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1 /* deflate.h -- internal compression state 1
2 * Copyright (C) 1995-2018 Jean-loup Gailly
3 * For conditions of distribution and use, see
4 */
5
6 /* WARNING: this file should *not* be used by
7 part of the implementation of the compressi
8 subject to change. Applications should only
9 */
10
11 /* @(#) $Id$ */
12
13 #ifndef DEFLATE_H
14 #define DEFLATE_H
15
16 #include "zutil.h"
17
18 /* define NO_GZIP when compiling if you want t
19 trailer creation by deflate(). NO_GZIP wou
20 the crc code when it is not needed. For sh
21 should be left enabled. */
22 #ifndef NO_GZIP
23 # define GZIP
24 #endif
25
26 /* ===========================================
27 * Internal compression state.
28 */
29
30 #define LENGTH_CODES 29
31 /* number of length codes, not counting the sp
32
33 #define LITERALS 256
34 /* number of literal bytes 0..255 */
35
36 #define L_CODES (LITERALS+1+LENGTH_CODES)
37 /* number of Literal or Length codes, includin
38
39 #define D_CODES 30
40 /* number of distance codes */
41
42 #define BL_CODES 19
43 /* number of codes used to transfer the bit le
44
45 #define HEAP_SIZE (2*L_CODES+1)
46 /* maximum heap size */
47
48 #define MAX_BITS 15
49 /* All codes must not exceed MAX_BITS bits */
50
51 #define Buf_size 16
52 /* size of bit buffer in bi_buf */
53
54 #define INIT_STATE 42 /* zlib header ->
55 #ifdef GZIP
56 # define GZIP_STATE 57 /* gzip header ->
57 #endif
58 #define EXTRA_STATE 69 /* gzip extra bloc
59 #define NAME_STATE 73 /* gzip file name
60 #define COMMENT_STATE 91 /* gzip comment ->
61 #define HCRC_STATE 103 /* gzip header CRC
62 #define BUSY_STATE 113 /* deflate -> FINI
63 #define FINISH_STATE 666 /* stream complete
64 /* Stream status */
65
66
67 /* Data structure describing a single value an
68 typedef struct ct_data_s {
69 union {
70 ush freq; /* frequency count */
71 ush code; /* bit string */
72 } fc;
73 union {
74 ush dad; /* father node in Huf
75 ush len; /* length of bit stri
76 } dl;
77 } FAR ct_data;
78
79 #define Freq fc.freq
80 #define Code fc.code
81 #define Dad dl.dad
82 #define Len dl.len
83
84 typedef struct static_tree_desc_s static_tree
85
86 typedef struct tree_desc_s {
87 ct_data *dyn_tree; /* the dynami
88 int max_code; /* largest co
89 const static_tree_desc *stat_desc; /* the
90 } FAR tree_desc;
91
92 typedef ush Pos;
93 typedef Pos FAR Posf;
94 typedef unsigned IPos;
95
96 /* A Pos is an index in the character window.
97 * save space in the various tables. IPos is u
98 */
99
100 typedef struct internal_state {
101 z_streamp strm; /* pointer back to th
102 int status; /* as the name implie
103 Bytef *pending_buf; /* output still pendi
104 ulg pending_buf_size; /* size of pending
105 Bytef *pending_out; /* next pending byte
106 ulg pending; /* nb of bytes in the
107 int wrap; /* bit 0 true for zli
108 gz_headerp gzhead; /* gzip header inform
109 ulg gzindex; /* where in extra, na
110 Byte method; /* can only be DEFLAT
111 int last_flush; /* value of flush par
112
113 /* used by deflate.c: */
114
115 uInt w_size; /* LZ77 window size (
116 uInt w_bits; /* log2(w_size) (8..
