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1 | /* deflate.h -- internal compression state |
2 | * Copyright (C) 1995-1998 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 | /* =========================================================================== | |
19 | * Internal compression state. | |
20 | */ | |
21 | ||
22 | #define LENGTH_CODES 29 | |
23 | /* number of length codes, not counting the special END_BLOCK code */ | |
24 | ||
25 | #define LITERALS 256 | |
26 | /* number of literal bytes 0..255 */ | |
27 | ||
28 | #define L_CODES (LITERALS+1+LENGTH_CODES) | |
29 | /* number of Literal or Length codes, including the END_BLOCK code */ | |
30 | ||
31 | #define D_CODES 30 | |
32 | /* number of distance codes */ | |
33 | ||
34 | #define BL_CODES 19 | |
35 | /* number of codes used to transfer the bit lengths */ | |
36 | ||
37 | #define HEAP_SIZE (2*L_CODES+1) | |
38 | /* maximum heap size */ | |
39 | ||
40 | #define MAX_BITS 15 | |
41 | /* All codes must not exceed MAX_BITS bits */ | |
42 | ||
43 | #define INIT_STATE 42 | |
44 | #define BUSY_STATE 113 | |
45 | #define FINISH_STATE 666 | |
46 | /* Stream status */ | |
47 | ||
48 | ||
49 | /* Data structure describing a single value and its code string. */ | |
50 | typedef struct ct_data_s { | |
51 | union { | |
52 | ush freq; /* frequency count */ | |
53 | ush code; /* bit string */ | |
54 | } fc; | |
55 | union { | |
56 | ush dad; /* father node in Huffman tree */ | |
57 | ush len; /* length of bit string */ | |
58 | } dl; | |
59 | } FAR ct_data; | |
60 | ||
61 | #define Freq fc.freq | |
62 | #define Code fc.code | |
63 | #define Dad dl.dad | |
64 | #define Len dl.len | |
65 | ||
66 | typedef struct static_tree_desc_s static_tree_desc; | |
67 | ||
68 | typedef struct tree_desc_s { | |
69 | ct_data *dyn_tree; /* the dynamic tree */ | |
70 | int max_code; /* largest code with non zero frequency */ | |
71 | static_tree_desc *stat_desc; /* the corresponding static tree */ | |
72 | } FAR tree_desc; | |
73 | ||
74 | typedef ush Pos; | |
75 | typedef Pos FAR Posf; | |
76 | typedef unsigned IPos; | |
77 | ||
78 | /* A Pos is an index in the character window. We use short instead of int to | |
79 | * save space in the various tables. IPos is used only for parameter passing. | |
80 | */ | |
81 | ||
82 | typedef struct internal_state { | |
83 | z_streamp strm; /* pointer back to this zlib stream */ | |
84 | int status; /* as the name implies */ | |
85 | Bytef *pending_buf; /* output still pending */ | |
86 | ulg pending_buf_size; /* size of pending_buf */ | |
87 | Bytef *pending_out; /* next pending byte to output to the stream */ | |
88 | int pending; /* nb of bytes in the pending buffer */ | |
89 | int noheader; /* suppress zlib header and adler32 */ | |
90 | Byte data_type; /* UNKNOWN, BINARY or ASCII */ | |
91 | Byte method; /* STORED (for zip only) or DEFLATED */ | |
92 | int last_flush; /* value of flush param for previous deflate call */ | |
93 | ||
94 | /* used by deflate.c: */ | |
95 | ||
96 | uInt w_size; /* LZ77 window size (32K by default) */ | |
97 | uInt w_bits; /* log2(w_size) (8..16) */ | |
98 | uInt w_mask; /* w_size - 1 */ | |
99 | ||
100 | Bytef *window; | |
101 | /* Sliding window. Input bytes are read into the second half of the window, | |
102 | * and move to the first half later to keep a dictionary of at least wSize | |
103 | * bytes. With this organization, matches are limited to a distance of | |
104 | * wSize-MAX_MATCH bytes, but this ensures that IO is always | |
105 | * performed with a length multiple of the block size. Also, it limits | |
106 | * the window size to 64K, which is quite useful on MSDOS. | |
107 | * To do: use the user input buffer as sliding window. | |
108 | */ | |
109 | ||
110 | ulg window_size; | |
111 | /* Actual size of window: 2*wSize, except when the user input buffer | |
112 | * is directly used as sliding window. | |
113 | */ | |
114 | ||
115 | Posf *prev; | |
116 | /* Link to older string with same hash index. To limit the size of this | |
117 | * array to 64K, this link is maintained only for the last 32K strings. | |
118 | * An index in this array is thus a window index modulo 32K. | |
119 | */ | |
120 | ||
121 | Posf *head; /* Heads of the hash chains or NIL. */ | |
122 | ||
