b24e7fce |
1 | /* deflate.h -- internal compression state |
648db22b |
2 | * Copyright (C) 1995-2024 Jean-loup Gailly |
b24e7fce |
3 | * For conditions of distribution and use, see copyright notice in zlib.h |
4 | */ |
5 | |
6 | /* WARNING: this file should *not* be used by applications. It is |
7 | part of the implementation of the compression library and is |
8 | subject to change. Applications should only use zlib.h. |
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 to disable gzip header and |
19 | trailer creation by deflate(). NO_GZIP would be used to avoid linking in |
20 | the crc code when it is not needed. For shared libraries, gzip encoding |
21 | should be left enabled. */ |
22 | #ifndef NO_GZIP |
23 | # define GZIP |
24 | #endif |
25 | |
648db22b |
26 | /* define LIT_MEM to slightly increase the speed of deflate (order 1% to 2%) at |
27 | the cost of a larger memory footprint */ |
28 | /* #define LIT_MEM */ |
29 | |
b24e7fce |
30 | /* =========================================================================== |
31 | * Internal compression state. |
32 | */ |
33 | |
34 | #define LENGTH_CODES 29 |
35 | /* number of length codes, not counting the special END_BLOCK code */ |
36 | |
37 | #define LITERALS 256 |
38 | /* number of literal bytes 0..255 */ |
39 | |
40 | #define L_CODES (LITERALS+1+LENGTH_CODES) |
41 | /* number of Literal or Length codes, including the END_BLOCK code */ |
42 | |
43 | #define D_CODES 30 |
44 | /* number of distance codes */ |
45 | |
46 | #define BL_CODES 19 |
47 | /* number of codes used to transfer the bit lengths */ |
48 | |
49 | #define HEAP_SIZE (2*L_CODES+1) |
50 | /* maximum heap size */ |
51 | |
52 | #define MAX_BITS 15 |
53 | /* All codes must not exceed MAX_BITS bits */ |
54 | |
55 | #define Buf_size 16 |
56 | /* size of bit buffer in bi_buf */ |
57 | |
58 | #define INIT_STATE 42 /* zlib header -> BUSY_STATE */ |
59 | #ifdef GZIP |
60 | # define GZIP_STATE 57 /* gzip header -> BUSY_STATE | EXTRA_STATE */ |
61 | #endif |
62 | #define EXTRA_STATE 69 /* gzip extra block -> NAME_STATE */ |
63 | #define NAME_STATE 73 /* gzip file name -> COMMENT_STATE */ |
64 | #define COMMENT_STATE 91 /* gzip comment -> HCRC_STATE */ |
65 | #define HCRC_STATE 103 /* gzip header CRC -> BUSY_STATE */ |
66 | #define BUSY_STATE 113 /* deflate -> FINISH_STATE */ |
67 | #define FINISH_STATE 666 /* stream complete */ |
68 | /* Stream status */ |
69 | |
70 | |
71 | /* Data structure describing a single value and its code string. */ |
72 | typedef struct ct_data_s { |
73 | union { |
74 | ush freq; /* frequency count */ |
75 | ush code; /* bit string */ |
76 | } fc; |
77 | union { |
78 | ush dad; /* father node in Huffman tree */ |
79 | ush len; /* length of bit string */ |
80 | } dl; |
81 | } FAR ct_data; |
82 | |
83 | #define Freq fc.freq |
84 | #define Code fc.code |
85 | #define Dad dl.dad |
86 | #define Len dl.len |
87 | |
88 | typedef struct static_tree_desc_s static_tree_desc; |
89 | |
90 | typedef struct tree_desc_s { |
91 | ct_data *dyn_tree; /* the dynamic tree */ |
92 | int max_code; /* largest code with non zero frequency */ |
93 | const static_tree_desc *stat_desc; /* the corresponding static tree */ |
94 | } FAR tree_desc; |
95 | |
96 | typedef ush Pos; |
97 | typedef Pos FAR Posf; |
98 | typedef unsigned IPos; |
99 | |
100 | /* A Pos is an index in the character window. We use short instead of int to |
101 | * save space in the various tables. IPos is used only for parameter passing. |
102 | */ |
103 | |
104 | typedef struct internal_state { |
105 | z_streamp strm; /* pointer back to this zlib stream */ |
106 | int status; /* as the name implies */ |
107 | Bytef *pending_buf; /* output still pending */ |
108 | ulg pending_buf_size; /* size of pending_buf */ |
109 | Bytef *pending_out; /* next pending byte to output to the stream */ |
110 | ulg pending; /* nb of bytes in the pending buffer */ |
