FreeBSD/Linux Kernel Cross Reference
sys/contrib/zlib/deflate.c

     /* deflate.c -- compress data using the deflation algorithm
      * Copyright (C) 1995-2022 Jean-loup Gailly and Mark Adler
      * For conditions of distribution and use, see copyright notice in zlib.h
      */
     
     /*
      *  ALGORITHM
      *
      *      The "deflation" process depends on being able to identify portions
     *      of the input text which are identical to earlier input (within a
     *      sliding window trailing behind the input currently being processed).
     *
     *      The most straightforward technique turns out to be the fastest for
     *      most input files: try all possible matches and select the longest.
     *      The key feature of this algorithm is that insertions into the string
     *      dictionary are very simple and thus fast, and deletions are avoided
     *      completely. Insertions are performed at each input character, whereas
     *      string matches are performed only when the previous match ends. So it
     *      is preferable to spend more time in matches to allow very fast string
     *      insertions and avoid deletions. The matching algorithm for small
     *      strings is inspired from that of Rabin & Karp. A brute force approach
     *      is used to find longer strings when a small match has been found.
     *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
     *      (by Leonid Broukhis).
     *         A previous version of this file used a more sophisticated algorithm
     *      (by Fiala and Greene) which is guaranteed to run in linear amortized
     *      time, but has a larger average cost, uses more memory and is patented.
     *      However the F&G algorithm may be faster for some highly redundant
     *      files if the parameter max_chain_length (described below) is too large.
     *
     *  ACKNOWLEDGEMENTS
     *
     *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
     *      I found it in 'freeze' written by Leonid Broukhis.
     *      Thanks to many people for bug reports and testing.
     *
     *  REFERENCES
     *
     *      Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
     *      Available in http://tools.ietf.org/html/rfc1951
     *
     *      A description of the Rabin and Karp algorithm is given in the book
     *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
     *
     *      Fiala,E.R., and Greene,D.H.
     *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
     *
     */
    
    /* @(#) $Id$ */
    
    #include "deflate.h"
    
    const char deflate_copyright[] =
       " deflate 1.2.12 Copyright 1995-2022 Jean-loup Gailly and Mark Adler ";
    /*
      If you use the zlib library in a product, an acknowledgment is welcome
      in the documentation of your product. If for some reason you cannot
      include such an acknowledgment, I would appreciate that you keep this
      copyright string in the executable of your product.
     */
    
    /* ===========================================================================
     *  Function prototypes.
     */
    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 */
    } block_state;
    
    typedef block_state (*compress_func) OF((deflate_state *s, int flush));
    /* Compression function. Returns the block state after the call. */
    
    local int deflateStateCheck      OF((z_streamp strm));
    local void slide_hash     OF((deflate_state *s));
    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));
    #ifndef FASTEST
    local block_state deflate_slow   OF((deflate_state *s, int flush));
    #endif
    local block_state deflate_rle    OF((deflate_state *s, int flush));
    local block_state deflate_huff   OF((deflate_state *s, int flush));
    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 unsigned read_buf   OF((z_streamp strm, Bytef *buf, unsigned size));
    #ifdef ASMV
    #  pragma message("Assembler code may have bugs -- use at your own risk")
          void match_init OF((void)); /* asm code initialization */
          uInt longest_match  OF((deflate_state *s, IPos cur_match));
    #else
    local uInt longest_match  OF((deflate_state *s, IPos cur_match));
    #endif
    
    #ifdef ZLIB_DEBUG
    local  void check_match OF((deflate_state *s, IPos start, IPos match,
                               int length));
   #endif
   
   /* ===========================================================================
    * Local data
    */
   
   #define NIL 0
   /* Tail of hash chains */
   
   #ifndef TOO_FAR
   #  define TOO_FAR 4096
   #endif
   /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
   
   /* Values for max_lazy_match, good_match and max_chain_length, depending on
    * the desired pack level (0..9). The values given below have been tuned to
    * exclude worst case performance for pathological files. Better values may be
    * found for specific files.
    */
   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;
   } config;
   
   #ifdef FASTEST
   local const config configuration_table[2] = {
   /*      good lazy nice chain */
   /* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
   /* 1 */ {4,    4,  8,    4, deflate_fast}}; /* max speed, no lazy matches */
   #else
   local const config configuration_table[10] = {
   /*      good lazy nice chain */
   /* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
   /* 1 */ {4,    4,  8,    4, deflate_fast}, /* max speed, no lazy matches */
   /* 2 */ {4,    5, 16,    8, deflate_fast},
   /* 3 */ {4,    6, 32,   32, deflate_fast},
   
   /* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
   /* 5 */ {8,   16, 32,   32, deflate_slow},
   /* 6 */ {8,   16, 128, 128, deflate_slow},
   /* 7 */ {8,   32, 128, 256, deflate_slow},
   /* 8 */ {32, 128, 258, 1024, deflate_slow},
   /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
   #endif
   
   /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
    * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
    * meaning.
    */
   
   /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
   #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0))
   
   /* ===========================================================================
    * Update a hash value with the given input byte
    * IN  assertion: all calls to UPDATE_HASH are made with consecutive input
    *    characters, so that a running hash key can be computed from the previous
    *    key instead of complete recalculation each time.
    */
   #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
   
   
   /* ===========================================================================
    * Insert string str in the dictionary and set match_head to the previous head
    * of the hash chain (the most recent string with same hash key). Return
    * the previous length of the hash chain.
    * If this file is compiled with -DFASTEST, the compression level is forced
    * to 1, and no hash chains are maintained.
    * IN  assertion: all calls to INSERT_STRING are made with consecutive input
    *    characters and the first MIN_MATCH bytes of str are valid (except for
    *    the last MIN_MATCH-1 bytes of the input file).
    */
   #ifdef FASTEST
   #define INSERT_STRING(s, str, match_head) \
      (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))
   #else
   #define INSERT_STRING(s, str, match_head) \
      (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))
   #endif
   
   /* ===========================================================================
    * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
    * prev[] will be initialized on the fly.
    */
   #define CLEAR_HASH(s) \
       do { \
           s->head[s->hash_size-1] = NIL; \
           zmemzero((Bytef *)s->head, \
                    (unsigned)(s->hash_size-1)*sizeof(*s->head)); \
       } while (0)
   
   /* ===========================================================================
    * Slide the hash table when sliding the window down (could be avoided with 32
    * bit values at the expense of memory usage). We slide even when level == 0 to
    * keep the hash table consistent if we switch back to level > 0 later.
    */
   local void slide_hash(s)
       deflate_state *s;
   {
       unsigned n, m;
       Posf *p;
       uInt wsize = s->w_size;
   
       n = s->hash_size;
       p = &s->head[n];
       do {
           m = *--p;
           *p = (Pos)(m >= wsize ? m - wsize : NIL);
       } while (--n);
       n = wsize;
   #ifndef FASTEST
       p = &s->prev[n];
       do {
           m = *--p;
           *p = (Pos)(m >= wsize ? m - wsize : NIL);
           /* If n is not on any hash chain, prev[n] is garbage but
            * its value will never be used.
            */
       } while (--n);
   #endif
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateInit_(strm, level, version, stream_size)
       z_streamp strm;
       int level;
       const char *version;
       int stream_size;
   {
       return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
                            Z_DEFAULT_STRATEGY, version, stream_size);
       /* To do: ignore strm->next_in if we use it as window */
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
                     version, stream_size)
       z_streamp strm;
       int  level;
       int  method;
       int  windowBits;
       int  memLevel;
       int  strategy;
       const char *version;
       int stream_size;
   {
       deflate_state *s;
       int wrap = 1;
       static const char my_version[] = ZLIB_VERSION;
   
       if (version == Z_NULL || version[0] != my_version[0] ||
           stream_size != sizeof(z_stream)) {
           return Z_VERSION_ERROR;
       }
       if (strm == Z_NULL) return Z_STREAM_ERROR;
   
       strm->msg = Z_NULL;
       if (strm->zalloc == (alloc_func)0) {
   #if defined(Z_SOLO) && !defined(_KERNEL)
           return Z_STREAM_ERROR;
   #else
           strm->zalloc = zcalloc;
           strm->opaque = (voidpf)0;
   #endif
       }
       if (strm->zfree == (free_func)0)
   #if defined(Z_SOLO) && !defined(_KERNEL)
           return Z_STREAM_ERROR;
   #else
           strm->zfree = zcfree;
   #endif
   
