/* deflate.c -- compress data using the deflation algorithm

  * Copyright (C) 1995-2005 Jean-loup Gailly.

  * 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://www.ietf.org/rfc/rfc1951.txt

  *

  *      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 <stdio.h>

 #include "deflate.h"

 const char deflate_copyright[] =

    " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly ";

 /*

   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 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 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));

 #ifndef FASTEST

 #ifdef ASMV

       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

 #endif

 local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));

 #ifdef 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 */

 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)

 /* Minimum amount of lookahead, except at the end of the input file.

  * See deflate.c for comments about the MIN_MATCH+1.

  */

 /* 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.

  */

 #define EQUAL 0

 /* result of memcmp for equal strings */

 #ifndef NO_DUMMY_DECL

 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */

 #endif

 /* ===========================================================================

  * Update a hash value with the given input byte

  * IN  assertion: all calls to 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 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) \

     s->head[s->hash_size-1] = NIL; \

     zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));

 /* ========================================================================= */

 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;

     ushf *overlay;

     /* We overlay pending_buf and d_buf+l_buf. This works since the average

      * output size for (length,distance) codes is <= 24 bits.

      */

     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) {

         strm->zalloc = zcalloc;

         strm->opaque = (voidpf)0;

     }

     if (strm->zfree == (free_func)0) strm->zfree = zcfree;

 #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) {

         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->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);

     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);

         return Z_MEM_ERROR;

     }

     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;

     return deflateReset(strm);

 }

 /* ========================================================================= */

 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)

     z_streamp strm;

     const Bytef *dictionary;

     uInt  dictLength;

 {

     deflate_state *s;

     uInt length = dictLength;

     uInt n;

     IPos hash_head = 0;

     if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||

         strm->state->wrap == 2 ||

         (strm->state->wrap == 1 && strm->state->status != INIT_STATE))

         return Z_STREAM_ERROR;

     s = strm->state;

     if (s->wrap)

         strm->adler = adler32(strm->adler, dictionary, dictLength);

     if (length < MIN_MATCH) return Z_OK;

     if (length > MAX_DIST(s)) {

         length = MAX_DIST(s);

         dictionary += dictLength - length; /* use the tail of the dictionary */

     }

     zmemcpy(s->window, dictionary, length);

     s->strstart = length;

     s->block_start = (long)length;

     /* Insert all strings in the hash table (except for the last two bytes).

      * s->lookahead stays null, so s->ins_h will be recomputed at the next

      * call of fill_window.

      */

     s->ins_h = s->window[0];

     UPDATE_HASH(s, s->ins_h, s->window[1]);

     for (n = 0; n <= length - MIN_MATCH; n++) {

         INSERT_STRING(s, n, hash_head);

     }

     if (hash_head) hash_head = 0;  /* to make compiler happy */

     return Z_OK;

 }

 /* ========================================================================= */

 int ZEXPORT deflateReset (strm)

     z_streamp strm;

 {

     deflate_state *s;

     if (strm == Z_NULL || strm->state == Z_NULL ||

         strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {

         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 = s->wrap ? INIT_STATE : BUSY_STATE;

     strm->adler =

 #ifdef GZIP

         s->wrap == 2 ? crc32(0L, Z_NULL, 0) :

 #endif

         adler32(0L, Z_NULL, 0);

     s->last_flush = Z_NO_FLUSH;

     _tr_init(s);

     lm_init(s);

     return Z_OK;

 }

 /* ========================================================================= */

 int ZEXPORT deflateSetHeader (strm, head)

     z_streamp strm;

     gz_headerp head;

 {

     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;

     if (strm->state->wrap != 2) return Z_STREAM_ERROR;

     strm->state->gzhead = head;

     return Z_OK;

 }

 /* ========================================================================= */

 int ZEXPORT deflatePrime (strm, bits, value)

     z_streamp strm;

     int bits;

     int value;

 {

     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));

     return Z_OK;

 }

 /* ========================================================================= */

 int ZEXPORT deflateParams(strm, level, strategy)

     z_streamp strm;

     int level;

     int strategy;

 {

     deflate_state *s;

     compress_func func;

     int err = Z_OK;

     if (strm == Z_NULL || strm->state == Z_NULL) 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 (func != configuration_table[level].func && strm->total_in != 0) {

         /* Flush the last buffer: */

         err = deflate(strm, Z_PARTIAL_FLUSH);

     }

     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;

     }

     s->strategy = strategy;

     return err;

 }

 /* ========================================================================= */

 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 (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;

     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, as well as wrap.

