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deflate.h
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1 /* +------------------------------------------------------------------------+
2  | Mobile Robot Programming Toolkit (MRPT) |
3  | http://www.mrpt.org/ |
4  | |
5  | Copyright (c) 2005-2018, Individual contributors, see AUTHORS file |
6  | See: http://www.mrpt.org/Authors - All rights reserved. |
7  | Released under BSD License. See details in http://www.mrpt.org/License |
8  +------------------------------------------------------------------------+ */
9 
10 /* WARNING: this file should *not* be used by applications. It is
11  part of the implementation of the compression library and is
12  subject to change. Applications should only use zlib.h.
13  */
14 
15 /* @(#) $Id: deflate.h 35458 2005-09-10 21:15:17Z MW $ */
16 
17 #ifndef DEFLATE_H
18 #define DEFLATE_H
19 
20 #include "zutil.h"
21 
22 /* define NO_GZIP when compiling if you want to disable gzip header and
23  trailer creation by deflate(). NO_GZIP would be used to avoid linking in
24  the crc code when it is not needed. For shared libraries, gzip encoding
25  should be left enabled. */
26 #ifndef NO_GZIP
27 #define GZIP
28 #endif
29 
30 /* ===========================================================================
31  * Internal compression state.
32  */
33 
34 #define LENGTH_CODES 29
35 /* number of length codes, not counting the special END_BLOCK code */
36 
37 #define LITERALS 256
38 /* number of literal bytes 0..255 */
39 
40 #define L_CODES (LITERALS + 1 + LENGTH_CODES)
41 /* number of Literal or Length codes, including the END_BLOCK code */
42 
43 #define D_CODES 30
44 /* number of distance codes */
45 
46 #define BL_CODES 19
47 /* number of codes used to transfer the bit lengths */
48 
49 #define HEAP_SIZE (2 * L_CODES + 1)
50 /* maximum heap size */
51 
52 #define MAX_BITS 15
53 /* All codes must not exceed MAX_BITS bits */
54 
55 #define INIT_STATE 42
56 #define EXTRA_STATE 69
57 #define NAME_STATE 73
58 #define COMMENT_STATE 91
59 #define HCRC_STATE 103
60 #define BUSY_STATE 113
61 #define FINISH_STATE 666
62 /* Stream status */
63 
64 /* Data structure describing a single value and its code string. */
65 typedef struct ct_data_s
66 {
67  union {
68  ush freq; /* frequency count */
69  ush code; /* bit string */
70  } fc;
71  union {
72  ush dad; /* father node in Huffman tree */
73  ush len; /* length of bit string */
74  } dl;
75 } FAR ct_data;
76 
77 #define Freq fc.freq
78 #define Code fc.code
79 #define Dad dl.dad
80 #define Len dl.len
81 
82 typedef struct static_tree_desc_s static_tree_desc;
83 
84 typedef struct tree_desc_s
85 {
86  ct_data* dyn_tree; /* the dynamic tree */
87  int max_code; /* largest code with non zero frequency */
88  static_tree_desc* stat_desc; /* the corresponding static tree */
89 } FAR tree_desc;
90 
91 typedef ush Pos;
92 typedef Pos FAR Posf;
93 typedef unsigned IPos;
94 
95 /* A Pos is an index in the character window. We use short instead of int to
96  * save space in the various tables. IPos is used only for parameter passing.
97  */
98 
99 typedef struct internal_state
100 {
101  z_streamp strm; /* pointer back to this zlib stream */
102  int status; /* as the name implies */
103  Bytef* pending_buf; /* output still pending */
104  ulg pending_buf_size; /* size of pending_buf */
105  Bytef* pending_out; /* next pending byte to output to the stream */
106  uInt pending; /* nb of bytes in the pending buffer */
107  int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
108  gz_headerp gzhead; /* gzip header information to write */
109  uInt gzindex; /* where in extra, name, or comment */
110  Byte method; /* STORED (for zip only) or DEFLATED */
111  int last_flush; /* value of flush param for previous deflate call */
112 
113  /* used by deflate.c: */
114 
115  uInt w_size; /* LZ77 window size (32K by default) */
116  uInt w_bits; /* log2(w_size) (8..16) */
117  uInt w_mask; /* w_size - 1 */
118 
120  /* Sliding window. Input bytes are read into the second half of the window,
121  * and move to the first half later to keep a dictionary of at least wSize
122  * bytes. With this organization, matches are limited to a distance of
123  * wSize-MAX_MATCH bytes, but this ensures that IO is always
124  * performed with a length multiple of the block size. Also, it limits
125  * the window size to 64K, which is quite useful on MSDOS.
