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<hr><h1>deflate.h</h1><div class="fragment"><pre>00001 <font class="comment">/* deflate.h -- internal compression state</font>
00002 <font class="comment"> * Copyright (C) 1995-1998 Jean-loup Gailly</font>
00003 <font class="comment"> * For conditions of distribution and use, see copyright notice in zlib.h </font>
00004 <font class="comment"> */</font>
00005
00006 <font class="comment">/* WARNING: this file should *not* be used by applications. It is</font>
00007 <font class="comment"> part of the implementation of the compression library and is</font>
00008 <font class="comment"> subject to change. Applications should only use zlib.h.</font>
00009 <font class="comment"> */</font>
00010
00011 <font class="comment">/* @(#) $Id: deflate_8h-source.html,v 1.3 2002/06/20 20:23:08 mgruner Exp $ */</font>
00012
00013 <font class="preprocessor">#ifndef _DEFLATE_H</font>
00014 <font class="preprocessor"></font><font class="preprocessor">#define _DEFLATE_H</font>
00015 <font class="preprocessor"></font>
00016 <font class="preprocessor">#include "zutil.h"</font>
00017
00018 <font class="comment">/* ===========================================================================</font>
00019 <font class="comment"> * Internal compression state.</font>
00020 <font class="comment"> */</font>
00021
00022 <font class="preprocessor">#define LENGTH_CODES 29</font>
00023 <font class="preprocessor"></font><font class="comment">/* number of length codes, not counting the special END_BLOCK code */</font>
00024
00025 <font class="preprocessor">#define LITERALS 256</font>
00026 <font class="preprocessor"></font><font class="comment">/* number of literal bytes 0..255 */</font>
00027
00028 <font class="preprocessor">#define L_CODES (LITERALS+1+LENGTH_CODES)</font>
00029 <font class="preprocessor"></font><font class="comment">/* number of Literal or Length codes, including the END_BLOCK code */</font>
00030
00031 <font class="preprocessor">#define D_CODES 30</font>
00032 <font class="preprocessor"></font><font class="comment">/* number of distance codes */</font>
00033
00034 <font class="preprocessor">#define BL_CODES 19</font>
00035 <font class="preprocessor"></font><font class="comment">/* number of codes used to transfer the bit lengths */</font>
00036
00037 <font class="preprocessor">#define HEAP_SIZE (2*L_CODES+1)</font>
00038 <font class="preprocessor"></font><font class="comment">/* maximum heap size */</font>
00039
00040 <font class="preprocessor">#define MAX_BITS 15</font>
00041 <font class="preprocessor"></font><font class="comment">/* All codes must not exceed MAX_BITS bits */</font>
00042
00043 <font class="preprocessor">#define INIT_STATE 42</font>
00044 <font class="preprocessor"></font><font class="preprocessor">#define BUSY_STATE 113</font>
00045 <font class="preprocessor"></font><font class="preprocessor">#define FINISH_STATE 666</font>
00046 <font class="preprocessor"></font><font class="comment">/* Stream status */</font>
00047
00048
00049 <font class="comment">/* Data structure describing a single value and its code string. */</font>
00050 <font class="keyword">typedef</font> <font class="keyword">struct </font>ct_data_s {
00051 <font class="keyword">union </font>{
00052 ush freq; <font class="comment">/* frequency count */</font>
00053 ush code; <font class="comment">/* bit string */</font>
00054 } fc;
00055 <font class="keyword">union </font>{
00056 ush dad; <font class="comment">/* father node in Huffman tree */</font>
00057 ush len; <font class="comment">/* length of bit string */</font>
00058 } dl;
00059 } FAR ct_data;
00060
00061 <font class="preprocessor">#define Freq fc.freq</font>
00062 <font class="preprocessor"></font><font class="preprocessor">#define Code fc.code</font>
00063 <font class="preprocessor"></font><font class="preprocessor">#define Dad dl.dad</font>
00064 <font class="preprocessor"></font><font class="preprocessor">#define Len dl.len</font>
00065 <font class="preprocessor"></font>
00066 <font class="keyword">typedef</font> <font class="keyword">struct </font>static_tree_desc_s static_tree_desc;
00067
00068 <font class="keyword">typedef</font> <font class="keyword">struct </font>tree_desc_s {
00069 ct_data *dyn_tree; <font class="comment">/* the dynamic tree */</font>
