; n++) {
INSERT_STRING(s, n, hash_head);
 351     }
 352     if (hash_head) hash_head = 0;  /* to make compiler happy */
 353     return Z_OK;
 354 }
 356 /* ========================================================================= */
 357 int ZEXPORT deflateReset (strm)
z_streamp strm;
 359 {
deflate_state *s;
 362     if (strm == Z_NULL || strm->state == Z_NULL ||
strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
 364         return Z_STREAM_ERROR;
 365     }
strm->total_in = strm->total_out = 0;
strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
strm->data_type = Z_UNKNOWN;
s = (deflate_state *)strm->state;
s->pending = 0;
s->pending_out = s->pending_buf;
 375     if (s->wrap < 0) {
s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
 377     }
s->status = s->wrap ? INIT_STATE : BUSY_STATE;
strm->adler =
 380 #ifdef GZIP
s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
 382 #endif
adler32(0L, Z_NULL, 0);
s->last_flush = Z_NO_FLUSH;
_tr_init(s);
lm_init(s);
 389     return Z_OK;
 390 }
 392 /* ========================================================================= */
 393 int ZEXPORT deflateSetHeader (strm, head)
z_streamp strm;
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;
strm->state->gzhead = head;
 400     return Z_OK;
 401 }
 403 /* ========================================================================= */
 404 int ZEXPORT deflatePrime (strm, bits, value)
z_streamp strm;
 406     int bits;
 407     int value;
 408 {
 409     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
strm->state->bi_valid = bits;
strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
 412     return Z_OK;
 413 }
 415 /* ========================================================================= */
 416 int ZEXPORT deflateParams(strm, level, strategy)
z_streamp strm;
 418     int level;
 419     int strategy;
 420 {
deflate_state *s;
compress_func func;
 423     int err = Z_OK;
 425     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
s = strm->state;
 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     }
func = configuration_table[s->level].func;
 438     if (func != configuration_table[level].func && strm->total_in != 0) {
 439         /* Flush the last buffer: */
err = deflate(strm, Z_PARTIAL_FLUSH);
 441     }
 442     if (s->level != level) {
s->level = level;
s->max_lazy_match   = configuration_table[level].max_lazy;
s->good_match       = configuration_table[level].good_length;
s->nice_match       = configuration_table[level].nice_length;
s->max_chain_length = configuration_table[level].max_chain;
 448     }
s->strategy = strategy;
 450     return err;
 451 }
 453 /* ========================================================================= */
 454 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
z_streamp strm;
 456     int good_length;
 457     int max_lazy;
 458     int nice_length;
 459     int max_chain;
 460 {
deflate_state *s;
 463     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
s = strm->state;
s->good_match = good_length;
s->max_lazy_match = max_lazy;
s->nice_match = nice_length;
s->max_chain_length = max_chain;
 469     return Z_OK;
 470 }
 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  */
uLong ZEXPORT deflateBound(strm, sourceLen)
z_streamp strm;
uLong sourceLen;
 492 {
deflate_state *s;
uLong destLen;
 496     /* conservative upper bound */
destLen = sourceLen +
 498               ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
 500     /* if can't get parameters, return conservative bound */
 501     if (strm == Z_NULL || strm->state == Z_NULL)
 502         return destLen;
 504     /* if not default parameters, return conservative bound */
s = strm->state;
 506     if (s->w_bits != 15 || s->hash_bits != 8 + 7)
 507         return destLen;
 509     /* default settings: return tight bound for that case */
 510     return compressBound(sourceLen);
 511 }
 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  */
local void putShortMSB (s, b)
deflate_state *s;
uInt b;
 521 {
put_byte(s, (Byte)(b >> 8));
put_byte(s, (Byte)(b & 0xff));
 524 }
 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  */
local void flush_pending(strm)
z_streamp strm;
 534 {
 535     unsigned len = strm->state->pending;
 537     if (len > strm->avail_out) len = strm->avail_out;
 538     if (len == 0) return;
zmemcpy(strm->next_out, strm->state->pending_out, len);
strm->next_out  += len;
strm->state->pending_out  += len;
strm->total_out += len;
strm->avail_out  -= len;
strm->state->pending -= len;
 546     if (strm->state->pending == 0) {
strm->state->pending_out = strm->state->pending_buf;
 548     }
 549 }
 551 /* ========================================================================= */
 552 int ZEXPORT deflate (strm, flush)
z_streamp strm;
 554     int flush;
 555 {
 556     int old_flush; /* value of flush param for previous deflate call */
deflate_state *s;
