Point Cloud Library (PCL)  1.15.1-dev
deflate.h
1 /* deflate.h -- internal compression state
2  * Copyright (C) 1995-2004 Jean-loup Gailly
3  * For conditions of distribution and use, see copyright notice in zlib.h
4  */
5 
6 /* WARNING: this file should *not* be used by applications. It is
7  part of the implementation of the compression library and is
8  subject to change. Applications should only use zlib.h.
9  */
10 
11 /* @(#) $Id$ */
12 
13 #ifndef DEFLATE_H
14 #define DEFLATE_H
15 
16 #include "zutil.h"
17 
18 /* define NO_GZIP when compiling if you want to disable gzip header and
19  trailer creation by deflate(). NO_GZIP would be used to avoid linking in
20  the crc code when it is not needed. For shared libraries, gzip encoding
21  should be left enabled. */
22 #ifndef NO_GZIP
23 # define GZIP
24 #endif
25 
26 /* ===========================================================================
27  * Internal compression state.
28  */
29 
30 #define LENGTH_CODES 29
31 /* number of length codes, not counting the special END_BLOCK code */
32 
33 #define LITERALS 256
34 /* number of literal bytes 0..255 */
35 
36 #define L_CODES (LITERALS+1+LENGTH_CODES)
37 /* number of Literal or Length codes, including the END_BLOCK code */
38 
39 #define D_CODES 30
40 /* number of distance codes */
41 
42 #define BL_CODES 19
43 /* number of codes used to transfer the bit lengths */
44 
45 #define HEAP_SIZE (2*L_CODES+1)
46 /* maximum heap size */
47 
48 #define MAX_BITS 15
49 /* All codes must not exceed MAX_BITS bits */
50 
51 #define INIT_STATE 42
52 #define EXTRA_STATE 69
53 #define NAME_STATE 73
54 #define COMMENT_STATE 91
55 #define HCRC_STATE 103
56 #define BUSY_STATE 113
57 #define FINISH_STATE 666
58 /* Stream status */
59 
60 
61 /* Data structure describing a single value and its code string. */
62 typedef struct ct_data_s {
63  union {
64  ush freq; /* frequency count */
65  ush code; /* bit string */
66  } fc;
67  union {
68  ush dad; /* father node in Huffman tree */
69  ush len; /* length of bit string */
70  } dl;
71 } FAR ct_data;
72 
73 #define Freq fc.freq
74 #define Code fc.code
75 #define Dad dl.dad
76 #define Len dl.len
77 
78 typedef struct static_tree_desc_s static_tree_desc;
79 
80 typedef struct tree_desc_s {
81  ct_data *dyn_tree; /* the dynamic tree */
82  int max_code; /* largest code with non zero frequency */
83  static_tree_desc *stat_desc; /* the corresponding static tree */
84 } FAR tree_desc;
85 
86 typedef ush Pos;
87 typedef Pos FAR Posf;
88 typedef unsigned IPos;
89 
90 /* A Pos is an index in the character window. We use short instead of int to
91  * save space in the various tables. IPos is used only for parameter passing.
92  */
93 
94 typedef struct internal_state {
95  z_streamp strm; /* pointer back to this zlib stream */
96  int status; /* as the name implies */
97  Bytef *pending_buf; /* output still pending */
98  ulg pending_buf_size; /* size of pending_buf */
99  Bytef *pending_out; /* next pending byte to output to the stream */
100  uInt pending; /* nb of bytes in the pending buffer */
101  int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
102  gz_headerp gzhead; /* gzip header information to write */
103  uInt gzindex; /* where in extra, name, or comment */
104  Byte method; /* STORED (for zip only) or DEFLATED */
105  int last_flush; /* value of flush param for previous deflate call */
106 
107  /* used by deflate.c: */
108 
109  uInt w_size; /* LZ77 window size (32K by default) */
110  uInt w_bits; /* log2(w_size) (8..16) */
111  uInt w_mask; /* w_size - 1 */
112 
113  Bytef *window;
114  /* Sliding window. Input bytes are read into the second half of the window,
115  * and move to the first half later to keep a dictionary of at least wSize
116  * bytes. With this organization, matches are limited to a distance of
117  * wSize-MAX_MATCH bytes, but this ensures that IO is always
118  * performed with a length multiple of the block size. Also, it limits
119  * the window size to 64K, which is quite useful on MSDOS.
120  * To do: use the user input buffer as sliding window.
121  */
122 
124  /* Actual size of window: 2*wSize, except when the user input buffer
125  * is directly used as sliding window.
