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 EXTRA_STATE 69 80#define NAME_STATE 73 81#define COMMENT_STATE 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. */ 89typedef 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 105typedef struct static_tree_desc_s static_tree_desc; 106 107typedef 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 113typedef ush Pos; 114typedef Pos FAR Posf; 115typedef 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 121typedef struct internal_state { 122 z_streamp strm; /* pointer back to this zlib stream */ 123 int status; /* as the name implies */ 124 Bytef *pending_buf; /* output still pending */ 125 ulg pending_buf_size; /* size of pending_buf */ 126 Bytef *pending_out; /* next pending byte to output to the stream */ 127 uInt pending; /* nb of bytes in the pending buffer */ 128 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ 129 gz_headerp gzhead; /* gzip header information to write */ 130 uInt gzindex; /* where in extra, name, or comment */ 131 Byte method; /* STORED (for zip only) or DEFLATED */ 132 int last_flush; /* value of flush param for previous deflate call */ 133 134 /* used by deflate.c: */ 135 136 uInt w_size; /* LZ77 window size (32K by default) */ 137 uInt w_bits; /* log2(w_size) (8..16) */ 138 uInt w_mask; /* w_size - 1 */ 139 140 Bytef *window; 141 /* Sliding window. Input bytes are read into the second half of the window, 142 * and move to the first half later to keep a dictionary of at least wSize 143 * bytes. With this organization, matches are limited to a distance of 144 * wSize-MAX_MATCH bytes, but this ensures that IO is always 145 * performed with a length multiple of the block size. Also, it limits 146 * the window size to 64K, which is quite useful on MSDOS. 147 * To do: use the user input buffer as sliding window. 148 */ 149 150 ulg window_size; 151 /* Actual size of window: 2*wSize, except when the user input buffer 152 * is directly used as sliding window. 153 */ 154 155 Posf *prev; 156 /* Link to older string with same hash index. To limit the size of this 157 * array to 64K, this link is maintained only for the last 32K strings. 158 * An index in this array is thus a window index modulo 32K. 159 */ 160 161 Posf *head; /* Heads of the hash chains or NIL. */ 162 163 uInt ins_h; /* hash index of string to be inserted */ 164 uInt hash_size; /* number of elements in hash table */ 165 uInt hash_bits; /* log2(hash_size) */ 166 uInt hash_mask; /* hash_size-1 */ 167 168 uInt hash_shift; 169 /* Number of bits by which ins_h must be shifted at each input 170 * step. It must be such that after MIN_MATCH steps, the oldest 171 * byte no longer takes part in the hash key, that is: 172 * hash_shift * MIN_MATCH >= hash_bits 173 */ 174 175 long block_start; 176 /* Window position at the beginning of the current output block. Gets 177 * negative when the window is moved backwards. 178 */ 179 180 uInt match_length; /* length of best match */ 181 IPos prev_match; /* previous match */ 182 int match_available; /* set if previous match exists */ 183 uInt strstart; /* start of string to insert */ 184 uInt match_start; /* start of matching string */ 185 uInt lookahead; /* number of valid bytes ahead in window */ 186 187 uInt prev_length; 188 /* Length of the best match at previous step. Matches not greater than this 189 * are discarded. This is used in the lazy match evaluation. 190 */ 191 192 uInt max_chain_length; 193 /* To speed up deflation, hash chains are never searched beyond this 194 * length. A higher limit improves compression ratio but degrades the 195 * speed. 196 */ 197 198 uInt max_lazy_match; 199 /* Attempt to find a better match only when the current match is strictly 200 * smaller than this value. This mechanism is used only for compression 201 * levels >= 4. 202 */ 203# define max_insert_length max_lazy_match 204 /* Insert new strings in the hash table only if the match length is not 205 * greater than this length. This saves time but degrades compression. 206 * max_insert_length is used only for compression levels <= 3. 207 */ 208 209 int level; /* compression level (1..9) */ 210 int strategy; /* favor or force Huffman coding*/ 211 212 uInt good_match; 213 /* Use a faster search when the previous match is longer than this */ 214 215 int nice_match; /* Stop searching when current match exceeds this */ 216 217 /* used by trees.c: */ 218 /* Didn't use ct_data typedef below to supress compiler warning */ 219 struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ 220 struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ 221 struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ 222 223 struct tree_desc_s l_desc; /* desc. for literal tree */ 224 struct tree_desc_s d_desc; /* desc. for distance tree */ 225 struct tree_desc_s bl_desc; /* desc. for bit length tree */ 226 227 ush bl_count[MAX_BITS+1]; 228 /* number of codes at each bit length for an optimal tree */ 229 230 int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ 231 int heap_len; /* number of elements in the heap */ 232 int heap_max; /* element of largest frequency */ 233 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. 