1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* deflate.h -- internal compression state
26 * Copyright (C) 1995-2012 Jean-loup Gailly
27 * For conditions of distribution and use, see copyright notice in zlib.h
28 */
29
30 /* WARNING: this file should *not* be used by applications. It is
31 part of the implementation of the compression library and is
32 subject to change. Applications should only use zlib.h.
33 */
34
35 /* @(#) $Id$ */
36
37 #ifndef DEFLATE_H
38 #define DEFLATE_H
39
40 #include "zutil.h"
41
42 /* define NO_GZIP when compiling if you want to disable gzip header and
43 trailer creation by deflate(). NO_GZIP would be used to avoid linking in
44 the crc code when it is not needed. For shared libraries, gzip encoding
45 should be left enabled. */
46 #ifndef NO_GZIP
47 # define GZIP
48 #endif
49
50 /* ===========================================================================
51 * Internal compression state.
52 */
53
54 #define LENGTH_CODES 29
55 /* number of length codes, not counting the special END_BLOCK code */
56
57 #define LITERALS 256
58 /* number of literal bytes 0..255 */
59
60 #define L_CODES (LITERALS+1+LENGTH_CODES)
61 /* number of Literal or Length codes, including the END_BLOCK code */
62
63 #define D_CODES 30
64 /* number of distance codes */
65
66 #define BL_CODES 19
67 /* number of codes used to transfer the bit lengths */
68
69 #define HEAP_SIZE (2*L_CODES+1)
70 /* maximum heap size */
71
72 #define MAX_BITS 15
73 /* All codes must not exceed MAX_BITS bits */
74
75 #define Buf_size 16
76 /* size of bit buffer in bi_buf */
77
78 #define INIT_STATE 42
79 #define EXTRA_STATE 69
80 #define NAME_STATE 73
81 #define COMMENT_STATE 91
82 #define HCRC_STATE 103
83 #define BUSY_STATE 113
84 #define FINISH_STATE 666
85 /* Stream status */
86
87
88 /* Data structure describing a single value and its code string. */
89 typedef struct ct_data_s {
90 union {
91 ush freq; /* frequency count */
92 ush code; /* bit string */
93 } fc;
94 union {
95 ush dad; /* father node in Huffman tree */
96 ush len; /* length of bit string */
97 } dl;
98 } FAR ct_data;
99
100 #define Freq fc.freq
101 #define Code fc.code
102 #define Dad dl.dad
103 #define Len dl.len
104
105 typedef struct static_tree_desc_s static_tree_desc;
106
107 typedef struct tree_desc_s {
108 ct_data *dyn_tree; /* the dynamic tree */
109 int max_code; /* largest code with non zero frequency */
110 static_tree_desc *stat_desc; /* the corresponding static tree */
111 } FAR tree_desc;
112
113 typedef ush Pos;
114 typedef Pos FAR Posf;
115 typedef unsigned IPos;
116
117 /* A Pos is an index in the character window. We use short instead of int to
118 * save space in the various tables. IPos is used only for parameter passing.
119 */
120
121 typedef struct internal_state {
122 z_streamp strm; /* pointer back to this zlib stream */
123 int status; /* as the name implies */
124 Bytef *pending_buf; /* output still pending */
125 ulg pending_buf_size; /* size of pending_buf */
126 Bytef *pending_out; /* next pending byte to output to the stream */
127 uInt pending; /* nb of bytes in the pending buffer */
128 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
129 gz_headerp gzhead; /* gzip header information to write */
130 uInt gzindex; /* where in extra, name, or comment */
131 Byte method; /* can only be DEFLATED */
132 int last_flush; /* value of flush param for previous deflate call */
133
134 /* used by deflate.c: */
135
136 uInt w_size; /* LZ77 window size (32K by default) */
137 uInt w_bits; /* log2(w_size) (8..16) */
138 uInt w_mask; /* w_size - 1 */
139
140 Bytef *window;
141 /* Sliding window. Input bytes are read into the second half of the window,
142 * and move to the first half later to keep a dictionary of at least wSize
143 * bytes. With this organization, matches are limited to a distance of
144 * wSize-MAX_MATCH bytes, but this ensures that IO is always
145 * performed with a length multiple of the block size. Also, it limits
146 * the window size to 64K, which is quite useful on MSDOS.
