/* deflate.c -- compress data using the deflation algorithm
 * Copyright (C) 1995-2010 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://www.ietf.org/rfc/rfc1951.txt
 *
 *      A description of the Rabin and Karp algorithm is given in the book
 *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
 *
 *      Fiala,E.R., and Greene,D.H.
 *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
 *
 */

/* @(#) $Id$ */

#include "deflate.h"

const char deflate_copyright[] =
    " deflate 1.2.5 Copyright 1995-2010 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 */

#ifndef NO_DUMMY_DECL
struct static_tree_desc_s {
	int dummy;
};				/* for buggy compilers */
#endif

/* ===========================================================================
 * Update a hash value with the given input byte
 * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
 *    input characters, so that a running hash key can be computed from the
 *    previous key instead of complete recalculation each time.
 */
#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)

/* ===========================================================================
 * Insert string str in the dictionary and set match_head to the previous head
 * of the hash chain (the most recent string with same hash key). Return
 * the previous length of the hash chain.
 * If this file is compiled with -DFASTEST, the compression level is forced
 * to 1, and no hash chains are maintained.
 * IN  assertion: all calls to to INSERT_STRING are made with consecutive
 *    input characters and the first MIN_MATCH bytes of str are valid
 *    (except for the last MIN_MATCH-1 bytes of the input file).
 */
#ifdef FASTEST
#define INSERT_STRING(s, str, match_head) \
   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
    match_head = s->head[s->ins_h], \
    s->head[s->ins_h] = (Pos)(str))
#else
#define INSERT_STRING(s, str, match_head) \
   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
    match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
    s->head[s->ins_h] = (Pos)(str))
#endif

/* ===========================================================================
 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
 * prev[] will be initialized on the fly.
 */
#define CLEAR_HASH(s) \
    s->head[s->hash_size-1] = NIL; \
    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));

/* ========================================================================= */
int ZEXPORT deflateInit_(strm, level, version, stream_size)
z_streamp strm;
int level;
const char *version;
int stream_size;
{
	return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
			     Z_DEFAULT_STRATEGY, version, stream_size);
	/* To do: ignore strm->next_in if we use it as window */
}

/* ========================================================================= */
int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
			  version, stream_size)
z_streamp strm;
int level;
int method;
int windowBits;
int memLevel;
int strategy;
const char *version;
int stream_size;
{
	deflate_state *s;
	int wrap = 1;
	static const char my_version[] = ZLIB_VERSION;

	ushf *overlay;
	/* We overlay pending_buf and d_buf+l_buf. This works since the average
	 * output size for (length,distance) codes is <= 24 bits.
	 */

	if (version == Z_NULL || version[0] != my_version[0] ||
	    stream_size != sizeof(z_stream)) {
		return Z_VERSION_ERROR;
	}
	if (strm == Z_NULL)
		return Z_STREAM_ERROR;

	strm->msg = Z_NULL;
	if (strm->zalloc == (alloc_func) 0) {
		strm->zalloc = zcalloc;
		strm->opaque = (voidpf) 0;
	}
	if (strm->zfree == (free_func) 0)
		strm->zfree = zcfree;

#ifdef FASTEST
	if (level != 0)
		level = 1;
#else
	if (level == Z_DEFAULT_COMPRESSION)
		level = 6;
#endif

	if (windowBits < 0) {	/* suppress zlib wrapper */
		wrap = 0;
		windowBits = -windowBits;
	}
#ifdef GZIP
	else if (windowBits > 15) {
		wrap = 2;	/* write gzip wrapper instead */
		windowBits -= 16;
	}
#endif
	if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
	    windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
	    strategy < 0 || strategy > Z_FIXED) {
		return Z_STREAM_ERROR;
	}
	if (windowBits == 8)
		windowBits = 9;	/* until 256-byte window bug fixed */
	s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
	if (s == Z_NULL)
		return Z_MEM_ERROR;
	strm->state = (struct internal_state FAR *)s;
	s->strm = strm;

	s->wrap = wrap;
	s->gzhead = Z_NULL;
	s->w_bits = windowBits;
	s->w_size = 1 << s->w_bits;
	s->w_mask = s->w_size - 1;