126  */
127 
128  Posf *prev;
129  /* Link to older string with same hash index. To limit the size of this
130  * array to 64K, this link is maintained only for the last 32K strings.
131  * An index in this array is thus a window index modulo 32K.
132  */
133 
134  Posf *head; /* Heads of the hash chains or NIL. */
135 
136  uInt ins_h; /* hash index of string to be inserted */
137  uInt hash_size; /* number of elements in hash table */
138  uInt hash_bits; /* log2(hash_size) */
139  uInt hash_mask; /* hash_size-1 */
140 
142  /* Number of bits by which ins_h must be shifted at each input
143  * step. It must be such that after MIN_MATCH steps, the oldest
144  * byte no longer takes part in the hash key, that is:
145  * hash_shift * MIN_MATCH >= hash_bits
146  */
147 
149  /* Window position at the beginning of the current output block. Gets
150  * negative when the window is moved backwards.
151  */
152 
153  uInt match_length; /* length of best match */
154  IPos prev_match; /* previous match */
155  int match_available; /* set if previous match exists */
156  uInt strstart; /* start of string to insert */
157  uInt match_start; /* start of matching string */
158  uInt lookahead; /* number of valid bytes ahead in window */
159 
161  /* Length of the best match at previous step. Matches not greater than this
162  * are discarded. This is used in the lazy match evaluation.
163  */
164 
166  /* To speed up deflation, hash chains are never searched beyond this
167  * length. A higher limit improves compression ratio but degrades the
168  * speed.
169  */
170 
172  /* Attempt to find a better match only when the current match is strictly
173  * smaller than this value. This mechanism is used only for compression
174  * levels >= 4.
175  */
176 # define max_insert_length max_lazy_match
177  /* Insert new strings in the hash table only if the match length is not
178  * greater than this length. This saves time but degrades compression.
179  * max_insert_length is used only for compression levels <= 3.
180  */
181 
182  int level; /* compression level (1..9) */
183  int strategy; /* favor or force Huffman coding*/
184 
186  /* Use a faster search when the previous match is longer than this */
187 
188  int nice_match; /* Stop searching when current match exceeds this */
189 
190  /* used by trees.c: */
191  /* Didn't use ct_data typedef below to supress compiler warning */
192  struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */
193  struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
194  struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */
195 
196  struct tree_desc_s l_desc; /* desc. for literal tree */
197  struct tree_desc_s d_desc; /* desc. for distance tree */
198  struct tree_desc_s bl_desc; /* desc. for bit length tree */
199 
200  ush bl_count[MAX_BITS+1];
201  /* number of codes at each bit length for an optimal tree */
202 
203  int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */
204  int heap_len; /* number of elements in the heap */
205  int heap_max; /* element of largest frequency */
206  /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
207  * The same heap array is used to build all trees.
208  */
209 
210  uch depth[2*L_CODES+1];
211  /* Depth of each subtree used as tie breaker for trees of equal frequency
212  */
213 
214  uchf *sym_buf; /* buffer for distances and literals/lengths */
215 
217  /* Size of match buffer for literals/lengths. There are 4 reasons for
218  * limiting lit_bufsize to 64K:
219  * - frequencies can be kept in 16 bit counters
220  * - if compression is not successful for the first block, all input
221  * data is still in the window so we can still emit a stored block even
222  * when input comes from standard input. (This can also be done for
223  * all blocks if lit_bufsize is not greater than 32K.)
224  * - if compression is not successful for a file smaller than 64K, we can
225  * even emit a stored file instead of a stored block (saving 5 bytes).
226  * This is applicable only for zip (not gzip or zlib).
227  * - creating new Huffman trees less frequently may not provide fast
228  * adaptation to changes in the input data statistics. (Take for
229  * example a binary file with poorly compressible code followed by
230  * a highly compressible string table.) Smaller buffer sizes give
231  * fast adaptation but have of course the overhead of transmitting
232  * trees more frequently.
233  * - I can't count above 4
234  */
235 
236  uInt sym_next; /* running index in sym_buf */
237  uInt sym_end; /* symbol table full when sym_next reaches this */
238 
239  ulg opt_len; /* bit length of current block with optimal trees */
240  ulg static_len; /* bit length of current block with static trees */
241  uInt matches; /* number of string matches in current block */
242  int last_eob_len; /* bit length of EOB code for last block */
243 
244 #ifdef DEBUG
245  ulg compressed_len; /* total bit length of compressed file mod 2^32 */
246  ulg bits_sent; /* bit length of compressed data sent mod 2^32 */
247 #endif
248 
249  ush bi_buf;
250  /* Output buffer. bits are inserted starting at the bottom (least
251  * significant bits).