147 * To do: use the user input buffer as sliding window.
148 */
149
150 ulg window_size;
151 /* Actual size of window: 2*wSize, except when the user input buffer
152 * is directly used as sliding window.
153 */
154
155 Posf *prev;
156 /* Link to older string with same hash index. To limit the size of this
157 * array to 64K, this link is maintained only for the last 32K strings.
158 * An index in this array is thus a window index modulo 32K.
159 */
160
161 Posf *head; /* Heads of the hash chains or NIL. */
162
163 uInt ins_h; /* hash index of string to be inserted */
164 uInt hash_size; /* number of elements in hash table */
165 uInt hash_bits; /* log2(hash_size) */
166 uInt hash_mask; /* hash_size-1 */
167
168 uInt hash_shift;
169 /* Number of bits by which ins_h must be shifted at each input
170 * step. It must be such that after MIN_MATCH steps, the oldest
171 * byte no longer takes part in the hash key, that is:
172 * hash_shift * MIN_MATCH >= hash_bits
173 */
174
175 long block_start;
176 /* Window position at the beginning of the current output block. Gets
177 * negative when the window is moved backwards.
178 */
179
180 uInt match_length; /* length of best match */
181 IPos prev_match; /* previous match */
182 int match_available; /* set if previous match exists */
183 uInt strstart; /* start of string to insert */
184 uInt match_start; /* start of matching string */
185 uInt lookahead; /* number of valid bytes ahead in window */
186
187 uInt prev_length;
188 /* Length of the best match at previous step. Matches not greater than this
189 * are discarded. This is used in the lazy match evaluation.
190 */
191
192 uInt max_chain_length;
193 /* To speed up deflation, hash chains are never searched beyond this
194 * length. A higher limit improves compression ratio but degrades the
195 * speed.
196 */
197
198 uInt max_lazy_match;
199 /* Attempt to find a better match only when the current match is strictly
200 * smaller than this value. This mechanism is used only for compression
201 * levels >= 4.
202 */
203 # define max_insert_length max_lazy_match
204 /* Insert new strings in the hash table only if the match length is not
205 * greater than this length. This saves time but degrades compression.
206 * max_insert_length is used only for compression levels <= 3.
207 */
208
209 int level; /* compression level (1..9) */
210 int strategy; /* favor or force Huffman coding*/
211
212 uInt good_match;
213 /* Use a faster search when the previous match is longer than this */
214
215 int nice_match; /* Stop searching when current match exceeds this */
216
217 /* used by trees.c: */
218 /* Didn't use ct_data typedef below to suppress compiler warning */
219 struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */
220 struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
221 struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */
222
223 struct tree_desc_s l_desc; /* desc. for literal tree */
224 struct tree_desc_s d_desc; /* desc. for distance tree */
225 struct tree_desc_s bl_desc; /* desc. for bit length tree */
226
227 ush bl_count[MAX_BITS+1];
228 /* number of codes at each bit length for an optimal tree */
229
230 int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */
231 int heap_len; /* number of elements in the heap */
232 int heap_max; /* element of largest frequency */
233 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
234 * The same heap array is used to build all trees.
235 */
236
237 uch depth[2*L_CODES+1];
238 /* Depth of each subtree used as tie breaker for trees of equal frequency
239 */
240
241 uchf *l_buf; /* buffer for literals or lengths */
242
243 uInt lit_bufsize;
244 /* Size of match buffer for literals/lengths. There are 4 reasons for
245 * limiting lit_bufsize to 64K:
246 * - frequencies can be kept in 16 bit counters
247 * - if compression is not successful for the first block, all input
248 * data is still in the window so we can still emit a stored block even
249 * when input comes from standard input. (This can also be done for
250 * all blocks if lit_bufsize is not greater than 32K.)
251 * - if compression is not successful for a file smaller than 64K, we can
252 * even emit a stored file instead of a stored block (saving 5 bytes).
253 * This is applicable only for zip (not gzip or zlib).
254 * - creating new Huffman trees less frequently may not provide fast
255 * adaptation to changes in the input data statistics. (Take for
256 * example a binary file with poorly compressible code followed by
257 * a highly compressible string table.) Smaller buffer sizes give
258 * fast adaptation but have of course the overhead of transmitting
259 * trees more frequently.