  * 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 destLen;

     /* conservative upper bound */

     destLen = sourceLen +

               ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;

     /* if can't get parameters, return conservative bound */

     if (strm == Z_NULL || strm->state == Z_NULL)

         return destLen;

     /* if not default parameters, return conservative bound */

     s = strm->state;

     if (s->w_bits != 15 || s->hash_bits != 8 + 7)

         return destLen;

     /* default settings: return tight bound for that case */

     return compressBound(sourceLen);

 }

 /* =========================================================================

  * 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 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 = strm->state->pending;

     if (len > strm->avail_out) len = strm->avail_out;

     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;

     if (strm->state->pending == 0) {

         strm->state->pending_out = strm->state->pending_buf;

     }

 }

 /* ========================================================================= */

 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 (strm == Z_NULL || strm->state == Z_NULL ||

         flush > Z_FINISH || flush < 0) {

         return Z_STREAM_ERROR;

     }

     s = strm->state;

     if (strm->next_out == Z_NULL ||

         (strm->next_in == Z_NULL && strm->avail_in != 0) ||

         (s->status == FINISH_STATE && flush != Z_FINISH)) {

         ERR_RETURN(strm, Z_STREAM_ERROR);

     }

     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;

     /* Write the header */

     if (s->status == INIT_STATE) {

 #ifdef GZIP

         if (s->wrap == 2) {

             strm->adler = crc32(0L, Z_NULL, 0);

             put_byte(s, 31);

             put_byte(s, 139);

             put_byte(s, 8);

             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 :

                             (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?

                              4 : 0));

                 put_byte(s, OS_CODE);

                 s->status = BUSY_STATE;

             }

             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 != 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;

             }

         }

         else

 #endif

         {

             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);

             s->status = BUSY_STATE;

             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);

         }

     }

 #ifdef GZIP

     if (s->status == EXTRA_STATE) {

         if (s->gzhead->extra != NULL) {

             uInt beg = s->pending;  /* start of bytes to update crc */

             while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {

                 if (s->pending == s->pending_buf_size) {

                     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;

                     if (s->pending == s->pending_buf_size)

                         break;

                 }

                 put_byte(s, s->gzhead->extra[s->gzindex]);

                 s->gzindex++;

             }

             if (s->gzhead->hcrc && s->pending > beg)

                 strm->adler = crc32(strm->adler, s->pending_buf + beg,

                                     s->pending - beg);

             if (s->gzindex == s->gzhead->extra_len) {

                 s->gzindex = 0;

                 s->status = NAME_STATE;

             }

         }

         else

             s->status = NAME_STATE;

     }

     if (s->status == NAME_STATE) {

         if (s->gzhead->name != NULL) {

             uInt beg = s->pending;  /* start of bytes to update crc */

             int val;

             do {

                 if (s->pending == s->pending_buf_size) {

                     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;

                     if (s->pending == s->pending_buf_size) {

                         val = 1;

                         break;

                     }

                 }

                 val = s->gzhead->name[s->gzindex++];

                 put_byte(s, val);

             } while (val != 0);

             if (s->gzhead->hcrc && s->pending > beg)

                 strm->adler = crc32(strm->adler, s->pending_buf + beg,

                                     s->pending - beg);

             if (val == 0) {

                 s->gzindex = 0;

                 s->status = COMMENT_STATE;

             }

         }

         else

             s->status = COMMENT_STATE;

     }

     if (s->status == COMMENT_STATE) {

         if (s->gzhead->comment != NULL) {

             uInt beg = s->pending;  /* start of bytes to update crc */

             int val;

             do {

                 if (s->pending == s->pending_buf_size) {

                     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;

                     if (s->pending == s->pending_buf_size) {

                         val = 1;

                         break;

                     }

                 }

                 val = s->gzhead->comment[s->gzindex++];

                 put_byte(s, val);

             } while (val != 0);

             if (s->gzhead->hcrc && s->pending > beg)

                 strm->adler = crc32(strm->adler, s->pending_buf + beg,

                                     s->pending - beg);

             if (val == 0)

                 s->status = HCRC_STATE;

         }

         else

             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 + 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;

             }

         }

         else

             s->status = BUSY_STATE;

     }

 #endif

     /* 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 && flush <= 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);

     }

     /* Start a new block or continue the current one.

      */