1 2 3 4 #define Assert(err, str) 5 #define Trace(dummy) 6 #define Tracev(dummy) 7 #define Tracecv(err, dummy) 8 #define Tracevv(dummy) 9 10 11 12 #define LENGTH_CODES 29 13 /* number of length codes, not counting the special END_BLOCK code */ 14 15 #define LITERALS 256 16 /* number of literal bytes 0..255 */ 17 18 #define L_CODES (LITERALS+1+LENGTH_CODES) 19 /* number of Literal or Length codes, including the END_BLOCK code */ 20 21 #define D_CODES 30 22 /* number of distance codes */ 23 24 #define BL_CODES 19 25 /* number of codes used to transfer the bit lengths */ 26 27 #define HEAP_SIZE (2*L_CODES+1) 28 /* maximum heap size */ 29 30 #define MAX_BITS 15 31 /* All codes must not exceed MAX_BITS bits */ 32 33 #define INIT_STATE 42 34 #define BUSY_STATE 113 35 #define FINISH_STATE 666 36 /* Stream status */ 37 38 39 /* Data structure describing a single value and its code string. */ 40 typedef struct ct_data_s { 41 union { 42 ush freq; /* frequency count */ 43 ush code; /* bit string */ 44 } fc; 45 union { 46 ush dad; /* father node in Huffman tree */ 47 ush len; /* length of bit string */ 48 } dl; 49 } ct_data; 50 51 #define Freq fc.freq 52 #define Code fc.code 53 #define Dad dl.dad 54 #define Len dl.len 55 56 typedef struct static_tree_desc_s static_tree_desc; 57 58 typedef struct tree_desc_s { 59 ct_data *dyn_tree; /* the dynamic tree */ 60 int max_code; /* largest code with non zero frequency */ 61 static_tree_desc *stat_desc; /* the corresponding static tree */ 62 } tree_desc; 63 64 typedef ush Pos; 65 typedef unsigned IPos; 66 67 /* A Pos is an index in the character window. We use short instead of int to 68 * save space in the various tables. IPos is used only for parameter passing. 69 */ 70 71 typedef struct deflate_state { 72 z_streamp strm; /* pointer back to this zlib stream */ 73 int status; /* as the name implies */ 74 Byte *pending_buf; /* output still pending */ 75 ulg pending_buf_size; /* size of pending_buf */ 76 Byte *pending_out; /* next pending byte to output to the stream */ 77 int pending; /* nb of bytes in the pending buffer */ 78 int noheader; /* suppress zlib header and adler32 */ 79 Byte data_type; /* UNKNOWN, BINARY or ASCII */ 80 Byte method; /* STORED (for zip only) or DEFLATED */ 81 int last_flush; /* value of flush param for previous deflate call */ 82 83 /* used by deflate.c: */ 84 85 uInt w_size; /* LZ77 window size (32K by default) */ 86 uInt w_bits; /* log2(w_size) (8..16) */ 87 uInt w_mask; /* w_size - 1 */ 88 89 Byte *window; 90 /* Sliding window. Input bytes are read into the second half of the window, 91 * and move to the first half later to keep a dictionary of at least wSize 92 * bytes. With this organization, matches are limited to a distance of 93 * wSize-MAX_MATCH bytes, but this ensures that IO is always 94 * performed with a length multiple of the block size. Also, it limits 95 * the window size to 64K, which is quite useful on MSDOS. 96 * To do: use the user input buffer as sliding window. 97 */ 98 99 ulg window_size; 100 /* Actual size of window: 2*wSize, except when the user input buffer 101 * is directly used as sliding window. 102 */ 103 104 Pos *prev; 105 /* Link to older string with same hash index. To limit the size of this 106 * array to 64K, this link is maintained only for the last 32K strings. 107 * An index in this array is thus a window index modulo 32K. 108 */ 109 110 Pos *head; /* Heads of the hash chains or NIL. */ 111 112 uInt ins_h; /* hash index of string to be inserted */ 113 uInt hash_size; /* number of elements in hash table */ 114 uInt hash_bits; /* log2(hash_size) */ 115 uInt hash_mask; /* hash_size-1 */ 116 117 uInt hash_shift; 118 /* Number of bits by which ins_h must be shifted at each input 119 * step. It must be such that after MIN_MATCH steps, the oldest 120 * byte no longer takes part in the hash key, that is: 121 * hash_shift * MIN_MATCH >= hash_bits 122 */ 123 124 long block_start; 125 /* Window position at the beginning of the current output block. Gets 126 * negative when the window is moved backwards. 