111 | int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ |
112 | gz_headerp gzhead; /* gzip header information to write */ |
113 | ulg gzindex; /* where in extra, name, or comment */ |
114 | Byte method; /* can only be DEFLATED */ |
115 | int last_flush; /* value of flush param for previous deflate call */ |
116 | |
117 | /* used by deflate.c: */ |
118 | |
119 | uInt w_size; /* LZ77 window size (32K by default) */ |
120 | uInt w_bits; /* log2(w_size) (8..16) */ |
121 | uInt w_mask; /* w_size - 1 */ |
122 | |
123 | Bytef *window; |
124 | /* Sliding window. Input bytes are read into the second half of the window, |
125 | * and move to the first half later to keep a dictionary of at least wSize |
126 | * bytes. With this organization, matches are limited to a distance of |
127 | * wSize-MAX_MATCH bytes, but this ensures that IO is always |
128 | * performed with a length multiple of the block size. Also, it limits |
129 | * the window size to 64K, which is quite useful on MSDOS. |
130 | * To do: use the user input buffer as sliding window. |
131 | */ |
132 | |
133 | ulg window_size; |
134 | /* Actual size of window: 2*wSize, except when the user input buffer |
135 | * is directly used as sliding window. |
136 | */ |
137 | |
138 | Posf *prev; |
139 | /* Link to older string with same hash index. To limit the size of this |
140 | * array to 64K, this link is maintained only for the last 32K strings. |
141 | * An index in this array is thus a window index modulo 32K. |
142 | */ |
143 | |
144 | Posf *head; /* Heads of the hash chains or NIL. */ |
145 | |
146 | uInt ins_h; /* hash index of string to be inserted */ |
147 | uInt hash_size; /* number of elements in hash table */ |
148 | uInt hash_bits; /* log2(hash_size) */ |
149 | uInt hash_mask; /* hash_size-1 */ |
150 | |
151 | uInt hash_shift; |
152 | /* Number of bits by which ins_h must be shifted at each input |
153 | * step. It must be such that after MIN_MATCH steps, the oldest |
154 | * byte no longer takes part in the hash key, that is: |
155 | * hash_shift * MIN_MATCH >= hash_bits |
156 | */ |
157 | |
158 | long block_start; |
159 | /* Window position at the beginning of the current output block. Gets |
160 | * negative when the window is moved backwards. |
161 | */ |
162 | |
163 | uInt match_length; /* length of best match */ |
164 | IPos prev_match; /* previous match */ |
165 | int match_available; /* set if previous match exists */ |
166 | uInt strstart; /* start of string to insert */ |
167 | uInt match_start; /* start of matching string */ |
168 | uInt lookahead; /* number of valid bytes ahead in window */ |
169 | |
170 | uInt prev_length; |
171 | /* Length of the best match at previous step. Matches not greater than this |
172 | * are discarded. This is used in the lazy match evaluation. |
173 | */ |
174 | |
175 | uInt max_chain_length; |
176 | /* To speed up deflation, hash chains are never searched beyond this |
177 | * length. A higher limit improves compression ratio but degrades the |
178 | * speed. |
179 | */ |
180 | |
181 | uInt max_lazy_match; |
182 | /* Attempt to find a better match only when the current match is strictly |
183 | * smaller than this value. This mechanism is used only for compression |
184 | * levels >= 4. |
185 | */ |
186 | # define max_insert_length max_lazy_match |
187 | /* Insert new strings in the hash table only if the match length is not |
188 | * greater than this length. This saves time but degrades compression. |
189 | * max_insert_length is used only for compression levels <= 3. |
190 | */ |
191 | |
192 | int level; /* compression level (1..9) */ |
193 | int strategy; /* favor or force Huffman coding*/ |
194 | |
195 | uInt good_match; |
196 | /* Use a faster search when the previous match is longer than this */ |
197 | |
198 | int nice_match; /* Stop searching when current match exceeds this */ |