126  * To do: use the user input buffer as sliding window.
127  */
128 
130  /* Actual size of window: 2*wSize, except when the user input buffer
131  * is directly used as sliding window.
132  */
133 
135  /* Link to older string with same hash index. To limit the size of this
136  * array to 64K, this link is maintained only for the last 32K strings.
137  * An index in this array is thus a window index modulo 32K.
138  */
139 
140  Posf* head; /* Heads of the hash chains or NIL. */
141 
142  uInt ins_h; /* hash index of string to be inserted */
143  uInt hash_size; /* number of elements in hash table */
144  uInt hash_bits; /* log2(hash_size) */
145  uInt hash_mask; /* hash_size-1 */
146 
148  /* Number of bits by which ins_h must be shifted at each input
149  * step. It must be such that after MIN_MATCH steps, the oldest
150  * byte no longer takes part in the hash key, that is:
151  * hash_shift * MIN_MATCH >= hash_bits
152  */
153 
155  /* Window position at the beginning of the current output block. Gets
156  * negative when the window is moved backwards.
157  */
158 
159  uInt match_length; /* length of best match */
160  IPos prev_match; /* previous match */
161  int match_available; /* set if previous match exists */
162  uInt strstart; /* start of string to insert */
163  uInt match_start; /* start of matching string */
164  uInt lookahead; /* number of valid bytes ahead in window */
165 
167  /* Length of the best match at previous step. Matches not greater than this
168  * are discarded. This is used in the lazy match evaluation.
169  */
170 
172  /* To speed up deflation, hash chains are never searched beyond this
173  * length. A higher limit improves compression ratio but degrades the
174  * speed.
175  */
176 
178 /* Attempt to find a better match only when the current match is strictly
179  * smaller than this value. This mechanism is used only for compression
180  * levels >= 4.
181  */
182 #define max_insert_length max_lazy_match
183  /* Insert new strings in the hash table only if the match length is not
184  * greater than this length. This saves time but degrades compression.
185  * max_insert_length is used only for compression levels <= 3.
186  */
187 
188  int level; /* compression level (1..9) */
189  int strategy; /* favor or force Huffman coding*/
190 
192  /* Use a faster search when the previous match is longer than this */
193 
194  int nice_match; /* Stop searching when current match exceeds this */
195 
196  /* used by trees.c: */
197  /* Didn't use ct_data typedef below to supress compiler warning */
198  struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */
199  struct ct_data_s dyn_dtree[2 * D_CODES + 1]; /* distance tree */
200  struct ct_data_s
201  bl_tree[2 * BL_CODES + 1]; /* Huffman tree for bit lengths */
202 
203  struct tree_desc_s l_desc; /* desc. for literal tree */
204  struct tree_desc_s d_desc; /* desc. for distance tree */
205  struct tree_desc_s bl_desc; /* desc. for bit length tree */
206 
208  /* number of codes at each bit length for an optimal tree */
209 
210  int heap[2 * L_CODES + 1]; /* heap used to build the Huffman trees */
211  int heap_len; /* number of elements in the heap */
212  int heap_max; /* element of largest frequency */
213  /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
214  * The same heap array is used to build all trees.
215  */
216 
217  uch depth[2 * L_CODES + 1];
218  /* Depth of each subtree used as tie breaker for trees of equal frequency
219  */
220 
221  uchf* l_buf; /* buffer for literals or lengths */
222 
224  /* Size of match buffer for literals/lengths. There are 4 reasons for
225  * limiting lit_bufsize to 64K:
226  * - frequencies can be kept in 16 bit counters
227  * - if compression is not successful for the first block, all input
228  * data is still in the window so we can still emit a stored block even
229  * when input comes from standard input. (This can also be done for
230  * all blocks if lit_bufsize is not greater than 32K.)
231  * - if compression is not successful for a file smaller than 64K, we can
232  * even emit a stored file instead of a stored block (saving 5 bytes).
233  * This is applicable only for zip (not gzip or zlib).
