deflate.cc File Reference

#include "deflate.h"

Include dependency graph for deflate.cc:

Go to the source code of this file.

Classes
struct	config_s
struct	static_tree_desc_s

Macros
#define	NIL   0
#define	TOO_FAR   4096
#define	EQUAL   0
#define	RANK(f)   (((f) << 1) - ((f) > 4 ? 9 : 0))
#define	UPDATE_HASH(s, h, c)   (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
#define	INSERT_STRING(s, str, match_head)
#define	CLEAR_HASH(s)
#define	check_match(s, start, match, length)
#define	FLUSH_BLOCK_ONLY(s, last)
#define	FLUSH_BLOCK(s, last)

Typedefs
typedef block_state compress_func	OF((deflate_state *s, int flush))
typedef struct config_s	config

Enumerations
enum	block_state { need_more, block_done, finish_started, finish_done }

Functions
local void fill_window	OF ((deflate_state *s))
local block_state deflate_stored	OF ((deflate_state *s, int flush))
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))
local uInt longest_match	OF ((deflate_state *s, IPos cur_match))
int ZEXPORT	deflateInit_ (z_streamp strm, int level, const char *version, int stream_size)
int ZEXPORT	deflateInit2_ (z_streamp strm, int level, int method, int windowBits, int memLevel, int strategy, const char *version, int stream_size)
int ZEXPORT	deflateSetDictionary (z_streamp strm, const Bytef *dictionary, uInt dictLength)
int ZEXPORT	deflateResetKeep (z_streamp strm)
int ZEXPORT	deflateReset (z_streamp strm)
int ZEXPORT	deflateSetHeader (z_streamp strm, gz_headerp head)
int ZEXPORT	deflatePending (z_streamp strm, unsigned *pending, int *bits)
int ZEXPORT	deflatePrime (z_streamp strm, int bits, int value)
int ZEXPORT	deflateParams (z_streamp strm, int level, int strategy)
int ZEXPORT	deflateTune (z_streamp strm, int good_length, int max_lazy, int nice_length, int max_chain)
uLong ZEXPORT	deflateBound (z_streamp strm, uLong sourceLen)
local void	putShortMSB (deflate_state *s, uInt b)
local void	flush_pending (z_streamp strm)
int ZEXPORT	deflate (z_streamp strm, int flush)
int ZEXPORT	deflateEnd (z_streamp strm)
int ZEXPORT	deflateCopy (z_streamp dest, z_streamp source)
local int	read_buf (z_streamp strm, Bytef *buf, unsigned size)
local void	lm_init (deflate_state *s)
local uInt	longest_match (deflate_state *s, IPos cur_match)
local void	fill_window (deflate_state *s)
local block_state	deflate_stored (deflate_state *s, int flush)
local block_state	deflate_fast (deflate_state *s, int flush)
local block_state	deflate_slow (deflate_state *s, int flush)
local block_state	deflate_rle (deflate_state *s, int flush)
local block_state	deflate_huff (deflate_state *s, int flush)

Variables
local const config	configuration_table [10]

Macro Definition Documentation

check_match

#define check_match	(		s,
			start,
			match,
			length
	)

Definition at line 1323 of file deflate.cc.

CLEAR_HASH

#define CLEAR_HASH

(

s

)

Value:

s->head[s->hash_size-1] = NIL; \
    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));

Definition at line 196 of file deflate.cc.

EQUAL

#define EQUAL   0

Definition at line 151 of file deflate.cc.

FLUSH_BLOCK

#define FLUSH_BLOCK	(		s,
			last
	)

Value:

{ \
   FLUSH_BLOCK_ONLY(s, last); \
   if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
}

Definition at line 1495 of file deflate.cc.

FLUSH_BLOCK_ONLY

#define FLUSH_BLOCK_ONLY	(		s,
			last
	)

Value:

{ \
   _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]")); \
}

Definition at line 1483 of file deflate.cc.