   #ifdef FASTEST
       if (level != 0) level = 1;
   #else
       if (level == Z_DEFAULT_COMPRESSION) level = 6;
   #endif
   
       if (windowBits < 0) { /* suppress zlib wrapper */
           wrap = 0;
           windowBits = -windowBits;
       }
   #ifdef GZIP
       else if (windowBits > 15) {
           wrap = 2;       /* write gzip wrapper instead */
           windowBits -= 16;
       }
   #endif
       if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
           windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
           strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) {
           return Z_STREAM_ERROR;
       }
       if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */
       s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
       if (s == Z_NULL) return Z_MEM_ERROR;
       strm->state = (struct internal_state FAR *)s;
       s->strm = strm;
       s->status = INIT_STATE;     /* to pass state test in deflateReset() */
   
       s->wrap = wrap;
       s->gzhead = Z_NULL;
       s->w_bits = (uInt)windowBits;
       s->w_size = 1 << s->w_bits;
       s->w_mask = s->w_size - 1;
   
       s->hash_bits = (uInt)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->high_water = 0;      /* nothing written to s->window yet */
   
       s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
   
       /* We overlay pending_buf and sym_buf. This works since the average size
        * for length/distance pairs over any compressed block is assured to be 31
        * bits or less.
        *
        * Analysis: The longest fixed codes are a length code of 8 bits plus 5
        * extra bits, for lengths 131 to 257. The longest fixed distance codes are
        * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest
        * possible fixed-codes length/distance pair is then 31 bits total.
        *
        * sym_buf starts one-fourth of the way into pending_buf. So there are
        * three bytes in sym_buf for every four bytes in pending_buf. Each symbol
        * in sym_buf is three bytes -- two for the distance and one for the
        * literal/length. As each symbol is consumed, the pointer to the next
        * sym_buf value to read moves forward three bytes. From that symbol, up to
        * 31 bits are written to pending_buf. The closest the written pending_buf
        * bits gets to the next sym_buf symbol to read is just before the last
        * code is written. At that time, 31*(n-2) bits have been written, just
        * after 24*(n-2) bits have been consumed from sym_buf. sym_buf starts at
        * 8*n bits into pending_buf. (Note that the symbol buffer fills when n-1
        * symbols are written.) The closest the writing gets to what is unread is
        * then n+14 bits. Here n is lit_bufsize, which is 16384 by default, and
        * can range from 128 to 32768.
        *
        * Therefore, at a minimum, there are 142 bits of space between what is
        * written and what is read in the overlain buffers, so the symbols cannot
        * be overwritten by the compressed data. That space is actually 139 bits,
        * due to the three-bit fixed-code block header.
        *
        * That covers the case where either Z_FIXED is specified, forcing fixed
        * codes, or when the use of fixed codes is chosen, because that choice
        * results in a smaller compressed block than dynamic codes. That latter
        * condition then assures that the above analysis also covers all dynamic
        * blocks. A dynamic-code block will only be chosen to be emitted if it has
        * fewer bits than a fixed-code block would for the same set of symbols.
        * Therefore its average symbol length is assured to be less than 31. So
        * the compressed data for a dynamic block also cannot overwrite the
        * symbols from which it is being constructed.
        */
   
       s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4);
       s->pending_buf_size = (ulg)s->lit_bufsize * 4;
   
       if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
           s->pending_buf == Z_NULL) {
           s->status = FINISH_STATE;
           strm->msg = ERR_MSG(Z_MEM_ERROR);
           deflateEnd (strm);
           return Z_MEM_ERROR;
       }
       s->sym_buf = s->pending_buf + s->lit_bufsize;
       s->sym_end = (s->lit_bufsize - 1) * 3;
       /* We avoid equality with lit_bufsize*3 because of wraparound at 64K
        * on 16 bit machines and because stored blocks are restricted to
        * 64K-1 bytes.
        */
   
       s->level = level;
       s->strategy = strategy;
       s->method = (Byte)method;
   
       return deflateReset(strm);
   }
   
   /* =========================================================================
    * Check for a valid deflate stream state. Return 0 if ok, 1 if not.
    */
   local int deflateStateCheck (strm)
       z_streamp strm;
   {
       deflate_state *s;
       if (strm == Z_NULL ||
           strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0)
           return 1;
       s = strm->state;
       if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE &&
   #ifdef GZIP
                                              s->status != GZIP_STATE &&
   #endif
                                              s->status != EXTRA_STATE &&
                                              s->status != NAME_STATE &&
                                              s->status != COMMENT_STATE &&
                                              s->status != HCRC_STATE &&
                                              s->status != BUSY_STATE &&
                                              s->status != FINISH_STATE))
           return 1;
       return 0;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
       z_streamp strm;
       const Bytef *dictionary;
       uInt  dictLength;
   {
       deflate_state *s;
       uInt str, n;
       int wrap;
       unsigned avail;
       z_const unsigned char *next;
   
       if (deflateStateCheck(strm) || dictionary == Z_NULL)
           return Z_STREAM_ERROR;
       s = strm->state;
       wrap = s->wrap;
       if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
           return Z_STREAM_ERROR;
   
       /* when using zlib wrappers, compute Adler-32 for provided dictionary */
       if (wrap == 1)
           strm->adler = adler32(strm->adler, dictionary, dictLength);
       s->wrap = 0;                    /* avoid computing Adler-32 in read_buf */
   
       /* if dictionary would fill window, just replace the history */
       if (dictLength >= s->w_size) {
           if (wrap == 0) {            /* already empty otherwise */
               CLEAR_HASH(s);
               s->strstart = 0;
               s->block_start = 0L;
               s->insert = 0;
           }
           dictionary += dictLength - s->w_size;  /* use the tail */
           dictLength = s->w_size;
       }
   
       /* insert dictionary into window and hash */
       avail = strm->avail_in;
       next = strm->next_in;
       strm->avail_in = dictLength;
       strm->next_in = (z_const Bytef *)dictionary;
       fill_window(s);
       while (s->lookahead >= MIN_MATCH) {
           str = s->strstart;
           n = s->lookahead - (MIN_MATCH-1);
           do {
               UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
   #ifndef FASTEST
               s->prev[str & s->w_mask] = s->head[s->ins_h];
   #endif
               s->head[s->ins_h] = (Pos)str;
               str++;
           } while (--n);
           s->strstart = str;
           s->lookahead = MIN_MATCH-1;
           fill_window(s);
       }
       s->strstart += s->lookahead;
       s->block_start = (long)s->strstart;
       s->insert = s->lookahead;
       s->lookahead = 0;
       s->match_length = s->prev_length = MIN_MATCH-1;
       s->match_available = 0;
       strm->next_in = next;
       strm->avail_in = avail;
       s->wrap = wrap;
       return Z_OK;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength)
       z_streamp strm;
       Bytef *dictionary;
       uInt  *dictLength;
   {
       deflate_state *s;
       uInt len;
   
       if (deflateStateCheck(strm))
           return Z_STREAM_ERROR;
       s = strm->state;
       len = s->strstart + s->lookahead;
       if (len > s->w_size)
           len = s->w_size;
       if (dictionary != Z_NULL && len)
           zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len);
       if (dictLength != Z_NULL)
           *dictLength = len;
       return Z_OK;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateResetKeep (strm)
       z_streamp strm;
   {
       deflate_state *s;
   
       if (deflateStateCheck(strm)) {
           return Z_STREAM_ERROR;
       }
   
       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;
   
       if (s->wrap < 0) {
           s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
       }
       s->status =
   #ifdef GZIP
           s->wrap == 2 ? GZIP_STATE :
   #endif
           INIT_STATE;
       strm->adler =
   #ifdef GZIP
           s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
   #endif
           adler32(0L, Z_NULL, 0);
       s->last_flush = -2;
   