 559     if (strm == Z_NULL || strm->state == Z_NULL ||
flush > Z_FINISH || flush < 0) {
 561         return Z_STREAM_ERROR;
 562     }
s = strm->state;
 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)) {
ERR_RETURN(strm, Z_STREAM_ERROR);
 569     }
 570     if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
s->strm = strm; /* just in case */
old_flush = s->last_flush;
s->last_flush = flush;
 576     /* Write the header */
 577     if (s->status == INIT_STATE) {
 578 #ifdef GZIP
 579         if (s->wrap == 2) {
strm->adler = crc32(0L, Z_NULL, 0);
put_byte(s, 31);
put_byte(s, 139);
put_byte(s, 8);
 584             if (s->gzhead == NULL) {
put_byte(s, 0);
put_byte(s, 0);
put_byte(s, 0);
put_byte(s, 0);
put_byte(s, 0);
put_byte(s, s->level == 9 ? 2 :
 591                             (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
 592                              4 : 0));
put_byte(s, OS_CODE);
s->status = BUSY_STATE;
 595             }
 596             else {
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                         );
put_byte(s, (Byte)(s->gzhead->time & 0xff));
put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
put_byte(s, s->level == 9 ? 2 :
 608                             (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
 609                              4 : 0));
put_byte(s, s->gzhead->os & 0xff);
 611                 if (s->gzhead->extra != NULL) {
put_byte(s, s->gzhead->extra_len & 0xff);
put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
 614                 }
 615                 if (s->gzhead->hcrc)
strm->adler = crc32(strm->adler, s->pending_buf,
s->pending);
s->gzindex = 0;
s->status = EXTRA_STATE;
 620             }
 621         }
 622         else
 623 #endif
 624         {
uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
uInt level_flags;
 628             if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
level_flags = 0;
 630             else if (s->level < 6)
level_flags = 1;
 632             else if (s->level == 6)
level_flags = 2;
 634             else
level_flags = 3;
header |= (level_flags << 6);
 637             if (s->strstart != 0) header |= PRESET_DICT;
header += 31 - (header % 31);
s->status = BUSY_STATE;
putShortMSB(s, header);
 643             /* Save the adler32 of the preset dictionary: */
 644             if (s->strstart != 0) {
putShortMSB(s, (uInt)(strm->adler >> 16));
putShortMSB(s, (uInt)(strm->adler & 0xffff));
 647             }
strm->adler = adler32(0L, Z_NULL, 0);
 649         }
 650     }
 651 #ifdef GZIP
 652     if (s->status == EXTRA_STATE) {
 653         if (s->gzhead->extra != NULL) {
uInt beg = s->pending;  /* start of bytes to update crc */
 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)
strm->adler = crc32(strm->adler, s->pending_buf + beg,
s->pending - beg);
flush_pending(strm);
beg = s->pending;
 663                     if (s->pending == s->pending_buf_size)
 664                         break;
 665                 }
put_byte(s, s->gzhead->extra[s->gzindex]);
s->gzindex++;
 668             }
 669             if (s->gzhead->hcrc && s->pending > beg)
strm->adler = crc32(strm->adler, s->pending_buf + beg,
s->pending - beg);
 672             if (s->gzindex == s->gzhead->extra_len) {
s->gzindex = 0;
s->status = NAME_STATE;
 675             }
 676         }
 677         else
s->status = NAME_STATE;
 679     }
 680     if (s->status == NAME_STATE) {
 681         if (s->gzhead->name != NULL) {
uInt beg = s->pending;  /* start of bytes to update crc */
 683             int val;
 685             do {
 686                 if (s->pending == s->pending_buf_size) {
 687                     if (s->gzhead->hcrc && s->pending > beg)
strm->adler = crc32(strm->adler, s->pending_buf + beg,
s->pending - beg);
flush_pending(strm);
beg = s->pending;
 692                     if (s->pending == s->pending_buf_size) {
val = 1;
 694                         break;
 695                     }
 696                 }
val = s->gzhead->name[s->gzindex++];
put_byte(s, val);
 699             } while (val != 0);
 700             if (s->gzhead->hcrc && s->pending > beg)
strm->adler = crc32(strm->adler, s->pending_buf + beg,
s->pending - beg);
 703             if (val == 0) {
s->gzindex = 0;
s->status = COMMENT_STATE;
 706             }
 707         }
 708         else
s->status = COMMENT_STATE;
 710     }
 711     if (s->status == COMMENT_STATE) {
 712         if (s->gzhead->comment != NULL) {
uInt beg = s->pending;  /* start of bytes to update crc */
 714             int val;
 716             do {
 717                 if (s->pending == s->pending_buf_size) {
 718                     if (s->gzhead->hcrc && s->pending > beg)
strm->adler = crc32(strm->adler, s->pending_buf + beg,
s->pending - beg);
flush_pending(strm);
beg = s->pending;
 723                     if (s->pending == s->pending_buf_size) {
val = 1;
 725                         break;