117 uInt w_mask; /* w_size - 1 */
118
119 Bytef *window;
120 /* Sliding window. Input bytes are read in
121 * and move to the first half later to kee
122 * bytes. With this organization, matches
123 * wSize-MAX_MATCH bytes, but this ensures
124 * performed with a length multiple of the
125 * the window size to 64K, which is quite
126 * To do: use the user input buffer as sli
127 */
128
129 ulg window_size;
130 /* Actual size of window: 2*wSize, except
131 * is directly used as sliding window.
132 */
133
134 Posf *prev;
135 /* Link to older string with same hash ind
136 * array to 64K, this link is maintained o
137 * An index in this array is thus a window
138 */
139
140 Posf *head; /* Heads of the hash chains or
141
142 uInt ins_h; /* hash index of str
143 uInt hash_size; /* number of element
144 uInt hash_bits; /* log2(hash_size) *
145 uInt hash_mask; /* hash_size-1 */
146
147 uInt hash_shift;
148 /* Number of bits by which ins_h must be s
149 * step. It must be such that after MIN_MA
150 * byte no longer takes part in the hash k
151 * hash_shift * MIN_MATCH >= hash_bits
152 */
153
154 long block_start;
155 /* Window position at the beginning of the
156 * negative when the window is moved backw
157 */
158
159 uInt match_length; /* length of
160 IPos prev_match; /* previous m
161 int match_available; /* set if pre
162 uInt strstart; /* start of s
163 uInt match_start; /* start of m
164 uInt lookahead; /* number of
165
166 uInt prev_length;
167 /* Length of the best match at previous st
168 * are discarded. This is used in the lazy
169 */
170
171 uInt max_chain_length;
172 /* To speed up deflation, hash chains are
173 * length. A higher limit improves compre
174 * speed.
175 */
176
177 uInt max_lazy_match;
178 /* Attempt to find a better match only whe
179 * smaller than this value. This mechanism
180 * levels >= 4.
181 */
182 # define max_insert_length max_lazy_match
183 /* Insert new strings in the hash table on
184 * greater than this length. This saves ti
185 * max_insert_length is used only for comp
186 */
187
188 int level; /* compression level (1..9)
189 int strategy; /* favor or force Huffman co
190
191 uInt good_match;
192 /* Use a faster search when the previous m
193
194 int nice_match; /* Stop searching when cur
195
196 /* used by trees.c: */
197 /* Didn't use ct_data typedef below to sup
198 struct ct_data_s dyn_ltree[HEAP_SIZE]; /
199 struct ct_data_s dyn_dtree[2*D_CODES+1]; /
200 struct ct_data_s bl_tree[2*BL_CODES+1]; /
201
202 struct tree_desc_s l_desc; /
203 struct tree_desc_s d_desc; /
204 struct tree_desc_s bl_desc; /
205
206 ush bl_count[MAX_BITS+1];
207 /* number of codes at each bit length for
208
209 int heap[2*L_CODES+1]; /* heap used t
210 int heap_len; /* number of e
211 int heap_max; /* element of
212 /* The sons of heap[n] are heap[2*n] and h
213 * The same heap array is used to build al
214 */
215
216 uch depth[2*L_CODES+1];
217 /* Depth of each subtree used as tie break
218 */
219
220 uchf *sym_buf; /* buffer for distan
221
222 uInt lit_bufsize;
223 /* Size of match buffer for literals/lengt
224 * limiting lit_bufsize to 64K:
225 * - frequencies can be kept in 16 bit c
226 * - if compression is not successful fo
227 * data is still in the window so we c
228 * when input comes from standard inpu
229 * all blocks if lit_bufsize is not gr
230 * - if compression is not successful fo
231 * even emit a stored file instead of
232 * This is applicable only for zip (no
233 * - creating new Huffman trees less fre
234 * adaptation to changes in the input
235 * example a binary file with poorly c
236 * a highly compressible string table.
237 * fast adaptation but have of course
238 * trees more frequently.