       _tr_init(s);
   
       return Z_OK;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateReset (strm)
       z_streamp strm;
   {
       int ret;
   
       ret = deflateResetKeep(strm);
       if (ret == Z_OK)
           lm_init(strm->state);
       return ret;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateSetHeader (strm, head)
       z_streamp strm;
       gz_headerp head;
   {
       if (deflateStateCheck(strm) || strm->state->wrap != 2)
           return Z_STREAM_ERROR;
       strm->state->gzhead = head;
       return Z_OK;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflatePending (strm, pending, bits)
       unsigned *pending;
       int *bits;
       z_streamp strm;
   {
       if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
       if (pending != Z_NULL)
           *pending = strm->state->pending;
       if (bits != Z_NULL)
           *bits = strm->state->bi_valid;
       return Z_OK;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflatePrime (strm, bits, value)
       z_streamp strm;
       int bits;
       int value;
   {
       deflate_state *s;
       int put;
   
       if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
       s = strm->state;
       if (bits < 0 || bits > 16 ||
           s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3))
           return Z_BUF_ERROR;
       do {
           put = Buf_size - s->bi_valid;
           if (put > bits)
               put = bits;
           s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
           s->bi_valid += put;
           _tr_flush_bits(s);
           value >>= put;
           bits -= put;
       } while (bits);
       return Z_OK;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateParams(strm, level, strategy)
       z_streamp strm;
       int level;
       int strategy;
   {
       deflate_state *s;
       compress_func func;
   
       if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
       s = strm->state;
   
   #ifdef FASTEST
       if (level != 0) level = 1;
   #else
       if (level == Z_DEFAULT_COMPRESSION) level = 6;
   #endif
       if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
           return Z_STREAM_ERROR;
       }
       func = configuration_table[s->level].func;
   
       if ((strategy != s->strategy || func != configuration_table[level].func) &&
           s->last_flush != -2) {
           /* Flush the last buffer: */
           int err = deflate(strm, Z_BLOCK);
           if (err == Z_STREAM_ERROR)
               return err;
           if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead)
               return Z_BUF_ERROR;
       }
       if (s->level != level) {
           if (s->level == 0 && s->matches != 0) {
               if (s->matches == 1)
                   slide_hash(s);
               else
                   CLEAR_HASH(s);
               s->matches = 0;
           }
           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;
       }
       s->strategy = strategy;
       return Z_OK;
   }
   
   /* ========================================================================= */
   int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
       z_streamp strm;
       int good_length;
       int max_lazy;
       int nice_length;
       int max_chain;
   {
       deflate_state *s;
   
       if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
       s = strm->state;
       s->good_match = (uInt)good_length;
       s->max_lazy_match = (uInt)max_lazy;
       s->nice_match = nice_length;
       s->max_chain_length = (uInt)max_chain;
       return Z_OK;
   }
   
   /* =========================================================================
    * For the default windowBits of 15 and memLevel of 8, this function returns
    * a close to exact, as well as small, upper bound on the compressed size.
    * They are coded as constants here for a reason--if the #define's are
    * changed, then this function needs to be changed as well.  The return
    * value for 15 and 8 only works for those exact settings.
    *
    * For any setting other than those defaults for windowBits and memLevel,
    * the value returned is a conservative worst case for the maximum expansion
    * resulting from using fixed blocks instead of stored blocks, which deflate
    * can emit on compressed data for some combinations of the parameters.
    *
    * This function could be more sophisticated to provide closer upper bounds for
    * every combination of windowBits and memLevel.  But even the conservative
    * upper bound of about 14% expansion does not seem onerous for output buffer
    * allocation.
    */
   uLong ZEXPORT deflateBound(strm, sourceLen)
       z_streamp strm;
       uLong sourceLen;
   {
       deflate_state *s;
       uLong complen, wraplen;
   
       /* conservative upper bound for compressed data */
       complen = sourceLen +
                 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
   
       /* if can't get parameters, return conservative bound plus zlib wrapper */
       if (deflateStateCheck(strm))
           return complen + 6;
   
       /* compute wrapper length */
       s = strm->state;
       switch (s->wrap) {
       case 0:                                 /* raw deflate */
           wraplen = 0;
           break;
       case 1:                                 /* zlib wrapper */
           wraplen = 6 + (s->strstart ? 4 : 0);
           break;
   #ifdef GZIP
       case 2:                                 /* gzip wrapper */
           wraplen = 18;
           if (s->gzhead != Z_NULL) {          /* user-supplied gzip header */
               Bytef *str;
               if (s->gzhead->extra != Z_NULL)
                   wraplen += 2 + s->gzhead->extra_len;
               str = s->gzhead->name;
               if (str != Z_NULL)
                   do {
                       wraplen++;
                   } while (*str++);
               str = s->gzhead->comment;
               if (str != Z_NULL)
                   do {
                       wraplen++;
                   } while (*str++);
               if (s->gzhead->hcrc)
                   wraplen += 2;
           }
           break;
   #endif
       default:                                /* for compiler happiness */
           wraplen = 6;
       }
   
       /* if not default parameters, return conservative bound */
       if (s->w_bits != 15 || s->hash_bits != 8 + 7)
           return complen + wraplen;
   
       /* default settings: return tight bound for that case */
       return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
              (sourceLen >> 25) + 13 - 6 + wraplen;
   }
   
   /* =========================================================================
    * Put a short in the pending buffer. The 16-bit value is put in MSB order.
    * IN assertion: the stream state is correct and there is enough room in
    * pending_buf.
    */
   local void putShortMSB (s, b)
       deflate_state *s;
       uInt b;
   {
       put_byte(s, (Byte)(b >> 8));
       put_byte(s, (Byte)(b & 0xff));
   }
   
   /* =========================================================================
    * Flush as much pending output as possible. All deflate() output, except for
    * some deflate_stored() output, goes through this function so some
    * applications may wish to modify it to avoid allocating a large
    * strm->next_out buffer and copying into it. (See also read_buf()).
    */
   local void flush_pending(strm)
       z_streamp strm;
   {
       unsigned len;
       deflate_state *s = strm->state;
   
       _tr_flush_bits(s);
       len = s->pending;
       if (len > strm->avail_out) len = strm->avail_out;
       if (len == 0) return;
   
       zmemcpy(strm->next_out, s->pending_out, len);
       strm->next_out  += len;
       s->pending_out  += len;
       strm->total_out += len;
       strm->avail_out -= len;
       s->pending      -= len;
       if (s->pending == 0) {
           s->pending_out = s->pending_buf;
       }
   }
   
   /* ===========================================================================
    * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1].
    */
   #define HCRC_UPDATE(beg) \
       do { \
           if (s->gzhead->hcrc && s->pending > (beg)) \
               strm->adler = crc32(strm->adler, s->pending_buf + (beg), \
                                   s->pending - (beg)); \
       } while (0)
   
   /* ========================================================================= */
   int ZEXPORT deflate (strm, flush)
       z_streamp strm;
       int flush;
   {
       int old_flush; /* value of flush param for previous deflate call */
       deflate_state *s;
   
       if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) {
           return Z_STREAM_ERROR;
       }
       s = strm->state;
   
       if (strm->next_out == Z_NULL ||
           (strm->avail_in != 0 && strm->next_in == Z_NULL) ||
           (s->status == FINISH_STATE && flush != Z_FINISH)) {
           ERR_RETURN(strm, Z_STREAM_ERROR);
       }
       if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
   
       old_flush = s->last_flush;
       s->last_flush = flush;
   
       /* Flush as much pending output as possible */
       if (s->pending != 0) {
           flush_pending(strm);
           if (strm->avail_out == 0) {
               /* Since avail_out is 0, deflate will be called again with
                * more output space, but possibly with both pending and
                * avail_in equal to zero. There won't be anything to do,
                * but this is not an error situation so make sure we
                * return OK instead of BUF_ERROR at next call of deflate:
                */
               s->last_flush = -1;
               return Z_OK;
           }
   