	s->hash_bits = memLevel + 7;
	s->hash_size = 1 << s->hash_bits;
	s->hash_mask = s->hash_size - 1;
	s->hash_shift = ((s->hash_bits + MIN_MATCH - 1) / MIN_MATCH);

	s->window = (Bytef *) ZALLOC(strm, s->w_size, 2 * sizeof(Byte));
	s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
	s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));

	s->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 = (char *)ERR_MSG(Z_MEM_ERROR);
		deflateEnd(strm);
		return Z_MEM_ERROR;
	}
	s->d_buf = overlay + s->lit_bufsize / sizeof(ush);
	s->l_buf = s->pending_buf + (1 + sizeof(ush)) * s->lit_bufsize;

	s->level = level;
	s->strategy = strategy;
	s->method = (Byte) method;

	return deflateReset(strm);
}

/* ========================================================================= */
int ZEXPORT deflateSetDictionary(strm, dictionary, dictLength)
z_streamp strm;
const Bytef *dictionary;
uInt dictLength;
{
	deflate_state *s;
	uInt length = dictLength;
	uInt n;
	IPos hash_head = 0;

	if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
	    strm->state->wrap == 2 ||
	    (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
		return Z_STREAM_ERROR;

	s = strm->state;
	if (s->wrap)
		strm->adler = adler32(strm->adler, dictionary, dictLength);

	if (length < MIN_MATCH)
		return Z_OK;
	if (length > s->w_size) {
		length = s->w_size;
		dictionary += dictLength - length;	/* use the tail of the dictionary */
	}
	zmemcpy(s->window, dictionary, length);
	s->strstart = length;
	s->block_start = (long)length;

	/* Insert all strings in the hash table (except for the last two bytes).
	 * s->lookahead stays null, so s->ins_h will be recomputed at the next
	 * call of fill_window.
	 */
	s->ins_h = s->window[0];
	UPDATE_HASH(s, s->ins_h, s->window[1]);
	for (n = 0; n <= length - MIN_MATCH; n++) {
		INSERT_STRING(s, n, hash_head);
	}
	if (hash_head)
		hash_head = 0;	/* to make compiler happy */
	return Z_OK;
}

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

	if (strm == Z_NULL || strm->state == Z_NULL ||
	    strm->zalloc == (alloc_func) 0 || strm->zfree == (free_func) 0) {
		return Z_STREAM_ERROR;
	}

	strm->total_in = strm->total_out = 0;
	strm->msg = Z_NULL;	/* use zfree if we ever allocate msg dynamically */
	strm->data_type = Z_UNKNOWN;

	s = (deflate_state *) strm->state;
	s->pending = 0;
	s->pending_out = s->pending_buf;

	if (s->wrap < 0) {
		s->wrap = -s->wrap;	/* was made negative by deflate(..., Z_FINISH); */
	}
	s->status = s->wrap ? INIT_STATE : BUSY_STATE;
	strm->adler =
#ifdef GZIP
	    s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
#endif
	    adler32(0L, Z_NULL, 0);
	s->last_flush = Z_NO_FLUSH;

	_tr_init(s);
	lm_init(s);

	return Z_OK;
}

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

/* ========================================================================= */
int ZEXPORT deflatePrime(strm, bits, value)
z_streamp strm;
int bits;
int value;
{
	if (strm == Z_NULL || strm->state == Z_NULL)
		return Z_STREAM_ERROR;
	strm->state->bi_valid = bits;
	strm->state->bi_buf = (ush) (value & ((1 << bits) - 1));
	return Z_OK;
}

/* ========================================================================= */
int ZEXPORT deflateParams(strm, level, strategy)
z_streamp strm;
int level;
int strategy;
{
	deflate_state *s;
	compress_func func;
	int err = Z_OK;

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

#ifdef FASTEST
	if (level != 0)
		level = 1;
#else
	if (level == Z_DEFAULT_COMPRESSION)
		level = 6;
#endif
	if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
		return Z_STREAM_ERROR;
	}
	func = configuration_table[s->level].func;

	if ((strategy != s->strategy || func != configuration_table[level].func)
	    && strm->total_in != 0) {
		/* Flush the last buffer: */
		err = deflate(strm, Z_BLOCK);
	}
	if (s->level != level) {
		s->level = level;
		s->max_lazy_match = configuration_table[level].max_lazy;
		s->good_match = configuration_table[level].good_length;
		s->nice_match = configuration_table[level].nice_length;
		s->max_chain_length = configuration_table[level].max_chain;
	}
	s->strategy = strategy;
	return err;
}