 726                     }
 727                 }
val = s->gzhead->comment[s->gzindex++];
put_byte(s, val);
 730             } while (val != 0);
 731             if (s->gzhead->hcrc && s->pending > beg)
strm->adler = crc32(strm->adler, s->pending_buf + beg,
s->pending - beg);
 734             if (val == 0)
s->status = HCRC_STATE;
 736         }
 737         else
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)
flush_pending(strm);
 744             if (s->pending + 2 <= s->pending_buf_size) {
put_byte(s, (Byte)(strm->adler & 0xff));
put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
strm->adler = crc32(0L, Z_NULL, 0);
s->status = BUSY_STATE;
 749             }
 750         }
 751         else
s->status = BUSY_STATE;
 753     }
 754 #endif
 756     /* Flush as much pending output as possible */
 757     if (s->pending != 0) {
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              */
s->last_flush = -1;
 767             return Z_OK;
 768         }
 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 &&
flush != Z_FINISH) {
ERR_RETURN(strm, Z_BUF_ERROR);
 777     }
 779     /* User must not provide more input after the first FINISH: */
 780     if (s->status == FINISH_STATE && strm->avail_in != 0) {
ERR_RETURN(strm, Z_BUF_ERROR);
 782     }
 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)) {
block_state bstate;
bstate = (*(configuration_table[s->level].func))(s, flush);
 792         if (bstate == finish_started || bstate == finish_done) {
s->status = FINISH_STATE;
 794         }
 795         if (bstate == need_more || bstate == finish_started) {
 796             if (strm->avail_out == 0) {
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) {
_tr_align(s);
 811             } else { /* FULL_FLUSH or SYNC_FLUSH */
_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) {
CLEAR_HASH(s);             /* forget history */
 818                 }
 819             }
flush_pending(strm);
 821             if (strm->avail_out == 0) {
s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
 823               return Z_OK;
 824             }
 825         }
 826     }
Assert(strm->avail_out > 0, "bug2");
 829     if (flush != Z_FINISH) return Z_OK;
 830     if (s->wrap <= 0) return Z_STREAM_END;
 832     /* Write the trailer */
 833 #ifdef GZIP
 834     if (s->wrap == 2) {
put_byte(s, (Byte)(strm->adler & 0xff));
put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
put_byte(s, (Byte)(strm->total_in & 0xff));
put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
 843     }
 844     else
 845 #endif
 846     {
putShortMSB(s, (uInt)(strm->adler >> 16));
putShortMSB(s, (uInt)(strm->adler & 0xffff));
 849     }
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 }
 858 /* ========================================================================= */
 859 int ZEXPORT deflateEnd (strm)
z_streamp strm;
 861 {
 862     int status;
 864     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
status = strm->state->status;
 867     if (status != INIT_STATE &&
status != EXTRA_STATE &&
status != NAME_STATE &&
status != COMMENT_STATE &&
status != HCRC_STATE &&
status != BUSY_STATE &&
status != FINISH_STATE) {
 874       return Z_STREAM_ERROR;
 875     }
 877     /* Deallocate in reverse order of allocations: */
TRY_FREE(strm, strm->state->pending_buf);
TRY_FREE(strm, strm->state->head);
TRY_FREE(strm, strm->state->prev);
TRY_FREE(strm, strm->state->window);
ZFREE(strm, strm->state);
strm->state = Z_NULL;
 886     return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
 887 }
 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)
z_streamp dest;
z_streamp source;
 897 {
 898 #ifdef MAXSEG_64K
 899     return Z_STREAM_ERROR;
 900 #else
deflate_state *ds;
deflate_state *ss;
ushf *overlay;
 906     if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
 907         return Z_STREAM_ERROR;
 908     }
ss = source->state;
zmemcpy(dest, source, sizeof(z_stream));
ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
 915     if (ds == Z_NULL) return Z_MEM_ERROR;
dest->state = (struct internal_state FAR *) ds;
zmemcpy(ds, ss, sizeof(deflate_state));
ds->strm = dest;
ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
ds->pending_buf = (uchf *) overlay;
 926     if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
ds->pending_buf == Z_NULL) {
deflateEnd (dest);
 929         return Z_MEM_ERROR;
 930     }
 931     /* following zmemcpy do not work for 16-bit MSDOS */
zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
ds->l_desc.dyn_tree = ds->dyn_ltree;
ds->d_desc.dyn_tree = ds->dyn_dtree;
ds->bl_desc.dyn_tree = ds->bl_tree;
 945     return Z_OK;
 946 #endif /* MAXSEG_64K */
 947 }
 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  */
local int read_buf(strm, buf, size)
z_streamp strm;
Bytef *buf;
 959     unsigned size;
 960 {
 961     unsigned len = strm->avail_in;