199 | |
200 | /* used by trees.c: */ |
201 | /* Didn't use ct_data typedef below to suppress compiler warning */ |
202 | struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ |
203 | struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ |
204 | struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ |
205 | |
206 | struct tree_desc_s l_desc; /* desc. for literal tree */ |
207 | struct tree_desc_s d_desc; /* desc. for distance tree */ |
208 | struct tree_desc_s bl_desc; /* desc. for bit length tree */ |
209 | |
210 | ush bl_count[MAX_BITS+1]; |
211 | /* number of codes at each bit length for an optimal tree */ |
212 | |
213 | int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ |
214 | int heap_len; /* number of elements in the heap */ |
215 | int heap_max; /* element of largest frequency */ |
216 | /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. |
217 | * The same heap array is used to build all trees. |
218 | */ |
219 | |
220 | uch depth[2*L_CODES+1]; |
221 | /* Depth of each subtree used as tie breaker for trees of equal frequency |
222 | */ |
223 | |
648db22b |
224 | #ifdef LIT_MEM |
225 | # define LIT_BUFS 5 |
226 | ushf *d_buf; /* buffer for distances */ |
227 | uchf *l_buf; /* buffer for literals/lengths */ |
228 | #else |
229 | # define LIT_BUFS 4 |
9e052883 |
230 | uchf *sym_buf; /* buffer for distances and literals/lengths */ |
648db22b |
231 | #endif |
b24e7fce |
232 | |
233 | uInt lit_bufsize; |
234 | /* Size of match buffer for literals/lengths. There are 4 reasons for |
235 | * limiting lit_bufsize to 64K: |
236 | * - frequencies can be kept in 16 bit counters |
237 | * - if compression is not successful for the first block, all input |
238 | * data is still in the window so we can still emit a stored block even |
239 | * when input comes from standard input. (This can also be done for |
240 | * all blocks if lit_bufsize is not greater than 32K.) |
241 | * - if compression is not successful for a file smaller than 64K, we can |
242 | * even emit a stored file instead of a stored block (saving 5 bytes). |
243 | * This is applicable only for zip (not gzip or zlib). |
244 | * - creating new Huffman trees less frequently may not provide fast |
245 | * adaptation to changes in the input data statistics. (Take for |
246 | * example a binary file with poorly compressible code followed by |
247 | * a highly compressible string table.) Smaller buffer sizes give |
248 | * fast adaptation but have of course the overhead of transmitting |
249 | * trees more frequently. |
250 | * - I can't count above 4 |
251 | */ |
252 | |
648db22b |
253 | uInt sym_next; /* running index in symbol buffer */ |
9e052883 |
254 | uInt sym_end; /* symbol table full when sym_next reaches this */ |
b24e7fce |
255 | |
256 | ulg opt_len; /* bit length of current block with optimal trees */ |
257 | ulg static_len; /* bit length of current block with static trees */ |
258 | uInt matches; /* number of string matches in current block */ |
259 | uInt insert; /* bytes at end of window left to insert */ |
260 | |
261 | #ifdef ZLIB_DEBUG |
262 | ulg compressed_len; /* total bit length of compressed file mod 2^32 */ |
263 | ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ |
264 | #endif |
265 | |
266 | ush bi_buf; |
267 | /* Output buffer. bits are inserted starting at the bottom (least |
268 | * significant bits). |
269 | */ |
270 | int bi_valid; |
271 | /* Number of valid bits in bi_buf. All bits above the last valid bit |
272 | * are always zero. |
273 | */ |
274 | |
275 | ulg high_water; |
276 | /* High water mark offset in window for initialized bytes -- bytes above |
277 | * this are set to zero in order to avoid memory check warnings when |
278 | * longest match routines access bytes past the input. This is then |
279 | * updated to the new high water mark. |
280 | */ |
281 | |
282 | } FAR deflate_state; |