123 | uInt ins_h; /* hash index of string to be inserted */ | |
124 | uInt hash_size; /* number of elements in hash table */ | |
125 | uInt hash_bits; /* log2(hash_size) */ | |
126 | uInt hash_mask; /* hash_size-1 */ | |
127 | ||
128 | uInt hash_shift; | |
129 | /* Number of bits by which ins_h must be shifted at each input | |
130 | * step. It must be such that after MIN_MATCH steps, the oldest | |
131 | * byte no longer takes part in the hash key, that is: | |
132 | * hash_shift * MIN_MATCH >= hash_bits | |
133 | */ | |
134 | ||
135 | long block_start; | |
136 | /* Window position at the beginning of the current output block. Gets | |
137 | * negative when the window is moved backwards. | |
138 | */ | |
139 | ||
140 | uInt match_length; /* length of best match */ | |
141 | IPos prev_match; /* previous match */ | |
142 | int match_available; /* set if previous match exists */ | |
143 | uInt strstart; /* start of string to insert */ | |
144 | uInt match_start; /* start of matching string */ | |
145 | uInt lookahead; /* number of valid bytes ahead in window */ | |
146 | ||
147 | uInt prev_length; | |
148 | /* Length of the best match at previous step. Matches not greater than this | |
149 | * are discarded. This is used in the lazy match evaluation. | |
150 | */ | |
151 | ||
152 | uInt max_chain_length; | |
153 | /* To speed up deflation, hash chains are never searched beyond this | |
154 | * length. A higher limit improves compression ratio but degrades the | |
155 | * speed. | |
156 | */ | |
157 | ||
158 | uInt max_lazy_match; | |
159 | /* Attempt to find a better match only when the current match is strictly | |
160 | * smaller than this value. This mechanism is used only for compression | |
161 | * levels >= 4. | |
162 | */ | |
163 | # define max_insert_length max_lazy_match | |
164 | /* Insert new strings in the hash table only if the match length is not | |
165 | * greater than this length. This saves time but degrades compression. | |
166 | * max_insert_length is used only for compression levels <= 3. | |
167 | */ | |
168 | ||
169 | int level; /* compression level (1..9) */ | |
170 | int strategy; /* favor or force Huffman coding*/ | |
171 | ||
172 | uInt good_match; | |
173 | /* Use a faster search when the previous match is longer than this */ | |
174 | ||
175 | int nice_match; /* Stop searching when current match exceeds this */ | |
176 | ||
177 | /* used by trees.c: */ | |
178 | /* Didn't use ct_data typedef below to supress compiler warning */ | |
179 | struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ | |
180 | struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ | |
181 | struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ | |
182 | ||
183 | struct tree_desc_s l_desc; /* desc. for literal tree */ | |
184 | struct tree_desc_s d_desc; /* desc. for distance tree */ | |
185 | struct tree_desc_s bl_desc; /* desc. for bit length tree */ | |
186 | ||
187 | ush bl_count[MAX_BITS+1]; | |
188 | /* number of codes at each bit length for an optimal tree */ | |
189 | ||
190 | int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ | |
191 | int heap_len; /* number of elements in the heap */ | |
192 | int heap_max; /* element of largest frequency */ | |
193 | /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. | |
194 | * The same heap array is used to build all trees. | |
195 | */ | |
196 | ||
197 | uch depth[2*L_CODES+1]; | |
198 | /* Depth of each subtree used as tie breaker for trees of equal frequency | |
199 | */ | |
200 | ||
201 | uchf *l_buf; /* buffer for literals or lengths */ | |
202 | ||
203 | uInt lit_bufsize; | |
204 | /* Size of match buffer for literals/lengths. There are 4 reasons for | |
205 | * limiting lit_bufsize to 64K: | |
206 | * - frequencies can be kept in 16 bit counters | |
207 | * - if compression is not successful for the first block, all input | |
208 | * data is still in the window so we can still emit a stored block even | |
209 | * when input comes from standard input. (This can also be done for | |
210 | * all blocks if lit_bufsize is not greater than 32K.) | |
211 | * - if compression is not successful for a file smaller than 64K, we can | |
212 | * even emit a stored file instead of a stored block (saving 5 bytes). | |
213 | * This is applicable only for zip (not gzip or zlib). | |