 963     if (len > size) len = size;
 964     if (len == 0) return 0;
strm->avail_in  -= len;
 968     if (strm->state->wrap == 1) {
strm->adler = adler32(strm->adler, strm->next_in, len);
 970     }
 971 #ifdef GZIP
 972     else if (strm->state->wrap == 2) {
strm->adler = crc32(strm->adler, strm->next_in, len);
 974     }
 975 #endif
zmemcpy(buf, strm->next_in, len);
strm->next_in  += len;
strm->total_in += len;
 980     return (int)len;
 981 }
 983 /* ===========================================================================

 984  * Initialize the "longest match" routines for a new zlib stream

 985  */
local void lm_init (s)
deflate_state *s;
 988 {
s->window_size = (ulg)2L*s->w_size;
CLEAR_HASH(s);
 993     /* Set the default configuration parameters:

 994      */
s->max_lazy_match   = configuration_table[s->level].max_lazy;
s->good_match       = configuration_table[s->level].good_length;
s->nice_match       = configuration_table[s->level].nice_length;
s->max_chain_length = configuration_table[s->level].max_chain;
s->strstart = 0;
s->block_start = 0L;
s->lookahead = 0;
s->match_length = s->prev_length = MIN_MATCH-1;
s->match_available = 0;
s->ins_h = 0;
1006 #ifndef FASTEST
1007 #ifdef ASMV
match_init(); /* initialize the asm code */
1009 #endif
1010 #endif
1011 }
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  */
local uInt longest_match(s, cur_match)
deflate_state *s;
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 */
IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
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      */
Posf *prev = s->prev;
uInt wmask = s->w_mask;
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
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      */
Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1063     /* Do not waste too much time if we already have a good match: */
1064     if (s->prev_length >= s->good_match) {
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;
Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1074     do {
Assert(cur_match < s->strstart, "no future");
match = s->window + cur_match;
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;
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          */
Assert(scan[2] == match[2], "scan[2]?");
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) &&
scan < strend);
1110         /* The funny "do {}" generates better code on most compilers */
1112         /* Here, scan <= window+strstart+257 */
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1114         if (*scan == *match) scan++;
len = (MAX_MATCH - 1) - (int)(strend-scan);
scan = strend - (MAX_MATCH-1);
1119 #else /* UNALIGNED_OK */
1121         if (match[best_len]   != scan_end  ||
match[best_len-1] != scan_end1 ||
1123             *match            != *scan     ||
1124             *++match          != scan[1])      continue;
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          */
scan += 2, match++;
Assert(*scan == *match, "match[2]?");
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 &&
scan < strend);
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
len = MAX_MATCH - (int)(strend - scan);
scan = strend - MAX_MATCH;
1150 #endif /* UNALIGNED_OK */
1152         if (len > best_len) {
s->match_start = cur_match;
best_len = len;
1155             if (len >= nice_match) break;
1156 #ifdef UNALIGNED_OK
scan_end = *(ushf*)(scan+best_len-1);
1158 #else
scan_end1  = scan[best_len-1];
scan_end   = scan[best_len];
1161 #endif
1162         }
1163     } while ((cur_match = prev[cur_match & wmask]) > limit
1164              && --chain_length != 0);
1166     if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1167     return s->lookahead;
1168 }
1169 #endif /* ASMV */
1170 #endif /* FASTEST */
1172 /* ---------------------------------------------------------------------------

1173  * Optimized version for level == 1 or strategy == Z_RLE only

1174  */
local uInt longest_match_fast(s, cur_match)
deflate_state *s;
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;
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      */
Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
Assert(cur_match < s->strstart, "no future");
match = s->window + cur_match;
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;
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      */
scan += 2, match += 2;
Assert(*scan == *match, "match[2]?");
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 &&
scan < strend);
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
len = MAX_MATCH - (int)(strend - scan);
1222     if (len < MIN_MATCH) return MIN_MATCH - 1;
s->match_start = cur_match;
1225     return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1226 }
1228 #ifdef DEBUG
1229 /* ===========================================================================

1230  * Check that the match at match_start is indeed a match.