127 */ 128 129 uInt match_length; /* length of best match */ 130 IPos prev_match; /* previous match */ 131 int match_available; /* set if previous match exists */ 132 uInt strstart; /* start of string to insert */ 133 uInt match_start; /* start of matching string */ 134 uInt lookahead; /* number of valid bytes ahead in window */ 135 136 uInt prev_length; 137 /* Length of the best match at previous step. Matches not greater than this 138 * are discarded. This is used in the lazy match evaluation. 139 */ 140 141 uInt max_chain_length; 142 /* To speed up deflation, hash chains are never searched beyond this 143 * length. A higher limit improves compression ratio but degrades the 144 * speed. 145 */ 146 147 uInt max_lazy_match; 148 /* Attempt to find a better match only when the current match is strictly 149 * smaller than this value. This mechanism is used only for compression 150 * levels >= 4. 151 */ 152 # define max_insert_length max_lazy_match 153 /* Insert new strings in the hash table only if the match length is not 154 * greater than this length. This saves time but degrades compression. 155 * max_insert_length is used only for compression levels <= 3. 156 */ 157 158 int level; /* compression level (1..9) */ 159 int strategy; /* favor or force Huffman coding*/ 160 161 uInt good_match; 162 /* Use a faster search when the previous match is longer than this */ 163 164 int nice_match; /* Stop searching when current match exceeds this */ 165 166 /* used by trees.c: */ 167 /* Didn't use ct_data typedef below to suppress compiler warning */ 168 struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ 169 struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ 170 struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ 171 172 struct tree_desc_s l_desc; /* desc. for literal tree */ 173 struct tree_desc_s d_desc; /* desc. for distance tree */ 174 struct tree_desc_s bl_desc; /* desc. for bit length tree */ 175 176 ush bl_count[MAX_BITS+1]; 177 /* number of codes at each bit length for an optimal tree */ 178 179 int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ 180 int heap_len; /* number of elements in the heap */ 181 int heap_max; /* element of largest frequency */ 182 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. 183 * The same heap array is used to build all trees. 184 */ 185 186 uch depth[2*L_CODES+1]; 187 /* Depth of each subtree used as tie breaker for trees of equal frequency 188 */ 189 190 uch *l_buf; /* buffer for literals or lengths */ 191 192 uInt lit_bufsize; 193 /* Size of match buffer for literals/lengths. There are 4 reasons for 194 * limiting lit_bufsize to 64K: 195 * - frequencies can be kept in 16 bit counters 196 * - if compression is not successful for the first block, all input 197 * data is still in the window so we can still emit a stored block even 198 * when input comes from standard input. (This can also be done for 199 * all blocks if lit_bufsize is not greater than 32K.) 200 * - if compression is not successful for a file smaller than 64K, we can 201 * even emit a stored file instead of a stored block (saving 5 bytes). 202 * This is applicable only for zip (not gzip or zlib). 203 * - creating new Huffman trees less frequently may not provide fast 204 * adaptation to changes in the input data statistics. (Take for 205 * example a binary file with poorly compressible code followed by 206 * a highly compressible string table.) Smaller buffer sizes give 207 * fast adaptation but have of course the overhead of transmitting 208 * trees more frequently. 209 * - I can't count above 4 210 */ 211 212 uInt last_lit; /* running index in l_buf */ 213 214 ush *d_buf; 215 /* Buffer for distances. To simplify the code, d_buf and l_buf have 216 * the same number of elements. To use different lengths, an extra flag 217 * array would be necessary. 