283 | |
284 | /* Output a byte on the stream. |
285 | * IN assertion: there is enough room in pending_buf. |
286 | */ |
287 | #define put_byte(s, c) {s->pending_buf[s->pending++] = (Bytef)(c);} |
288 | |
289 | |
290 | #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) |
291 | /* Minimum amount of lookahead, except at the end of the input file. |
292 | * See deflate.c for comments about the MIN_MATCH+1. |
293 | */ |
294 | |
295 | #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) |
296 | /* In order to simplify the code, particularly on 16 bit machines, match |
297 | * distances are limited to MAX_DIST instead of WSIZE. |
298 | */ |
299 | |
300 | #define WIN_INIT MAX_MATCH |
301 | /* Number of bytes after end of data in window to initialize in order to avoid |
302 | memory checker errors from longest match routines */ |
303 | |
304 | /* in trees.c */ |
648db22b |
305 | void ZLIB_INTERNAL _tr_init(deflate_state *s); |
306 | int ZLIB_INTERNAL _tr_tally(deflate_state *s, unsigned dist, unsigned lc); |
307 | void ZLIB_INTERNAL _tr_flush_block(deflate_state *s, charf *buf, |
308 | ulg stored_len, int last); |
309 | void ZLIB_INTERNAL _tr_flush_bits(deflate_state *s); |
310 | void ZLIB_INTERNAL _tr_align(deflate_state *s); |
311 | void ZLIB_INTERNAL _tr_stored_block(deflate_state *s, charf *buf, |
312 | ulg stored_len, int last); |
b24e7fce |
313 | |
314 | #define d_code(dist) \ |
315 | ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)]) |
316 | /* Mapping from a distance to a distance code. dist is the distance - 1 and |
317 | * must not have side effects. _dist_code[256] and _dist_code[257] are never |
318 | * used. |
319 | */ |
320 | |
321 | #ifndef ZLIB_DEBUG |
322 | /* Inline versions of _tr_tally for speed: */ |
323 | |
324 | #if defined(GEN_TREES_H) || !defined(STDC) |
325 | extern uch ZLIB_INTERNAL _length_code[]; |
326 | extern uch ZLIB_INTERNAL _dist_code[]; |
327 | #else |
328 | extern const uch ZLIB_INTERNAL _length_code[]; |
329 | extern const uch ZLIB_INTERNAL _dist_code[]; |
330 | #endif |
331 | |
648db22b |
332 | #ifdef LIT_MEM |
333 | # define _tr_tally_lit(s, c, flush) \ |
334 | { uch cc = (c); \ |
335 | s->d_buf[s->sym_next] = 0; \ |
336 | s->l_buf[s->sym_next++] = cc; \ |
337 | s->dyn_ltree[cc].Freq++; \ |
338 | flush = (s->sym_next == s->sym_end); \ |
339 | } |
340 | # define _tr_tally_dist(s, distance, length, flush) \ |
341 | { uch len = (uch)(length); \ |
342 | ush dist = (ush)(distance); \ |
343 | s->d_buf[s->sym_next] = dist; \ |
344 | s->l_buf[s->sym_next++] = len; \ |
345 | dist--; \ |
346 | s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ |
347 | s->dyn_dtree[d_code(dist)].Freq++; \ |
348 | flush = (s->sym_next == s->sym_end); \ |
349 | } |
350 | #else |
b24e7fce |
351 | # define _tr_tally_lit(s, c, flush) \ |
352 | { uch cc = (c); \ |
9e052883 |
353 | s->sym_buf[s->sym_next++] = 0; \ |
354 | s->sym_buf[s->sym_next++] = 0; \ |
355 | s->sym_buf[s->sym_next++] = cc; \ |
b24e7fce |
356 | s->dyn_ltree[cc].Freq++; \ |
9e052883 |
357 | flush = (s->sym_next == s->sym_end); \ |
b24e7fce |
358 | } |
359 | # define _tr_tally_dist(s, distance, length, flush) \ |
360 | { uch len = (uch)(length); \ |
361 | ush dist = (ush)(distance); \ |
9e052883 |
362 | s->sym_buf[s->sym_next++] = (uch)dist; \ |
363 | s->sym_buf[s->sym_next++] = (uch)(dist >> 8); \ |
364 | s->sym_buf[s->sym_next++] = len; \ |
b24e7fce |
365 | dist--; \ |
366 | s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ |
367 | s->dyn_dtree[d_code(dist)].Freq++; \ |
9e052883 |
368 | flush = (s->sym_next == s->sym_end); \ |
b24e7fce |
369 | } |
648db22b |
370 | #endif |
b24e7fce |
371 | #else |
372 | # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) |
373 | # define _tr_tally_dist(s, distance, length, flush) \ |
374 | flush = _tr_tally(s, distance, length) |
375 | #endif |
376 | |
377 | #endif /* DEFLATE_H */ |