Mercurial > repos > blastem
comparison zlib/deflate.h @ 1530:00d788dac91a
Added support for reading gzipped ROMs
author | Michael Pavone <pavone@retrodev.com> |
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date | Fri, 23 Mar 2018 22:30:02 -0700 |
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1 /* deflate.h -- internal compression state | |
2 * Copyright (C) 1995-2016 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 /* zlib header -> BUSY_STATE */ | |
55 #ifdef GZIP | |
56 # define GZIP_STATE 57 /* gzip header -> BUSY_STATE | EXTRA_STATE */ | |
57 #endif | |
58 #define EXTRA_STATE 69 /* gzip extra block -> NAME_STATE */ | |
59 #define NAME_STATE 73 /* gzip file name -> COMMENT_STATE */ | |
60 #define COMMENT_STATE 91 /* gzip comment -> HCRC_STATE */ | |
61 #define HCRC_STATE 103 /* gzip header CRC -> BUSY_STATE */ | |
62 #define BUSY_STATE 113 /* deflate -> FINISH_STATE */ | |
63 #define FINISH_STATE 666 /* stream complete */ | |
64 /* Stream status */ | |
65 | |
66 | |
67 /* Data structure describing a single value and its code string. */ | |
68 typedef struct ct_data_s { | |
69 union { | |
70 ush freq; /* frequency count */ | |
71 ush code; /* bit string */ | |
72 } fc; | |
73 union { | |
74 ush dad; /* father node in Huffman tree */ | |
75 ush len; /* length of bit string */ | |
76 } dl; | |
77 } FAR ct_data; | |
78 | |
79 #define Freq fc.freq | |
80 #define Code fc.code | |
81 #define Dad dl.dad | |
82 #define Len dl.len | |
83 | |
84 typedef struct static_tree_desc_s static_tree_desc; | |
85 | |
86 typedef struct tree_desc_s { | |
87 ct_data *dyn_tree; /* the dynamic tree */ | |
88 int max_code; /* largest code with non zero frequency */ | |
89 const static_tree_desc *stat_desc; /* the corresponding static tree */ | |
90 } FAR tree_desc; | |
91 | |
92 typedef ush Pos; | |
93 typedef Pos FAR Posf; | |
94 typedef unsigned IPos; | |
95 | |
96 /* A Pos is an index in the character window. We use short instead of int to | |
97 * save space in the various tables. IPos is used only for parameter passing. | |
98 */ | |
99 | |
100 typedef struct internal_state { | |
101 z_streamp strm; /* pointer back to this zlib stream */ | |
102 int status; /* as the name implies */ | |
103 Bytef *pending_buf; /* output still pending */ | |
104 ulg pending_buf_size; /* size of pending_buf */ | |
105 Bytef *pending_out; /* next pending byte to output to the stream */ | |
106 ulg pending; /* nb of bytes in the pending buffer */ | |
107 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ | |
108 gz_headerp gzhead; /* gzip header information to write */ | |
109 ulg gzindex; /* where in extra, name, or comment */ | |
110 Byte method; /* can only be DEFLATED */ | |
111 int last_flush; /* value of flush param for previous deflate call */ | |
112 | |
113 /* used by deflate.c: */ | |
114 | |
115 uInt w_size; /* LZ77 window size (32K by default) */ | |
116 uInt w_bits; /* log2(w_size) (8..16) */ | |
117 uInt w_mask; /* w_size - 1 */ | |
118 | |
119 Bytef *window; | |
120 /* Sliding window. Input bytes are read into the second half of the window, | |
121 * and move to the first half later to keep a dictionary of at least wSize | |
122 * bytes. With this organization, matches are limited to a distance of | |
123 * wSize-MAX_MATCH bytes, but this ensures that IO is always | |
124 * performed with a length multiple of the block size. Also, it limits | |
125 * the window size to 64K, which is quite useful on MSDOS. | |
126 * To do: use the user input buffer as sliding window. | |
127 */ | |
128 | |
129 ulg window_size; | |
130 /* Actual size of window: 2*wSize, except when the user input buffer | |
131 * is directly used as sliding window. | |
132 */ | |
133 | |
134 Posf *prev; | |
135 /* Link to older string with same hash index. To limit the size of this | |
136 * array to 64K, this link is maintained only for the last 32K strings. | |
137 * An index in this array is thus a window index modulo 32K. | |
138 */ | |
139 | |
140 Posf *head; /* Heads of the hash chains or NIL. */ | |
141 | |
142 uInt ins_h; /* hash index of string to be inserted */ | |
143 uInt hash_size; /* number of elements in hash table */ | |
144 uInt hash_bits; /* log2(hash_size) */ | |
145 uInt hash_mask; /* hash_size-1 */ | |
146 | |
147 uInt hash_shift; | |
148 /* Number of bits by which ins_h must be shifted at each input | |