/* ========================================================================= */
int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
z_streamp strm;
int good_length;
int max_lazy;
int nice_length;
int max_chain;
{
	deflate_state *s;

	if (strm == Z_NULL || strm->state == Z_NULL)
		return Z_STREAM_ERROR;
	s = strm->state;
	s->good_match = good_length;
	s->max_lazy_match = max_lazy;
	s->nice_match = nice_length;
	s->max_chain_length = max_chain;
	return Z_OK;
}

/* =========================================================================
 * For the default windowBits of 15 and memLevel of 8, this function returns
 * a close to exact, as well as small, upper bound on the compressed size.
 * They are coded as constants here for a reason--if the #define's are
 * changed, then this function needs to be changed as well.  The return
 * value for 15 and 8 only works for those exact settings.
 *
 * For any setting other than those defaults for windowBits and memLevel,
 * the value returned is a conservative worst case for the maximum expansion
 * resulting from using fixed blocks instead of stored blocks, which deflate
 * can emit on compressed data for some combinations of the parameters.
 *
 * This function could be more sophisticated to provide closer upper bounds for
 * every combination of windowBits and memLevel.  But even the conservative
 * upper bound of about 14% expansion does not seem onerous for output buffer
 * allocation.
 */
uLong ZEXPORT deflateBound(strm, sourceLen)
z_streamp strm;
uLong sourceLen;
{
	deflate_state *s;
	uLong complen, wraplen;
	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 = 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(s, b)
deflate_state *s;
uInt b;
{
	put_byte(s, (Byte) (b >> 8));
	put_byte(s, (Byte) (b & 0xff));
}

/* =========================================================================
 * Flush as much pending output as possible. All deflate() output goes
 * through this function so some applications may wish to modify it
 * to avoid allocating a large strm->next_out buffer and copying into it.
 * (See also read_buf()).
 */
local void flush_pending(strm)
z_streamp strm;
{
	unsigned len = strm->state->pending;

	if (len > strm->avail_out)
		len = strm->avail_out;
	if (len == 0)
		return;

	zmemcpy(strm->next_out, strm->state->pending_out, len);
	strm->next_out += len;
	strm->state->pending_out += len;
	strm->total_out += len;
	strm->avail_out -= len;
	strm->state->pending -= len;
	if (strm->state->pending == 0) {
		strm->state->pending_out = strm->state->pending_buf;
	}
}

/* ========================================================================= */
int ZEXPORT deflate(strm, flush)
z_streamp strm;
int flush;
{
	int old_flush;		/* value of flush param for previous deflate call */
	deflate_state *s;

	if (strm == Z_NULL || strm->state == Z_NULL ||
	    flush > Z_BLOCK || flush < 0) {
		return Z_STREAM_ERROR;
	}
	s = strm->state;

	if (strm->next_out == Z_NULL ||
	    (strm->next_in == Z_NULL && strm->avail_in != 0) ||
	    (s->status == FINISH_STATE && flush != Z_FINISH)) {
		ERR_RETURN(strm, Z_STREAM_ERROR);
	}
	if (strm->avail_out == 0)
		ERR_RETURN(strm, Z_BUF_ERROR);

	s->strm = strm;		/* just in case */
	old_flush = s->last_flush;
	s->last_flush = flush;

	/* Write the header */
	if (s->status == INIT_STATE) {
#ifdef GZIP
		if (s->wrap == 2) {
			strm->adler = crc32(0L, Z_NULL, 0);
			put_byte(s, 31);
			put_byte(s, 139);
			put_byte(s, 8);
			if (s->gzhead == 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 && flush <= old_flush &&
		   flush != Z_FINISH) {
		ERR_RETURN(strm, Z_BUF_ERROR);
	}

	/* User must not provide more input after the first FINISH: */
	if (s->status == FINISH_STATE && strm->avail_in != 0) {
		ERR_RETURN(strm, Z_BUF_ERROR);
	}

	/* Start a new block or continue the current one.
	 */
	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;
					}
				}
			}
			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(strm)
z_streamp strm;
{
	int status;

