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f3919878 | 1 | /* deflate.h -- internal compression state |
2 | * Copyright (C) 1995-2012 Jean-loup Gailly | |
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 | ||
26 | /* =========================================================================== | |
27 | * Internal compression state. | |
28 | */ | |
29 | ||
30 | #define LENGTH_CODES 29 | |
31 | /* number of length codes, not counting the special END_BLOCK code */ | |
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, including the END_BLOCK code */ | |
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 lengths */ | |
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 | |
55 | #define EXTRA_STATE 69 | |
56 | #define NAME_STATE 73 | |
57 | #define COMMENT_STATE 91 | |
58 | #define HCRC_STATE 103 | |
59 | #define BUSY_STATE 113 | |
60 | #define FINISH_STATE 666 | |
61 | /* Stream status */ | |
62 | ||
63 | ||
64 | /* Data structure describing a single value and its code string. */ | |
65 | typedef struct ct_data_s { | |
66 | union { | |
67 | ush freq; /* frequency count */ | |
68 | ush code; /* bit string */ | |
69 | } fc; | |
70 | union { | |
71 | ush dad; /* father node in Huffman tree */ | |
72 | ush len; /* length of bit string */ | |
73 | } dl; | |
74 | } FAR ct_data; | |
75 | ||
76 | #define Freq fc.freq | |
77 | #define Code fc.code | |
78 | #define Dad dl.dad | |
79 | #define Len dl.len | |
80 | ||
81 | typedef struct static_tree_desc_s static_tree_desc; | |
82 | ||
83 | typedef struct tree_desc_s { | |
84 | ct_data *dyn_tree; /* the dynamic tree */ | |
85 | int max_code; /* largest code with non zero frequency */ | |
86 | static_tree_desc *stat_desc; /* the corresponding static tree */ | |
87 | } FAR tree_desc; | |
88 | ||
89 | typedef ush Pos; | |
90 | typedef Pos FAR Posf; | |
91 | typedef unsigned IPos; | |
92 | ||
93 | /* A Pos is an index in the character window. We use short instead of int to | |
94 | * save space in the various tables. IPos is used only for parameter passing. | |
95 | */ | |
96 | ||
97 | typedef struct internal_state { | |
98 | z_streamp strm; /* pointer back to this zlib stream */ | |
99 | int status; /* as the name implies */ | |
100 | Bytef *pending_buf; /* output still pending */ | |
101 | ulg pending_buf_size; /* size of pending_buf */ | |
102 | Bytef *pending_out; /* next pending byte to output to the stream */ | |
103 | uInt pending; /* nb of bytes in the pending buffer */ | |
104 | int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ | |
105 | gz_headerp gzhead; /* gzip header information to write */ | |
106 | uInt gzindex; /* where in extra, name, or comment */ | |
107 | Byte method; /* can only be DEFLATED */ | |
108 | int last_flush; /* value of flush param for previous deflate call */ | |
109 | ||
110 | /* used by deflate.c: */ | |
111 | ||
112 | uInt w_size; /* LZ77 window size (32K by default) */ | |
113 | uInt w_bits; /* log2(w_size) (8..16) */ | |
114 | uInt w_mask; /* w_size - 1 */ | |
115 | ||
116 | Bytef *window; | |
117 | /* Sliding window. Input bytes are read into the second half of the window, | |
118 | * and move to the first half later to keep a dictionary of at least wSize | |
119 | * bytes. With this organization, matches are limited to a distance of | |
120 | * wSize-MAX_MATCH bytes, but this ensures that IO is always | |
121 | * performed with a length multiple of the block size. Also, it limits | |
122 | * the window size to 64K, which is quite useful on MSDOS. | |
123 | * To do: use the user input buffer as sliding window. | |
124 | */ | |
125 | ||
126 | ulg window_size; | |
127 | /* Actual size of window: 2*wSize, except when the user input buffer | |
128 | * is directly used as sliding window. | |
129 | */ | |
130 | ||
131 | Posf *prev; | |
132 | /* Link to older string with same hash index. To limit the size of this | |
133 | * array to 64K, this link is maintained only for the last 32K strings. | |
134 | * An index in this array is thus a window index modulo 32K. | |
135 | */ | |
136 | ||
137 | Posf *head; /* Heads of the hash chains or NIL. */ | |
138 | ||
139 | uInt ins_h; /* hash index of string to be inserted */ | |
140 | uInt hash_size; /* number of elements in hash table */ | |
141 | uInt hash_bits; /* log2(hash_size) */ | |
142 | uInt hash_mask; /* hash_size-1 */ | |
143 | ||
144 | uInt hash_shift; | |
145 | /* Number of bits by which ins_h must be shifted at each input | |