234  * - creating new Huffman trees less frequently may not provide fast
235  * adaptation to changes in the input data statistics. (Take for
236  * example a binary file with poorly compressible code followed by
237  * a highly compressible string table.) Smaller buffer sizes give
238  * fast adaptation but have of course the overhead of transmitting
239  * trees more frequently.
240  * - I can't count above 4
241  */
242 
243  uInt last_lit; /* running index in l_buf */
244 
246  /* Buffer for distances. To simplify the code, d_buf and l_buf have
247  * the same number of elements. To use different lengths, an extra flag
248  * array would be necessary.
249  */
250 
251  ulg opt_len; /* bit length of current block with optimal trees */
252  ulg static_len; /* bit length of current block with static trees */
253  uInt matches; /* number of string matches in current block */
254  int last_eob_len; /* bit length of EOB code for last block */
255 
256 #ifdef DEBUG
257  ulg compressed_len; /* total bit length of compressed file mod 2^32 */
258  ulg bits_sent; /* bit length of compressed data sent mod 2^32 */
259 #endif
260 
262  /* Output buffer. bits are inserted starting at the bottom (least
263  * significant bits).
264  */
265  int bi_valid;
266  /* Number of valid bits in bi_buf. All bits above the last valid bit
267  * are always zero.
268  */
269 
271 
272 /* Output a byte on the stream.
273  * IN assertion: there is enough room in pending_buf.
274  */
275 #define put_byte(s, c) \
276  { \
277  s->pending_buf[s->pending++] = (c); \
278  }
279 
280 #define MIN_LOOKAHEAD (MAX_MATCH + MIN_MATCH + 1)
281 /* Minimum amount of lookahead, except at the end of the input file.
282  * See deflate.c for comments about the MIN_MATCH+1.
283  */
284 
285 #define MAX_DIST(s) ((s)->w_size - MIN_LOOKAHEAD)
286 /* In order to simplify the code, particularly on 16 bit machines, match
287  * distances are limited to MAX_DIST instead of WSIZE.
288  */
289 
290 /* in trees.c */
291 void _tr_init OF((deflate_state * s));
292 int _tr_tally OF((deflate_state * s, unsigned dist, unsigned lc));
293 void _tr_flush_block
294  OF((deflate_state * s, charf* buf, ulg stored_len, int eof));
295 void _tr_align OF((deflate_state * s));
296 void _tr_stored_block
297  OF((deflate_state * s, charf* buf, ulg stored_len, int eof));
298 
299 #define d_code(dist) \
300  ((dist) < 256 ? _dist_code[dist] : _dist_code[256 + ((dist) >> 7)])
301 /* Mapping from a distance to a distance code. dist is the distance - 1 and
302  * must not have side effects. _dist_code[256] and _dist_code[257] are never
303  * used.
304  */
305 
306 #ifndef DEBUG
307 /* Inline versions of _tr_tally for speed: */
308 
309 #if defined(GEN_TREES_H) || !defined(STDC)
310 extern uch _length_code[];
311 extern uch _dist_code[];
312 #else
313 extern const uch _length_code[];
314 extern const uch _dist_code[];
315 #endif
316 
317 #define _tr_tally_lit(s, c, flush) \
318  { \
319  uch cc = (c); \
320  s->d_buf[s->last_lit] = 0; \
321  s->l_buf[s->last_lit++] = cc; \
322  s->dyn_ltree[cc].Freq++; \
323  flush = (s->last_lit == s->lit_bufsize - 1); \
324  }
325 #define _tr_tally_dist(s, distance, length, flush) \
326  { \
327  uch len = (length); \
328  ush dist = (distance); \
329  s->d_buf[s->last_lit] = dist; \
330  s->l_buf[s->last_lit++] = len; \
331  dist--; \
332  s->dyn_ltree[_length_code[len] + LITERALS + 1].Freq++; \
333  s->dyn_dtree[d_code(dist)].Freq++; \
334  flush = (s->last_lit == s->lit_bufsize - 1); \
335  }
336 #else
337 #define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