00070 <font class="keywordtype">int</font> max_code; <font class="comment">/* largest code with non zero frequency */</font>
00071 static_tree_desc *stat_desc; <font class="comment">/* the corresponding static tree */</font>
00072 } FAR tree_desc;
00073
00074 <font class="keyword">typedef</font> ush Pos;
00075 <font class="keyword">typedef</font> Pos FAR Posf;
00076 <font class="keyword">typedef</font> <font class="keywordtype">unsigned</font> IPos;
00077
00078 <font class="comment">/* A Pos is an index in the character window. We use short instead of int to</font>
00079 <font class="comment"> * save space in the various tables. IPos is used only for parameter passing.</font>
00080 <font class="comment"> */</font>
00081
00082 <font class="keyword">typedef</font> <font class="keyword">struct </font>internal_state {
00083 z_streamp strm; <font class="comment">/* pointer back to this zlib stream */</font>
00084 <font class="keywordtype">int</font> status; <font class="comment">/* as the name implies */</font>
00085 Bytef *pending_buf; <font class="comment">/* output still pending */</font>
00086 ulg pending_buf_size; <font class="comment">/* size of pending_buf */</font>
00087 Bytef *pending_out; <font class="comment">/* next pending byte to output to the stream */</font>
00088 <font class="keywordtype">int</font> pending; <font class="comment">/* nb of bytes in the pending buffer */</font>
00089 <font class="keywordtype">int</font> noheader; <font class="comment">/* suppress zlib header and adler32 */</font>
00090 Byte data_type; <font class="comment">/* UNKNOWN, BINARY or ASCII */</font>
00091 Byte method; <font class="comment">/* STORED (for zip only) or DEFLATED */</font>
00092 <font class="keywordtype">int</font> last_flush; <font class="comment">/* value of flush param for previous deflate call */</font>
00093
00094 <font class="comment">/* used by deflate.c: */</font>
00095
00096 uInt w_size; <font class="comment">/* LZ77 window size (32K by default) */</font>
00097 uInt w_bits; <font class="comment">/* log2(w_size) (8..16) */</font>
00098 uInt w_mask; <font class="comment">/* w_size - 1 */</font>
00099
00100 Bytef *window;
00101 <font class="comment">/* Sliding window. Input bytes are read into the second half of the window,</font>
00102 <font class="comment"> * and move to the first half later to keep a dictionary of at least wSize</font>
00103 <font class="comment"> * bytes. With this organization, matches are limited to a distance of</font>
00104 <font class="comment"> * wSize-MAX_MATCH bytes, but this ensures that IO is always</font>
00105 <font class="comment"> * performed with a length multiple of the block size. Also, it limits</font>
00106 <font class="comment"> * the window size to 64K, which is quite useful on MSDOS.</font>
00107 <font class="comment"> * To do: use the user input buffer as sliding window.</font>
00108 <font class="comment"> */</font>
00109
00110 ulg window_size;
00111 <font class="comment">/* Actual size of window: 2*wSize, except when the user input buffer</font>
00112 <font class="comment"> * is directly used as sliding window.</font>
00113 <font class="comment"> */</font>
00114
00115 Posf *prev;
00116 <font class="comment">/* Link to older string with same hash index. To limit the size of this</font>
00117 <font class="comment"> * array to 64K, this link is maintained only for the last 32K strings.</font>
00118 <font class="comment"> * An index in this array is thus a window index modulo 32K.</font>
00119 <font class="comment"> */</font>
00120
00121 Posf *head; <font class="comment">/* Heads of the hash chains or NIL. */</font>
00122
00123 uInt ins_h; <font class="comment">/* hash index of string to be inserted */</font>
00124 uInt hash_size; <font class="comment">/* number of elements in hash table */</font>
00125 uInt hash_bits; <font class="comment">/* log2(hash_size) */</font>
00126 uInt hash_mask; <font class="comment">/* hash_size-1 */</font>
00127
00128 uInt hash_shift;
00129 <font class="comment">/* Number of bits by which ins_h must be shifted at each input</font>
00130 <font class="comment"> * step. It must be such that after MIN_MATCH steps, the oldest</font>
00131 <font class="comment"> * byte no longer takes part in the hash key, that is:</font>
00132 <font class="comment"> * hash_shift * MIN_MATCH >= hash_bits</font>
00133 <font class="comment"> */</font>
00134