214 | * - creating new Huffman trees less frequently may not provide fast | |
215 | * adaptation to changes in the input data statistics. (Take for | |
216 | * example a binary file with poorly compressible code followed by | |
217 | * a highly compressible string table.) Smaller buffer sizes give | |
218 | * fast adaptation but have of course the overhead of transmitting | |
219 | * trees more frequently. | |
220 | * - I can't count above 4 | |
221 | */ | |
222 | ||
223 | uInt last_lit; /* running index in l_buf */ | |
224 | ||
225 | ushf *d_buf; | |
226 | /* Buffer for distances. To simplify the code, d_buf and l_buf have | |
227 | * the same number of elements. To use different lengths, an extra flag | |
228 | * array would be necessary. | |
229 | */ | |
230 | ||
231 | ulg opt_len; /* bit length of current block with optimal trees */ | |
232 | ulg static_len; /* bit length of current block with static trees */ | |
233 | ulg compressed_len; /* total bit length of compressed file */ | |
234 | uInt matches; /* number of string matches in current block */ | |
235 | int last_eob_len; /* bit length of EOB code for last block */ | |
236 | ||
85504cac | 237 | #ifdef __WXDEBUG__ |
c801d85f KB |
238 | ulg bits_sent; /* bit length of the compressed data */ |
239 | #endif | |
240 | ||
241 | ush bi_buf; | |
242 | /* Output buffer. bits are inserted starting at the bottom (least | |
243 | * significant bits). | |
244 | */ | |
245 | int bi_valid; | |
246 | /* Number of valid bits in bi_buf. All bits above the last valid bit | |
247 | * are always zero. | |
248 | */ | |
249 | ||
250 | } FAR deflate_state; | |
251 | ||
252 | /* Output a byte on the stream. | |
253 | * IN assertion: there is enough room in pending_buf. | |
254 | */ | |
255 | #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);} | |
256 | ||
257 | ||
258 | #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) | |
259 | /* Minimum amount of lookahead, except at the end of the input file. | |
260 | * See deflate.c for comments about the MIN_MATCH+1. | |
261 | */ | |
262 | ||
263 | #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) | |
264 | /* In order to simplify the code, particularly on 16 bit machines, match | |
265 | * distances are limited to MAX_DIST instead of WSIZE. | |
266 | */ | |
267 | ||
268 | /* in trees.c */ | |
269 | void _tr_init OF((deflate_state *s)); | |
270 | int _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); | |
271 | ulg _tr_flush_block OF((deflate_state *s, charf *buf, ulg stored_len, | |
272 | int eof)); | |
273 | void _tr_align OF((deflate_state *s)); | |
274 | void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len, | |
275 | int eof)); | |
276 | ||
277 | #define d_code(dist) \ | |
278 | ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)]) | |
279 | /* Mapping from a distance to a distance code. dist is the distance - 1 and | |
280 | * must not have side effects. _dist_code[256] and _dist_code[257] are never | |
281 | * used. | |
282 | */ | |
283 | ||
85504cac | 284 | #ifndef __WXDEBUG__ |
c801d85f KB |
285 | /* Inline versions of _tr_tally for speed: */ |
286 | ||
287 | #if defined(GEN_TREES_H) || !defined(STDC) | |
288 | extern uch _length_code[]; | |
289 | extern uch _dist_code[]; | |
290 | #else | |
291 | extern const uch _length_code[]; | |
292 | extern const uch _dist_code[]; | |
293 | #endif | |
294 | ||
295 | # define _tr_tally_lit(s, c, flush) \ | |
296 | { uch cc = (c); \ | |
297 | s->d_buf[s->last_lit] = 0; \ | |
298 | s->l_buf[s->last_lit++] = cc; \ | |
299 | s->dyn_ltree[cc].Freq++; \ | |
300 | flush = (s->last_lit == s->lit_bufsize-1); \ | |
301 | } | |
302 | # define _tr_tally_dist(s, distance, length, flush) \ | |
303 | { uch len = (length); \ | |
304 | ush dist = (distance); \ | |
305 | s->d_buf[s->last_lit] = dist; \ | |
306 | s->l_buf[s->last_lit++] = len; \ | |
307 | dist--; \ | |
308 | s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ | |
309 | s->dyn_dtree[d_code(dist)].Freq++; \ | |
310 | flush = (s->last_lit == s->lit_bufsize-1); \ | |
311 | } | |
312 | #else | |
313 | # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) | |
314 | # define _tr_tally_dist(s, distance, length, flush) \ | |
315 | flush = _tr_tally(s, distance, length) | |
316 | #endif | |
317 | ||
318 | #endif |