Details | Last modification | View Log | RSS feed
Rev | Author | Line No. | Line |
---|---|---|---|
4349 | Serge | 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 */>=> |