146 | * step. It must be such that after MIN_MATCH steps, the oldest | |
147 | * byte no longer takes part in the hash key, that is: | |
148 | * hash_shift * MIN_MATCH >= hash_bits | |
149 | */ | |
150 | ||
151 | long block_start; | |
152 | /* Window position at the beginning of the current output block. Gets | |
153 | * negative when the window is moved backwards. | |
154 | */ | |
155 | ||
156 | uInt match_length; /* length of best match */ | |
157 | IPos prev_match; /* previous match */ | |
158 | int match_available; /* set if previous match exists */ | |
159 | uInt strstart; /* start of string to insert */ | |
160 | uInt match_start; /* start of matching string */ | |
161 | uInt lookahead; /* number of valid bytes ahead in window */ | |
162 | ||
163 | uInt prev_length; | |
164 | /* Length of the best match at previous step. Matches not greater than this | |
165 | * are discarded. This is used in the lazy match evaluation. | |
166 | */ | |
167 | ||
168 | uInt max_chain_length; | |
169 | /* To speed up deflation, hash chains are never searched beyond this | |
170 | * length. A higher limit improves compression ratio but degrades the | |
171 | * speed. | |
172 | */ | |
173 | ||
174 | uInt max_lazy_match; | |
175 | /* Attempt to find a better match only when the current match is strictly | |
176 | * smaller than this value. This mechanism is used only for compression | |
177 | * levels >= 4. | |
178 | */ | |
179 | # define max_insert_length max_lazy_match | |
180 | /* Insert new strings in the hash table only if the match length is not | |
181 | * greater than this length. This saves time but degrades compression. | |
182 | * max_insert_length is used only for compression levels <= 3. | |
183 | */ | |
184 | ||
185 | int level; /* compression level (1..9) */ | |
186 | int strategy; /* favor or force Huffman coding*/ | |
187 | ||
188 | uInt good_match; | |
189 | /* Use a faster search when the previous match is longer than this */ | |
190 | ||
191 | int nice_match; /* Stop searching when current match exceeds this */ | |
192 | ||
193 | /* used by trees.c: */ | |
194 | /* Didn't use ct_data typedef below to suppress compiler warning */ | |
195 | struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ | |
196 | struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ | |
197 | struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ | |
198 | ||
199 | struct tree_desc_s l_desc; /* desc. for literal tree */ | |
200 | struct tree_desc_s d_desc; /* desc. for distance tree */ | |
201 | struct tree_desc_s bl_desc; /* desc. for bit length tree */ | |
202 | ||
203 | ush bl_count[MAX_BITS+1]; | |
204 | /* number of codes at each bit length for an optimal tree */ | |
205 | ||
206 | int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ | |
207 | int heap_len; /* number of elements in the heap */ | |
208 | int heap_max; /* element of largest frequency */ | |
209 | /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. | |
210 | * The same heap array is used to build all trees. | |
211 | */ | |
212 | ||
213 | uch depth[2*L_CODES+1]; | |
214 | /* Depth of each subtree used as tie breaker for trees of equal frequency | |
215 | */ | |
216 | ||
217 | uchf *l_buf; /* buffer for literals or lengths */ | |
218 | ||
219 | uInt lit_bufsize; | |
220 | /* Size of match buffer for literals/lengths. There are 4 reasons for | |
221 | * limiting lit_bufsize to 64K: | |
222 | * - frequencies can be kept in 16 bit counters | |
223 | * - if compression is not successful for the first block, all input | |
224 | * data is still in the window so we can still emit a stored block even | |
225 | * when input comes from standard input. (This can also be done for | |
226 | * all blocks if lit_bufsize is not greater than 32K.) | |
227 | * - if compression is not successful for a file smaller than 64K, we can | |
228 | * even emit a stored file instead of a stored block (saving 5 bytes). | |
229 | * This is applicable only for zip (not gzip or zlib). | |
230 | * - creating new Huffman trees less frequently may not provide fast | |
231 | * adaptation to changes in the input data statistics. (Take for | |
232 | * example a binary file with poorly compressible code followed by | |
233 | * a highly compressible string table.) Smaller buffer sizes give | |
234 | * fast adaptation but have of course the overhead of transmitting | |
235 | * trees more frequently. | |
236 | * - I can't count above 4 | |
237 | */ | |
238 | ||
239 | uInt last_lit; /* running index in l_buf */ | |