       /* Make sure there is something to do and avoid duplicate consecutive
        * flushes. For repeated and useless calls with Z_FINISH, we keep
        * returning Z_STREAM_END instead of Z_BUF_ERROR.
        */
       } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
                  flush != Z_FINISH) {
           ERR_RETURN(strm, Z_BUF_ERROR);
       }
   
       /* User must not provide more input after the first FINISH: */
       if (s->status == FINISH_STATE && strm->avail_in != 0) {
           ERR_RETURN(strm, Z_BUF_ERROR);
       }
   
       /* Write the header */
       if (s->status == INIT_STATE && s->wrap == 0)
           s->status = BUSY_STATE;
       if (s->status == INIT_STATE) {
           /* zlib header */
           uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
           uInt level_flags;
   
           if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
               level_flags = 0;
           else if (s->level < 6)
               level_flags = 1;
           else if (s->level == 6)
               level_flags = 2;
           else
               level_flags = 3;
           header |= (level_flags << 6);
           if (s->strstart != 0) header |= PRESET_DICT;
           header += 31 - (header % 31);
   
           putShortMSB(s, header);
   
           /* Save the adler32 of the preset dictionary: */
           if (s->strstart != 0) {
               putShortMSB(s, (uInt)(strm->adler >> 16));
               putShortMSB(s, (uInt)(strm->adler & 0xffff));
           }
           strm->adler = adler32(0L, Z_NULL, 0);
           s->status = BUSY_STATE;
   
           /* Compression must start with an empty pending buffer */
           flush_pending(strm);
           if (s->pending != 0) {
               s->last_flush = -1;
               return Z_OK;
           }
       }
   #ifdef GZIP
       if (s->status == GZIP_STATE) {
           /* gzip header */
           strm->adler = crc32(0L, Z_NULL, 0);
           put_byte(s, 31);
           put_byte(s, 139);
           put_byte(s, 8);
           if (s->gzhead == Z_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 :
                        (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
                         4 : 0));
               put_byte(s, OS_CODE);
               s->status = BUSY_STATE;
   
               /* Compression must start with an empty pending buffer */
               flush_pending(strm);
               if (s->pending != 0) {
                   s->last_flush = -1;
                   return Z_OK;
               }
           }
           else {
               put_byte(s, (s->gzhead->text ? 1 : 0) +
                        (s->gzhead->hcrc ? 2 : 0) +
                        (s->gzhead->extra == Z_NULL ? 0 : 4) +
                        (s->gzhead->name == Z_NULL ? 0 : 8) +
                        (s->gzhead->comment == Z_NULL ? 0 : 16)
                        );
               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 :
                        (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
                         4 : 0));
               put_byte(s, s->gzhead->os & 0xff);
               if (s->gzhead->extra != Z_NULL) {
                   put_byte(s, s->gzhead->extra_len & 0xff);
                   put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
               }
               if (s->gzhead->hcrc)
                   strm->adler = crc32(strm->adler, s->pending_buf,
                                       s->pending);
               s->gzindex = 0;
               s->status = EXTRA_STATE;
           }
       }
       if (s->status == EXTRA_STATE) {
           if (s->gzhead->extra != Z_NULL) {
               ulg beg = s->pending;   /* start of bytes to update crc */
               uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex;
               while (s->pending + left > s->pending_buf_size) {
                   uInt copy = s->pending_buf_size - s->pending;
                   zmemcpy(s->pending_buf + s->pending,
                           s->gzhead->extra + s->gzindex, copy);
                   s->pending = s->pending_buf_size;
                   HCRC_UPDATE(beg);
                   s->gzindex += copy;
                   flush_pending(strm);
                   if (s->pending != 0) {
                       s->last_flush = -1;
                       return Z_OK;
                   }
                   beg = 0;
                   left -= copy;
               }
               zmemcpy(s->pending_buf + s->pending,
                       s->gzhead->extra + s->gzindex, left);
               s->pending += left;
               HCRC_UPDATE(beg);
               s->gzindex = 0;
           }
           s->status = NAME_STATE;
       }
       if (s->status == NAME_STATE) {
           if (s->gzhead->name != Z_NULL) {
               ulg beg = s->pending;   /* start of bytes to update crc */
               int val;
               do {
                   if (s->pending == s->pending_buf_size) {
                       HCRC_UPDATE(beg);
                       flush_pending(strm);
                       if (s->pending != 0) {
                           s->last_flush = -1;
                           return Z_OK;
                       }
                       beg = 0;
                   }
                   val = s->gzhead->name[s->gzindex++];
                   put_byte(s, val);
               } while (val != 0);
               HCRC_UPDATE(beg);
               s->gzindex = 0;
           }
           s->status = COMMENT_STATE;
       }
       if (s->status == COMMENT_STATE) {
           if (s->gzhead->comment != Z_NULL) {
               ulg beg = s->pending;   /* start of bytes to update crc */
               int val;
               do {
                   if (s->pending == s->pending_buf_size) {
                       HCRC_UPDATE(beg);
                       flush_pending(strm);
                      if (s->pending != 0) {
                          s->last_flush = -1;
                          return Z_OK;
                      }
                      beg = 0;
                  }
                  val = s->gzhead->comment[s->gzindex++];
                  put_byte(s, val);
              } while (val != 0);
              HCRC_UPDATE(beg);
          }
          s->status = HCRC_STATE;
      }
      if (s->status == HCRC_STATE) {
          if (s->gzhead->hcrc) {
              if (s->pending + 2 > s->pending_buf_size) {
                  flush_pending(strm);
                  if (s->pending != 0) {
                      s->last_flush = -1;
                      return Z_OK;
                  }
              }
              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;
  
          /* Compression must start with an empty pending buffer */
          flush_pending(strm);
          if (s->pending != 0) {
              s->last_flush = -1;
              return Z_OK;
          }
      }
  #endif
  
      /* Start a new block or continue the current one.
       */
      if (strm->avail_in != 0 || s->lookahead != 0 ||
          (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
          block_state bstate;
  
          bstate = s->level == 0 ? deflate_stored(s, flush) :
                   s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
                   s->strategy == Z_RLE ? deflate_rle(s, flush) :
                   (*(configuration_table[s->level].func))(s, flush);
  
          if (bstate == finish_started || bstate == finish_done) {
              s->status = FINISH_STATE;
          }
          if (bstate == need_more || bstate == finish_started) {
              if (strm->avail_out == 0) {
                  s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
              }
              return Z_OK;
              /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
               * of deflate should use the same flush parameter to make sure
               * that the flush is complete. So we don't have to output an
               * empty block here, this will be done at next call. This also
               * ensures that for a very small output buffer, we emit at most
               * one empty block.
               */
          }
          if (bstate == block_done) {
              if (flush == Z_PARTIAL_FLUSH) {
                  _tr_align(s);
              } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
                  _tr_stored_block(s, (char*)0, 0L, 0);
                  /* For a full flush, this empty block will be recognized
                   * as a special marker by inflate_sync().
                   */
                  if (flush == Z_FULL_FLUSH) {
                      CLEAR_HASH(s);             /* forget history */
                      if (s->lookahead == 0) {
                          s->strstart = 0;
                          s->block_start = 0L;
                          s->insert = 0;
                      }
                  }
              }
              flush_pending(strm);
              if (strm->avail_out == 0) {
                s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
                return Z_OK;
              }
          }
      }
  
      if (flush != Z_FINISH) return Z_OK;
      if (s->wrap <= 0) return Z_STREAM_END;
  
      /* Write the trailer */
  #ifdef GZIP
      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));
      }
      else
  #endif
      {
          putShortMSB(s, (uInt)(strm->adler >> 16));
          putShortMSB(s, (uInt)(strm->adler & 0xffff));
      }
      flush_pending(strm);
      /* If avail_out is zero, the application will call deflate again
       * to flush the rest.
       */
      if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
      return s->pending != 0 ? Z_OK : Z_STREAM_END;
  }
  
  /* ========================================================================= */
  int ZEXPORT deflateEnd (strm)
      z_streamp strm;
  {
      int status;
  
      if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
  
      status = strm->state->status;
  