260 * - I can't count above 4
261 */
262
263 uInt last_lit; /* running index in l_buf */
264
265 ushf *d_buf;
266 /* Buffer for distances. To simplify the code, d_buf and l_buf have
267 * the same number of elements. To use different lengths, an extra flag
268 * array would be necessary.
269 */
270
271 ulg opt_len; /* bit length of current block with optimal trees */
272 ulg static_len; /* bit length of current block with static trees */
273 uInt matches; /* number of string matches in current block */
274 uInt insert; /* bytes at end of window left to insert */
275
276 #ifdef DEBUG
277 ulg compressed_len; /* total bit length of compressed file mod 2^32 */
278 ulg bits_sent; /* bit length of compressed data sent mod 2^32 */
279 #endif
280
281 ush bi_buf;
282 /* Output buffer. bits are inserted starting at the bottom (least
283 * significant bits).
284 */
285 int bi_valid;
286 /* Number of valid bits in bi_buf. All bits above the last valid bit
287 * are always zero.
288 */
289
290 ulg high_water;
291 /* High water mark offset in window for initialized bytes -- bytes above
292 * this are set to zero in order to avoid memory check warnings when
293 * longest match routines access bytes past the input. This is then
294 * updated to the new high water mark.
295 */
296
297 } FAR deflate_state;
298
299 /* Output a byte on the stream.
300 * IN assertion: there is enough room in pending_buf.
301 */
302 #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}
303
304
305 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
306 /* Minimum amount of lookahead, except at the end of the input file.
307 * See deflate.c for comments about the MIN_MATCH+1.
308 */
309
310 #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD)
311 /* In order to simplify the code, particularly on 16 bit machines, match
312 * distances are limited to MAX_DIST instead of WSIZE.
313 */
314
315 #define WIN_INIT MAX_MATCH
316 /* Number of bytes after end of data in window to initialize in order to avoid
317 memory checker errors from longest match routines */
318
319 /* in trees.c */
320 void ZLIB_INTERNAL _tr_init OF((deflate_state *s));
321 int ZLIB_INTERNAL _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc));
322 void ZLIB_INTERNAL _tr_flush_block OF((deflate_state *s, charf *buf,
323 ulg stored_len, int last));
324 void ZLIB_INTERNAL _tr_flush_bits OF((deflate_state *s));
325 void ZLIB_INTERNAL _tr_align OF((deflate_state *s));
326 void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf,
327 ulg stored_len, int last));
328
329 #define d_code(dist) \
330 ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])
331 /* Mapping from a distance to a distance code. dist is the distance - 1 and
332 * must not have side effects. _dist_code[256] and _dist_code[257] are never
333 * used.
334 */
335
336 #ifndef DEBUG
337 /* Inline versions of _tr_tally for speed: */
338
339 #if defined(GEN_TREES_H) || !defined(STDC)
340 extern uch ZLIB_INTERNAL _length_code[];
341 extern uch ZLIB_INTERNAL _dist_code[];
342 #else
343 extern const uch ZLIB_INTERNAL _length_code[];
344 extern const uch ZLIB_INTERNAL _dist_code[];
345 #endif
346
347 # define _tr_tally_lit(s, c, flush) \
348 { uch cc = (c); \
349 s->d_buf[s->last_lit] = 0; \
350 s->l_buf[s->last_lit++] = cc; \
351 s->dyn_ltree[cc].Freq++; \
352 flush = (s->last_lit == s->lit_bufsize-1); \
353 }
354 # define _tr_tally_dist(s, distance, length, flush) \
355 { uch len = (length); \
356 ush dist = (distance); \
357 s->d_buf[s->last_lit] = dist; \
358 s->l_buf[s->last_lit++] = len; \
359 dist--; \
360 s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
361 s->dyn_dtree[d_code(dist)].Freq++; \
362 flush = (s->last_lit == s->lit_bufsize-1); \
363 }
364 #else
365 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
366 # define _tr_tally_dist(s, distance, length, flush) \
367 flush = _tr_tally(s, distance, length)
368 #endif
369
370 #endif /* DEFLATE_H */