1 | /* |
2 | * Copyright (c) 2008 Apple Inc. All rights reserved. |
3 | * |
4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ |
5 | * |
6 | * This file contains Original Code and/or Modifications of Original Code |
7 | * as defined in and that are subject to the Apple Public Source License |
8 | * Version 2.0 (the 'License'). You may not use this file except in |
9 | * compliance with the License. The rights granted to you under the License |
10 | * may not be used to create, or enable the creation or redistribution of, |
11 | * unlawful or unlicensed copies of an Apple operating system, or to |
12 | * circumvent, violate, or enable the circumvention or violation of, any |
13 | * terms of an Apple operating system software license agreement. |
14 | * |
15 | * Please obtain a copy of the License at |
16 | * http://www.opensource.apple.com/apsl/ and read it before using this file. |
17 | * |
18 | * The Original Code and all software distributed under the License are |
19 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, |
22 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. |
23 | * Please see the License for the specific language governing rights and |
24 | * limitations under the License. |
25 | * |
26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ |
27 | */ |
28 | /* deflate.h -- internal compression state |
29 | * Copyright (C) 1995-2004 Jean-loup Gailly |
30 | * For conditions of distribution and use, see copyright notice in zlib.h |
31 | */ |
32 | |
33 | /* WARNING: this file should *not* be used by applications. It is |
34 | part of the implementation of the compression library and is |
35 | subject to change. Applications should only use zlib.h. |
36 | */ |
37 | |
38 | /* @(#) $Id$ */ |
39 | |
40 | #ifndef DEFLATE_H |
41 | #define DEFLATE_H |
42 | |
43 | #include "zutil.h" |
44 | |
45 | /* define NO_GZIP when compiling if you want to disable gzip header and |
46 | trailer creation by deflate(). NO_GZIP would be used to avoid linking in |
47 | the crc code when it is not needed. For shared libraries, gzip encoding |
48 | should be left enabled. */ |
49 | #ifndef NO_GZIP |
50 | # define GZIP |
51 | #endif |
52 | |
53 | /* =========================================================================== |
54 | * Internal compression state. |
55 | */ |
56 | |
57 | #define LENGTH_CODES 29 |
58 | /* number of length codes, not counting the special END_BLOCK code */ |
59 | |
60 | #define LITERALS 256 |
61 | /* number of literal bytes 0..255 */ |
62 | |
63 | #define L_CODES (LITERALS+1+LENGTH_CODES) |
64 | /* number of Literal or Length codes, including the END_BLOCK code */ |
65 | |
66 | #define D_CODES 30 |
67 | /* number of distance codes */ |
68 | |
69 | #define BL_CODES 19 |
70 | /* number of codes used to transfer the bit lengths */ |
71 | |
72 | #define HEAP_SIZE (2*L_CODES+1) |
73 | /* maximum heap size */ |
74 | |
75 | #define MAX_BITS 15 |
76 | /* All codes must not exceed MAX_BITS bits */ |
77 | |
78 | #define INIT_STATE 42 |
79 | #define 69 |
80 | #define NAME_STATE 73 |
81 | #define 91 |
82 | #define HCRC_STATE 103 |
83 | #define BUSY_STATE 113 |
84 | #define FINISH_STATE 666 |
85 | /* Stream status */ |
86 | |
87 | |
88 | /* Data structure describing a single value and its code string. */ |
89 | typedef struct ct_data_s { |
90 | union { |
91 | ush freq; /* frequency count */ |
92 | ush code; /* bit string */ |
93 | } fc; |
94 | union { |
95 | ush dad; /* father node in Huffman tree */ |
96 | ush len; /* length of bit string */ |
97 | } dl; |
98 | } FAR ct_data; |
99 | |
100 | #define Freq fc.freq |
101 | #define Code fc.code |
102 | #define Dad dl.dad |
103 | #define Len dl.len |
104 | |
105 | typedef struct static_tree_desc_s static_tree_desc; |
106 | |
107 | typedef struct tree_desc_s { |
108 | ct_data *dyn_tree; /* the dynamic tree */ |
109 | int max_code; /* largest code with non zero frequency */ |
110 | static_tree_desc *stat_desc; /* the corresponding static tree */ |
111 | } FAR tree_desc; |
112 | |
113 | typedef ush Pos; |
114 | typedef Pos FAR Posf; |
115 | typedef unsigned IPos; |
116 | |
117 | /* A Pos is an index in the character window. We use short instead of int to |
118 | * save space in the various tables. IPos is used only for parameter passing. |
119 | */ |
120 | |
121 | typedef struct internal_state { |
122 | z_streamp strm; /* pointer back to this zlib stream */ |
123 | z_input_func zinput; |
124 | z_output_func zoutput; |
125 | int status; /* as the name implies */ |
126 | Bytef *pending_buf; /* output still pending */ |
127 | ulg pending_buf_size; /* size of pending_buf */ |
128 | Bytef *pending_out; /* next pending byte to output to the stream */ |
129 | uInt pending; /* nb of bytes in the pending buffer */ |
130 | int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ |
131 | gz_headerp gzhead; /* gzip header information to write */ |