00135 <font class="keywordtype">long</font> block_start;
00136 <font class="comment">/* Window position at the beginning of the current output block. Gets</font>
00137 <font class="comment"> * negative when the window is moved backwards.</font>
00138 <font class="comment"> */</font>
00139
00140 uInt match_length; <font class="comment">/* length of best match */</font>
00141 IPos prev_match; <font class="comment">/* previous match */</font>
00142 <font class="keywordtype">int</font> match_available; <font class="comment">/* set if previous match exists */</font>
00143 uInt strstart; <font class="comment">/* start of string to insert */</font>
00144 uInt match_start; <font class="comment">/* start of matching string */</font>
00145 uInt lookahead; <font class="comment">/* number of valid bytes ahead in window */</font>
00146
00147 uInt prev_length;
00148 <font class="comment">/* Length of the best match at previous step. Matches not greater than this</font>
00149 <font class="comment"> * are discarded. This is used in the lazy match evaluation.</font>
00150 <font class="comment"> */</font>
00151
00152 uInt max_chain_length;
00153 <font class="comment">/* To speed up deflation, hash chains are never searched beyond this</font>
00154 <font class="comment"> * length. A higher limit improves compression ratio but degrades the</font>
00155 <font class="comment"> * speed.</font>
00156 <font class="comment"> */</font>
00157
00158 uInt max_lazy_match;
00159 <font class="comment">/* Attempt to find a better match only when the current match is strictly</font>
00160 <font class="comment"> * smaller than this value. This mechanism is used only for compression</font>
00161 <font class="comment"> * levels >= 4.</font>
00162 <font class="comment"> */</font>
00163 <font class="preprocessor"># define max_insert_length max_lazy_match</font>
00164 <font class="preprocessor"></font> <font class="comment">/* Insert new strings in the hash table only if the match length is not</font>
00165 <font class="comment"> * greater than this length. This saves time but degrades compression.</font>
00166 <font class="comment"> * max_insert_length is used only for compression levels <= 3.</font>
00167 <font class="comment"> */</font>
00168
00169 <font class="keywordtype">int</font> level; <font class="comment">/* compression level (1..9) */</font>
00170 <font class="keywordtype">int</font> strategy; <font class="comment">/* favor or force Huffman coding*/</font>
00171
00172 uInt good_match;
00173 <font class="comment">/* Use a faster search when the previous match is longer than this */</font>
00174
00175 <font class="keywordtype">int</font> nice_match; <font class="comment">/* Stop searching when current match exceeds this */</font>
00176
00177 <font class="comment">/* used by trees.c: */</font>
00178 <font class="comment">/* Didn't use ct_data typedef below to supress compiler warning */</font>
00179 <font class="keyword">struct </font>ct_data_s dyn_ltree[HEAP_SIZE]; <font class="comment">/* literal and length tree */</font>
00180 <font class="keyword">struct </font>ct_data_s dyn_dtree[2*D_CODES+1]; <font class="comment">/* distance tree */</font>
00181 <font class="keyword">struct </font>ct_data_s bl_tree[2*BL_CODES+1]; <font class="comment">/* Huffman tree for bit lengths */</font>
00182
00183 <font class="keyword">struct </font>tree_desc_s l_desc; <font class="comment">/* desc. for literal tree */</font>
00184 <font class="keyword">struct </font>tree_desc_s d_desc; <font class="comment">/* desc. for distance tree */</font>
00185 <font class="keyword">struct </font>tree_desc_s bl_desc; <font class="comment">/* desc. for bit length tree */</font>
00186
00187 ush bl_count[MAX_BITS+1];
00188 <font class="comment">/* number of codes at each bit length for an optimal tree */</font>
00189
00190 <font class="keywordtype">int</font> heap[2*L_CODES+1]; <font class="comment">/* heap used to build the Huffman trees */</font>
00191 <font class="keywordtype">int</font> heap_len; <font class="comment">/* number of elements in the heap */</font>
00192 <font class="keywordtype">int</font> heap_max; <font class="comment">/* element of largest frequency */</font>
00193 <font class="comment">/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.</font>
00194 <font class="comment"> * The same heap array is used to build all trees.</font>
