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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) 2005-2017, 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 
65 /* Data structure describing a single value and its code string. */
66 typedef struct ct_data_s {
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  ct_data *dyn_tree; /* the dynamic tree */
86  int max_code; /* largest code with non zero frequency */
87  static_tree_desc *stat_desc; /* the corresponding static tree */
88 } FAR tree_desc;
89 
90 typedef ush Pos;
91 typedef Pos FAR Posf;
92 typedef unsigned IPos;
93 
94 /* A Pos is an index in the character window. We use short instead of int to
95  * save space in the various tables. IPos is used only for parameter passing.
96  */
97 
98 typedef struct internal_state {
99  z_streamp strm; /* pointer back to this zlib stream */
100  int status; /* as the name implies */
101  Bytef *pending_buf; /* output still pending */
102  ulg pending_buf_size; /* size of pending_buf */
103  Bytef *pending_out; /* next pending byte to output to the stream */
104  uInt pending; /* nb of bytes in the pending buffer */
105  int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
106  gz_headerp gzhead; /* gzip header information to write */
107  uInt gzindex; /* where in extra, name, or comment */
108  Byte method; /* STORED (for zip only) or DEFLATED */
109  int last_flush; /* value of flush param for previous deflate call */
110 
111  /* used by deflate.c: */
112 
113  uInt w_size; /* LZ77 window size (32K by default) */
114  uInt w_bits; /* log2(w_size) (8..16) */
115  uInt w_mask; /* w_size - 1 */
116 
118  /* Sliding window. Input bytes are read into the second half of the window,
119  * and move to the first half later to keep a dictionary of at least wSize
120  * bytes. With this organization, matches are limited to a distance of
121  * wSize-MAX_MATCH bytes, but this ensures that IO is always
122  * performed with a length multiple of the block size. Also, it limits
123  * the window size to 64K, which is quite useful on MSDOS.
124  * To do: use the user input buffer as sliding window.
125  */
126 
128  /* Actual size of window: 2*wSize, except when the user input buffer
129  * is directly used as sliding window.
130  */
131 
133  /* Link to older string with same hash index. To limit the size of this
134  * array to 64K, this link is maintained only for the last 32K strings.
135  * An index in this array is thus a window index modulo 32K.
136  */
137 
138  Posf *head; /* Heads of the hash chains or NIL. */
139 
140  uInt ins_h; /* hash index of string to be inserted */
141  uInt hash_size; /* number of elements in hash table */
142  uInt hash_bits; /* log2(hash_size) */
143  uInt hash_mask; /* hash_size-1 */
144 
146  /* Number of bits by which ins_h must be shifted at each input
147  * step. It must be such that after MIN_MATCH steps, the oldest
148  * byte no longer takes part in the hash key, that is:
149  * hash_shift * MIN_MATCH >= hash_bits
150  */
151 
153  /* Window position at the beginning of the current output block. Gets
154  * negative when the window is moved backwards.
155  */
156 
157  uInt match_length; /* length of best match */
158  IPos prev_match; /* previous match */
159  int match_available; /* set if previous match exists */
160  uInt strstart; /* start of string to insert */
161  uInt match_start; /* start of matching string */
162  uInt lookahead; /* number of valid bytes ahead in window */
163 
165  /* Length of the best match at previous step. Matches not greater than this
166  * are discarded. This is used in the lazy match evaluation.
167  */
168 
170  /* To speed up deflation, hash chains are never searched beyond this
171  * length. A higher limit improves compression ratio but degrades the
172  * speed.
173  */
174 
176  /* Attempt to find a better match only when the current match is strictly
177  * smaller than this value. This mechanism is used only for compression
178  * levels >= 4.
179  */
180 # define max_insert_length max_lazy_match
181  /* Insert new strings in the hash table only if the match length is not
182  * greater than this length. This saves time but degrades compression.
183  * max_insert_length is used only for compression levels <= 3.
184  */
185 
186  int level; /* compression level (1..9) */
187  int strategy; /* favor or force Huffman coding*/
188 
190  /* Use a faster search when the previous match is longer than this */
191 
192  int nice_match; /* Stop searching when current match exceeds this */
193 
194  /* used by trees.c: */
195  /* Didn't use ct_data typedef below to supress compiler warning */
196  struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */
197  struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
198  struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */
199 
200  struct tree_desc_s l_desc; /* desc. for literal tree */
201  struct tree_desc_s d_desc; /* desc. for distance tree */
202  struct tree_desc_s bl_desc; /* desc. for bit length tree */
203 
205  /* number of codes at each bit length for an optimal tree */
206 
207  int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */
208  int heap_len; /* number of elements in the heap */
209  int heap_max; /* element of largest frequency */
210  /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
211  * The same heap array is used to build all trees.
