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) 1995-2004 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 INIT_STATE 42 |
|
76 #define EXTRA_STATE 69 |
|
77 #define NAME_STATE 73 |
|
78 #define COMMENT_STATE 91 |
|
79 #define HCRC_STATE 103 |
|
80 #define BUSY_STATE 113 |
|
81 #define FINISH_STATE 666 |
|
82 /* Stream status */ |
|
83 |
|
84 |
|
85 /* Data structure describing a single value and its code string. */ |
|
86 typedef struct ct_data_s { |
|
87 union { |
|
88 ush freq; /* frequency count */ |
|
89 ush code; /* bit string */ |
|
90 } fc; |
|
91 union { |
|
92 ush dad; /* father node in Huffman tree */ |
|
93 ush len; /* length of bit string */ |
|
94 } dl; |
|
95 } FAR ct_data; |
|
96 |
|
97 #define Freq fc.freq |
|
98 #define Code fc.code |
|
99 #define Dad dl.dad |
|
100 #define Len dl.len |
|
101 |
|
102 typedef struct static_tree_desc_s static_tree_desc; |
|
103 |
|
104 typedef struct tree_desc_s { |
|
105 ct_data *dyn_tree; /* the dynamic tree */ |
|
106 int max_code; /* largest code with non zero frequency */ |
|
107 static_tree_desc *stat_desc; /* the corresponding static tree */ |
|
108 } FAR tree_desc; |
|
109 |
|
110 typedef ush Pos; |
|
111 typedef Pos FAR Posf; |
|
112 typedef unsigned IPos; |
|
113 |
|
114 /* A Pos is an index in the character window. We use short instead of int to |
|
115 * save space in the various tables. IPos is used only for parameter passing. |
|
116 */ |
|
117 |
|
118 typedef struct internal_state { |
|
119 z_streamp strm; /* pointer back to this zlib stream */ |
|
120 int status; /* as the name implies */ |
|
121 Bytef *pending_buf; /* output still pending */ |
|
122 ulg pending_buf_size; /* size of pending_buf */ |
|
123 Bytef *pending_out; /* next pending byte to output to the stream */ |
|
124 uInt pending; /* nb of bytes in the pending buffer */ |
|
125 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ |
|
126 gz_headerp gzhead; /* gzip header information to write */ |
|
127 uInt gzindex; /* where in extra, name, or comment */ |
|
128 Byte method; /* STORED (for zip only) or DEFLATED */ |
|
129 int last_flush; /* value of flush param for previous deflate call */ |
|
130 |
|
131 /* used by deflate.c: */ |
|
132 |
|
133 uInt w_size; /* LZ77 window size (32K by default) */ |
|
134 uInt w_bits; /* log2(w_size) (8..16) */ |
|
135 uInt w_mask; /* w_size - 1 */ |
|
136 |
|
137 Bytef *window; |
|
138 /* Sliding window. Input bytes are read into the second half of the window, |
|
139 * and move to the first half later to keep a dictionary of at least wSize |
|
140 * bytes. With this organization, matches are limited to a distance of |
|
141 * wSize-MAX_MATCH bytes, but this ensures that IO is always |
|
142 * performed with a length multiple of the block size. Also, it limits |
|
143 * the window size to 64K, which is quite useful on MSDOS. |
|
144 * To do: use the user input buffer as sliding window. |
|
145 */ |
|
146 |
|
147 ulg window_size; |
|
148 /* Actual size of window: 2*wSize, except when the user input buffer |
|
149 * is directly used as sliding window. |
|
150 */ |
|
151 |
|
152 Posf *prev; |
|
153 /* Link to older string with same hash index. To limit the size of this |
|
154 * array to 64K, this link is maintained only for the last 32K strings. |
|
155 * An index in this array is thus a window index modulo 32K. |
|
156 */ |
|
157 |
|
158 Posf *head; /* Heads of the hash chains or NIL. */ |
|
159 |
|
160 uInt ins_h; /* hash index of string to be inserted */ |
|
161 uInt hash_size; /* number of elements in hash table */ |
|
162 uInt hash_bits; /* log2(hash_size) */ |
|
163 uInt hash_mask; /* hash_size-1 */ |
|
164 |
|
165 uInt hash_shift; |
|
166 /* Number of bits by which ins_h must be shifted at each input |
|
167 * step. It must be such that after MIN_MATCH steps, the oldest |