1231  */
local void check_match(s, start, match, length)
deflate_state *s;
IPos start, match;
1235     int length;
1236 {
1237     /* check that the match is indeed a match */
1238     if (zmemcmp(s->window + match,
s->window + start, length) != EQUAL) {
fprintf(stderr, " start %u, match %u, length %d\n",
start, match, length);
1242         do {
fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1244         } while (--length != 0);
z_error("invalid match");
1246     }
1247     if (z_verbose > 1) {
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 */
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  */
local void fill_window(s)
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. */
uInt wsize = s->w_size;
1274     do {
more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1277         /* Deal with !@#$% 64K limit: */
1278         if (sizeof(int) <= 2) {
1279             if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
more = wsize;
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                  */
more--;
1287             }
1288         }
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)) {
zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
s->match_start -= wsize;
s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
s->block_start -= (long) wsize;
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 */
n = s->hash_size;
p = &s->head[n];
1309             do {
m = *--p;
1311                 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1312             } while (--n);
n = wsize;
1315 #ifndef FASTEST
p = &s->prev[n];
1317             do {
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
more += wsize;
1326         }
1327         if (s->strm->avail_in == 0) return;
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          */
Assert(more >= 2, "more < 2");
n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
s->lookahead += n;
1345         /* Initialize the hash value now that we have some input: */
1346         if (s->lookahead >= MIN_MATCH) {
s->ins_h = s->window[s->strstart];
UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1349 #if MIN_MATCH != 3
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          */
1357     } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1358 }
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) { \
_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)); \
s->block_start = s->strstart; \
flush_pending(s->strm); \
Tracev((stderr,"[FLUSH]")); \
1373 }
1375 /* Same but force premature exit if necessary. */
1376 #define FLUSH_BLOCK(s, eof) { \
FLUSH_BLOCK_ONLY(s, eof); \
1378    if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1379 }
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  */
local block_state deflate_stored(s, flush)
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      */
ulg max_block_size = 0xffff;
ulg max_start;
1400     if (max_block_size > s->pending_buf_size - 5) {
max_block_size = s->pending_buf_size - 5;
1402     }
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) {
Assert(s->strstart < s->w_size+MAX_DIST(s) ||
s->block_start >= (long)s->w_size, "slide too late");
fill_window(s);
1413             if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1415             if (s->lookahead == 0) break; /* flush the current block */
1416         }
Assert(s->block_start >= 0L, "block gone");
s->strstart += s->lookahead;
s->lookahead = 0;
1422         /* Emit a stored block if pending_buf will be full: */
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 */
s->lookahead = (uInt)(s->strstart - max_start);
s->strstart = (uInt)max_start;
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)) {
FLUSH_BLOCK(s, 0);
1435         }
1436     }
FLUSH_BLOCK(s, flush == Z_FINISH);
1438     return flush == Z_FINISH ? finish_done : block_done;
1439 }
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  */
local block_state deflate_fast(s, flush)
deflate_state *s;
1450     int flush;
1451 {
IPos hash_head = NIL; /* head of the hash chain */
1453     int bflush;           /* set if current block must be flushed */
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) {
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         }
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) {
INSERT_STRING(s, s->strstart, hash_head);
1474         }
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)) {
s->match_length = longest_match_fast (s, hash_head);
1488             }
1489 #else
1490             if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
s->match_length = longest_match (s, hash_head);
1492             } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
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) {
check_match(s, s->strstart, s->match_start, s->match_length);
_tr_tally_dist(s, s->strstart - s->match_start,
s->match_length - MIN_MATCH, bflush);
s->lookahead -= s->match_length;
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 &&
s->lookahead >= MIN_MATCH) {
s->match_length--; /* string at strstart already in table */
1513                 do {
s->strstart++;
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);
s->strstart++;
1521             } else
1522 #endif
1523             {
s->strstart += s->match_length;
s->match_length = 0;
s->ins_h = s->window[s->strstart];
UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1528 #if MIN_MATCH != 3
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 */
Tracevv((stderr,"%c", s->window[s->strstart]));
_tr_tally_lit (s, s->window[s->strstart], bflush);
s->lookahead--;
s->strstart++;
1541         }
1542         if (bflush) FLUSH_BLOCK(s, 0);
1543     }
FLUSH_BLOCK(s, flush == Z_FINISH);
1545     return flush == Z_FINISH ? finish_done : block_done;
1546 }
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  */
local block_state deflate_slow(s, flush)
deflate_state *s;
1556     int flush;
1557 {
IPos hash_head = NIL;    /* head of hash chain */
1559     int bflush;              /* set if current block must be flushed */
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) {
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         }
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) {
INSERT_STRING(s, s->strstart, hash_head);
1581         }
1583         /* Find the longest match, discarding those <= prev_length.