149 * step. It must be such that after MIN_MATCH steps, the oldest | |
150 * byte no longer takes part in the hash key, that is: | |
151 * hash_shift * MIN_MATCH >= hash_bits | |
152 */ | |
153 | |
154 long block_start; | |
155 /* Window position at the beginning of the current output block. Gets | |
156 * negative when the window is moved backwards. | |
157 */ | |
158 | |
159 uInt match_length; /* length of best match */ | |
160 IPos prev_match; /* previous match */ | |
161 int match_available; /* set if previous match exists */ | |
162 uInt strstart; /* start of string to insert */ | |
163 uInt match_start; /* start of matching string */ | |
164 uInt lookahead; /* number of valid bytes ahead in window */ | |
165 | |
166 uInt prev_length; | |
167 /* Length of the best match at previous step. Matches not greater than this | |
168 * are discarded. This is used in the lazy match evaluation. | |
169 */ | |
170 | |
171 uInt max_chain_length; | |
172 /* To speed up deflation, hash chains are never searched beyond this | |
173 * length. A higher limit improves compression ratio but degrades the | |
174 * speed. | |
175 */ | |
176 | |
177 uInt max_lazy_match; | |
178 /* Attempt to find a better match only when the current match is strictly | |
179 * smaller than this value. This mechanism is used only for compression | |
180 * levels >= 4. | |
181 */ | |
182 # define max_insert_length max_lazy_match | |
183 /* Insert new strings in the hash table only if the match length is not | |
184 * greater than this length. This saves time but degrades compression. | |
185 * max_insert_length is used only for compression levels <= 3. | |
186 */ | |
187 | |
188 int level; /* compression level (1..9) */ | |
189 int strategy; /* favor or force Huffman coding*/ | |
190 | |
191 uInt good_match; | |
192 /* Use a faster search when the previous match is longer than this */ | |
193 | |
194 int nice_match; /* Stop searching when current match exceeds this */ | |
195 | |
196 /* used by trees.c: */ | |
197 /* Didn't use ct_data typedef below to suppress compiler warning */ | |
198 struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ | |
199 struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ | |
200 struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ | |
201 | |
202 struct tree_desc_s l_desc; /* desc. for literal tree */ | |
203 struct tree_desc_s d_desc; /* desc. for distance tree */ | |
204 struct tree_desc_s bl_desc; /* desc. for bit length tree */ | |
205 | |
206 ush bl_count[MAX_BITS+1]; | |
207 /* number of codes at each bit length for an optimal tree */ | |
208 | |
209 int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ | |
210 int heap_len; /* number of elements in the heap */ | |
211 int heap_max; /* element of largest frequency */ | |
212 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. | |
213 * The same heap array is used to build all trees. | |
214 */ | |
215 | |
216 uch depth[2*L_CODES+1]; | |
217 /* Depth of each subtree used as tie breaker for trees of equal frequency | |
218 */ | |
219 | |
220 uchf *l_buf; /* buffer for literals or lengths */ | |
221 | |
222 uInt lit_bufsize; | |
223 /* Size of match buffer for literals/lengths. There are 4 reasons for | |
224 * limiting lit_bufsize to 64K: | |
225 * - frequencies can be kept in 16 bit counters | |
226 * - if compression is not successful for the first block, all input | |
227 * data is still in the window so we can still emit a stored block even | |
228 * when input comes from standard input. (This can also be done for | |
229 * all blocks if lit_bufsize is not greater than 32K.) | |
230 * - if compression is not successful for a file smaller than 64K, we can | |
231 * even emit a stored file instead of a stored block (saving 5 bytes). | |
232 * This is applicable only for zip (not gzip or zlib). | |
233 * - creating new Huffman trees less frequently may not provide fast | |
234 * adaptation to changes in the input data statistics. (Take for | |
235 * example a binary file with poorly compressible code followed by | |
236 * a highly compressible string table.) Smaller buffer sizes give | |
237 * fast adaptation but have of course the overhead of transmitting | |
238 * trees more frequently. | |
239 * - I can't count above 4 | |
240 */ | |
241 | |
