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

 * Copyright (C) 1995-2017 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 1.2.11 Copyright 1995-2017 Jean-loup Gailly and Mark Adler ";

/*

  If you use the zlib library in a product, an acknowledgment is welcome

  in the documentation of your product. If for some reason you cannot

  include such an acknowledgment, I would appreciate that you keep this

  copyright string in the executable of your product.

 */

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

 *  Function prototypes.

 */

typedef enum {

    need_more,      /* block not completed, need more input or more output */

    block_done,     /* block flush performed */

    finish_started, /* finish started, need only more output at next deflate */

    finish_done     /* finish done, accept no more input or output */

} block_state;

typedef block_state (*compress_func) OF((deflate_state *s, int flush));

/* Compression function. Returns the block state after the call. */

local int deflateStateCheck      OF((z_streamp strm));

local void slide_hash     OF((deflate_state *s));

local void fill_window    OF((deflate_state *s));

local block_state deflate_stored OF((deflate_state *s, int flush));

local block_state deflate_fast   OF((deflate_state *s, int flush));

#ifndef FASTEST

local block_state deflate_slow   OF((deflate_state *s, int flush));

#endif

local block_state deflate_rle    OF((deflate_state *s, int flush));

local block_state deflate_huff   OF((deflate_state *s, int flush));

local void lm_init        OF((deflate_state *s));

local void putShortMSB    OF((deflate_state *s, uInt b));

local void flush_pending  OF((z_streamp strm));

local unsigned read_buf   OF((z_streamp strm, Bytef *buf, unsigned size));

#ifdef ASMV

#  pragma message("Assembler code may have bugs -- use at your own risk")

      void match_init OF((void)); /* asm code initialization */

      uInt longest_match  OF((deflate_state *s, IPos cur_match));

#else

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

#endif

#ifdef ZLIB_DEBUG

local  void check_match OF((deflate_state *s, IPos start, IPos match,

                            int length));

#endif

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

 * Local data

 */

#define NIL 0

/* Tail of hash chains */

#ifndef TOO_FAR

#  define TOO_FAR 4096

#endif

/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */

/* Values for max_lazy_match, good_match and max_chain_length, depending on

 * the desired pack level (0..9). The values given below have been tuned to

 * exclude worst case performance for pathological files. Better values may be

 * found for specific files.

 */

typedef struct config_s {

   ush good_length; /* reduce lazy search above this match length */

   ush max_lazy;    /* do not perform lazy search above this match length */

   ush nice_length; /* quit search above this match length */

   ush max_chain;

   compress_func func;

} config;

#ifdef FASTEST

local const config configuration_table[2] = {

/*      good lazy nice chain */

/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */

/* 1 */ {4,    4,  8,    4, deflate_fast}}; /* max speed, no lazy matches */

#else

local const config configuration_table[10] = {

/*      good lazy nice chain */

/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */

/* 1 */ {4,    4,  8,    4, deflate_fast}, /* max speed, no lazy matches */

/* 2 */ {4,    5, 16,    8, deflate_fast},

/* 3 */ {4,    6, 32,   32, deflate_fast},

/* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */

/* 5 */ {8,   16, 32,   32, deflate_slow},

/* 6 */ {8,   16, 128, 128, deflate_slow},

/* 7 */ {8,   32, 128, 256, deflate_slow},

/* 8 */ {32, 128, 258, 1024, deflate_slow},

/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */

#endif

/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4

 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different

 * meaning.

 */

/* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */

#define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0))

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

 * Update a hash value with the given input byte

 * IN  assertion: all calls to UPDATE_HASH are made with consecutive input

 *    characters, so that a running hash key can be computed from the previous

 *    key instead of complete recalculation each time.

 */

#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)

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

 * Insert string str in the dictionary and set match_head to the previous head

 * of the hash chain (the most recent string with same hash key). Return

 * the previous length of the hash chain.

 * If this file is compiled with -DFASTEST, the compression level is forced

 * to 1, and no hash chains are maintained.

