Commit | Line | Data |
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1da177e4 LT |
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: */ | |
643d1f7f | 167 | /* Didn't use ct_data typedef below to suppress compiler warning */ |
1da177e4 LT |
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[2 * (1 << MAX_WBITS)]; | |
245 | Pos prev_memory[1 << MAX_WBITS]; | |
246 | Pos head_memory[1 << (MAX_MEM_LEVEL + 7)]; | |
247 | char overlay_memory[(1 << (MAX_MEM_LEVEL + 6)) * (sizeof(ush)+2)]; | |
248 | } deflate_workspace; | |
249 | ||
250 | /* Output a byte on the stream. | |
251 | * IN assertion: there is enough room in pending_buf. | |
252 | */ | |
253 | #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);} | |
254 | ||
255 | ||
256 | #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) | |
257 | /* Minimum amount of lookahead, except at the end of the input file. | |
258 | * See deflate.c for comments about the MIN_MATCH+1. | |
259 | */ | |
260 | ||
261 | #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD) | |
262 | /* In order to simplify the code, particularly on 16 bit machines, match | |
263 | * distances are limited to MAX_DIST instead of WSIZE. | |
264 | */ | |
265 | ||
266 | /* in trees.c */ | |
267 | void zlib_tr_init (deflate_state *s); | |
268 | int zlib_tr_tally (deflate_state *s, unsigned dist, unsigned lc); | |
269 | ulg zlib_tr_flush_block (deflate_state *s, char *buf, ulg stored_len, | |
270 | int eof); | |
271 | void zlib_tr_align (deflate_state *s); | |
272 | void zlib_tr_stored_block (deflate_state *s, char *buf, ulg stored_len, | |
273 | int eof); | |
274 | void zlib_tr_stored_type_only (deflate_state *); | |
275 | ||
276 | ||
277 | /* =========================================================================== | |
278 | * Output a short LSB first on the stream. | |
279 | * IN assertion: there is enough room in pendingBuf. | |
280 | */ | |
281 | #define put_short(s, w) { \ | |
282 | put_byte(s, (uch)((w) & 0xff)); \ | |
283 | put_byte(s, (uch)((ush)(w) >> 8)); \ | |
284 | } | |
285 | ||
286 | /* =========================================================================== | |
287 | * Reverse the first len bits of a code, using straightforward code (a faster | |
288 | * method would use a table) | |
289 | * IN assertion: 1 <= len <= 15 | |
290 | */ | |
291 | static inline unsigned bi_reverse(unsigned code, /* the value to invert */ | |
292 | int len) /* its bit length */ | |
293 | { | |
294 | register unsigned res = 0; | |
295 | do { | |
296 | res |= code & 1; | |
297 | code >>= 1, res <<= 1; | |
298 | } while (--len > 0); | |
299 | return res >> 1; | |
300 | } | |
301 | ||
302 | /* =========================================================================== | |
303 | * Flush the bit buffer, keeping at most 7 bits in it. | |
304 | */ | |
305 | static inline void bi_flush(deflate_state *s) | |
306 | { | |
307 | if (s->bi_valid == 16) { | |
308 | put_short(s, s->bi_buf); | |
309 | s->bi_buf = 0; | |
310 | s->bi_valid = 0; | |
311 | } else if (s->bi_valid >= 8) { | |
312 | put_byte(s, (Byte)s->bi_buf); | |
313 | s->bi_buf >>= 8; | |
314 | s->bi_valid -= 8; | |
315 | } | |
316 | } | |
317 | ||
318 | /* =========================================================================== | |
319 | * Flush the bit buffer and align the output on a byte boundary | |
320 | */ | |
321 | static inline void bi_windup(deflate_state *s) | |
322 | { | |
323 | if (s->bi_valid > 8) { | |
324 | put_short(s, s->bi_buf); | |
325 | } else if (s->bi_valid > 0) { | |
326 | put_byte(s, (Byte)s->bi_buf); | |
327 | } | |
328 | s->bi_buf = 0; | |
329 | s->bi_valid = 0; | |
330 | #ifdef DEBUG_ZLIB | |
331 | s->bits_sent = (s->bits_sent+7) & ~7; | |
332 | #endif | |
333 | } | |
334 |