338 #define _tr_tally_dist(s, distance, length, flush) \
339  flush = _tr_tally(s, distance, length)
340 #endif
341 
342 #endif /* DEFLATE_H */
uInt good_match
Definition: deflate.h:191
uInt hash_bits
Definition: deflate.h:144
ulg static_len
Definition: deflate.h:252
ush FAR ushf
Definition: zutil.h:54
Bytef * window
Definition: deflate.h:119
#define BL_CODES
Definition: deflate.h:46
int heap[2 *L_CODES+1]
Definition: deflate.h:210
unsigned char Byte
Definition: zconf.h:266
struct static_tree_desc_s static_tree_desc
Definition: deflate.h:82
uInt max_lazy_match
Definition: deflate.h:177
uInt hash_mask
Definition: deflate.h:145
uInt match_length
Definition: deflate.h:159
#define MAX_BITS
Definition: deflate.h:52
ush Pos
Definition: deflate.h:91
uInt hash_shift
Definition: deflate.h:147
uInt prev_length
Definition: deflate.h:166
GLint GLint GLsizei GLsizei GLsizei depth
Definition: glext.h:3600
Posf * prev
Definition: deflate.h:134
struct ct_data_s dyn_ltree[HEAP_SIZE]
Definition: deflate.h:198
ct_data * dyn_tree
Definition: deflate.h:86
static_tree_desc * stat_desc
Definition: deflate.h:88
Bytef * pending_out
Definition: deflate.h:105
uInt match_start
Definition: deflate.h:163
gz_header FAR * gz_headerp
Definition: zlib.h:107
GLdouble s
Definition: glext.h:3676
ush code
Definition: deflate.h:69
gz_headerp gzhead
Definition: deflate.h:108
Byte FAR Bytef
Definition: zconf.h:275
uInt lookahead
Definition: deflate.h:164
int max_code
Definition: deflate.h:87
ulg window_size
Definition: deflate.h:129
void _tr_init OF((deflate_state *s))
int last_eob_len
Definition: deflate.h:254
z_streamp strm
Definition: deflate.h:101
struct tree_desc_s bl_desc
Definition: deflate.h:205
struct tree_desc_s d_desc
Definition: deflate.h:204
Posf * head
Definition: deflate.h:140
union ct_data_s::@95 fc
ush dad
Definition: deflate.h:72
unsigned short ush
Definition: zutil.h:53
ush freq
Definition: deflate.h:68
const uch _dist_code[]
Definition: trees.h:78
uchf * l_buf
Definition: deflate.h:221
Pos FAR Posf
Definition: deflate.h:92
#define HEAP_SIZE
Definition: deflate.h:49
ush bl_count[MAX_BITS+1]
Definition: deflate.h:207
Bytef * pending_buf
Definition: deflate.h:103
uInt lit_bufsize
Definition: deflate.h:223
ushf * d_buf
Definition: deflate.h:245
long block_start
Definition: deflate.h:154
int match_available
Definition: deflate.h:161
struct ct_data_s dyn_dtree[2 *D_CODES+1]
Definition: deflate.h:199
uInt gzindex
Definition: deflate.h:109
struct tree_desc_s l_desc
Definition: deflate.h:203
struct ct_data_s ct_data
uInt max_chain_length
Definition: deflate.h:171
int nice_match
Definition: deflate.h:194
struct internal_state deflate_state
uInt last_lit
Definition: deflate.h:243
unsigned char uch
Definition: zutil.h:51
uInt pending
Definition: deflate.h:106
unsigned long ulg
Definition: zutil.h:55
uInt strstart
Definition: deflate.h:162
const uch _length_code[]
Definition: trees.h:107
ulg pending_buf_size
Definition: deflate.h:104
ush len
Definition: deflate.h:73
uInt matches
Definition: deflate.h:253
#define FAR
Definition: zconf.h:262
union ct_data_s::@96 dl
z_stream FAR * z_streamp
Definition: zlib.h:83
IPos prev_match
Definition: deflate.h:160
int last_flush
Definition: deflate.h:111
#define D_CODES
Definition: deflate.h:43
uch FAR uchf
Definition: zutil.h:52
struct ct_data_s bl_tree[2 *BL_CODES+1]
Definition: deflate.h:200
uInt hash_size
Definition: deflate.h:143
unsigned int uInt
Definition: zconf.h:268
char FAR charf
Definition: zconf.h:277
struct tree_desc_s tree_desc
unsigned IPos
Definition: deflate.h:93
#define L_CODES
Definition: deflate.h:40



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