 * IN  assertion: all calls to INSERT_STRING are made with consecutive input

 *    characters and the first MIN_MATCH bytes of str are valid (except for

 *    the last MIN_MATCH-1 bytes of the input file).

 */

#ifdef FASTEST

#define INSERT_STRING(s, str, match_head) \

   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \

    match_head = s->head[s->ins_h], \

    s->head[s->ins_h] = (Pos)(str))

#else

#define INSERT_STRING(s, str, match_head) \

   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \

    match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \

    s->head[s->ins_h] = (Pos)(str))

#endif

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

 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).

 * prev[] will be initialized on the fly.

 */

#define CLEAR_HASH(s) \

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

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

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

 * Slide the hash table when sliding the window down (could be avoided with 32

 * bit values at the expense of memory usage). We slide even when level == 0 to

 * keep the hash table consistent if we switch back to level > 0 later.

 */

local void slide_hash(

    deflate_state *s)

{

    unsigned n, m;

    Posf *p;

    uInt wsize = s->w_size;

    n = s->hash_size;

    p = &s->head[n];

    do {

        m = *--p;

        *p = (Pos)(m >= wsize ? m - wsize : NIL);

    } while (--n);

    n = wsize;

#ifndef FASTEST

    p = &s->prev[n];

    do {

        m = *--p;

        *p = (Pos)(m >= wsize ? m - wsize : NIL);

        /* If n is not on any hash chain, prev[n] is garbage but

         * its value will never be used.

         */

    } while (--n);

#endif

}

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

int ZEXPORT deflateInit_(

    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 == (free_func)0)

#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 || (windowBits == 8 && wrap != 1)) {

        return Z_STREAM_ERROR;

    }

    if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */

    s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));

    if (s == Z_NULL) return Z_MEM_ERROR;

    strm->state = (struct internal_state FAR *)s;

    s->strm = strm;

    s->status = INIT_STATE;     /* to pass state test in deflateReset() */

    s->wrap = wrap;

    s->gzhead = Z_NULL;

    s->w_bits = (uInt)windowBits;

    s->w_size = 1 << s->w_bits;

    s->w_mask = s->w_size - 1;

    s->hash_bits = (uInt)memLevel + 7;

    s->hash_size = 1 << s->hash_bits;

    s->hash_mask = s->hash_size - 1;

    s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);

    s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));

    s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));

    s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));

    s->high_water = 0;      /* nothing written to s->window yet */

    s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */

    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);

}

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

 * Check for a valid deflate stream state. Return 0 if ok, 1 if not.

 */

local int deflateStateCheck (

    z_streamp strm)

{

    deflate_state *s;

    if (strm == Z_NULL ||

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

        return 1;

    s = strm->state;

    if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE &&

#ifdef GZIP

                                           s->status != GZIP_STATE &&

#endif

                                           s->status != EXTRA_STATE &&

                                           s->status != NAME_STATE &&

                                           s->status != COMMENT_STATE &&

                                           s->status != HCRC_STATE &&

                                           s->status != BUSY_STATE &&

                                           s->status != FINISH_STATE))

        return 1;

    return 0;

}

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

int ZEXPORT deflateSetDictionary (

    z_streamp strm,

    const Bytef *dictionary,

    uInt  dictLength)

{

    deflate_state *s;

    uInt str, n;

    int wrap;

    unsigned avail;

    z_const unsigned char *next;

    if (deflateStateCheck(strm) || dictionary == Z_NULL)

        return Z_STREAM_ERROR;

    s = strm->state;

    wrap = s->wrap;

    if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)

        return Z_STREAM_ERROR;

    /* when using zlib wrappers, compute Adler-32 for provided dictionary */

    if (wrap == 1)

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

    s->wrap = 0;                    /* avoid computing Adler-32 in read_buf */

    /* if dictionary would fill window, just replace the history */

    if (dictLength >= s->w_size) {

        if (wrap == 0) {            /* already empty otherwise */

            CLEAR_HASH(s);

            s->strstart = 0;

            s->block_start = 0L;

            s->insert = 0;