      /* 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;
  
      return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
  }
  
  /* =========================================================================
   * Copy the source state to the destination state.
   * To simplify the source, this is not supported for 16-bit MSDOS (which
   * doesn't have enough memory anyway to duplicate compression states).
   */
  int ZEXPORT deflateCopy (dest, source)
      z_streamp dest;
      z_streamp source;
  {
  #ifdef MAXSEG_64K
      return Z_STREAM_ERROR;
  #else
      deflate_state *ds;
      deflate_state *ss;
  
  
      if (deflateStateCheck(source) || dest == Z_NULL) {
          return Z_STREAM_ERROR;
      }
  
      ss = source->state;
  
      zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
  
      ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
      if (ds == Z_NULL) return Z_MEM_ERROR;
      dest->state = (struct internal_state FAR *) ds;
      zmemcpy((voidpf)ds, (voidpf)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));
      ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4);
  
      if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
          ds->pending_buf == Z_NULL) {
          deflateEnd (dest);
          return Z_MEM_ERROR;
      }
      /* following zmemcpy do not work for 16-bit MSDOS */
      zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
      zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
      zmemcpy((voidpf)ds->head, (voidpf)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->sym_buf = ds->pending_buf + 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;
  
      return Z_OK;
  #endif /* MAXSEG_64K */
  }
  
  /* ===========================================================================
   * Read a new buffer from the current input stream, update the adler32
   * and total number of bytes read.  All deflate() input goes through
   * this function so some applications may wish to modify it to avoid
   * allocating a large strm->next_in buffer and copying from it.
   * (See also flush_pending()).
   */
  local unsigned read_buf(strm, buf, size)
      z_streamp strm;
      Bytef *buf;
      unsigned size;
  {
      unsigned len = strm->avail_in;
  
      if (len > size) len = size;
      if (len == 0) return 0;
  
      strm->avail_in  -= len;
  
      zmemcpy(buf, strm->next_in, len);
      if (strm->state->wrap == 1) {
          strm->adler = adler32(strm->adler, buf, len);
      }
  #ifdef GZIP
      else if (strm->state->wrap == 2) {
          strm->adler = crc32(strm->adler, buf, len);
      }
  #endif
      strm->next_in  += len;
      strm->total_in += len;
  
      return len;
  }
  
  /* ===========================================================================
   * Initialize the "longest match" routines for a new zlib stream
   */
  local void lm_init (s)
      deflate_state *s;
  {
      s->window_size = (ulg)2L*s->w_size;
  
      CLEAR_HASH(s);
  
      /* Set the default configuration parameters:
       */
      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->insert = 0;
      s->match_length = s->prev_length = MIN_MATCH-1;
      s->match_available = 0;
      s->ins_h = 0;
  #ifndef FASTEST
  #ifdef ASMV
      match_init(); /* initialize the asm code */
  #endif
  #endif
  }
  
  #ifndef FASTEST
  /* ===========================================================================
   * Set match_start to the longest match starting at the given string and
   * return its length. Matches shorter or equal to prev_length are discarded,
   * in which case the result is equal to prev_length and match_start is
   * garbage.
   * IN assertions: cur_match is the head of the hash chain for the current
   *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
   * OUT assertion: the match length is not greater than s->lookahead.
   */
  #ifndef ASMV
  /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
   * match.S. The code will be functionally equivalent.
   */
  local uInt longest_match(s, cur_match)
      deflate_state *s;
      IPos cur_match;                             /* current match */
  {
      unsigned chain_length = s->max_chain_length;/* max hash chain length */
      register Bytef *scan = s->window + s->strstart; /* current string */
      register Bytef *match;                      /* matched string */
      register int len;                           /* length of current match */
      int best_len = (int)s->prev_length;         /* best match length so far */
      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;
      /* Stop when cur_match becomes <= limit. To simplify the code,
       * we prevent matches with the string of window index 0.
       */
      Posf *prev = s->prev;
      uInt wmask = s->w_mask;
  
  #ifdef UNALIGNED_OK
      /* Compare two bytes at a time. Note: this is not always beneficial.
       * Try with and without -DUNALIGNED_OK to check.
       */
      register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
      register ush scan_start = *(ushf*)scan;
      register ush scan_end   = *(ushf*)(scan+best_len-1);
  #else
      register Bytef *strend = s->window + s->strstart + MAX_MATCH;
      register Byte scan_end1  = scan[best_len-1];
      register Byte scan_end   = scan[best_len];
  #endif
  
      /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
       * It is easy to get rid of this optimization if necessary.
       */
      Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
  
      /* Do not waste too much time if we already have a good match: */
      if (s->prev_length >= s->good_match) {
          chain_length >>= 2;
      }
      /* Do not look for matches beyond the end of the input. This is necessary
       * to make deflate deterministic.
       */
      if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead;
  
      Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
  
      do {
          Assert(cur_match < s->strstart, "no future");
          match = s->window + cur_match;
  
          /* Skip to next match if the match length cannot increase
           * or if the match length is less than 2.  Note that the checks below
           * for insufficient lookahead only occur occasionally for performance
           * reasons.  Therefore uninitialized memory will be accessed, and
           * conditional jumps will be made that depend on those values.
           * However the length of the match is limited to the lookahead, so
           * the output of deflate is not affected by the uninitialized values.
           */
  #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
          /* This code assumes sizeof(unsigned short) == 2. Do not use
           * UNALIGNED_OK if your compiler uses a different size.
           */
          if (*(ushf*)(match+best_len-1) != scan_end ||
              *(ushf*)match != scan_start) continue;
  
          /* It is not necessary to compare scan[2] and match[2] since they are
           * always equal when the other bytes match, given that the hash keys
           * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
           * strstart+3, +5, ... up to strstart+257. We check for insufficient
           * lookahead only every 4th comparison; the 128th check will be made
           * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
           * necessary to put more guard bytes at the end of the window, or
           * to check more often for insufficient lookahead.
           */
          Assert(scan[2] == match[2], "scan[2]?");
          scan++, match++;
          do {
          } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
                   *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
                   *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
                   *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
                   scan < strend);
          /* The funny "do {}" generates better code on most compilers */
  
          /* Here, scan <= window+strstart+257 */
          Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
          if (*scan == *match) scan++;
  
          len = (MAX_MATCH - 1) - (int)(strend-scan);
          scan = strend - (MAX_MATCH-1);
  
  #else /* UNALIGNED_OK */
  
          if (match[best_len]   != scan_end  ||
              match[best_len-1] != scan_end1 ||
              *match            != *scan     ||
              *++match          != scan[1])      continue;
  
          /* The check at best_len-1 can be removed because it will be made
           * again later. (This heuristic is not always a win.)
           * It is not necessary to compare scan[2] and match[2] since they
           * are always equal when the other bytes match, given that
           * the hash keys are equal and that HASH_BITS >= 8.
           */
          scan += 2, match++;
          Assert(*scan == *match, "match[2]?");
  
          /* We check for insufficient lookahead only every 8th comparison;
           * the 256th check will be made at strstart+258.
           */
          do {
          } while (*++scan == *++match && *++scan == *++match &&
                   *++scan == *++match && *++scan == *++match &&
                   *++scan == *++match && *++scan == *++match &&
                   *++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;
  
  #endif /* UNALIGNED_OK */
  
          if (len > best_len) {
              s->match_start = cur_match;
              best_len = len;
              if (len >= nice_match) break;
  #ifdef UNALIGNED_OK
              scan_end = *(ushf*)(scan+best_len-1);
  #else
              scan_end1  = scan[best_len-1];
              scan_end   = scan[best_len];
  #endif
          }
      } while ((cur_match = prev[cur_match & wmask]) > limit
               && --chain_length != 0);
  
      if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
      return s->lookahead;
  }
  #endif /* ASMV */
  
  #else /* FASTEST */
  
  /* ---------------------------------------------------------------------------
   * Optimized version for FASTEST only
   */
  local uInt longest_match(s, cur_match)
      deflate_state *s;
      IPos cur_match;                             /* current match */
  {
      register Bytef *scan = s->window + s->strstart; /* current string */
      register Bytef *match;                       /* matched string */
      register int len;                           /* length of current match */
      register Bytef *strend = s->window + s->strstart + MAX_MATCH;
  