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

	status = strm->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, strm->state->pending_buf);
	TRY_FREE(strm, strm->state->head);
	TRY_FREE(strm, strm->state->prev);
	TRY_FREE(strm, strm->state->window);

	ZFREE(strm, strm->state);
	strm->state = Z_NULL;

	return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
}

/* =========================================================================
 * Copy the source state to the destination state.
 * To simplify the source, this is not supported for 16-bit MSDOS (which
 * doesn't have enough memory anyway to duplicate compression states).
 */
int ZEXPORT deflateCopy(dest, source)
z_streamp dest;
z_streamp source;
{
#ifdef MAXSEG_64K
	return Z_STREAM_ERROR;
#else
	deflate_state *ds;
	deflate_state *ss;
	ushf *overlay;

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

	ss = source->state;

	zmemcpy(dest, 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(ds, ss, sizeof(deflate_state));
	ds->strm = dest;

	ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2 * sizeof(Byte));
	ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
	ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
	overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush) + 2);
	ds->pending_buf = (uchf *) overlay;

	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(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
	zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
	zmemcpy(ds->pending_buf, ss->pending_buf, (uInt) ds->pending_buf_size);

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

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

	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(strm, buf, size)
z_streamp strm;
Bytef *buf;
unsigned size;
{
	unsigned len = strm->avail_in;

	if (len > size)
		len = size;
	if (len == 0)
		return 0;

	strm->avail_in -= len;

	if (strm->state->wrap == 1) {
		strm->adler = adler32(strm->adler, strm->next_in, len);
	}
#ifdef GZIP
	else if (strm->state->wrap == 2) {
		strm->adler = crc32(strm->adler, strm->next_in, len);
	}
#endif
	zmemcpy(buf, strm->next_in, len);
	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(s)
deflate_state *s;
{
	s->window_size = (ulg) 2L *s->w_size;

	CLEAR_HASH(s);

	/* Set the default configuration parameters:
	 */
	s->max_lazy_match = configuration_table[s->level].max_lazy;
	s->good_match = configuration_table[s->level].good_length;
	s->nice_match = configuration_table[s->level].nice_length;
	s->max_chain_length = configuration_table[s->level].max_chain;

	s->strstart = 0;
	s->block_start = 0L;
	s->lookahead = 0;
	s->match_length = s->prev_length = MIN_MATCH - 1;
	s->match_available = 0;
	s->ins_h = 0;
#ifndef FASTEST
#ifdef ASMV
	match_init();		/* initialize the asm code */
#endif
#endif
}

#ifndef FASTEST
/* ===========================================================================
 * Set match_start to the longest match starting at the given string and
 * return its length. Matches shorter or equal to prev_length are discarded,
 * in which case the result is equal to prev_length and match_start is
 * garbage.
 * IN assertions: cur_match is the head of the hash chain for the current
 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
 * OUT assertion: the match length is not greater than s->lookahead.
 */
#ifndef ASMV
/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
 * match.S. The code will be functionally equivalent.
 */
local uInt longest_match(s, cur_match)
deflate_state *s;
IPos cur_match;			/* current match */
{
	unsigned chain_length = s->max_chain_length;	/* max hash chain length */
	register Bytef *scan = s->window + s->strstart;	/* current string */
	register Bytef *match;	/* matched string */
	register int len;	/* length of current match */
	int best_len = 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(s)
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;

	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)
			return;

		/* 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 >= MIN_MATCH) {
			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 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;
		}
	}
}

/* ===========================================================================
 * 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(s, flush)
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);
		}
	}
	FLUSH_BLOCK(s, flush == Z_FINISH);
	return flush == Z_FINISH ? finish_done : 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(s, flush)
deflate_state *s;
int flush;
{
	IPos hash_head;		/* head of the hash chain */
	int bflush;		/* set if current block must be flushed */

	for (;;) {
		/* Make sure that we always have enough lookahead, except
		 * at the end of the input file. We need MAX_MATCH bytes
		 * for the next match, plus MIN_MATCH bytes to insert the
		 * string following the next match.
		 */
		if (s->lookahead < MIN_LOOKAHEAD) {
			fill_window(s);
			if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
				return need_more;
			}
			if (s->lookahead == 0)
				break;	/* flush the current block */
		}

		/* Insert the string window[strstart .. strstart+2] in the
		 * dictionary, and set hash_head to the head of the hash chain:
		 */
		hash_head = NIL;
		if (s->lookahead >= MIN_MATCH) {
			INSERT_STRING(s, s->strstart, hash_head);
		}