240 | ||
241 | ushf *d_buf; | |
242 | /* Buffer for distances. To simplify the code, d_buf and l_buf have | |
243 | * the same number of elements. To use different lengths, an extra flag | |
244 | * array would be necessary. | |
245 | */ | |
246 | ||
247 | ulg opt_len; /* bit length of current block with optimal trees */ | |
248 | ulg static_len; /* bit length of current block with static trees */ | |
249 | uInt matches; /* number of string matches in current block */ | |
250 | uInt insert; /* bytes at end of window left to insert */ | |
251 | ||
252 | #ifdef DEBUG | |
253 | ulg compressed_len; /* total bit length of compressed file mod 2^32 */ | |
254 | ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ | |
255 | #endif | |
256 | ||
257 | ush bi_buf; | |
258 | /* Output buffer. bits are inserted starting at the bottom (least | |
259 | * significant bits). | |
260 | */ | |
261 | int bi_valid; | |
262 | /* Number of valid bits in bi_buf. All bits above the last valid bit | |
263 | * are always zero. | |
264 | */ | |
265 | ||
266 | ulg high_water; | |
267 | /* High water mark offset in window for initialized bytes -- bytes above | |
268 | * this are set to zero in order to avoid memory check warnings when | |
269 | * longest match routines access bytes past the input. This is then | |
270 | * updated to the new high water mark. | |
271 | */ | |
272 | ||
273 | } FAR deflate_state; | |
274 | ||
275 | /* Output a byte on the stream. | |
276 | * IN assertion: there is enough room in pending_buf. | |
277 | */ | |
278 | #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);} | |
279 | ||
280 | ||
281 | #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) | |
282 | /* Minimum amount of lookahead, except at the end of the input file. | |
283 | * See deflate.c for comments about the MIN_MATCH+1. | |
284 | */ | |
285 | ||
286 | #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) | |
287 | /* In order to simplify the code, particularly on 16 bit machines, match | |
288 | * distances are limited to MAX_DIST instead of WSIZE. | |
289 | */ | |
290 | ||
291 | #define WIN_INIT MAX_MATCH | |
292 | /* Number of bytes after end of data in window to initialize in order to avoid | |
293 | memory checker errors from longest match routines */ | |
294 | ||
295 | /* in trees.c */ | |
296 | void ZLIB_INTERNAL _tr_init OF((deflate_state *s)); | |
297 | int ZLIB_INTERNAL _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); | |
298 | void ZLIB_INTERNAL _tr_flush_block OF((deflate_state *s, charf *buf, | |
299 | ulg stored_len, int last)); | |
300 | void ZLIB_INTERNAL _tr_flush_bits OF((deflate_state *s)); | |
301 | void ZLIB_INTERNAL _tr_align OF((deflate_state *s)); | |
302 | void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf, | |
303 | ulg stored_len, int last)); | |
304 | ||
305 | #define d_code(dist) \ | |
306 | ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)]) | |
307 | /* Mapping from a distance to a distance code. dist is the distance - 1 and | |
308 | * must not have side effects. _dist_code[256] and _dist_code[257] are never | |
309 | * used. | |
310 | */ | |
311 | ||
312 | #ifndef DEBUG | |
313 | /* Inline versions of _tr_tally for speed: */ | |
314 | ||
315 | #if defined(GEN_TREES_H) || !defined(STDC) | |
316 | extern uch ZLIB_INTERNAL _length_code[]; | |
317 | extern uch ZLIB_INTERNAL _dist_code[]; | |
318 | #else | |
319 | extern const uch ZLIB_INTERNAL _length_code[]; | |
320 | extern const uch ZLIB_INTERNAL _dist_code[]; | |
321 | #endif | |
322 | ||
323 | # define _tr_tally_lit(s, c, flush) \ | |
324 | { uch cc = (c); \ | |
325 | s->d_buf[s->last_lit] = 0; \ | |
326 | s->l_buf[s->last_lit++] = cc; \ | |
327 | s->dyn_ltree[cc].Freq++; \ | |
328 | flush = (s->last_lit == s->lit_bufsize-1); \ | |
329 | } | |
330 | # define _tr_tally_dist(s, distance, length, flush) \ | |
331 | { uch len = (length); \ | |
332 | ush dist = (distance); \ | |
333 | s->d_buf[s->last_lit] = dist; \ | |
334 | s->l_buf[s->last_lit++] = len; \ | |
335 | dist--; \ | |
336 | s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ | |
337 | s->dyn_dtree[d_code(dist)].Freq++; \ | |
338 | flush = (s->last_lit == s->lit_bufsize-1); \ | |
339 | } | |
340 | #else | |
341 | # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) | |
342 | # define _tr_tally_dist(s, distance, length, flush) \ | |
343 | flush = _tr_tally(s, distance, length) | |
344 | #endif | |
345 | ||
346 | #endif /* DEFLATE_H */ |