deflate.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation. Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/* deflate.h -- internal compression state
 * Copyright (C) 1995-2024 Jean-loup Gailly
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/* WARNING: this file should *not* be used by applications. It is
 part of the implementation of the compression library and is
 subject to change. Applications should only use zlib.h.
 */

/* @(#) $Id$ */

#ifndefDEFLATE_H
#defineDEFLATE_H

#include"zutil.h"

/* define NO_GZIP when compiling if you want to disable gzip header and
 trailer creation by deflate(). NO_GZIP would be used to avoid linking in
 the crc code when it is not needed. For shared libraries, gzip encoding
 should be left enabled. */
#ifndefNO_GZIP
# defineGZIP
#endif

/* define LIT_MEM to slightly increase the speed of deflate (order 1% to 2%) at
 the cost of a larger memory footprint */
/* #define LIT_MEM */

/* ===========================================================================
 * Internal compression state.
 */

#defineLENGTH_CODES 29
/* number of length codes, not counting the special END_BLOCK code */

#defineLITERALS 256
/* number of literal bytes 0..255 */

#defineL_CODES (LITERALS+1+LENGTH_CODES)
/* number of Literal or Length codes, including the END_BLOCK code */

#defineD_CODES 30
/* number of distance codes */

#defineBL_CODES 19
/* number of codes used to transfer the bit lengths */

#defineHEAP_SIZE (2*L_CODES+1)
/* maximum heap size */

#defineMAX_BITS 15
/* All codes must not exceed MAX_BITS bits */

#defineBuf_size 16
/* size of bit buffer in bi_buf */

#defineINIT_STATE 42 /* zlib header -> BUSY_STATE */
#ifdefGZIP
# defineGZIP_STATE 57 /* gzip header -> BUSY_STATE | EXTRA_STATE */
#endif
#defineEXTRA_STATE 69 /* gzip extra block -> NAME_STATE */
#defineNAME_STATE 73 /* gzip file name -> COMMENT_STATE */
#defineCOMMENT_STATE 91 /* gzip comment -> HCRC_STATE */
#defineHCRC_STATE 103 /* gzip header CRC -> BUSY_STATE */
#defineBUSY_STATE 113 /* deflate -> FINISH_STATE */
#defineFINISH_STATE 666 /* stream complete */
/* Stream status */


/* Data structure describing a single value and its code string. */
typedefstructct_data_s {
union {
ushfreq; /* frequency count */
ushcode; /* bit string */
 } fc;
union {
ushdad; /* father node in Huffman tree */
ushlen; /* length of bit string */
 } dl;
} FARct_data;

#defineFreq fc.freq
#defineCode fc.code
#defineDad dl.dad
#defineLen dl.len

typedefstructstatic_tree_desc_sstatic_tree_desc;

typedefstructtree_desc_s {
ct_data*dyn_tree; /* the dynamic tree */
intmax_code; /* largest code with non zero frequency */
conststatic_tree_desc*stat_desc; /* the corresponding static tree */
} FARtree_desc;

typedefushPos;
typedefPosFARPosf;
typedefunsignedIPos;

/* A Pos is an index in the character window. We use short instead of int to
 * save space in the various tables. IPos is used only for parameter passing.
 */

typedefstructinternal_state {
z_streampstrm; /* pointer back to this zlib stream */
intstatus; /* as the name implies */
Bytef*pending_buf; /* output still pending */
ulgpending_buf_size; /* size of pending_buf */
Bytef*pending_out; /* next pending byte to output to the stream */
ulgpending; /* nb of bytes in the pending buffer */
intwrap; /* bit 0 true for zlib, bit 1 true for gzip */
gz_headerpgzhead; /* gzip header information to write */
ulggzindex; /* where in extra, name, or comment */
Bytemethod; /* can only be DEFLATED */
intlast_flush; /* value of flush param for previous deflate call */

/* used by deflate.c: */

uIntw_size; /* LZ77 window size (32K by default) */
uIntw_bits; /* log2(w_size) (8..16) */
uIntw_mask; /* w_size - 1 */

Bytef*window;
/* Sliding window. Input bytes are read into the second half of the window,
 * and move to the first half later to keep a dictionary of at least wSize
 * bytes. With this organization, matches are limited to a distance of
 * wSize-MAX_MATCH bytes, but this ensures that IO is always
 * performed with a length multiple of the block size. Also, it limits
 * the window size to 64K, which is quite useful on MSDOS.
 * To do: use the user input buffer as sliding window.
 */

ulgwindow_size;
/* Actual size of window: 2*wSize, except when the user input buffer
 * is directly used as sliding window.
 */