1584          */
s->prev_length = s->match_length, s->prev_match = s->match_start;
s->match_length = MIN_MATCH-1;
1588         if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
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) {
s->match_length = longest_match (s, hash_head);
1596             } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
s->match_length = longest_match_fast (s, hash_head);
1598             }
1599             /* longest_match() or longest_match_fast() sets match_start */
1601             if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1602 #if TOO_FAR <= 32767
1603                 || (s->match_length == MIN_MATCH &&
s->strstart - s->match_start > TOO_FAR)
1605 #endif
1606                 )) {
1608                 /* If prev_match is also MIN_MATCH, match_start is garbage

1609                  * but we will ignore the current match anyway.

1610                  */
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) {
uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1619             /* Do not insert strings in hash table beyond this. */
check_match(s, s->strstart-1, s->prev_match, s->prev_length);
_tr_tally_dist(s, s->strstart -1 - s->prev_match,
s->prev_length - MIN_MATCH, bflush);
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              */
s->lookahead -= s->prev_length-1;
s->prev_length -= 2;
1633             do {
1634                 if (++s->strstart <= max_insert) {
INSERT_STRING(s, s->strstart, hash_head);
1636                 }
1637             } while (--s->prev_length != 0);
s->match_available = 0;
s->match_length = MIN_MATCH-1;
s->strstart++;
1642             if (bflush) FLUSH_BLOCK(s, 0);
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              */
Tracevv((stderr,"%c", s->window[s->strstart-1]));
_tr_tally_lit(s, s->window[s->strstart-1], bflush);
1651             if (bflush) {
FLUSH_BLOCK_ONLY(s, 0);
1653             }
s->strstart++;
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              */
s->match_available = 1;
s->strstart++;
s->lookahead--;
1664         }
1665     }
Assert (flush != Z_NO_FLUSH, "no flush?");
1667     if (s->match_available) {
Tracevv((stderr,"%c", s->window[s->strstart-1]));
_tr_tally_lit(s, s->window[s->strstart-1], bflush);
s->match_available = 0;
1671     }
FLUSH_BLOCK(s, flush == Z_FINISH);
1673     return flush == Z_FINISH ? finish_done : block_done;
1674 }
1675 #endif /* FASTEST */
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  */
local block_state deflate_rle(s, flush)
deflate_state *s;
1685     int flush;
1686 {
1687     int bflush;         /* set if current block must be flushed */
uInt run;           /* length of run */
uInt max;           /* maximum length of run */
uInt prev;          /* byte at distance one to match */
Bytef *scan;        /* scan for end of run */
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) {
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         }
1706         /* See how many times the previous byte repeats */
run = 0;
1708         if (s->strstart > 0) {      /* if there is a previous byte, that is */
max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH;
scan = s->window + s->strstart - 1;
prev = *scan++;
1712             do {
1713                 if (*scan++ != prev)
1714                     break;
1715             } while (++run < max);
1716         }
1718         /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1719         if (run >= MIN_MATCH) {
check_match(s, s->strstart, s->strstart - 1, run);
_tr_tally_dist(s, 1, run - MIN_MATCH, bflush);
s->lookahead -= run;
s->strstart += run;
1724         } else {
1725             /* No match, output a literal byte */
Tracevv((stderr,"%c", s->window[s->strstart]));
_tr_tally_lit (s, s->window[s->strstart], bflush);
s->lookahead--;
s->strstart++;
1730         }
1731         if (bflush) FLUSH_BLOCK(s, 0);
1732     }
FLUSH_BLOCK(s, flush == Z_FINISH);
1734     return flush == Z_FINISH ? finish_done : block_done;
1735 }
1736 #endif