|
168 * byte no longer takes part in the hash key, that is: |
|
169 * hash_shift * MIN_MATCH >= hash_bits |
|
170 */ |
|
171 |
|
172 long block_start; |
|
173 /* Window position at the beginning of the current output block. Gets |
|
174 * negative when the window is moved backwards. |
|
175 */ |
|
176 |
|
177 uInt match_length; /* length of best match */ |
|
178 IPos prev_match; /* previous match */ |
|
179 int match_available; /* set if previous match exists */ |
|
180 uInt strstart; /* start of string to insert */ |
|
181 uInt match_start; /* start of matching string */ |
|
182 uInt lookahead; /* number of valid bytes ahead in window */ |
|
183 |
|
184 uInt prev_length; |
|
185 /* Length of the best match at previous step. Matches not greater than this |
|
186 * are discarded. This is used in the lazy match evaluation. |
|
187 */ |
|
188 |
|
189 uInt max_chain_length; |
|
190 /* To speed up deflation, hash chains are never searched beyond this |
|
191 * length. A higher limit improves compression ratio but degrades the |
|
192 * speed. |
|
193 */ |
|
194 |
|
195 uInt max_lazy_match; |
|
196 /* Attempt to find a better match only when the current match is strictly |
|
197 * smaller than this value. This mechanism is used only for compression |
|
198 * levels >= 4. |
|
199 */ |
|
200 # define max_insert_length max_lazy_match |
|
201 /* Insert new strings in the hash table only if the match length is not |
|
202 * greater than this length. This saves time but degrades compression. |
|
203 * max_insert_length is used only for compression levels <= 3. |
|
204 */ |
|
205 |
|
206 int level; /* compression level (1..9) */ |
|
207 int strategy; /* favor or force Huffman coding*/ |
|
208 |
|
209 uInt good_match; |
|
210 /* Use a faster search when the previous match is longer than this */ |
|
211 |
|
212 int nice_match; /* Stop searching when current match exceeds this */ |
|
213 |
|
214 /* used by trees.c: */ |
|
215 /* Didn't use ct_data typedef below to supress compiler warning */ |
|
216 struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ |
|
217 struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ |
|
218 struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ |
|
219 |
|
220 struct tree_desc_s l_desc; /* desc. for literal tree */ |
|
221 struct tree_desc_s d_desc; /* desc. for distance tree */ |
|
222 struct tree_desc_s bl_desc; /* desc. for bit length tree */ |
|
223 |
|
224 ush bl_count[MAX_BITS+1]; |
|
225 /* number of codes at each bit length for an optimal tree */ |
|
226 |
|
227 int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ |
|
228 int heap_len; /* number of elements in the heap */ |
|
229 int heap_max; /* element of largest frequency */ |
|
230 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. |
|
231 * The same heap array is used to build all trees. |
|
232 */ |
|
233 |
|
234 uch depth[2*L_CODES+1]; |
|
235 /* Depth of each subtree used as tie breaker for trees of equal frequency |
|
236 */ |
|
237 |
|
238 uchf *l_buf; /* buffer for literals or lengths */ |
|
239 |
|
240 uInt lit_bufsize; |
|
241 /* Size of match buffer for literals/lengths. There are 4 reasons for |
|
242 * limiting lit_bufsize to 64K: |
|
243 * - frequencies can be kept in 16 bit counters |
|
244 * - if compression is not successful for the first block, all input |
|
245 * data is still in the window so we can still emit a stored block even |
|
246 * when input comes from standard input. (This can also be done for |
|
247 * all blocks if lit_bufsize is not greater than 32K.) |
|
248 * - if compression is not successful for a file smaller than 64K, we can |
|
249 * even emit a stored file instead of a stored block (saving 5 bytes). |
|
250 * This is applicable only for zip (not gzip or zlib). |
|