Posf*prev;
/* Link to older string with same hash index. To limit the size of this
 * array to 64K, this link is maintained only for the last 32K strings.
 * An index in this array is thus a window index modulo 32K.
 */

Posf*head; /* Heads of the hash chains or NIL. */

uIntins_h; /* hash index of string to be inserted */
uInthash_size; /* number of elements in hash table */
uInthash_bits; /* log2(hash_size) */
uInthash_mask; /* hash_size-1 */

uInthash_shift;
/* Number of bits by which ins_h must be shifted at each input
 * step. It must be such that after MIN_MATCH steps, the oldest
 * byte no longer takes part in the hash key, that is:
 * hash_shift * MIN_MATCH >= hash_bits
 */

longblock_start;
/* Window position at the beginning of the current output block. Gets
 * negative when the window is moved backwards.
 */

uIntmatch_length; /* length of best match */
IPosprev_match; /* previous match */
intmatch_available; /* set if previous match exists */
uIntstrstart; /* start of string to insert */
uIntmatch_start; /* start of matching string */
uIntlookahead; /* number of valid bytes ahead in window */

uIntprev_length;
/* Length of the best match at previous step. Matches not greater than this
 * are discarded. This is used in the lazy match evaluation.
 */

uIntmax_chain_length;
/* To speed up deflation, hash chains are never searched beyond this
 * length. A higher limit improves compression ratio but degrades the
 * speed.
 */

uIntmax_lazy_match;
/* Attempt to find a better match only when the current match is strictly
 * smaller than this value. This mechanism is used only for compression
 * levels >= 4.
 */
# definemax_insert_length max_lazy_match
/* Insert new strings in the hash table only if the match length is not
 * greater than this length. This saves time but degrades compression.
 * max_insert_length is used only for compression levels <= 3.
 */

intlevel; /* compression level (1..9) */
intstrategy; /* favor or force Huffman coding*/

uIntgood_match;
/* Use a faster search when the previous match is longer than this */

intnice_match; /* Stop searching when current match exceeds this */

/* used by trees.c: */
/* Didn't use ct_data typedef below to suppress compiler warning */
structct_data_sdyn_ltree[HEAP_SIZE]; /* literal and length tree */
structct_data_sdyn_dtree[2*D_CODES+1]; /* distance tree */
structct_data_sbl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */

structtree_desc_sl_desc; /* desc. for literal tree */
structtree_desc_sd_desc; /* desc. for distance tree */
structtree_desc_sbl_desc; /* desc. for bit length tree */

ushbl_count[MAX_BITS+1];
/* number of codes at each bit length for an optimal tree */

intheap[2*L_CODES+1]; /* heap used to build the Huffman trees */
intheap_len; /* number of elements in the heap */
intheap_max; /* element of largest frequency */
/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
 * The same heap array is used to build all trees.
 */

uchdepth[2*L_CODES+1];
/* Depth of each subtree used as tie breaker for trees of equal frequency
 */

#ifdefLIT_MEM
# defineLIT_BUFS 5
ushf*d_buf; /* buffer for distances */
uchf*l_buf; /* buffer for literals/lengths */
#else
# defineLIT_BUFS 4
uchf*sym_buf; /* buffer for distances and literals/lengths */
#endif

uIntlit_bufsize;
/* Size of match buffer for literals/lengths. There are 4 reasons for
 * limiting lit_bufsize to 64K:
 * - frequencies can be kept in 16 bit counters
 * - if compression is not successful for the first block, all input
 * data is still in the window so we can still emit a stored block even
 * when input comes from standard input. (This can also be done for
 * all blocks if lit_bufsize is not greater than 32K.)
 * - if compression is not successful for a file smaller than 64K, we can
 * even emit a stored file instead of a stored block (saving 5 bytes).
 * This is applicable only for zip (not gzip or zlib).
 * - creating new Huffman trees less frequently may not provide fast
 * adaptation to changes in the input data statistics. (Take for
 * example a binary file with poorly compressible code followed by
 * a highly compressible string table.) Smaller buffer sizes give
 * fast adaptation but have of course the overhead of transmitting
 * trees more frequently.
 * - I can't count above 4
 */

uIntsym_next; /* running index in symbol buffer */
uIntsym_end; /* symbol table full when sym_next reaches this */

ulgopt_len; /* bit length of current block with optimal trees */
ulgstatic_len; /* bit length of current block with static trees */
uIntmatches; /* number of string matches in current block */
uIntinsert; /* bytes at end of window left to insert */