132 | uInt gzindex; /* where in extra, name, or comment */ |
133 | Byte method; /* STORED (for zip only) or DEFLATED */ |
134 | int last_flush; /* value of flush param for previous deflate call */ |
135 | |
136 | /* used by deflate.c: */ |
137 | |
138 | uInt w_size; /* LZ77 window size (32K by default) */ |
139 | uInt w_bits; /* log2(w_size) (8..16) */ |
140 | uInt w_mask; /* w_size - 1 */ |
141 | |
142 | Bytef *window; |
143 | /* Sliding window. Input bytes are read into the second half of the window, |
144 | * and move to the first half later to keep a dictionary of at least wSize |
145 | * bytes. With this organization, matches are limited to a distance of |
146 | * wSize-MAX_MATCH bytes, but this ensures that IO is always |
147 | * performed with a length multiple of the block size. Also, it limits |
148 | * the window size to 64K, which is quite useful on MSDOS. |
149 | * To do: use the user input buffer as sliding window. |
150 | */ |
151 | |
152 | ulg window_size; |
153 | /* Actual size of window: 2*wSize, except when the user input buffer |
154 | * is directly used as sliding window. |
155 | */ |
156 | |
157 | Posf *prev; |
158 | /* Link to older string with same hash index. To limit the size of this |
159 | * array to 64K, this link is maintained only for the last 32K strings. |
160 | * An index in this array is thus a window index modulo 32K. |
161 | */ |
162 | |
163 | Posf *head; /* Heads of the hash chains or NIL. */ |
164 | |
165 | uInt ins_h; /* hash index of string to be inserted */ |
166 | uInt hash_size; /* number of elements in hash table */ |
167 | uInt hash_bits; /* log2(hash_size) */ |
168 | uInt hash_mask; /* hash_size-1 */ |
169 | |
170 | uInt hash_shift; |
171 | /* Number of bits by which ins_h must be shifted at each input |
172 | * step. It must be such that after MIN_MATCH steps, the oldest |
173 | * byte no longer takes part in the hash key, that is: |
174 | * hash_shift * MIN_MATCH >= hash_bits |
175 | */ |
176 | |
177 | long block_start; |
178 | /* Window position at the beginning of the current output block. Gets |
179 | * negative when the window is moved backwards. |
180 | */ |
181 | |
182 | uInt match_length; /* length of best match */ |
183 | IPos prev_match; /* previous match */ |
184 | int match_available; /* set if previous match exists */ |
185 | uInt strstart; /* start of string to insert */ |
186 | uInt match_start; /* start of matching string */ |
187 | uInt lookahead; /* number of valid bytes ahead in window */ |
188 | |
189 | uInt prev_length; |
190 | /* Length of the best match at previous step. Matches not greater than this |
191 | * are discarded. This is used in the lazy match evaluation. |
192 | */ |
193 | |
194 | uInt max_chain_length; |
195 | /* To speed up deflation, hash chains are never searched beyond this |
196 | * length. A higher limit improves compression ratio but degrades the |
197 | * speed. |
198 | */ |
199 | |
200 | uInt max_lazy_match; |
201 | /* Attempt to find a better match only when the current match is strictly |
202 | * smaller than this value. This mechanism is used only for compression |
203 | * levels >= 4. |
204 | */ |
205 | # define max_insert_length max_lazy_match |
206 | /* Insert new strings in the hash table only if the match length is not |
207 | * greater than this length. This saves time but degrades compression. |
208 | * max_insert_length is used only for compression levels <= 3. |
209 | */ |
210 | |
211 | int level; /* compression level (1..9) */ |
212 | int strategy; /* favor or force Huffman coding*/ |
213 | |
214 | uInt good_match; |
215 | /* Use a faster search when the previous match is longer than this */ |
216 | |
217 | int nice_match; /* Stop searching when current match exceeds this */ |
218 | |
219 | /* used by trees.c: */ |
220 | /* Didn't use ct_data typedef below to supress compiler warning */ |
221 | struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ |
222 | struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ |
223 | struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ |
224 | |
225 | struct tree_desc_s l_desc; /* desc. for literal tree */ |
226 | struct tree_desc_s d_desc; /* desc. for distance tree */ |
227 | struct tree_desc_s bl_desc; /* desc. for bit length tree */ |
228 | |
229 | ush bl_count[MAX_BITS+1]; |
230 | /* number of codes at each bit length for an optimal tree */ |
231 | |
232 | int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ |
233 | int heap_len; /* number of elements in the heap */ |
234 | int heap_max; /* element of largest frequency */ |
235 | /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. |
236 | * The same heap array is used to build all trees. |
237 | */ |
238 | |
239 | uch depth[2*L_CODES+1]; |
240 | /* Depth of each subtree used as tie breaker for trees of equal frequency |
241 | */ |
242 | |