239 * - I can't count above 4
240 */
241
242 uInt sym_next; /* running index in sy
243 uInt sym_end; /* symbol table full w
244
245 ulg opt_len; /* bit length of curre
246 ulg static_len; /* bit length of curre
247 uInt matches; /* number of string ma
248 uInt insert; /* bytes at end of win
249
250 #ifdef ZLIB_DEBUG
251 ulg compressed_len; /* total bit length of
252 ulg bits_sent; /* bit length of compr
253 #endif
254
255 ush bi_buf;
256 /* Output buffer. bits are inserted starti
257 * significant bits).
258 */
259 int bi_valid;
260 /* Number of valid bits in bi_buf. All bi
261 * are always zero.
262 */
263
264 ulg high_water;
265 /* High water mark offset in window for in
266 * this are set to zero in order to avoid
267 * longest match routines access bytes pas
268 * updated to the new high water mark.
269 */
270
271 } FAR deflate_state;
272
273 /* Output a byte on the stream.
274 * IN assertion: there is enough room in pendi
275 */
276 #define put_byte(s, c) {s->pending_buf[s->pend
277
278
279 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
280 /* Minimum amount of lookahead, except at the
281 * See deflate.c for comments about the MIN_MA
282 */
283
284 #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEA
285 /* In order to simplify the code, particularly
286 * distances are limited to MAX_DIST instead o
287 */
288
289 #define WIN_INIT MAX_MATCH
290 /* Number of bytes after end of data in window
291 memory checker errors from longest match ro
292
293 /* in trees.c */
294 void ZLIB_INTERNAL _tr_init OF((deflate_state
295 int ZLIB_INTERNAL _tr_tally OF((deflate_state
296 void ZLIB_INTERNAL _tr_flush_block OF((deflate
297 ulg stored_len, int la
298 void ZLIB_INTERNAL _tr_flush_bits OF((deflate_
299 void ZLIB_INTERNAL _tr_align OF((deflate_state
300 void ZLIB_INTERNAL _tr_stored_block OF((deflat
301 ulg stored_len, int la
302
303 #define d_code(dist) \
304 ((dist) < 256 ? _dist_code[dist] : _dist_co
305 /* Mapping from a distance to a distance code.
306 * must not have side effects. _dist_code[256]
307 * used.
308 */
309
310 #ifndef ZLIB_DEBUG
311 /* Inline versions of _tr_tally for speed: */
312
313 #if defined(GEN_TREES_H) || !defined(STDC)
314 extern uch ZLIB_INTERNAL _length_code[];
315 extern uch ZLIB_INTERNAL _dist_code[];
316 #else
317 extern const uch ZLIB_INTERNAL _length_code[
318 extern const uch ZLIB_INTERNAL _dist_code[];
319 #endif
320
321 # define _tr_tally_lit(s, c, flush) \
322 { uch cc = (c); \
323 s->sym_buf[s->sym_next++] = 0; \
324 s->sym_buf[s->sym_next++] = 0; \
325 s->sym_buf[s->sym_next++] = cc; \
326 s->dyn_ltree[cc].Freq++; \
327 flush = (s->sym_next == s->sym_end); \
328 }
329 # define _tr_tally_dist(s, distance, length, f
330 { uch len = (uch)(length); \
331 ush dist = (ush)(distance); \
332 s->sym_buf[s->sym_next++] = (uch)dist; \
333 s->sym_buf[s->sym_next++] = (uch)(dist >>
334 s->sym_buf[s->sym_next++] = len; \
335 dist--; \
336 s->dyn_ltree[_length_code[len]+LITERALS+1]
337 s->dyn_dtree[d_code(dist)].Freq++; \
338 flush = (s->sym_next == s->sym_end); \
339 }
340 #else
341 # define _tr_tally_lit(s, c, flush) flush = _t
342 # define _tr_tally_dist(s, distance, length, f
343 flush = _tr_tally(s, distance, l
344 #endif
345
346 #endif /* DEFLATE_H */
347