        }

        dictionary += dictLength - s->w_size;  /* use the tail */

        dictLength = s->w_size;

    }

    /* insert dictionary into window and hash */

    avail = strm->avail_in;

    next = strm->next_in;

    strm->avail_in = dictLength;

    strm->next_in = (z_const Bytef *)dictionary;

    fill_window(s);

    while (s->lookahead >= MIN_MATCH) {

        str = s->strstart;

        n = s->lookahead - (MIN_MATCH-1);

        do {

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

#ifndef FASTEST

            s->prev[str & s->w_mask] = s->head[s->ins_h];

#endif

            s->head[s->ins_h] = (Pos)str;

            str++;

        } while (--n);

        s->strstart = str;

        s->lookahead = MIN_MATCH-1;

        fill_window(s);

    }

    s->strstart += s->lookahead;

    s->block_start = (long)s->strstart;

    s->insert = s->lookahead;

    s->lookahead = 0;

    s->match_length = s->prev_length = MIN_MATCH-1;

    s->match_available = 0;

    strm->next_in = next;

    strm->avail_in = avail;

    s->wrap = wrap;

    return Z_OK;

}

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

int ZEXPORT deflateGetDictionary (

    z_streamp strm,

    Bytef *dictionary,

    uInt  *dictLength)

{

    deflate_state *s;

    uInt len;

    if (deflateStateCheck(strm))

        return Z_STREAM_ERROR;

    s = strm->state;

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

    if (len > s->w_size)

        len = s->w_size;

    if (dictionary != Z_NULL && len)

        zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len);

    if (dictLength != Z_NULL)

        *dictLength = len;

    return Z_OK;

}

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

int ZEXPORT deflateResetKeep (

    z_streamp strm)

{

    deflate_state *s;

    if (deflateStateCheck(strm)) {

        return Z_STREAM_ERROR;

    }

    strm->total_in = strm->total_out = 0;

    strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */

    strm->data_type = Z_UNKNOWN;

    s = (deflate_state *)strm->state;

    s->pending = 0;

    s->pending_out = s->pending_buf;

    if (s->wrap < 0) {

        s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */

    }

    s->status =

#ifdef GZIP

        s->wrap == 2 ? GZIP_STATE :

#endif

        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(strm->state);

    return ret;

}

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

int ZEXPORT deflateSetHeader (

    z_streamp strm,

    gz_headerp head)

{

    if (deflateStateCheck(strm) || strm->state->wrap != 2)

        return Z_STREAM_ERROR;

    strm->state->gzhead = head;

    return Z_OK;

}

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

int ZEXPORT deflatePending (

    z_streamp strm,

    unsigned *pending,

    int *bits)

{

    if (deflateStateCheck(strm)) return Z_STREAM_ERROR;

    if (pending != Z_NULL)

        *pending = strm->state->pending;

    if (bits != Z_NULL)

        *bits = strm->state->bi_valid;

    return Z_OK;

}

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

int ZEXPORT deflatePrime (

    z_streamp strm,

    int bits,

    int value)

{

    deflate_state *s;

    int put;

    if (deflateStateCheck(strm)) return Z_STREAM_ERROR;

    s = 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;

    if (deflateStateCheck(strm)) return Z_STREAM_ERROR;

    s = strm->state;

#ifdef FASTEST

    if (level != 0) level = 1;

#else

    if (level == Z_DEFAULT_COMPRESSION) level = 6;

#endif

    if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {

        return Z_STREAM_ERROR;

    }

    func = configuration_table[s->level].func;

    if ((strategy != s->strategy || func != configuration_table[level].func) &&

        s->high_water) {

        /* Flush the last buffer: */

        int err = deflate(strm, Z_BLOCK);

        if (err == Z_STREAM_ERROR)

            return err;

        if (strm->avail_out == 0)

            return Z_BUF_ERROR;

    }

    if (s->level != level) {

        if (s->level == 0 && s->matches != 0) {

            if (s->matches == 1)

                slide_hash(s);

            else

                CLEAR_HASH(s);

            s->matches = 0;