INSERT_STRING

#define INSERT_STRING	(		s,
			str,
			match_head
	)

Value:

(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))

Definition at line 186 of file deflate.cc.

NIL

#define NIL   0

Definition at line 104 of file deflate.cc.

RANK

#define RANK

(

f

)

(((f) << 1) - ((f) > 4 ? 9 : 0))

Definition at line 159 of file deflate.cc.

TOO_FAR

#define TOO_FAR   4096

Definition at line 108 of file deflate.cc.

UPDATE_HASH

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

Definition at line 167 of file deflate.cc.

Typedef Documentation

config

typedef struct config_s config

OF

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

Definition at line 73 of file deflate.cc.

Enumeration Type Documentation

block_state

enum block_state

Enumerator
need_more
block_done
finish_started
finish_done

Definition at line 66 of file deflate.cc.

             {
    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;

Function Documentation

deflate()

int ZEXPORT deflate	(	z_streamp	strm,
		int	flush
	)

Definition at line 627 of file deflate.cc.

{
    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 && 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;
}

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deflate_fast()

local block_state deflate_fast	(	deflate_state *	s,
		int	flush
	)

Definition at line 1571 of file deflate.cc.

{
    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;
}

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deflate_huff()

local block_state deflate_huff	(	deflate_state *	s,
		int	flush
	)

Definition at line 1871 of file deflate.cc.

{
    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;
}

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deflate_rle()

local block_state deflate_rle	(	deflate_state *	s,
		int	flush
	)

Definition at line 1800 of file deflate.cc.

{
    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;
}

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deflate_slow()

local block_state deflate_slow	(	deflate_state *	s,
		int	flush
	)

Definition at line 1671 of file deflate.cc.

{
    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;
}

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deflate_stored()

local block_state deflate_stored	(	deflate_state *	s,
		int	flush
	)

Definition at line 1509 of file deflate.cc.

{
    /* 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;
}

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deflateBound()

uLong ZEXPORT deflateBound	(	z_streamp	strm,
		uLong	sourceLen
	)

Definition at line 533 of file deflate.cc.

{
    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;
}

deflateCopy()

int ZEXPORT deflateCopy	(	z_streamp	dest,
		z_streamp	source
	)

Definition at line 973 of file deflate.cc.

{
#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((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 */
}

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deflateEnd()

int ZEXPORT deflateEnd

(

z_streamp

strm

)

Definition at line 939 of file deflate.cc.

{
    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;
}

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deflateInit2_()

int ZEXPORT deflateInit2_	(	z_streamp	strm,
		int	level,
		int	method,
		int	windowBits,
		int	memLevel,
		int	strategy,
		const char *	version,
		int	stream_size
	)

Definition at line 209 of file deflate.cc.

{
    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) {
        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 = 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);
}

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deflateInit_()

int ZEXPORT deflateInit_	(	z_streamp	strm,
		int	level,
		const char *	version,
		int	stream_size
	)

Definition at line 201 of file deflate.cc.

{
    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 */
}

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deflateParams()

int ZEXPORT deflateParams	(	z_streamp	strm,
		int	level,
		int	strategy
	)

Definition at line 465 of file deflate.cc.

{
    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 (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;
}

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deflatePending()

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

Definition at line 431 of file deflate.cc.

{
    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
    if (pending != Z_NULL)
        *pending = strm->state->pending;
    if (bits != Z_NULL)
        *bits = strm->state->bi_valid;
    return Z_OK;
}

deflatePrime()

int ZEXPORT deflatePrime	(	z_streamp	strm,
		int	bits,
		int	value
	)

Definition at line 442 of file deflate.cc.

{
    deflate_state *s;
    int put;

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

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deflateReset()

int ZEXPORT deflateReset

(

z_streamp

strm

)

Definition at line 411 of file deflate.cc.

{
    int ret;

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

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deflateResetKeep()

int ZEXPORT deflateResetKeep

(

z_streamp

strm

)

Definition at line 377 of file deflate.cc.