234 * The same heap array is used to build all trees. 235 */ 236 237 uch depth[2*L_CODES+1]; 238 /* Depth of each subtree used as tie breaker for trees of equal frequency 239 */ 240 241 uchf *l_buf; /* buffer for literals or lengths */ 242 243 uInt lit_bufsize; 244 /* Size of match buffer for literals/lengths. There are 4 reasons for 245 * limiting lit_bufsize to 64K: 246 * - frequencies can be kept in 16 bit counters 247 * - if compression is not successful for the first block, all input 248 * data is still in the window so we can still emit a stored block even 249 * when input comes from standard input. (This can also be done for 250 * all blocks if lit_bufsize is not greater than 32K.) 251 * - if compression is not successful for a file smaller than 64K, we can 252 * even emit a stored file instead of a stored block (saving 5 bytes). 253 * This is applicable only for zip (not gzip or zlib). 254 * - creating new Huffman trees less frequently may not provide fast 255 * adaptation to changes in the input data statistics. (Take for 256 * example a binary file with poorly compressible code followed by 257 * a highly compressible string table.) Smaller buffer sizes give 258 * fast adaptation but have of course the overhead of transmitting 259 * trees more frequently. 260 * - I can't count above 4 261 */ 262 263 uInt last_lit; /* running index in l_buf */ 264 265 ushf *d_buf; 266 /* Buffer for distances. To simplify the code, d_buf and l_buf have 267 * the same number of elements. To use different lengths, an extra flag 268 * array would be necessary. 269 */ 270 271 ulg opt_len; /* bit length of current block with optimal trees */ 272 ulg static_len; /* bit length of current block with static trees */ 273 uInt matches; /* number of string matches in current block */ 274 int last_eob_len; /* bit length of EOB code for last block */ 275 276#ifdef DEBUG 277 ulg compressed_len; /* total bit length of compressed file mod 2^32 */ 278 ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ 279#endif 280 281 ush bi_buf; 282 /* Output buffer. bits are inserted starting at the bottom (least 283 * significant bits). 284 */ 285 int bi_valid; 286 /* Number of valid bits in bi_buf. All bits above the last valid bit 287 * are always zero. 288 */ 289 290} FAR deflate_state; 291 292/* Output a byte on the stream. 293 * IN assertion: there is enough room in pending_buf. 294 */ 295#define put_byte(s, c) {s->pending_buf[s->pending++] = (c);} 296 297 298#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) 299/* Minimum amount of lookahead, except at the end of the input file. 300 * See deflate.c for comments about the MIN_MATCH+1. 301 */ 302 303#define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) 304/* In order to simplify the code, particularly on 16 bit machines, match 305 * distances are limited to MAX_DIST instead of WSIZE. 306 */ 307 308 /* in trees.c */ 309void _tr_init OF((deflate_state *s)); 310int _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); 311void _tr_flush_block OF((deflate_state *s, charf *buf, ulg stored_len, 312 int eof)); 313void _tr_align OF((deflate_state *s)); 314void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len, 315 int eof)); 316 317#define d_code(dist) \ 318 ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)]) 319/* Mapping from a distance to a distance code. dist is the distance - 1 and 320 * must not have side effects. _dist_code[256] and _dist_code[257] are never 321 * used. 322 */ 323 324#ifndef DEBUG 325/* Inline versions of _tr_tally for speed: */ 326 327#if defined(GEN_TREES_H) || !defined(STDC) 328 extern uch _length_code[]; 329 extern uch _dist_code[]; 330#else 331 extern const uch _length_code[]; 332 extern const uch _dist_code[]; 333#endif 334 335# define _tr_tally_lit(s, c, flush) \ 336 { uch cc = (c); \ 337 s->d_buf[s->last_lit] = 0; \ 338 s->l_buf[s->last_lit++] = cc; \ 339 s->dyn_ltree[cc].Freq++; \ 340 flush = (s->last_lit == s->lit_bufsize-1); \ 341 } 342# define _tr_tally_dist(s, distance, length, flush) \ 343 { uch len = (length); \ 344 ush dist = (distance); \ 345 s->d_buf[s->last_lit] = dist; \ 346 s->l_buf[s->last_lit++] = len; \ 347 dist--; \ 348 s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ 349 s->dyn_dtree[d_code(dist)].Freq++; \ 350 flush = (s->last_lit == s->lit_bufsize-1); \ 351 } 352#else 353# define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) 354# define _tr_tally_dist(s, distance, length, flush) \ 355 flush = _tr_tally(s, distance, length) 356#endif 357 358#endif /* DEFLATE_H */ 359