      /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
       * It is easy to get rid of this optimization if necessary.
       */
      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;
  
      /* Return failure if the match length is less than 2:
       */
      if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
  
      /* The check at best_len-1 can be removed because it will be made
       * again later. (This heuristic is not always a win.)
       * It is not necessary to compare scan[2] and match[2] since they
       * are always equal when the other bytes match, given that
       * the hash keys are equal and that HASH_BITS >= 8.
       */
      scan += 2, match += 2;
      Assert(*scan == *match, "match[2]?");
  
      /* We check for insufficient lookahead only every 8th comparison;
       * the 256th check will be made at strstart+258.
       */
      do {
      } while (*++scan == *++match && *++scan == *++match &&
               *++scan == *++match && *++scan == *++match &&
               *++scan == *++match && *++scan == *++match &&
               *++scan == *++match && *++scan == *++match &&
               scan < strend);
  
      Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
  
      len = MAX_MATCH - (int)(strend - scan);
  
      if (len < MIN_MATCH) return MIN_MATCH - 1;
  
      s->match_start = cur_match;
      return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
  }
  
  #endif /* FASTEST */
  
  #ifdef ZLIB_DEBUG
  
  #define EQUAL 0
  /* result of memcmp for equal strings */
  
  /* ===========================================================================
   * Check that the match at match_start is indeed a match.
   */
  local void check_match(s, start, match, length)
      deflate_state *s;
      IPos start, match;
      int length;
  {
      /* check that the match is indeed a match */
      if (zmemcmp(s->window + match,
                  s->window + start, length) != EQUAL) {
          fprintf(stderr, " start %u, match %u, length %d\n",
                  start, match, length);
          do {
              fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
          } while (--length != 0);
          z_error("invalid match");
      }
      if (z_verbose > 1) {
          fprintf(stderr,"\\[%d,%d]", start-match, length);
          do { putc(s->window[start++], stderr); } while (--length != 0);
      }
  }
  #else
  #  define check_match(s, start, match, length)
  #endif /* ZLIB_DEBUG */
  
  /* ===========================================================================
   * Fill the window when the lookahead becomes insufficient.
   * Updates strstart and lookahead.
   *
   * IN assertion: lookahead < MIN_LOOKAHEAD
   * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
   *    At least one byte has been read, or avail_in == 0; reads are
   *    performed for at least two bytes (required for the zip translate_eol
   *    option -- not supported here).
   */
  local void fill_window(s)
      deflate_state *s;
  {
      unsigned n;
      unsigned more;    /* Amount of free space at the end of the window. */
      uInt wsize = s->w_size;
  
      Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
  
      do {
          more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
  
          /* Deal with !@#$% 64K limit: */
          if (sizeof(int) <= 2) {
              if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
                  more = wsize;
  
              } else if (more == (unsigned)(-1)) {
                  /* Very unlikely, but possible on 16 bit machine if
                   * strstart == 0 && lookahead == 1 (input done a byte at time)
                   */
                  more--;
              }
          }
  
          /* If the window is almost full and there is insufficient lookahead,
           * move the upper half to the lower one to make room in the upper half.
           */
          if (s->strstart >= wsize+MAX_DIST(s)) {
  
              zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more);
              s->match_start -= wsize;
              s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
              s->block_start -= (long) wsize;
              if (s->insert > s->strstart)
                  s->insert = s->strstart;
              slide_hash(s);
              more += wsize;
          }
          if (s->strm->avail_in == 0) break;
  
          /* If there was no sliding:
           *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
           *    more == window_size - lookahead - strstart
           * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
           * => more >= window_size - 2*WSIZE + 2
           * In the BIG_MEM or MMAP case (not yet supported),
           *   window_size == input_size + MIN_LOOKAHEAD  &&
           *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
           * Otherwise, window_size == 2*WSIZE so more >= 2.
           * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
           */
          Assert(more >= 2, "more < 2");
  
          n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
          s->lookahead += n;
  
          /* Initialize the hash value now that we have some input: */
          if (s->lookahead + s->insert >= MIN_MATCH) {
              uInt str = s->strstart - s->insert;
              s->ins_h = s->window[str];
              UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
  #if MIN_MATCH != 3
              Call UPDATE_HASH() MIN_MATCH-3 more times
  #endif
              while (s->insert) {
                  UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
  #ifndef FASTEST
                  s->prev[str & s->w_mask] = s->head[s->ins_h];
  #endif
                  s->head[s->ins_h] = (Pos)str;
                  str++;
                  s->insert--;
                  if (s->lookahead + s->insert < MIN_MATCH)
                      break;
              }
          }
          /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
           * but this is not important since only literal bytes will be emitted.
           */
  
      } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
  
      /* If the WIN_INIT bytes after the end of the current data have never been
       * written, then zero those bytes in order to avoid memory check reports of
       * the use of uninitialized (or uninitialised as Julian writes) bytes by
       * the longest match routines.  Update the high water mark for the next
       * time through here.  WIN_INIT is set to MAX_MATCH since the longest match
       * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
       */
      if (s->high_water < s->window_size) {
          ulg curr = s->strstart + (ulg)(s->lookahead);
          ulg init;
  
          if (s->high_water < curr) {
              /* Previous high water mark below current data -- zero WIN_INIT
               * bytes or up to end of window, whichever is less.
               */
              init = s->window_size - curr;
              if (init > WIN_INIT)
                  init = WIN_INIT;
              zmemzero(s->window + curr, (unsigned)init);
              s->high_water = curr + init;
          }
          else if (s->high_water < (ulg)curr + WIN_INIT) {
              /* High water mark at or above current data, but below current data
               * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
               * to end of window, whichever is less.
               */
              init = (ulg)curr + WIN_INIT - s->high_water;
              if (init > s->window_size - s->high_water)
                  init = s->window_size - s->high_water;
              zmemzero(s->window + s->high_water, (unsigned)init);
              s->high_water += init;
          }
      }
  
      Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
             "not enough room for search");
  }
  
  /* ===========================================================================
   * Flush the current block, with given end-of-file flag.
   * IN assertion: strstart is set to the end of the current match.
   */
  #define FLUSH_BLOCK_ONLY(s, last) { \
     _tr_flush_block(s, (s->block_start >= 0L ? \
                     (charf *)&s->window[(unsigned)s->block_start] : \
                     (charf *)Z_NULL), \
                  (ulg)((long)s->strstart - s->block_start), \
                  (last)); \
     s->block_start = s->strstart; \
     flush_pending(s->strm); \
     Tracev((stderr,"[FLUSH]")); \
  }
  
  /* Same but force premature exit if necessary. */
  #define FLUSH_BLOCK(s, last) { \
     FLUSH_BLOCK_ONLY(s, last); \
     if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
  }
  
  /* Maximum stored block length in deflate format (not including header). */
  #define MAX_STORED 65535
  
  #if !defined(MIN)
  /* Minimum of a and b. */
  #define MIN(a, b) ((a) > (b) ? (b) : (a))
  #endif
  
  /* ===========================================================================
   * Copy without compression as much as possible from the input stream, return
   * the current block state.
   *
   * In case deflateParams() is used to later switch to a non-zero compression
   * level, s->matches (otherwise unused when storing) keeps track of the number
   * of hash table slides to perform. If s->matches is 1, then one hash table
   * slide will be done when switching. If s->matches is 2, the maximum value
   * allowed here, then the hash table will be cleared, since two or more slides
   * is the same as a clear.
   *
   * deflate_stored() is written to minimize the number of times an input byte is
   * copied. It is most efficient with large input and output buffers, which
   * maximizes the opportunites to have a single copy from next_in to next_out.
   */
  local block_state deflate_stored(s, flush)
      deflate_state *s;
      int flush;
  {
      /* Smallest worthy block size when not flushing or finishing. By default
       * this is 32K. This can be as small as 507 bytes for memLevel == 1. For
       * large input and output buffers, the stored block size will be larger.
       */
      unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size);
  