{
    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);

    return Z_OK;
}

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deflateSetDictionary()

int ZEXPORT deflateSetDictionary	(	z_streamp	strm,
		const Bytef *	dictionary,
		uInt	dictLength
	)

Definition at line 311 of file deflate.cc.

{
    deflate_state *s;
    uInt str, n;
    int wrap;
    unsigned avail;
    z_const unsigned char *next;

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

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deflateSetHeader()

int ZEXPORT deflateSetHeader	(	z_streamp	strm,
		gz_headerp	head
	)

Definition at line 422 of file deflate.cc.

{
    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;
}

deflateTune()

int ZEXPORT deflateTune	(	z_streamp	strm,
		int	good_length,
		int	max_lazy,
		int	nice_length,
		int	max_chain
	)

Definition at line 503 of file deflate.cc.

{
    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;
}

fill_window()

local void fill_window

(

deflate_state *

s

)

Definition at line 1336 of file deflate.cc.

{
    unsigned n, m;
    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");
}

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flush_pending()

local void flush_pending

(

z_streamp

strm

)

Definition at line 605 of file deflate.cc.

{
    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;
    }
}

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lm_init()

local void lm_init

(

deflate_state *

s

)

Definition at line 1060 of file deflate.cc.

{
    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
}

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longest_match()

local uInt longest_match	(	deflate_state *	s,
		IPos	cur_match
	)

Definition at line 1101 of file deflate.cc.

{
    unsigned chain_length = s->max_chain_length;/* max hash chain length */
    Bytef *scan = s->window + s->strstart; /* current string */
    Bytef *match;                       /* matched string */
    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.
     */
    Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
    ush scan_start = *(ushf*)scan;
    ush scan_end   = *(ushf*)(scan+best_len-1);
#else
    Bytef *strend = s->window + s->strstart + MAX_MATCH;
    Byte scan_end1  = scan[best_len-1];
    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;
}

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OF() [1/6]

local void fill_window OF

(

(deflate_state *s)

)

OF() [2/6]

local block_state deflate_stored OF

(

(deflate_state *s, int flush)

)

OF() [3/6]

local void putShortMSB OF

(

(deflate_state *s, uInt b)

)

OF() [4/6]

local void flush_pending OF

(

(z_streamp strm)

)

OF() [5/6]

local int read_buf OF

(

(z_streamp strm, Bytef *buf, unsigned size)

)

OF() [6/6]

local uInt longest_match OF

(

(deflate_state *s, IPos cur_match)

)

putShortMSB()

local void putShortMSB	(	deflate_state *	s,
		uInt	b
	)

Definition at line 593 of file deflate.cc.

{
    put_byte(s, (Byte)(b >> 8));
    put_byte(s, (Byte)(b & 0xff));
}

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read_buf()

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

Definition at line 1033 of file deflate.cc.

{
    unsigned len = strm->avail_in;

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

    strm->avail_in  -= len;

    zmemcpy(buf, strm->next_in, len);
    if (strm->state->wrap == 1) {
        strm->adler = adler32(strm->adler, buf, len);
    }
#ifdef GZIP
    else if (strm->state->wrap == 2) {
        strm->adler = crc32(strm->adler, buf, len);
    }
#endif
    strm->next_in  += len;
    strm->total_in += len;

    return (int)len;
}

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Variable Documentation

configuration_table

local const config configuration_table[10]

Initial value:

= {

 {0,    0,  0,    0, deflate_stored},  
 {4,    4,  8,    4, deflate_fast}, 
 {4,    5, 16,    8, deflate_fast},
 {4,    6, 32,   32, deflate_fast},

 {4,    4, 16,   16, deflate_slow},  
 {8,   16, 32,   32, deflate_slow},
 {8,   16, 128, 128, deflate_slow},
 {8,   32, 128, 256, deflate_slow},
 {32, 128, 258, 1024, deflate_slow},
 {32, 258, 258, 4096, deflate_slow}}

Definition at line 131 of file deflate.cc.