218 */ 219 220 ulg opt_len; /* bit length of current block with optimal trees */ 221 ulg static_len; /* bit length of current block with static trees */ 222 ulg compressed_len; /* total bit length of compressed file */ 223 uInt matches; /* number of string matches in current block */ 224 int last_eob_len; /* bit length of EOB code for last block */ 225 226 #ifdef DEBUG_ZLIB 227 ulg bits_sent; /* bit length of the compressed data */ 228 #endif 229 230 ush bi_buf; 231 /* Output buffer. bits are inserted starting at the bottom (least 232 * significant bits). 233 */ 234 int bi_valid; 235 /* Number of valid bits in bi_buf. All bits above the last valid bit 236 * are always zero. 237 */ 238 239 } deflate_state; 240 241 typedef struct deflate_workspace { 242 /* State memory for the deflator */ 243 deflate_state deflate_memory; 244 Byte *window_memory; 245 Pos *prev_memory; 246 Pos *head_memory; 247 char *overlay_memory; 248 } deflate_workspace; 249 250 #define zlib_deflate_window_memsize(windowBits) \ 251 (2 * (1 << (windowBits)) * sizeof(Byte)) 252 #define zlib_deflate_prev_memsize(windowBits) \ 253 ((1 << (windowBits)) * sizeof(Pos)) 254 #define zlib_deflate_head_memsize(memLevel) \ 255 ((1 << ((memLevel)+7)) * sizeof(Pos)) 256 #define zlib_deflate_overlay_memsize(memLevel) \ 257 ((1 << ((memLevel)+6)) * (sizeof(ush)+2)) 258 259 /* Output a byte on the stream. 260 * IN assertion: there is enough room in pending_buf. 261 */ 262 #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);} 263 264 265 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) 266 /* Minimum amount of lookahead, except at the end of the input file. 267 * See deflate.c for comments about the MIN_MATCH+1. 268 */ 269 270 #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) 271 /* In order to simplify the code, particularly on 16 bit machines, match 272 * distances are limited to MAX_DIST instead of WSIZE. 273 */ 274 275 /* in trees.c */ 276 void zlib_tr_init (deflate_state *s); 277 int zlib_tr_tally (deflate_state *s, unsigned dist, unsigned lc); 278 ulg zlib_tr_flush_block (deflate_state *s, char *buf, ulg stored_len, 279 int eof); 280 void zlib_tr_align (deflate_state *s); 281 void zlib_tr_stored_block (deflate_state *s, char *buf, ulg stored_len, 282 int eof); 283 void zlib_tr_stored_type_only (deflate_state *); 284 285 286 /* =========================================================================== 287 * Output a short LSB first on the stream. 288 * IN assertion: there is enough room in pendingBuf. 289 */ 290 #define put_short(s, w) { \ 291 put_byte(s, (uch)((w) & 0xff)); \ 292 put_byte(s, (uch)((ush)(w) >> 8)); \ 293 } 294 295 /* =========================================================================== 296 * Reverse the first len bits of a code, using straightforward code (a faster 297 * method would use a table) 298 * IN assertion: 1 <= len <= 15 299 */ 300 static inline unsigned bi_reverse(unsigned code, /* the value to invert */ 301 int len) /* its bit length */ 302 { 303 register unsigned res = 0; 304 do { 305 res |= code & 1; 306 code >>= 1, res <<= 1; 307 } while (--len > 0); 308 return res >> 1; 309 } 310 311 /* =========================================================================== 312 * Flush the bit buffer, keeping at most 7 bits in it. 313 */ 314 static inline void bi_flush(deflate_state *s) 315 { 316 if (s->bi_valid == 16) { 317 put_short(s, s->bi_buf); 318 s->bi_buf = 0; 319 s->bi_valid = 0; 320 } else if (s->bi_valid >= 8) { 321 put_byte(s, (Byte)s->bi_buf); 322 s->bi_buf >>= 8; 323 s->bi_valid -= 8; 324 } 325 } 326 327 /* =========================================================================== 328 * Flush the bit buffer and align the output on a byte boundary 329 */ 330 static inline void bi_windup(deflate_state *s) 331 { 332 if (s->bi_valid > 8) { 333 put_short(s, s->bi_buf); 334 } else if (s->bi_valid > 0) { 335 put_byte(s, (Byte)s->bi_buf); 336 } 337 s->bi_buf = 0; 338 s->bi_valid = 0; 339 #ifdef DEBUG_ZLIB 340 s->bits_sent = (s->bits_sent+7) & ~7; 341 #endif 342 } 343 344