merge remote-tracking branch 'notaz/master'

[pcsx_rearmed.git] / deps / zlib / deflate.c

/* deflate.c -- compress data using the deflation algorithm
 * Copyright (C) 1995-2013 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 1.2.8 Copyright 1995-2013 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 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 int read_buf        OF((z_streamp strm, Bytef *buf, unsigned size));
#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

#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 */

/* 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 */

/* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
#define RANK(f) (((f) << 1) - ((f) > 4 ? 9 : 0))

/* ===========================================================================
 * 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 deflateResetKeep (z_streamp strm);

int ZEXPORT deflatePending (z_streamp strm, unsigned *pending, int *bits);

/* ========================================================================= */
int ZEXPORT deflateInit_(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_(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) {
#ifdef Z_SOLO
      return Z_STREAM_ERROR;
#else
      strm->zalloc = zcalloc;
      strm->opaque = (voidpf)0;
#endif
   }
   if (strm->zfree == NULL)
#ifdef Z_SOLO
      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) {
      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*)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->high_water = 0;      /* nothing written to s->window yet */

   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 = 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 (z_streamp strm, const Bytef *dictionary, uInt dictLength)
{
   deflate_state *s;
   uInt str, n;
   int wrap;
   unsigned avail;
   unsigned char *next;

   if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL)
      return Z_STREAM_ERROR;
   s = (deflate_state*)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 = (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 deflateResetKeep (z_streamp strm)
{
   deflate_state *s;

   if (strm == Z_NULL || strm->state == Z_NULL ||
         strm->zalloc == Z_NULL || strm->zfree == Z_NULL) {
      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);

   return Z_OK;
}

/* ========================================================================= */
int ZEXPORT deflateReset (z_streamp strm)
{
   int ret;

   ret = deflateResetKeep(strm);
   if (ret == Z_OK)
      lm_init((deflate_state*)strm->state);
   return ret;
}

/* ========================================================================= */
int ZEXPORT deflateSetHeader (z_streamp strm, gz_headerp head)
{
   struct internal_state_deflate *state = (struct internal_state_deflate*)strm->state;
   if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
   if (state->wrap != 2)
      return Z_STREAM_ERROR;
   state->gzhead = head;
   return Z_OK;
}

/* ========================================================================= */
int ZEXPORT deflatePending (z_streamp strm, unsigned *pending, int *bits)
{
   struct internal_state_deflate *state = (struct internal_state_deflate*)strm->state;
   if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
   if (pending != Z_NULL)
      *pending = state->pending;
   if (bits != Z_NULL)
      *bits = state->bi_valid;
   return Z_OK;
}

/* ========================================================================= */
int ZEXPORT deflatePrime (z_streamp strm, int bits, int value)
{
   deflate_state *s;
   int put;

   if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
   s = (deflate_state*)strm->state;
   if ((Bytef *)(s->d_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(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 = (deflate_state*)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) &&
         strm->total_in != 0) {
      /* Flush the last buffer: */
      err = deflate(strm, Z_BLOCK);
      if (err == Z_BUF_ERROR && s->pending == 0)
         err = Z_OK;
   }
   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(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 = (deflate_state*)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.  But even the conservative
 * upper bound of about 14% expansion does not seem onerous for output buffer
 * allocation.
 */
uLong ZEXPORT deflateBound(z_streamp strm, uLong sourceLen)
{
   deflate_state *s;
   uLong complen, wraplen;
   Bytef *str;

   /* 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 (strm == Z_NULL || strm->state == Z_NULL)
      return complen + 6;

   /* compute wrapper length */
   s = (deflate_state*)strm->state;
   switch (s->wrap) {
      case 0:                                 /* raw deflate */
         wraplen = 0;
         break;
      case 1:                                 /* zlib wrapper */
         wraplen = 6 + (s->strstart ? 4 : 0);
         break;
      case 2:                                 /* gzip wrapper */
         wraplen = 18;
         if (s->gzhead != Z_NULL) {          /* user-supplied gzip header */
            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;
      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 (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(z_streamp strm)
{
   unsigned len;
   deflate_state *s = (deflate_state*)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;
   }
}

/* ========================================================================= */
int ZEXPORT deflate (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_BLOCK || flush < 0) {
      return Z_STREAM_ERROR;
   }
   s = (deflate_state*)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 == 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;
         }
         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;
         }
      }
      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 != Z_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 != Z_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 != Z_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 && 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);
   }

   /* 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->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;
         }
      }
   }
   Assert(strm->avail_out > 0, "bug2");

