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comparison: modules/zlib/src/deflate.h
modules/zlib/src/deflate.h
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| -1:000000000000 | 0:3274257ae7f8 |
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| 1 /* deflate.h -- internal compression state | |
| 2 * Copyright (C) 1995-2012 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 | |
| 55 #define EXTRA_STATE 69 | |
| 56 #define NAME_STATE 73 | |
| 57 #define COMMENT_STATE 91 | |
| 58 #define HCRC_STATE 103 | |
| 59 #define BUSY_STATE 113 | |
| 60 #define FINISH_STATE 666 | |
| 61 /* Stream status */ | |
| 62 | |
| 63 | |
| 64 /* Data structure describing a single value and its code string. */ | |
| 65 typedef struct ct_data_s { | |
| 66 union { | |
| 67 ush freq; /* frequency count */ | |
| 68 ush code; /* bit string */ | |
| 69 } fc; | |
| 70 union { | |
| 71 ush dad; /* father node in Huffman tree */ | |
| 72 ush len; /* length of bit string */ | |
| 73 } dl; | |
| 74 } FAR ct_data; | |
| 75 | |
| 76 #define Freq fc.freq | |
| 77 #define Code fc.code | |
| 78 #define Dad dl.dad | |
| 79 #define Len dl.len | |
| 80 | |
| 81 typedef struct static_tree_desc_s static_tree_desc; | |
| 82 | |
| 83 typedef struct tree_desc_s { | |
| 84 ct_data *dyn_tree; /* the dynamic tree */ | |
| 85 int max_code; /* largest code with non zero frequency */ | |
| 86 static_tree_desc *stat_desc; /* the corresponding static tree */ | |
| 87 } FAR tree_desc; | |
| 88 | |
| 89 typedef ush Pos; | |
| 90 typedef Pos FAR Posf; | |
| 91 typedef unsigned IPos; | |
| 92 | |
| 93 /* A Pos is an index in the character window. We use short instead of int to | |
| 94 * save space in the various tables. IPos is used only for parameter passing. | |
| 95 */ | |
| 96 | |
| 97 typedef struct internal_state { | |
| 98 z_streamp strm; /* pointer back to this zlib stream */ | |
| 99 int status; /* as the name implies */ | |
| 100 Bytef *pending_buf; /* output still pending */ | |
| 101 ulg pending_buf_size; /* size of pending_buf */ | |
| 102 Bytef *pending_out; /* next pending byte to output to the stream */ | |
| 103 uInt pending; /* nb of bytes in the pending buffer */ | |
| 104 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ | |
| 105 gz_headerp gzhead; /* gzip header information to write */ | |
| 106 uInt gzindex; /* where in extra, name, or comment */ | |
| 107 Byte method; /* can only be DEFLATED */ | |
| 108 int last_flush; /* value of flush param for previous deflate call */ | |
| 109 | |
| 110 /* used by deflate.c: */ | |
| 111 | |
| 112 uInt w_size; /* LZ77 window size (32K by default) */ | |
| 113 uInt w_bits; /* log2(w_size) (8..16) */ | |
| 114 uInt w_mask; /* w_size - 1 */ | |
| 115 | |
| 116 Bytef *window; | |
| 117 /* Sliding window. Input bytes are read into the second half of the window, | |
| 118 * and move to the first half later to keep a dictionary of at least wSize | |
| 119 * bytes. With this organization, matches are limited to a distance of | |
| 120 * wSize-MAX_MATCH bytes, but this ensures that IO is always | |
| 121 * performed with a length multiple of the block size. Also, it limits | |
| 122 * the window size to 64K, which is quite useful on MSDOS. | |
| 123 * To do: use the user input buffer as sliding window. | |
| 124 */ | |
| 125 | |
| 126 ulg window_size; | |
| 127 /* Actual size of window: 2*wSize, except when the user input buffer | |
| 128 * is directly used as sliding window. | |
| 129 */ | |
| 130 | |
| 131 Posf *prev; | |
| 132 /* Link to older string with same hash index. To limit the size of this | |
| 133 * array to 64K, this link is maintained only for the last 32K strings. | |
| 134 * An index in this array is thus a window index modulo 32K. | |
| 135 */ | |
| 136 | |
| 137 Posf *head; /* Heads of the hash chains or NIL. */ | |
| 138 | |
| 139 uInt ins_h; /* hash index of string to be inserted */ | |
| 140 uInt hash_size; /* number of elements in hash table */ | |
| 141 uInt hash_bits; /* log2(hash_size) */ | |
| 142 uInt hash_mask; /* hash_size-1 */ | |
| 143 | |
| 144 uInt hash_shift; | |
| 145 /* Number of bits by which ins_h must be shifted at each input | |
| 146 * step. It must be such that after MIN_MATCH steps, the oldest | |
| 147 * byte no longer takes part in the hash key, that is: | |
| 148 * hash_shift * MIN_MATCH >= hash_bits | |
| 149 */ | |
| 150 | |
| 151 long block_start; | |