        }

        s->level = level;

        s->max_lazy_match   = configuration_table[level].max_lazy;

        s->good_match       = configuration_table[level].good_length;

        s->nice_match       = configuration_table[level].nice_length;

        s->max_chain_length = configuration_table[level].max_chain;

    }

    s->strategy = strategy;

    return Z_OK;

}

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

int ZEXPORT deflateTune(

    z_streamp strm,

    int good_length,

    int max_lazy,

    int nice_length,

    int max_chain)

{

    deflate_state *s;

    if (deflateStateCheck(strm)) return Z_STREAM_ERROR;

    s = strm->state;

    s->good_match = (uInt)good_length;

    s->max_lazy_match = (uInt)max_lazy;

    s->nice_match = nice_length;

    s->max_chain_length = (uInt)max_chain;

    return Z_OK;

}

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

 * For the default windowBits of 15 and memLevel of 8, this function returns

 * a close to exact, as well as small, upper bound on the compressed size.

 * They are coded as constants here for a reason--if the #define's are

 * changed, then this function needs to be changed as well.  The return

 * value for 15 and 8 only works for those exact settings.

 *

 * For any setting other than those defaults for windowBits and memLevel,

 * the value returned is a conservative worst case for the maximum expansion

 * resulting from using fixed blocks instead of stored blocks, which deflate

 * can emit on compressed data for some combinations of the parameters.

 *

 * This function could be more sophisticated to provide closer upper bounds for

 * every combination of windowBits and memLevel.  But even the conservative

 * upper bound of about 14% expansion does not seem onerous for output buffer

 * allocation.

 */

uLong ZEXPORT deflateBound(

    z_streamp strm,

    uLong sourceLen)

{

    deflate_state *s;

    uLong complen, wraplen;

    /* conservative upper bound for compressed data */

    complen = sourceLen +

              ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;

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

    if (deflateStateCheck(strm))

        return complen + 6;

    /* compute wrapper length */

    s = strm->state;

    switch (s->wrap) {

    case 0:                                 /* raw deflate */

        wraplen = 0;

        break;

    case 1:                                 /* zlib wrapper */

        wraplen = 6 + (s->strstart ? 4 : 0);

        break;

#ifdef GZIP

    case 2:                                 /* gzip wrapper */

        wraplen = 18;

        if (s->gzhead != Z_NULL) {          /* user-supplied gzip header */

            Bytef *str;

            if (s->gzhead->extra != Z_NULL)

                wraplen += 2 + s->gzhead->extra_len;

            str = s->gzhead->name;

            if (str != Z_NULL)

                do {

                    wraplen++;

                } while (*str++);

            str = s->gzhead->comment;

            if (str != Z_NULL)

                do {

                    wraplen++;

                } while (*str++);

            if (s->gzhead->hcrc)

                wraplen += 2;

        }

        break;

#endif

    default:                                /* for compiler happiness */

        wraplen = 6;

    }

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

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

        return complen + wraplen;

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

    return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +

           (sourceLen >> 25) + 13 - 6 + wraplen;

}

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

 * Put a short in the pending buffer. The 16-bit value is put in MSB order.

 * IN assertion: the stream state is correct and there is enough room in

 * pending_buf.

 */

local void putShortMSB (

    deflate_state *s,

    uInt b)

{

    put_byte(s, (Byte)(b >> 8));

    put_byte(s, (Byte)(b & 0xff));

}

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

 * Flush as much pending output as possible. All deflate() output, except for

 * some deflate_stored() output, goes through this function so some

 * applications may wish to modify it to avoid allocating a large

 * strm->next_out buffer and copying into it. (See also read_buf()).

 */

local void flush_pending(

    z_streamp strm)

{

    unsigned len;

    deflate_state *s = strm->state;

    _tr_flush_bits(s);

    len = s->pending;

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

    if (len == 0) return;

    zmemcpy(strm->next_out, s->pending_out, len);

    strm->next_out  += len;

    s->pending_out  += len;

    strm->total_out += len;

    strm->avail_out -= len;

    s->pending      -= len;

    if (s->pending == 0) {

        s->pending_out = s->pending_buf;

    }

}

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

 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1].