243 | uchf *l_buf; /* buffer for literals or lengths */ |
244 | |
245 | uInt lit_bufsize; |
246 | /* Size of match buffer for literals/lengths. There are 4 reasons for |
247 | * limiting lit_bufsize to 64K: |
248 | * - frequencies can be kept in 16 bit counters |
249 | * - if compression is not successful for the first block, all input |
250 | * data is still in the window so we can still emit a stored block even |
251 | * when input comes from standard input. (This can also be done for |
252 | * all blocks if lit_bufsize is not greater than 32K.) |
253 | * - if compression is not successful for a file smaller than 64K, we can |
254 | * even emit a stored file instead of a stored block (saving 5 bytes). |
255 | * This is applicable only for zip (not gzip or zlib). |
256 | * - creating new Huffman trees less frequently may not provide fast |
257 | * adaptation to changes in the input data statistics. (Take for |
258 | * example a binary file with poorly compressible code followed by |
259 | * a highly compressible string table.) Smaller buffer sizes give |
260 | * fast adaptation but have of course the overhead of transmitting |
261 | * trees more frequently. |
262 | * - I can't count above 4 |
263 | */ |
264 | |
265 | uInt last_lit; /* running index in l_buf */ |
266 | |
267 | ushf *d_buf; |
268 | /* Buffer for distances. To simplify the code, d_buf and l_buf have |
269 | * the same number of elements. To use different lengths, an extra flag |
270 | * array would be necessary. |
271 | */ |
272 | |
273 | ulg opt_len; /* bit length of current block with optimal trees */ |
274 | ulg static_len; /* bit length of current block with static trees */ |
275 | uInt matches; /* number of string matches in current block */ |
276 | int last_eob_len; /* bit length of EOB code for last block */ |
277 | |
278 | #ifdef DEBUG |
279 | ulg compressed_len; /* total bit length of compressed file mod 2^32 */ |
280 | ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ |
281 | #endif |
282 | |
283 | ush bi_buf; |
284 | /* Output buffer. bits are inserted starting at the bottom (least |
285 | * significant bits). |
286 | */ |
287 | int bi_valid; |
288 | /* Number of valid bits in bi_buf. All bits above the last valid bit |
289 | * are always zero. |
290 | */ |
291 | |
292 | } FAR deflate_state; |
293 | |
294 | /* Output a byte on the stream. |
295 | * IN assertion: there is enough room in pending_buf. |
296 | */ |
297 | #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);} |
298 | |
299 | |
300 | #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) |
301 | /* Minimum amount of lookahead, except at the end of the input file. |
302 | * See deflate.c for comments about the MIN_MATCH+1. |
303 | */ |
304 | |
305 | #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) |
306 | /* In order to simplify the code, particularly on 16 bit machines, match |
307 | * distances are limited to MAX_DIST instead of WSIZE. |
308 | */ |
309 | |
310 | /* in trees.c */ |
311 | void _tr_init OF((deflate_state *s)); |
312 | int _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); |
313 | void _tr_flush_block OF((deflate_state *s, charf *buf, ulg stored_len, |
314 | int eof)); |
315 | void _tr_align OF((deflate_state *s)); |
316 | void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len, |
317 | int eof)); |
318 | |
319 | #define d_code(dist) \ |
320 | ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)]) |
321 | /* Mapping from a distance to a distance code. dist is the distance - 1 and |
322 | * must not have side effects. _dist_code[256] and _dist_code[257] are never |
323 | * used. |
324 | */ |
325 | |
326 | #ifndef DEBUG |
327 | /* Inline versions of _tr_tally for speed: */ |
328 | |
329 | #if defined(GEN_TREES_H) || !defined(STDC) |
330 | extern uch _length_code[]; |
331 | extern uch _dist_code[]; |
332 | #else |
333 | extern const uch _length_code[]; |
334 | extern const uch _dist_code[]; |
335 | #endif |
336 | |
337 | # define _tr_tally_lit(s, c, flush) \ |
338 | { uch cc = (c); \ |
339 | s->d_buf[s->last_lit] = 0; \ |
340 | s->l_buf[s->last_lit++] = cc; \ |
341 | s->dyn_ltree[cc].Freq++; \ |
342 | flush = (s->last_lit == s->lit_bufsize-1); \ |
343 | } |
344 | # define _tr_tally_dist(s, distance, length, flush) \ |
345 | { uch len = (uch)(length); \ |
346 | ush dist = (ush)(distance); \ |
347 | s->d_buf[s->last_lit] = dist; \ |
348 | s->l_buf[s->last_lit++] = len; \ |
349 | dist--; \ |
350 | s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ |
351 | s->dyn_dtree[d_code(dist)].Freq++; \ |
352 | flush = (s->last_lit == s->lit_bufsize-1); \ |
353 | } |
354 | #else |
355 | # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) |
356 | # define _tr_tally_dist(s, distance, length, flush) \ |
357 | flush = _tr_tally(s, distance, length) |
358 | #endif |
359 | |
360 | #endif /* DEFLATE_H */ |
361 | |