      /* Copy as many min_block or larger stored blocks directly to next_out as
       * possible. If flushing, copy the remaining available input to next_out as
       * stored blocks, if there is enough space.
       */
      unsigned len, left, have, last = 0;
      unsigned used = s->strm->avail_in;
      do {
          /* Set len to the maximum size block that we can copy directly with the
           * available input data and output space. Set left to how much of that
           * would be copied from what's left in the window.
           */
          len = MAX_STORED;       /* maximum deflate stored block length */
          have = (s->bi_valid + 42) >> 3;         /* number of header bytes */
          if (s->strm->avail_out < have)          /* need room for header */
              break;
              /* maximum stored block length that will fit in avail_out: */
          have = s->strm->avail_out - have;
          left = s->strstart - s->block_start;    /* bytes left in window */
          if (len > (ulg)left + s->strm->avail_in)
              len = left + s->strm->avail_in;     /* limit len to the input */
          if (len > have)
              len = have;                         /* limit len to the output */
  
          /* If the stored block would be less than min_block in length, or if
           * unable to copy all of the available input when flushing, then try
           * copying to the window and the pending buffer instead. Also don't
           * write an empty block when flushing -- deflate() does that.
           */
          if (len < min_block && ((len == 0 && flush != Z_FINISH) ||
                                  flush == Z_NO_FLUSH ||
                                  len != left + s->strm->avail_in))
              break;
  
          /* Make a dummy stored block in pending to get the header bytes,
           * including any pending bits. This also updates the debugging counts.
           */
          last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0;
          _tr_stored_block(s, (char *)0, 0L, last);
  
          /* Replace the lengths in the dummy stored block with len. */
          s->pending_buf[s->pending - 4] = len;
          s->pending_buf[s->pending - 3] = len >> 8;
          s->pending_buf[s->pending - 2] = ~len;
          s->pending_buf[s->pending - 1] = ~len >> 8;
  
          /* Write the stored block header bytes. */
          flush_pending(s->strm);
  
  #ifdef ZLIB_DEBUG
          /* Update debugging counts for the data about to be copied. */
          s->compressed_len += len << 3;
          s->bits_sent += len << 3;
  #endif
  
          /* Copy uncompressed bytes from the window to next_out. */
          if (left) {
              if (left > len)
                  left = len;
              zmemcpy(s->strm->next_out, s->window + s->block_start, left);
              s->strm->next_out += left;
              s->strm->avail_out -= left;
              s->strm->total_out += left;
              s->block_start += left;
              len -= left;
          }
  
          /* Copy uncompressed bytes directly from next_in to next_out, updating
           * the check value.
           */
          if (len) {
              read_buf(s->strm, s->strm->next_out, len);
              s->strm->next_out += len;
              s->strm->avail_out -= len;
              s->strm->total_out += len;
          }
      } while (last == 0);
  
      /* Update the sliding window with the last s->w_size bytes of the copied
       * data, or append all of the copied data to the existing window if less
       * than s->w_size bytes were copied. Also update the number of bytes to
       * insert in the hash tables, in the event that deflateParams() switches to
       * a non-zero compression level.
       */
      used -= s->strm->avail_in;      /* number of input bytes directly copied */
      if (used) {
          /* If any input was used, then no unused input remains in the window,
           * therefore s->block_start == s->strstart.
           */
          if (used >= s->w_size) {    /* supplant the previous history */
              s->matches = 2;         /* clear hash */
              zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);
              s->strstart = s->w_size;
              s->insert = s->strstart;
          }
          else {
              if (s->window_size - s->strstart <= used) {
                  /* Slide the window down. */
                  s->strstart -= s->w_size;
                  zmemcpy(s->window, s->window + s->w_size, s->strstart);
                  if (s->matches < 2)
                      s->matches++;   /* add a pending slide_hash() */
                  if (s->insert > s->strstart)
                      s->insert = s->strstart;
              }
              zmemcpy(s->window + s->strstart, s->strm->next_in - used, used);
              s->strstart += used;
              s->insert += MIN(used, s->w_size - s->insert);
          }
          s->block_start = s->strstart;
      }
      if (s->high_water < s->strstart)
          s->high_water = s->strstart;
  
      /* If the last block was written to next_out, then done. */
      if (last)
          return finish_done;
  
      /* If flushing and all input has been consumed, then done. */
      if (flush != Z_NO_FLUSH && flush != Z_FINISH &&
          s->strm->avail_in == 0 && (long)s->strstart == s->block_start)
          return block_done;
  
      /* Fill the window with any remaining input. */
      have = s->window_size - s->strstart;
      if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) {
          /* Slide the window down. */
          s->block_start -= s->w_size;
          s->strstart -= s->w_size;
          zmemcpy(s->window, s->window + s->w_size, s->strstart);
          if (s->matches < 2)
              s->matches++;           /* add a pending slide_hash() */
          have += s->w_size;          /* more space now */
          if (s->insert > s->strstart)
              s->insert = s->strstart;
      }
      if (have > s->strm->avail_in)
          have = s->strm->avail_in;
      if (have) {
          read_buf(s->strm, s->window + s->strstart, have);
          s->strstart += have;
          s->insert += MIN(have, s->w_size - s->insert);
      }
      if (s->high_water < s->strstart)
          s->high_water = s->strstart;
  
      /* There was not enough avail_out to write a complete worthy or flushed
       * stored block to next_out. Write a stored block to pending instead, if we
       * have enough input for a worthy block, or if flushing and there is enough
       * room for the remaining input as a stored block in the pending buffer.
       */
      have = (s->bi_valid + 42) >> 3;         /* number of header bytes */
          /* maximum stored block length that will fit in pending: */
      have = MIN(s->pending_buf_size - have, MAX_STORED);
      min_block = MIN(have, s->w_size);
      left = s->strstart - s->block_start;
      if (left >= min_block ||
          ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH &&
           s->strm->avail_in == 0 && left <= have)) {
          len = MIN(left, have);
          last = flush == Z_FINISH && s->strm->avail_in == 0 &&
                 len == left ? 1 : 0;
          _tr_stored_block(s, (charf *)s->window + s->block_start, len, last);
          s->block_start += len;
          flush_pending(s->strm);
      }
  
      /* We've done all we can with the available input and output. */
      return last ? finish_started : need_more;
  }
  
  /* ===========================================================================
   * Compress as much as possible from the input stream, return the current
   * block state.
   * This function does not perform lazy evaluation of matches and inserts
   * new strings in the dictionary only for unmatched strings or for short
   * matches. It is used only for the fast compression options.
   */
  local block_state deflate_fast(s, flush)
      deflate_state *s;
      int flush;
  {
      IPos hash_head;       /* head of the hash chain */
      int bflush;           /* set if current block must be flushed */
  
      for (;;) {
          /* Make sure that we always have enough lookahead, except
           * at the end of the input file. We need MAX_MATCH bytes
           * for the next match, plus MIN_MATCH bytes to insert the
           * string following the next match.
           */
          if (s->lookahead < MIN_LOOKAHEAD) {
              fill_window(s);
              if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
                  return need_more;
              }
              if (s->lookahead == 0) break; /* flush the current block */
          }
  
          /* Insert the string window[strstart .. strstart+2] in the
           * dictionary, and set hash_head to the head of the hash chain:
           */
          hash_head = NIL;
          if (s->lookahead >= MIN_MATCH) {
              INSERT_STRING(s, s->strstart, hash_head);
          }
  
          /* Find the longest match, discarding those <= prev_length.
           * At this point we have always match_length < MIN_MATCH
           */
          if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
              /* To simplify the code, we prevent matches with the string
               * of window index 0 (in particular we have to avoid a match
               * of the string with itself at the start of the input file).
               */
              s->match_length = longest_match (s, hash_head);
              /* longest_match() sets match_start */
          }
          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;
  