		/* Find the longest match, discarding those <= prev_length.
		 * At this point we have always match_length < MIN_MATCH
		 */
		if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
			/* To simplify the code, we prevent matches with the string
			 * of window index 0 (in particular we have to avoid a match
			 * of the string with itself at the start of the input file).
			 */
			s->match_length = longest_match(s, hash_head);
			/* longest_match() sets match_start */
		}
		if (s->match_length >= MIN_MATCH) {
			check_match(s, s->strstart, s->match_start,
				    s->match_length);

			_tr_tally_dist(s, s->strstart - s->match_start,
				       s->match_length - MIN_MATCH, bflush);

			s->lookahead -= s->match_length;

			/* Insert new strings in the hash table only if the match length
			 * is not too large. This saves time but degrades compression.
			 */
#ifndef FASTEST
			if (s->match_length <= s->max_insert_length &&
			    s->lookahead >= MIN_MATCH) {
				s->match_length--;	/* string at strstart already in table */
				do {
					s->strstart++;
					INSERT_STRING(s, s->strstart,
						      hash_head);
					/* strstart never exceeds WSIZE-MAX_MATCH, so there are
					 * always MIN_MATCH bytes ahead.
					 */
				} while (--s->match_length != 0);
				s->strstart++;
			} else
#endif
			{
				s->strstart += s->match_length;
				s->match_length = 0;
				s->ins_h = s->window[s->strstart];
				UPDATE_HASH(s, s->ins_h,
					    s->window[s->strstart + 1]);
#if MIN_MATCH != 3
				Call UPDATE_HASH() MIN_MATCH - 3 more times
#endif
				    /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
				     * matter since it will be recomputed at next deflate call.
				     */
		}} else {
			/* No match, output a literal byte */
			Tracevv((stderr, "%c", s->window[s->strstart]));
			_tr_tally_lit(s, s->window[s->strstart], bflush);
			s->lookahead--;
			s->strstart++;
		}
		if (bflush)
			FLUSH_BLOCK(s, 0);
	}
	FLUSH_BLOCK(s, flush == Z_FINISH);
	return flush == Z_FINISH ? finish_done : block_done;
}

#ifndef FASTEST
/* ===========================================================================
 * Same as above, but achieves better compression. We use a lazy
 * evaluation for matches: a match is finally adopted only if there is
 * no better match at the next window position.
 */
local block_state deflate_slow(s, flush)
deflate_state *s;
int flush;
{
	IPos hash_head;		/* head of hash chain */
	int bflush;		/* set if current block must be flushed */

	/* Process the input block. */
	for (;;) {
		/* Make sure that we always have enough lookahead, except
		 * at the end of the input file. We need MAX_MATCH bytes
		 * for the next match, plus MIN_MATCH bytes to insert the
		 * string following the next match.
		 */
		if (s->lookahead < MIN_LOOKAHEAD) {
			fill_window(s);
			if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
				return need_more;
			}
			if (s->lookahead == 0)
				break;	/* flush the current block */
		}

		/* Insert the string window[strstart .. strstart+2] in the
		 * dictionary, and set hash_head to the head of the hash chain:
		 */
		hash_head = NIL;
		if (s->lookahead >= MIN_MATCH) {
			INSERT_STRING(s, s->strstart, hash_head);
		}

		/* Find the longest match, discarding those <= prev_length.
		 */
		s->prev_length = s->match_length, s->prev_match =
		    s->match_start;
		s->match_length = MIN_MATCH - 1;

		if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
		    s->strstart - hash_head <= MAX_DIST(s)) {
			/* To simplify the code, we prevent matches with the string
			 * of window index 0 (in particular we have to avoid a match
			 * of the string with itself at the start of the input file).
			 */
			s->match_length = longest_match(s, hash_head);
			/* longest_match() sets match_start */

			if (s->match_length <= 5 && (s->strategy == Z_FILTERED
#if TOO_FAR <= 32767
						     || (s->match_length ==
							 MIN_MATCH
							 && s->strstart -
							 s->match_start >
							 TOO_FAR)
#endif
			    )) {