#ifdefZLIB_DEBUG
ulgcompressed_len; /* total bit length of compressed file mod 2^32 */
ulgbits_sent; /* bit length of compressed data sent mod 2^32 */
#endif

ushbi_buf;
/* Output buffer. bits are inserted starting at the bottom (least
 * significant bits).
 */
intbi_valid;
/* Number of valid bits in bi_buf. All bits above the last valid bit
 * are always zero.
 */

ulghigh_water;
/* High water mark offset in window for initialized bytes -- bytes above
 * this are set to zero in order to avoid memory check warnings when
 * longest match routines access bytes past the input. This is then
 * updated to the new high water mark.
 */

} FARdeflate_state;

/* Output a byte on the stream.
 * IN assertion: there is enough room in pending_buf.
 */
#defineput_byte(s, c) {s->pending_buf[s->pending++] = (Bytef)(c);}


#defineMIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
/* Minimum amount of lookahead, except at the end of the input file.
 * See deflate.c for comments about the MIN_MATCH+1.
 */

#defineMAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD)
/* In order to simplify the code, particularly on 16 bit machines, match
 * distances are limited to MAX_DIST instead of WSIZE.
 */

#defineWIN_INIT MAX_MATCH
/* Number of bytes after end of data in window to initialize in order to avoid
 memory checker errors from longest match routines */

/* in trees.c */
voidZLIB_INTERNAL_tr_init(deflate_state*s);
intZLIB_INTERNAL_tr_tally(deflate_state*s, unsigneddist, unsignedlc);
voidZLIB_INTERNAL_tr_flush_block(deflate_state*s, charf*buf,
ulgstored_len, intlast);
voidZLIB_INTERNAL_tr_flush_bits(deflate_state*s);
voidZLIB_INTERNAL_tr_align(deflate_state*s);
voidZLIB_INTERNAL_tr_stored_block(deflate_state*s, charf*buf,
ulgstored_len, intlast);

#defined_code(dist) \
 ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])
/* Mapping from a distance to a distance code. dist is the distance - 1 and
 * must not have side effects. _dist_code[256] and _dist_code[257] are never
 * used.
 */

#ifndefZLIB_DEBUG
/* Inline versions of _tr_tally for speed: */

#if defined(GEN_TREES_H) || !defined(STDC)
externuchZLIB_INTERNAL_length_code[];
externuchZLIB_INTERNAL_dist_code[];
#else
externconstuchZLIB_INTERNAL_length_code[];
externconstuchZLIB_INTERNAL_dist_code[];
#endif

#ifdefLIT_MEM
# define_tr_tally_lit(s, c, flush) \
 { uch cc = (c); \
 s->d_buf[s->sym_next] = 0; \
 s->l_buf[s->sym_next++] = cc; \
 s->dyn_ltree[cc].Freq++; \
 flush = (s->sym_next == s->sym_end); \
 }
# define_tr_tally_dist(s, distance, length, flush) \
 { uch len = (uch)(length); \
 ush dist = (ush)(distance); \
 s->d_buf[s->sym_next] = dist; \
 s->l_buf[s->sym_next++] = len; \
 dist--; \
 s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
 s->dyn_dtree[d_code(dist)].Freq++; \
 flush = (s->sym_next == s->sym_end); \
 }
#else
# define_tr_tally_lit(s, c, flush) \
 { uch cc = (c); \
 s->sym_buf[s->sym_next++] = 0; \
 s->sym_buf[s->sym_next++] = 0; \
 s->sym_buf[s->sym_next++] = cc; \
 s->dyn_ltree[cc].Freq++; \
 flush = (s->sym_next == s->sym_end); \
 }
# define_tr_tally_dist(s, distance, length, flush) \
 { uch len = (uch)(length); \
 ush dist = (ush)(distance); \
 s->sym_buf[s->sym_next++] = (uch)dist; \
 s->sym_buf[s->sym_next++] = (uch)(dist >> 8); \
 s->sym_buf[s->sym_next++] = len; \
 dist--; \
 s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
 s->dyn_dtree[d_code(dist)].Freq++; \
 flush = (s->sym_next == s->sym_end); \
 }
#endif
#else
# define_tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
# define_tr_tally_dist(s, distance, length, flush) \
 flush = _tr_tally(s, distance, length)
#endif

#endif/* DEFLATE_H */