00195 <font class="comment"> */</font>
00196
00197 uch depth[2*L_CODES+1];
00198 <font class="comment">/* Depth of each subtree used as tie breaker for trees of equal frequency</font>
00199 <font class="comment"> */</font>
00200
00201 uchf *l_buf; <font class="comment">/* buffer for literals or lengths */</font>
00202
00203 uInt lit_bufsize;
00204 <font class="comment">/* Size of match buffer for literals/lengths. There are 4 reasons for</font>
00205 <font class="comment"> * limiting lit_bufsize to 64K:</font>
00206 <font class="comment"> * - frequencies can be kept in 16 bit counters</font>
00207 <font class="comment"> * - if compression is not successful for the first block, all input</font>
00208 <font class="comment"> * data is still in the window so we can still emit a stored block even</font>
00209 <font class="comment"> * when input comes from standard input. (This can also be done for</font>
00210 <font class="comment"> * all blocks if lit_bufsize is not greater than 32K.)</font>
00211 <font class="comment"> * - if compression is not successful for a file smaller than 64K, we can</font>
00212 <font class="comment"> * even emit a stored file instead of a stored block (saving 5 bytes).</font>
00213 <font class="comment"> * This is applicable only for zip (not gzip or zlib).</font>
00214 <font class="comment"> * - creating new Huffman trees less frequently may not provide fast</font>
00215 <font class="comment"> * adaptation to changes in the input data statistics. (Take for</font>
00216 <font class="comment"> * example a binary file with poorly compressible code followed by</font>
00217 <font class="comment"> * a highly compressible string table.) Smaller buffer sizes give</font>
00218 <font class="comment"> * fast adaptation but have of course the overhead of transmitting</font>
00219 <font class="comment"> * trees more frequently.</font>
00220 <font class="comment"> * - I can't count above 4</font>
00221 <font class="comment"> */</font>
00222
00223 uInt last_lit; <font class="comment">/* running index in l_buf */</font>
00224
00225 ushf *d_buf;
00226 <font class="comment">/* Buffer for distances. To simplify the code, d_buf and l_buf have</font>
00227 <font class="comment"> * the same number of elements. To use different lengths, an extra flag</font>
00228 <font class="comment"> * array would be necessary.</font>
00229 <font class="comment"> */</font>
00230
00231 ulg opt_len; <font class="comment">/* bit length of current block with optimal trees */</font>
00232 ulg static_len; <font class="comment">/* bit length of current block with static trees */</font>
00233 uInt matches; <font class="comment">/* number of string matches in current block */</font>
00234 <font class="keywordtype">int</font> last_eob_len; <font class="comment">/* bit length of EOB code for last block */</font>
00235
00236 <font class="preprocessor">#ifdef DEBUG</font>
00237 <font class="preprocessor"></font> ulg compressed_len; <font class="comment">/* total bit length of compressed file mod 2^32 */</font>
00238 ulg bits_sent; <font class="comment">/* bit length of compressed data sent mod 2^32 */</font>
00239 <font class="preprocessor">#endif</font>
00240 <font class="preprocessor"></font>
00241 ush bi_buf;
00242 <font class="comment">/* Output buffer. bits are inserted starting at the bottom (least</font>
00243 <font class="comment"> * significant bits).</font>
00244 <font class="comment"> */</font>
00245 <font class="keywordtype">int</font> bi_valid;
00246 <font class="comment">/* Number of valid bits in bi_buf. All bits above the last valid bit</font>
00247 <font class="comment"> * are always zero.</font>
00248 <font class="comment"> */</font>
00249
00250 } FAR deflate_state;
00251
00252 <font class="comment">/* Output a byte on the stream.</font>
00253 <font class="comment"> * IN assertion: there is enough room in pending_buf.</font>
00254 <font class="comment"> */</font>
00255 <font class="preprocessor">#define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}</font>
00256 <font class="preprocessor"></font>
00257
00258 <font class="preprocessor">#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)</font>
00259 <font class="preprocessor"></font><font class="comment">/* Minimum amount of lookahead, except at the end of the input file.</font>