212  */
213 
215  /* Depth of each subtree used as tie breaker for trees of equal frequency
216  */
217 
218  uchf *l_buf; /* buffer for literals or lengths */
219 
221  /* Size of match buffer for literals/lengths. There are 4 reasons for
222  * limiting lit_bufsize to 64K:
223  * - frequencies can be kept in 16 bit counters
224  * - if compression is not successful for the first block, all input
225  * data is still in the window so we can still emit a stored block even
226  * when input comes from standard input. (This can also be done for
227  * all blocks if lit_bufsize is not greater than 32K.)
228  * - if compression is not successful for a file smaller than 64K, we can
229  * even emit a stored file instead of a stored block (saving 5 bytes).
230  * This is applicable only for zip (not gzip or zlib).
231  * - creating new Huffman trees less frequently may not provide fast
232  * adaptation to changes in the input data statistics. (Take for
233  * example a binary file with poorly compressible code followed by
234  * a highly compressible string table.) Smaller buffer sizes give
235  * fast adaptation but have of course the overhead of transmitting
236  * trees more frequently.
237  * - I can't count above 4
238  */
239 
240  uInt last_lit; /* running index in l_buf */
241 
243  /* Buffer for distances. To simplify the code, d_buf and l_buf have
244  * the same number of elements. To use different lengths, an extra flag
245  * array would be necessary.
246  */
247 
248  ulg opt_len; /* bit length of current block with optimal trees */
249  ulg static_len; /* bit length of current block with static trees */
250  uInt matches; /* number of string matches in current block */
251  int last_eob_len; /* bit length of EOB code for last block */
252 
253 #ifdef DEBUG
254  ulg compressed_len; /* total bit length of compressed file mod 2^32 */
255  ulg bits_sent; /* bit length of compressed data sent mod 2^32 */
256 #endif
257 
259  /* Output buffer. bits are inserted starting at the bottom (least
260  * significant bits).
261  */
262  int bi_valid;
263  /* Number of valid bits in bi_buf. All bits above the last valid bit
264  * are always zero.
265  */
266 
268 
269 /* Output a byte on the stream.
270  * IN assertion: there is enough room in pending_buf.
271  */
272 #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}
273 
274 
275 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
276 /* Minimum amount of lookahead, except at the end of the input file.
277  * See deflate.c for comments about the MIN_MATCH+1.
278  */
279 
280 #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD)
281 /* In order to simplify the code, particularly on 16 bit machines, match
282  * distances are limited to MAX_DIST instead of WSIZE.
283  */
284 
285  /* in trees.c */
286 void _tr_init OF((deflate_state *s));
287 int _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc));
288 void _tr_flush_block OF((deflate_state *s, charf *buf, ulg stored_len,
289  int eof));
290 void _tr_align OF((deflate_state *s));
291 void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len,
292  int eof));
293 
294 #define d_code(dist) \
295  ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])
296 /* Mapping from a distance to a distance code. dist is the distance - 1 and
297  * must not have side effects. _dist_code[256] and _dist_code[257] are never
298  * used.
