Mercurial > mm7
comparison lib/zlib/deflate.h @ 0:9c0607679772
init
author | Ritor1 |
---|---|
date | Sat, 12 Jan 2013 09:45:18 +0600 |
parents | |
children |
comparison
equal
deleted
inserted
replaced
-1:000000000000 | 0:9c0607679772 |
---|---|
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 uInt matches; /* number of string matches in current block */ | |
234 int last_eob_len; /* bit length of EOB code for last block */ | |
235 | |
236 #ifdef DEBUG | |
237 ulg compressed_len; /* total bit length of compressed file mod 2^32 */ | |
238 ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ | |
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 void _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 | |
284 #ifndef DEBUG | |
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 |