| 152 /* Window position at the beginning of the current output block. Gets | |
| 153 * negative when the window is moved backwards. | |
| 154 */ | |
| 155 | |
| 156 uInt match_length; /* length of best match */ | |
| 157 IPos prev_match; /* previous match */ | |
| 158 int match_available; /* set if previous match exists */ | |
| 159 uInt strstart; /* start of string to insert */ | |
| 160 uInt match_start; /* start of matching string */ | |
| 161 uInt lookahead; /* number of valid bytes ahead in window */ | |
| 162 | |
| 163 uInt prev_length; | |
| 164 /* Length of the best match at previous step. Matches not greater than this | |
| 165 * are discarded. This is used in the lazy match evaluation. | |
| 166 */ | |
| 167 | |
| 168 uInt max_chain_length; | |
| 169 /* To speed up deflation, hash chains are never searched beyond this | |
| 170 * length. A higher limit improves compression ratio but degrades the | |
| 171 * speed. | |
| 172 */ | |
| 173 | |
| 174 uInt max_lazy_match; | |
| 175 /* Attempt to find a better match only when the current match is strictly | |
| 176 * smaller than this value. This mechanism is used only for compression | |
| 177 * levels >= 4. | |
| 178 */ | |
| 179 # define max_insert_length max_lazy_match | |
| 180 /* Insert new strings in the hash table only if the match length is not | |
| 181 * greater than this length. This saves time but degrades compression. | |
| 182 * max_insert_length is used only for compression levels <= 3. | |
| 183 */ | |
| 184 | |
| 185 int level; /* compression level (1..9) */ | |
| 186 int strategy; /* favor or force Huffman coding*/ | |
| 187 | |
| 188 uInt good_match; | |
| 189 /* Use a faster search when the previous match is longer than this */ | |
| 190 | |
| 191 int nice_match; /* Stop searching when current match exceeds this */ | |
| 192 | |
| 193 /* used by trees.c: */ | |
| 194 /* Didn't use ct_data typedef below to suppress compiler warning */ | |
| 195 struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ | |
| 196 struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ | |
| 197 struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ | |
| 198 | |
| 199 struct tree_desc_s l_desc; /* desc. for literal tree */ | |
| 200 struct tree_desc_s d_desc; /* desc. for distance tree */ | |
| 201 struct tree_desc_s bl_desc; /* desc. for bit length tree */ | |
| 202 | |
| 203 ush bl_count[MAX_BITS+1]; | |
| 204 /* number of codes at each bit length for an optimal tree */ | |
| 205 | |
| 206 int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ | |
| 207 int heap_len; /* number of elements in the heap */ | |
| 208 int heap_max; /* element of largest frequency */ | |
| 209 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. | |
| 210 * The same heap array is used to build all trees. | |
| 211 */ | |
| 212 | |
| 213 uch depth[2*L_CODES+1]; | |
| 214 /* Depth of each subtree used as tie breaker for trees of equal frequency | |
| 215 */ | |
| 216 | |
| 217 uchf *l_buf; /* buffer for literals or lengths */ | |
| 218 | |
| 219 uInt lit_bufsize; | |
| 220 /* Size of match buffer for literals/lengths. There are 4 reasons for | |
| 221 * limiting lit_bufsize to 64K: | |
| 222 * - frequencies can be kept in 16 bit counters | |
| 223 * - if compression is not successful for the first block, all input | |
| 224 * data is still in the window so we can still emit a stored block even | |
| 225 * when input comes from standard input. (This can also be done for | |
| 226 * all blocks if lit_bufsize is not greater than 32K.) | |
| 227 * - if compression is not successful for a file smaller than 64K, we can | |
| 228 * even emit a stored file instead of a stored block (saving 5 bytes). | |
| 229 * This is applicable only for zip (not gzip or zlib). | |
| 230 * - creating new Huffman trees less frequently may not provide fast | |
| 231 * adaptation to changes in the input data statistics. (Take for | |
| 232 * example a binary file with poorly compressible code followed by | |
| 233 * a highly compressible string table.) Smaller buffer sizes give | |
| 234 * fast adaptation but have of course the overhead of transmitting | |
| 235 * trees more frequently. | |
| 236 * - I can't count above 4 | |
| 237 */ | |
| 238 | |
| 239 uInt last_lit; /* running index in l_buf */ | |
| 240 | |
| 241 ushf *d_buf; | |
| 242 /* Buffer for distances. To simplify the code, d_buf and l_buf have | |