242 uInt last_lit; /* running index in l_buf */ | |
243 | |
244 ushf *d_buf; | |
245 /* Buffer for distances. To simplify the code, d_buf and l_buf have | |
246 * the same number of elements. To use different lengths, an extra flag | |
247 * array would be necessary. | |
248 */ | |
249 | |
250 ulg opt_len; /* bit length of current block with optimal trees */ | |
251 ulg static_len; /* bit length of current block with static trees */ | |
252 uInt matches; /* number of string matches in current block */ | |
253 uInt insert; /* bytes at end of window left to insert */ | |
254 | |
255 #ifdef ZLIB_DEBUG | |
256 ulg compressed_len; /* total bit length of compressed file mod 2^32 */ | |
257 ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ | |
258 #endif | |
259 | |
260 ush bi_buf; | |
261 /* Output buffer. bits are inserted starting at the bottom (least | |
262 * significant bits). | |
263 */ | |
264 int bi_valid; | |
265 /* Number of valid bits in bi_buf. All bits above the last valid bit | |
266 * are always zero. | |
267 */ | |
268 | |
269 ulg high_water; | |
270 /* High water mark offset in window for initialized bytes -- bytes above | |
271 * this are set to zero in order to avoid memory check warnings when | |
272 * longest match routines access bytes past the input. This is then | |
273 * updated to the new high water mark. | |
274 */ | |
275 | |
276 } FAR deflate_state; | |
277 | |
278 /* Output a byte on the stream. | |
279 * IN assertion: there is enough room in pending_buf. | |
280 */ | |
281 #define put_byte(s, c) {s->pending_buf[s->pending++] = (Bytef)(c);} | |
282 | |
283 | |
284 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) | |
285 /* Minimum amount of lookahead, except at the end of the input file. | |
286 * See deflate.c for comments about the MIN_MATCH+1. | |
287 */ | |
288 | |
289 #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) | |
290 /* In order to simplify the code, particularly on 16 bit machines, match | |
291 * distances are limited to MAX_DIST instead of WSIZE. | |
292 */ | |
293 | |
294 #define WIN_INIT MAX_MATCH | |
295 /* Number of bytes after end of data in window to initialize in order to avoid | |
296 memory checker errors from longest match routines */ | |
297 | |
298 /* in trees.c */ | |
299 void ZLIB_INTERNAL _tr_init OF((deflate_state *s)); | |
300 int ZLIB_INTERNAL _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); | |
301 void ZLIB_INTERNAL _tr_flush_block OF((deflate_state *s, charf *buf, | |
302 ulg stored_len, int last)); | |
303 void ZLIB_INTERNAL _tr_flush_bits OF((deflate_state *s)); | |
304 void ZLIB_INTERNAL _tr_align OF((deflate_state *s)); | |
305 void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf, | |
306 ulg stored_len, int last)); | |
307 | |
308 #define d_code(dist) \ | |
309 ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)]) | |
310 /* Mapping from a distance to a distance code. dist is the distance - 1 and | |
311 * must not have side effects. _dist_code[256] and _dist_code[257] are never | |
312 * used. | |
313 */ | |
314 | |
315 #ifndef ZLIB_DEBUG | |
316 /* Inline versions of _tr_tally for speed: */ | |
317 | |
318 #if defined(GEN_TREES_H) || !defined(STDC) | |
319 extern uch ZLIB_INTERNAL _length_code[]; | |
320 extern uch ZLIB_INTERNAL _dist_code[]; | |
321 #else | |
322 extern const uch ZLIB_INTERNAL _length_code[]; | |
323 extern const uch ZLIB_INTERNAL _dist_code[]; | |
324 #endif | |
325 | |
326 # define _tr_tally_lit(s, c, flush) \ | |
327 { uch cc = (c); \ | |
328 s->d_buf[s->last_lit] = 0; \ | |
329 s->l_buf[s->last_lit++] = cc; \ | |
330 s->dyn_ltree[cc].Freq++; \ | |
331 flush = (s->last_lit == s->lit_bufsize-1); \ | |
332 } | |
333 # define _tr_tally_dist(s, distance, length, flush) \ | |
334 { uch len = (uch)(length); \ | |
335 ush dist = (ush)(distance); \ | |
336 s->d_buf[s->last_lit] = dist; \ | |
337 s->l_buf[s->last_lit++] = len; \ | |
338 dist--; \ | |
339 s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ | |
340 s->dyn_dtree[d_code(dist)].Freq++; \ | |
341 flush = (s->last_lit == s->lit_bufsize-1); \ | |
342 } | |
343 #else | |
344 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) | |
345 # define _tr_tally_dist(s, distance, length, flush) \ | |
346 flush = _tr_tally(s, distance, length) | |
347 #endif | |
348 | |
349 #endif /* DEFLATE_H */ |