              /* Insert new strings in the hash table only if the match length
               * is not too large. This saves time but degrades compression.
               */
  #ifndef FASTEST
              if (s->match_length <= s->max_insert_length &&
                  s->lookahead >= MIN_MATCH) {
                  s->match_length--; /* string at strstart already in table */
                  do {
                      s->strstart++;
                      INSERT_STRING(s, s->strstart, hash_head);
                      /* strstart never exceeds WSIZE-MAX_MATCH, so there are
                       * always MIN_MATCH bytes ahead.
                       */
                  } while (--s->match_length != 0);
                  s->strstart++;
              } else
  #endif
              {
                  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]);
  #if MIN_MATCH != 3
                  Call UPDATE_HASH() MIN_MATCH-3 more times
  #endif
                  /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
                   * matter since it will be recomputed at next deflate call.
                   */
              }
          } else {
              /* 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++;
          }
          if (bflush) FLUSH_BLOCK(s, 0);
      }
      s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
      if (flush == Z_FINISH) {
          FLUSH_BLOCK(s, 1);
          return finish_done;
      }
      if (s->sym_next)
          FLUSH_BLOCK(s, 0);
      return block_done;
  }
  
  #ifndef FASTEST
  /* ===========================================================================
   * Same as above, but achieves better compression. We use a lazy
   * evaluation for matches: a match is finally adopted only if there is
   * no better match at the next window position.
   */
  local block_state deflate_slow(s, flush)
      deflate_state *s;
      int flush;
  {
      IPos hash_head;          /* head of hash chain */
      int bflush;              /* set if current block must be flushed */
  
      /* Process the input block. */
      for (;;) {
          /* Make sure that we always have enough lookahead, except
           * at the end of the input file. We need MAX_MATCH bytes
           * for the next match, plus MIN_MATCH bytes to insert the
           * string following the next match.
           */
          if (s->lookahead < MIN_LOOKAHEAD) {
              fill_window(s);
              if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
                  return need_more;
              }
              if (s->lookahead == 0) break; /* flush the current block */
          }
  
          /* Insert the string window[strstart .. strstart+2] in the
           * dictionary, and set hash_head to the head of the hash chain:
           */
          hash_head = NIL;
          if (s->lookahead >= MIN_MATCH) {
              INSERT_STRING(s, s->strstart, hash_head);
          }
  
          /* Find the longest match, discarding those <= prev_length.
           */
          s->prev_length = s->match_length, s->prev_match = s->match_start;
          s->match_length = MIN_MATCH-1;
  
          if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
              s->strstart - hash_head <= MAX_DIST(s)) {
              /* To simplify the code, we prevent matches with the string
               * of window index 0 (in particular we have to avoid a match
               * of the string with itself at the start of the input file).
               */
              s->match_length = longest_match (s, hash_head);
              /* longest_match() sets match_start */
  
              if (s->match_length <= 5 && (s->strategy == Z_FILTERED
  #if TOO_FAR <= 32767
                  || (s->match_length == MIN_MATCH &&
                      s->strstart - s->match_start > TOO_FAR)
  #endif
                  )) {
  
                  /* If prev_match is also MIN_MATCH, match_start is garbage
                   * but we will ignore the current match anyway.
                   */
                  s->match_length = MIN_MATCH-1;
              }
          }
          /* If there was a match at the previous step and the current
           * match is not better, output the previous match:
           */
          if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
              uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
              /* 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);
  
              /* Insert in hash table all strings up to the end of the match.
               * strstart-1 and strstart are already inserted. If there is not
               * enough lookahead, the last two strings are not inserted in
               * the hash table.
               */
              s->lookahead -= s->prev_length-1;
              s->prev_length -= 2;
              do {
                  if (++s->strstart <= max_insert) {
                      INSERT_STRING(s, s->strstart, hash_head);
                  }
              } while (--s->prev_length != 0);
              s->match_available = 0;
              s->match_length = MIN_MATCH-1;
              s->strstart++;
  
              if (bflush) FLUSH_BLOCK(s, 0);
  
          } else if (s->match_available) {
              /* If there was no match at the previous position, output a
               * single literal. If there was a match but the current match
               * is longer, truncate the previous match to a single literal.
               */
              Tracevv((stderr,"%c", s->window[s->strstart-1]));
              _tr_tally_lit(s, s->window[s->strstart-1], bflush);
              if (bflush) {
                  FLUSH_BLOCK_ONLY(s, 0);
              }
              s->strstart++;
              s->lookahead--;
              if (s->strm->avail_out == 0) return need_more;
          } else {
              /* There is no previous match to compare with, wait for
               * the next step to decide.
               */
              s->match_available = 1;
              s->strstart++;
              s->lookahead--;
          }
      }
      Assert (flush != Z_NO_FLUSH, "no flush?");
      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;
      }
      s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
      if (flush == Z_FINISH) {
          FLUSH_BLOCK(s, 1);
          return finish_done;
      }
      if (s->sym_next)
          FLUSH_BLOCK(s, 0);
      return block_done;
  }
  #endif /* FASTEST */
  
  /* ===========================================================================
   * For Z_RLE, simply look for runs of bytes, generate matches only of distance
   * one.  Do not maintain a hash table.  (It will be regenerated if this run of
   * deflate switches away from Z_RLE.)
   */
  local block_state deflate_rle(s, flush)
      deflate_state *s;
      int flush;
  {
      int bflush;             /* set if current block must be flushed */
      uInt prev;              /* byte at distance one to match */
      Bytef *scan, *strend;   /* scan goes up to strend for length of run */
  
      for (;;) {
          /* Make sure that we always have enough lookahead, except
           * at the end of the input file. We need MAX_MATCH bytes
           * for the longest run, plus one for the unrolled loop.
           */
          if (s->lookahead <= MAX_MATCH) {
              fill_window(s);
              if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
                  return need_more;
              }
              if (s->lookahead == 0) break; /* flush the current block */
          }
  
          /* See how many times the previous byte repeats */
          s->match_length = 0;
          if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
              scan = s->window + s->strstart - 1;
              prev = *scan;
              if (prev == *++scan && prev == *++scan && prev == *++scan) {
                  strend = s->window + s->strstart + MAX_MATCH;
                  do {
                  } while (prev == *++scan && prev == *++scan &&
                           prev == *++scan && prev == *++scan &&
                           prev == *++scan && prev == *++scan &&
                           prev == *++scan && prev == *++scan &&
                           scan < strend);
                  s->match_length = MAX_MATCH - (uInt)(strend - scan);
                  if (s->match_length > s->lookahead)
                      s->match_length = s->lookahead;
              }
              Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
          }
  
          /* Emit match if have run of MIN_MATCH or longer, else emit literal */
          if (s->match_length >= MIN_MATCH) {
              check_match(s, s->strstart, s->strstart - 1, s->match_length);
  
              _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
  
              s->lookahead -= s->match_length;
              s->strstart += s->match_length;
              s->match_length = 0;
          } else {
              /* 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++;
          }
          if (bflush) FLUSH_BLOCK(s, 0);
      }
      s->insert = 0;
      if (flush == Z_FINISH) {
          FLUSH_BLOCK(s, 1);
          return finish_done;
      }
      if (s->sym_next)
          FLUSH_BLOCK(s, 0);
      return block_done;
  }
  
  /* ===========================================================================
   * For Z_HUFFMAN_ONLY, do not look for matches.  Do not maintain a hash table.
   * (It will be regenerated if this run of deflate switches away from Huffman.)
   */
  local block_state deflate_huff(s, flush)
      deflate_state *s;
      int flush;
  {
      int bflush;             /* set if current block must be flushed */
  
      for (;;) {
          /* Make sure that we have a literal to write. */
          if (s->lookahead == 0) {
              fill_window(s);
              if (s->lookahead == 0) {
                  if (flush == Z_NO_FLUSH)
                      return need_more;
                  break;      /* flush the current block */
              }
          }
  
          /* Output a literal byte */
          s->match_length = 0;
          Tracevv((stderr,"%c", s->window[s->strstart]));
          _tr_tally_lit (s, s->window[s->strstart], bflush);
          s->lookahead--;
          s->strstart++;
          if (bflush) FLUSH_BLOCK(s, 0);
      }
      s->insert = 0;
      if (flush == Z_FINISH) {
          FLUSH_BLOCK(s, 1);
          return finish_done;
      }
      if (s->sym_next)
          FLUSH_BLOCK(s, 0);
      return block_done;
  }

Cache object: ff65575dd47f8053b02e75bfa9971415