				/* If prev_match is also MIN_MATCH, match_start is garbage
				 * but we will ignore the current match anyway.
				 */
				s->match_length = MIN_MATCH - 1;
			}
		}
		/* If there was a match at the previous step and the current
		 * match is not better, output the previous match:
		 */
		if (s->prev_length >= MIN_MATCH
		    && s->match_length <= s->prev_length) {
			uInt max_insert =
			    s->strstart + s->lookahead - MIN_MATCH;
			/* Do not insert strings in hash table beyond this. */

			check_match(s, s->strstart - 1, s->prev_match,
				    s->prev_length);

			_tr_tally_dist(s, s->strstart - 1 - s->prev_match,
				       s->prev_length - MIN_MATCH, bflush);

			/* Insert in hash table all strings up to the end of the match.
			 * strstart-1 and strstart are already inserted. If there is not
			 * enough lookahead, the last two strings are not inserted in
			 * the hash table.
			 */
			s->lookahead -= s->prev_length - 1;
			s->prev_length -= 2;
			do {
				if (++s->strstart <= max_insert) {
					INSERT_STRING(s, s->strstart,
						      hash_head);
				}
			} while (--s->prev_length != 0);
			s->match_available = 0;
			s->match_length = MIN_MATCH - 1;
			s->strstart++;

			if (bflush)
				FLUSH_BLOCK(s, 0);

		} else if (s->match_available) {
			/* If there was no match at the previous position, output a
			 * single literal. If there was a match but the current match
			 * is longer, truncate the previous match to a single literal.
			 */
			Tracevv((stderr, "%c", s->window[s->strstart - 1]));
			_tr_tally_lit(s, s->window[s->strstart - 1], bflush);
			if (bflush) {
				FLUSH_BLOCK_ONLY(s, 0);
			}
			s->strstart++;
			s->lookahead--;
			if (s->strm->avail_out == 0)
				return need_more;
		} else {
			/* There is no previous match to compare with, wait for
			 * the next step to decide.
			 */
			s->match_available = 1;
			s->strstart++;
			s->lookahead--;
		}
	}
	Assert(flush != Z_NO_FLUSH, "no flush?");
	if (s->match_available) {
		Tracevv((stderr, "%c", s->window[s->strstart - 1]));
		_tr_tally_lit(s, s->window[s->strstart - 1], bflush);
		s->match_available = 0;
	}
	FLUSH_BLOCK(s, flush == Z_FINISH);
	return flush == Z_FINISH ? finish_done : block_done;
}
#endif				/* FASTEST */

/* ===========================================================================
 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
 * one.  Do not maintain a hash table.  (It will be regenerated if this run of
 * deflate switches away from Z_RLE.)
 */
local block_state deflate_rle(s, flush)
deflate_state *s;
int flush;
{
	int bflush;		/* set if current block must be flushed */
	uInt prev;		/* byte at distance one to match */
	Bytef *scan, *strend;	/* scan goes up to strend for length of run */

	for (;;) {
		/* Make sure that we always have enough lookahead, except
		 * at the end of the input file. We need MAX_MATCH bytes
		 * for the longest encodable run.
		 */
		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;
			}
		}

		/* 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);
	}
	FLUSH_BLOCK(s, flush == Z_FINISH);
	return flush == Z_FINISH ? finish_done : block_done;
}

/* ===========================================================================
 * For Z_HUFFMAN_ONLY, do not look for matches.  Do not maintain a hash table.
 * (It will be regenerated if this run of deflate switches away from Huffman.)
 */
local block_state deflate_huff(s, flush)
deflate_state *s;
int flush;
{
	int bflush;		/* set if current block must be flushed */

	for (;;) {
		/* Make sure that we have a literal to write. */
		if (s->lookahead == 0) {
			fill_window(s);
			if (s->lookahead == 0) {
				if (flush == Z_NO_FLUSH)
					return need_more;
				break;	/* flush the current block */
			}
		}

		/* Output a literal byte */
		s->match_length = 0;
		Tracevv((stderr, "%c", s->window[s->strstart]));
		_tr_tally_lit(s, s->window[s->strstart], bflush);
		s->lookahead--;
		s->strstart++;
		if (bflush)
			FLUSH_BLOCK(s, 0);
	}
	FLUSH_BLOCK(s, flush == Z_FINISH);
	return flush == Z_FINISH ? finish_done : block_done;
}