251 * - creating new Huffman trees less frequently may not provide fast |
|
252 * adaptation to changes in the input data statistics. (Take for |
|
253 * example a binary file with poorly compressible code followed by |
|
254 * a highly compressible string table.) Smaller buffer sizes give |
|
255 * fast adaptation but have of course the overhead of transmitting |
|
256 * trees more frequently. |
|
257 * - I can't count above 4 |
|
258 */ |
|
259 |
|
260 uInt last_lit; /* running index in l_buf */ |
|
261 |
|
262 ushf *d_buf; |
|
263 /* Buffer for distances. To simplify the code, d_buf and l_buf have |
|
264 * the same number of elements. To use different lengths, an extra flag |
|
265 * array would be necessary. |
|
266 */ |
|
267 |
|
268 ulg opt_len; /* bit length of current block with optimal trees */ |
|
269 ulg static_len; /* bit length of current block with static trees */ |
|
270 uInt matches; /* number of string matches in current block */ |
|
271 int last_eob_len; /* bit length of EOB code for last block */ |
|
272 |
|
273 #ifdef DEBUG |
|
274 ulg compressed_len; /* total bit length of compressed file mod 2^32 */ |
|
275 ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ |
|
276 #endif |
|
277 |
|
278 ush bi_buf; |
|
279 /* Output buffer. bits are inserted starting at the bottom (least |
|
280 * significant bits). |
|
281 */ |
|
282 int bi_valid; |
|
283 /* Number of valid bits in bi_buf. All bits above the last valid bit |
|
284 * are always zero. |
|
285 */ |
|
286 |
|
287 } FAR deflate_state; |
|
288 |
|
289 /* Output a byte on the stream. |
|
290 * IN assertion: there is enough room in pending_buf. |
|
291 */ |
|
292 #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);} |
|
293 |
|
294 |
|
295 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) |
|
296 /* Minimum amount of lookahead, except at the end of the input file. |
|
297 * See deflate.c for comments about the MIN_MATCH+1. |
|
298 */ |
|
299 |
|
300 #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) |
|
301 /* In order to simplify the code, particularly on 16 bit machines, match |
|
302 * distances are limited to MAX_DIST instead of WSIZE. |
|
303 */ |
|
304 |
|
305 /* in trees.c */ |
|
306 void _tr_init OF((deflate_state *s)); |
|
307 int _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); |
|
308 void _tr_flush_block OF((deflate_state *s, charf *buf, ulg stored_len, |
|
309 int eof)); |
|
310 void _tr_align OF((deflate_state *s)); |
|
311 void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len, |
|
312 int eof)); |
|
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 DEBUG |
|
322 /* Inline versions of _tr_tally for speed: */ |
|
323 |
|
324 #if defined(GEN_TREES_H) || !defined(STDC) |
|
325 extern uch _length_code[]; |
|
326 extern uch _dist_code[]; |
|
327 #else |
|
328 extern const uch _length_code[]; |
|
329 extern const uch _dist_code[]; |
|
330 #endif |
|
331 |
|
332 # define _tr_tally_lit(s, c, flush) \ |
|
333 { uch cc = (c); \ |
|
334 s->d_buf[s->last_lit] = 0; \ |
|
335 s->l_buf[s->last_lit++] = cc; \ |
|
336 s->dyn_ltree[cc].Freq++; \ |
|
337 flush = (s->last_lit == s->lit_bufsize-1); \ |
|
338 } |
|
339 # define _tr_tally_dist(s, distance, length, flush) \ |
|
340 { uch len = (length); \ |
|
341 ush dist = (distance); \ |
|
342 s->d_buf[s->last_lit] = dist; \ |
|
343 s->l_buf[s->last_lit++] = len; \ |
|
344 dist--; \ |
|
345 s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ |
|
346 s->dyn_dtree[d_code(dist)].Freq++; \ |
|
347 flush = (s->last_lit == s->lit_bufsize-1); \ |
|
348 } |
|
349 #else |
|
350 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) |
|
351 # define _tr_tally_dist(s, distance, length, flush) \ |
|
352 flush = _tr_tally(s, distance, length) |
|
353 #endif |
|
354 |
|
355 #endif /* DEFLATE_H */ |
|