299  */
300 
301 #ifndef DEBUG
302 /* Inline versions of _tr_tally for speed: */
303 
304 #if defined(GEN_TREES_H) || !defined(STDC)
305  extern uch _length_code[];
306  extern uch _dist_code[];
307 #else
308  extern const uch _length_code[];
309  extern const uch _dist_code[];
310 #endif
311 
312 # define _tr_tally_lit(s, c, flush) \
313  { uch cc = (c); \
314  s->d_buf[s->last_lit] = 0; \
315  s->l_buf[s->last_lit++] = cc; \
316  s->dyn_ltree[cc].Freq++; \
317  flush = (s->last_lit == s->lit_bufsize-1); \
318  }
319 # define _tr_tally_dist(s, distance, length, flush) \
320  { uch len = (length); \
321  ush dist = (distance); \
322  s->d_buf[s->last_lit] = dist; \
323  s->l_buf[s->last_lit++] = len; \
324  dist--; \
325  s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
326  s->dyn_dtree[d_code(dist)].Freq++; \
327  flush = (s->last_lit == s->lit_bufsize-1); \
328  }
329 #else
330 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
331 # define _tr_tally_dist(s, distance, length, flush) \
332  flush = _tr_tally(s, distance, length)
333 #endif
334 
335 #endif /* DEFLATE_H */
uInt good_match
Definition: deflate.h:189
uInt hash_bits
Definition: deflate.h:142
ulg static_len
Definition: deflate.h:249
ush FAR ushf
Definition: zutil.h:54
Bytef * window
Definition: deflate.h:117
#define BL_CODES
Definition: deflate.h:46
int heap[2 *L_CODES+1]
Definition: deflate.h:207
unsigned char Byte
Definition: zconf.h:265
struct static_tree_desc_s static_tree_desc
Definition: deflate.h:82
union ct_data_s::@74 dl
uInt max_lazy_match
Definition: deflate.h:175
uInt hash_mask
Definition: deflate.h:143
uInt match_length
Definition: deflate.h:157
#define MAX_BITS
Definition: deflate.h:52
ush Pos
Definition: deflate.h:90
uInt hash_shift
Definition: deflate.h:145
uInt prev_length
Definition: deflate.h:164
GLint GLint GLsizei GLsizei GLsizei depth
Definition: glext.h:3545
Posf * prev
Definition: deflate.h:132
struct ct_data_s dyn_ltree[HEAP_SIZE]
Definition: deflate.h:196
ct_data * dyn_tree
Definition: deflate.h:85
static_tree_desc * stat_desc
Definition: deflate.h:87
Bytef * pending_out
Definition: deflate.h:103
uInt match_start
Definition: deflate.h:161
gz_header FAR * gz_headerp
Definition: zlib.h:105
GLdouble s
Definition: glext.h:3602
ush code
Definition: deflate.h:69
gz_headerp gzhead
Definition: deflate.h:106
Byte FAR Bytef
Definition: zconf.h:274
uInt lookahead
Definition: deflate.h:162
int max_code
Definition: deflate.h:86
ulg window_size
Definition: deflate.h:127
void _tr_init OF((deflate_state *s))
int last_eob_len
Definition: deflate.h:251
z_streamp strm
Definition: deflate.h:99
struct tree_desc_s bl_desc
Definition: deflate.h:202
struct tree_desc_s d_desc
Definition: deflate.h:201
Posf * head
Definition: deflate.h:138
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:80
uchf * l_buf
Definition: deflate.h:218
Pos FAR Posf
Definition: deflate.h:91
#define HEAP_SIZE
Definition: deflate.h:49
ush bl_count[MAX_BITS+1]
Definition: deflate.h:204
Bytef * pending_buf
Definition: deflate.h:101
uInt lit_bufsize
Definition: deflate.h:220
ushf * d_buf
Definition: deflate.h:242
long block_start
Definition: deflate.h:152
int match_available
Definition: deflate.h:159
struct ct_data_s dyn_dtree[2 *D_CODES+1]
Definition: deflate.h:197
uInt gzindex
Definition: deflate.h:107
struct tree_desc_s l_desc
Definition: deflate.h:200
union ct_data_s::@73 fc
struct ct_data_s ct_data
uInt max_chain_length
Definition: deflate.h:169
int nice_match
Definition: deflate.h:192
struct internal_state deflate_state
uInt last_lit
Definition: deflate.h:240
unsigned char uch
Definition: zutil.h:51
uInt pending
Definition: deflate.h:104
unsigned long ulg
Definition: zutil.h:55
uInt strstart
Definition: deflate.h:160
const uch _length_code[]
Definition: trees.h:109
ulg pending_buf_size
Definition: deflate.h:102
ush len
Definition: deflate.h:73
uInt matches
Definition: deflate.h:250
#define FAR
Definition: zconf.h:261
z_stream FAR * z_streamp
Definition: zlib.h:82
IPos prev_match
Definition: deflate.h:158
int last_flush
Definition: deflate.h:109
#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:198
uInt hash_size
Definition: deflate.h:141
unsigned int uInt
Definition: zconf.h:267
char FAR charf
Definition: zconf.h:276
struct tree_desc_s tree_desc
unsigned IPos
Definition: deflate.h:92
#define L_CODES
Definition: deflate.h:40



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