   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 (z_streamp strm)
{
   struct internal_state_deflate *state;
   int status;

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

   status = state->status;
   if (status != INIT_STATE &&
         status != EXTRA_STATE &&
         status != NAME_STATE &&
         status != COMMENT_STATE &&
         status != HCRC_STATE &&
         status != BUSY_STATE &&
         status != FINISH_STATE) {
      return Z_STREAM_ERROR;
   }

   /* Deallocate in reverse order of allocations: */
   TRY_FREE(strm, state->pending_buf);
   TRY_FREE(strm, state->head);
   TRY_FREE(strm, state->prev);
   TRY_FREE(strm, state->window);

   ZFREE(strm, state);
   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 (z_streamp dest, z_streamp source)
{
#ifdef MAXSEG_64K
   return Z_STREAM_ERROR;
#else
   deflate_state *ds;
   deflate_state *ss;
   ushf *overlay;


   if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
      return Z_STREAM_ERROR;
   }

   ss = (deflate_state*)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));
   overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
   ds->pending_buf = (uchf *) overlay;

   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->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
   ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;

   ds->l_desc.dyn_tree = ds->dyn_ltree;
   ds->d_desc.dyn_tree = ds->dyn_dtree;
   ds->bl_desc.dyn_tree = ds->bl_tree;

   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 int read_buf(z_streamp strm, Bytef *buf, unsigned size)
{
   struct internal_state_deflate *state = (struct internal_state_deflate*)strm->state;
   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 (state->wrap == 1) {
      strm->adler = adler32(strm->adler, buf, len);
   }
#ifdef GZIP
   else if (state->wrap == 2) {
      strm->adler = crc32(strm->adler, buf, len);
   }
#endif
   strm->next_in  += len;
   strm->total_in += len;

   return (int)len;
}

/* ===========================================================================
 * Initialize the "longest match" routines for a new zlib stream
 */
local void lm_init (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(deflate_state *s, IPos cur_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 = 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 = 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 DEBUG
/* ===========================================================================
 * 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 /* 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(deflate_state *s)
{
   register unsigned n, m;
   register Posf *p;
   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);
         s->match_start -= wsize;
         s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
         s->block_start -= (long) wsize;

         /* Slide the hash table (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. (Using level 0 permanently is not an optimal usage of
            zlib, so we don't care about this pathological case.)
            */
         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
         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; \
}

/* ===========================================================================
 * Copy without compression as much as possible from the input stream, return
 * the current block state.
 * This function does not insert new strings in the dictionary since
 * uncompressible data is probably not useful. This function is used
 * only for the level=0 compression option.
 * NOTE: this function should be optimized to avoid extra copying from
 * window to pending_buf.
 */
local block_state deflate_stored(deflate_state *s, int flush)
{
   /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
    * to pending_buf_size, and each stored block has a 5 byte header:
    */
   ulg max_block_size = 0xffff;
   ulg max_start;

   if (max_block_size > s->pending_buf_size - 5) {
      max_block_size = s->pending_buf_size - 5;
   }

   /* Copy as much as possible from input to output: */
   for (;;) {
      /* Fill the window as much as possible: */
      if (s->lookahead <= 1) {

         Assert(s->strstart < s->w_size+MAX_DIST(s) ||
               s->block_start >= (long)s->w_size, "slide too late");

         fill_window(s);
         if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;

         if (s->lookahead == 0) break; /* flush the current block */
      }
      Assert(s->block_start >= 0L, "block gone");

      s->strstart += s->lookahead;
      s->lookahead = 0;

      /* Emit a stored block if pending_buf will be full: */
      max_start = s->block_start + max_block_size;
      if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
         /* strstart == 0 is possible when wraparound on 16-bit machine */
         s->lookahead = (uInt)(s->strstart - max_start);
         s->strstart = (uInt)max_start;
         FLUSH_BLOCK(s, 0);
      }
      /* Flush if we may have to slide, otherwise block_start may become
       * negative and the data will be gone:
       */
      if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
         FLUSH_BLOCK(s, 0);
      }
   }
   s->insert = 0;
   if (flush == Z_FINISH) {
      FLUSH_BLOCK(s, 1);
      return finish_done;
   }
   if ((long)s->strstart > s->block_start)
      FLUSH_BLOCK(s, 0);
   return block_done;
}

/* ===========================================================================
 * 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(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->last_lit)
      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(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->last_lit)
      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(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 - (int)(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->last_lit)
      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(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->last_lit)
      FLUSH_BLOCK(s, 0);
   return block_done;
}