00260 <font class="comment"> * See deflate.c for comments about the MIN_MATCH+1.</font>
00261 <font class="comment"> */</font>
00262
00263 <font class="preprocessor">#define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD)</font>
00264 <font class="preprocessor"></font><font class="comment">/* In order to simplify the code, particularly on 16 bit machines, match</font>
00265 <font class="comment"> * distances are limited to MAX_DIST instead of WSIZE.</font>
00266 <font class="comment"> */</font>
00267
00268 <font class="comment">/* in trees.c */</font>
00269 <font class="keywordtype">void</font> _tr_init OF((deflate_state *s));
00270 <font class="keywordtype">int</font> _tr_tally OF((deflate_state *s, <font class="keywordtype">unsigned</font> dist, <font class="keywordtype">unsigned</font> lc));
00271 <font class="keywordtype">void</font> _tr_flush_block OF((deflate_state *s, charf *buf, ulg stored_len,
00272 <font class="keywordtype">int</font> eof));
00273 <font class="keywordtype">void</font> _tr_align OF((deflate_state *s));
00274 <font class="keywordtype">void</font> _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len,
00275 <font class="keywordtype">int</font> eof));
00276
00277 <font class="preprocessor">#define d_code(dist) \</font>
00278 <font class="preprocessor"> ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])</font>
00279 <font class="preprocessor"></font><font class="comment">/* Mapping from a distance to a distance code. dist is the distance - 1 and</font>
00280 <font class="comment"> * must not have side effects. _dist_code[256] and _dist_code[257] are never</font>
00281 <font class="comment"> * used.</font>
00282 <font class="comment"> */</font>
00283
00284 <font class="preprocessor">#ifndef DEBUG</font>
00285 <font class="preprocessor"></font><font class="comment">/* Inline versions of _tr_tally for speed: */</font>
00286
00287 <font class="preprocessor">#if defined(GEN_TREES_H) || !defined(STDC)</font>
00288 <font class="preprocessor"></font> <font class="keyword">extern</font> uch _length_code[];
00289 <font class="keyword">extern</font> uch _dist_code[];
00290 <font class="preprocessor">#else</font>
00291 <font class="preprocessor"></font> <font class="keyword">extern</font> <font class="keyword">const</font> uch _length_code[];
00292 <font class="keyword">extern</font> <font class="keyword">const</font> uch _dist_code[];
00293 <font class="preprocessor">#endif</font>
00294 <font class="preprocessor"></font>
00295 <font class="preprocessor"># define _tr_tally_lit(s, c, flush) \</font>
00296 <font class="preprocessor"> { uch cc = (c); \</font>
00297 <font class="preprocessor"> s->d_buf[s->last_lit] = 0; \</font>
00298 <font class="preprocessor"> s->l_buf[s->last_lit++] = cc; \</font>
00299 <font class="preprocessor"> s->dyn_ltree[cc].Freq++; \</font>
00300 <font class="preprocessor"> flush = (s->last_lit == s->lit_bufsize-1); \</font>
00301 <font class="preprocessor"> }</font>
00302 <font class="preprocessor"></font><font class="preprocessor"># define _tr_tally_dist(s, distance, length, flush) \</font>
00303 <font class="preprocessor"> { uch len = (length); \</font>
00304 <font class="preprocessor"> ush dist = (distance); \</font>
00305 <font class="preprocessor"> s->d_buf[s->last_lit] = dist; \</font>
00306 <font class="preprocessor"> s->l_buf[s->last_lit++] = len; \</font>
00307 <font class="preprocessor"> dist--; \</font>
00308 <font class="preprocessor"> s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \</font>
00309 <font class="preprocessor"> s->dyn_dtree[d_code(dist)].Freq++; \</font>
00310 <font class="preprocessor"> flush = (s->last_lit == s->lit_bufsize-1); \</font>
00311 <font class="preprocessor"> }</font>
00312 <font class="preprocessor"></font><font class="preprocessor">#else</font>
00313 <font class="preprocessor"></font><font class="preprocessor"># define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)</font>
00314 <font class="preprocessor"></font><font class="preprocessor"># define _tr_tally_dist(s, distance, length, flush) \</font>
00315 <font class="preprocessor"> flush = _tr_tally(s, distance, length) </font>
00316 <font class="preprocessor"></font><font class="preprocessor">#endif</font>
00317 <font class="preprocessor"></font>
00318 <font class="preprocessor">#endif</font>
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