| 243 * the same number of elements. To use different lengths, an extra flag | |
| 244 * array would be necessary. | |
| 245 */ | |
| 246 | |
| 247 ulg opt_len; /* bit length of current block with optimal trees */ | |
| 248 ulg static_len; /* bit length of current block with static trees */ | |
| 249 uInt matches; /* number of string matches in current block */ | |
| 250 uInt insert; /* bytes at end of window left to insert */ | |
| 251 | |
| 252 #ifdef DEBUG | |
| 253 ulg compressed_len; /* total bit length of compressed file mod 2^32 */ | |
| 254 ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ | |
| 255 #endif | |
| 256 | |
| 257 ush bi_buf; | |
| 258 /* Output buffer. bits are inserted starting at the bottom (least | |
| 259 * significant bits). | |
| 260 */ | |
| 261 int bi_valid; | |
| 262 /* Number of valid bits in bi_buf. All bits above the last valid bit | |
| 263 * are always zero. | |
| 264 */ | |
| 265 | |
| 266 ulg high_water; | |
| 267 /* High water mark offset in window for initialized bytes -- bytes above | |
| 268 * this are set to zero in order to avoid memory check warnings when | |
| 269 * longest match routines access bytes past the input. This is then | |
| 270 * updated to the new high water mark. | |
| 271 */ | |
| 272 | |
| 273 } FAR deflate_state; | |
| 274 | |
| 275 /* Output a byte on the stream. | |
| 276 * IN assertion: there is enough room in pending_buf. | |
| 277 */ | |
| 278 #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);} | |
| 279 | |
| 280 | |
| 281 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) | |
| 282 /* Minimum amount of lookahead, except at the end of the input file. | |
| 283 * See deflate.c for comments about the MIN_MATCH+1. | |
| 284 */ | |
| 285 | |
| 286 #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) | |
| 287 /* In order to simplify the code, particularly on 16 bit machines, match | |
| 288 * distances are limited to MAX_DIST instead of WSIZE. | |
| 289 */ | |
| 290 | |
| 291 #define WIN_INIT MAX_MATCH | |
| 292 /* Number of bytes after end of data in window to initialize in order to avoid | |
| 293 memory checker errors from longest match routines */ | |
| 294 | |
| 295 /* in trees.c */ | |
| 296 void ZLIB_INTERNAL _tr_init OF((deflate_state *s)); | |
| 297 int ZLIB_INTERNAL _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); | |
| 298 void ZLIB_INTERNAL _tr_flush_block OF((deflate_state *s, charf *buf, | |
| 299 ulg stored_len, int last)); | |
| 300 void ZLIB_INTERNAL _tr_flush_bits OF((deflate_state *s)); | |
| 301 void ZLIB_INTERNAL _tr_align OF((deflate_state *s)); | |
| 302 void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf, | |
| 303 ulg stored_len, int last)); | |
| 304 | |
| 305 #define d_code(dist) \ | |
| 306 ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)]) | |
| 307 /* Mapping from a distance to a distance code. dist is the distance - 1 and | |
| 308 * must not have side effects. _dist_code[256] and _dist_code[257] are never | |
| 309 * used. | |
| 310 */ | |
| 311 | |
| 312 #ifndef DEBUG | |
| 313 /* Inline versions of _tr_tally for speed: */ | |
| 314 | |
| 315 #if defined(GEN_TREES_H) || !defined(STDC) | |
| 316 extern uch ZLIB_INTERNAL _length_code[]; | |
| 317 extern uch ZLIB_INTERNAL _dist_code[]; | |
| 318 #else | |
| 319 extern const uch ZLIB_INTERNAL _length_code[]; | |
| 320 extern const uch ZLIB_INTERNAL _dist_code[]; | |
| 321 #endif | |
| 322 | |
| 323 # define _tr_tally_lit(s, c, flush) \ | |
| 324 { uch cc = (c); \ | |
| 325 s->d_buf[s->last_lit] = 0; \ | |
| 326 s->l_buf[s->last_lit++] = cc; \ | |
| 327 s->dyn_ltree[cc].Freq++; \ | |
| 328 flush = (s->last_lit == s->lit_bufsize-1); \ | |
| 329 } | |
| 330 # define _tr_tally_dist(s, distance, length, flush) \ | |
| 331 { uch len = (length); \ | |
| 332 ush dist = (distance); \ | |
| 333 s->d_buf[s->last_lit] = dist; \ | |
| 334 s->l_buf[s->last_lit++] = len; \ | |
| 335 dist--; \ | |
| 336 s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ | |
| 337 s->dyn_dtree[d_code(dist)].Freq++; \ | |
| 338 flush = (s->last_lit == s->lit_bufsize-1); \ | |
| 339 } | |
| 340 #else | |
| 341 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) | |
| 342 # define _tr_tally_dist(s, distance, length, flush) \ | |
| 343 flush = _tr_tally(s, distance, length) | |
| 344 #endif | |
| 345 | |
| 346 #endif /* DEFLATE_H */ |