 */

#define HCRC_UPDATE(beg) \

    do { \

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

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

                                s->pending - (beg)); \

    } while (0)

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

int ZEXPORT deflate (

    z_streamp strm,

    int flush)

{

    int old_flush; /* value of flush param for previous deflate call */

    deflate_state *s;

    if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) {

        return Z_STREAM_ERROR;

    }

    s = strm->state;

    if (strm->next_out == Z_NULL ||

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

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

        ERR_RETURN(strm, Z_STREAM_ERROR);

    }

    if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);

    old_flush = s->last_flush;

    s->last_flush = flush;

    /* Flush as much pending output as possible */

    if (s->pending != 0) {

        flush_pending(strm);

        if (strm->avail_out == 0) {

            /* Since avail_out is 0, deflate will be called again with

             * more output space, but possibly with both pending and

             * avail_in equal to zero. There won't be anything to do,

             * but this is not an error situation so make sure we

             * return OK instead of BUF_ERROR at next call of deflate:

             */

            s->last_flush = -1;

            return Z_OK;

        }

    /* Make sure there is something to do and avoid duplicate consecutive

     * flushes. For repeated and useless calls with Z_FINISH, we keep

     * returning Z_STREAM_END instead of Z_BUF_ERROR.

     */

    } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&

               flush != Z_FINISH) {

        ERR_RETURN(strm, Z_BUF_ERROR);

    }

    /* User must not provide more input after the first FINISH: */

    if (s->status == FINISH_STATE && strm->avail_in != 0) {

        ERR_RETURN(strm, Z_BUF_ERROR);

    }

    /* Write the header */

    if (s->status == INIT_STATE) {

        /* zlib header */

        uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;

        uInt level_flags;

        if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)

            level_flags = 0;

        else if (s->level < 6)

            level_flags = 1;

        else if (s->level == 6)

            level_flags = 2;

        else

            level_flags = 3;

        header |= (level_flags << 6);

        if (s->strstart != 0) header |= PRESET_DICT;

        header += 31 - (header % 31);

        putShortMSB(s, header);

        /* Save the adler32 of the preset dictionary: */

        if (s->strstart != 0) {

            putShortMSB(s, (uInt)(strm->adler >> 16));

            putShortMSB(s, (uInt)(strm->adler & 0xffff));

        }

        strm->adler = adler32(0L, Z_NULL, 0);

        s->status = BUSY_STATE;

        /* Compression must start with an empty pending buffer */

        flush_pending(strm);

        if (s->pending != 0) {

            s->last_flush = -1;

            return Z_OK;

        }

    }

#ifdef GZIP

    if (s->status == GZIP_STATE) {

        /* gzip header */

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

        put_byte(s, 31);

        put_byte(s, 139);

        put_byte(s, 8);

        if (s->gzhead == Z_NULL) {

            put_byte(s, 0);

            put_byte(s, 0);

            put_byte(s, 0);

            put_byte(s, 0);

            put_byte(s, 0);

            put_byte(s, s->level == 9 ? 2 :

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

                      4 : 0));

            put_byte(s, OS_CODE);

            s->status = BUSY_STATE;

            /* Compression must start with an empty pending buffer */

            flush_pending(strm);

            if (s->pending != 0) {

                s->last_flush = -1;

                return Z_OK;

            }

        }

        else {

            put_byte(s, (s->gzhead->text ? 1 : 0) +

                     (s->gzhead->hcrc ? 2 : 0) +

                     (s->gzhead->extra == Z_NULL ? 0 : 4) +

                     (s->gzhead->name == Z_NULL ? 0 : 8) +

                     (s->gzhead->comment == Z_NULL ? 0 : 16)

                     );

            put_byte(s, (Byte)(s->gzhead->time & 0xff));