252  */
253  int bi_valid;
254  /* Number of valid bits in bi_buf. All bits above the last valid bit
255  * are always zero.
256  */
257 
258 } FAR deflate_state;
259 
260 /* Output a byte on the stream.
261  * IN assertion: there is enough room in pending_buf.
262  */
263 #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}
264 
265 
266 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
267 /* Minimum amount of lookahead, except at the end of the input file.
268  * See deflate.c for comments about the MIN_MATCH+1.
269  */
270 
271 #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD)
272 /* In order to simplify the code, particularly on 16 bit machines, match
273  * distances are limited to MAX_DIST instead of WSIZE.
274  */
275 
276  /* in trees.c */
277 void _tr_init OF((deflate_state *s));
278 int _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc));
279 void _tr_flush_block OF((deflate_state *s, charf *buf, ulg stored_len,
280  int eof));
281 void _tr_align OF((deflate_state *s));
282 void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len,
283  int eof));
284 
285 #define d_code(dist) \
286  ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])
287 /* Mapping from a distance to a distance code. dist is the distance - 1 and
288  * must not have side effects. _dist_code[256] and _dist_code[257] are never
289  * used.
290  */
291 
292 #ifndef DEBUG
293 /* Inline versions of _tr_tally for speed: */
294 
295 #if defined(GEN_TREES_H) || !defined(STDC)
296  extern uch _length_code[];
297  extern uch _dist_code[];
298 #else
299  extern const uch _length_code[];
300  extern const uch _dist_code[];
301 #endif
302 
303 # define _tr_tally_lit(s, c, flush) \
304  { uch cc = (c); \
305  s->sym_buf[s->sym_next++] = 0; \
306  s->sym_buf[s->sym_next++] = 0; \
307  s->sym_buf[s->sym_next++] = cc; \
308  s->dyn_ltree[cc].Freq++; \
309  flush = (s->sym_next == s->sym_end); \
310  }
311 # define _tr_tally_dist(s, distance, length, flush) \
312  { uch len = (length); \
313  ush dist = (ush)(distance); \
314  s->sym_buf[s->sym_next++] = dist; \
315  s->sym_buf[s->sym_next++] = dist >> 8; \
316  s->sym_buf[s->sym_next++] = len; \
317  dist--; \
318  s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
319  s->dyn_dtree[d_code(dist)].Freq++; \
320  flush = (s->sym_next == s->sym_end); \
321  }
322 #else
323 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
324 # define _tr_tally_dist(s, distance, length, flush) \
325  flush = _tr_tally(s, distance, length)
326 #endif
327 
328 #endif /* DEFLATE_H */
ush code
Definition: deflate.h:65
union ct_data_s::@139 fc
ush freq
Definition: deflate.h:64
ush dad
Definition: deflate.h:68
union ct_data_s::@140 dl
ush len
Definition: deflate.h:69
struct tree_desc_s l_desc
Definition: deflate.h:196
IPos prev_match
Definition: deflate.h:154
uInt sym_next
Definition: deflate.h:236
uInt lit_bufsize
Definition: deflate.h:216
int nice_match
Definition: deflate.h:188
uInt lookahead
Definition: deflate.h:158
struct ct_data_s dyn_dtree[2 *D_CODES+1]
Definition: deflate.h:193
ulg window_size
Definition: deflate.h:123
uInt sym_end
Definition: deflate.h:237
uInt hash_bits
Definition: deflate.h:138
uInt gzindex
Definition: deflate.h:103
uInt good_match
Definition: deflate.h:185
Bytef * pending_out
Definition: deflate.h:99
uInt prev_length
Definition: deflate.h:160
uInt hash_mask
Definition: deflate.h:139
ulg static_len
Definition: deflate.h:240
Bytef * window
Definition: deflate.h:113
uch depth[2 *L_CODES+1]
Definition: deflate.h:210
ulg pending_buf_size
Definition: deflate.h:98
Posf * prev
Definition: deflate.h:128
uInt strstart
Definition: deflate.h:156
struct ct_data_s bl_tree[2 *BL_CODES+1]
Definition: deflate.h:194
struct tree_desc_s bl_desc
Definition: deflate.h:198
uInt match_length
Definition: deflate.h:153
int last_flush
Definition: deflate.h:105
uInt hash_size
Definition: deflate.h:137
z_streamp strm
Definition: deflate.h:95
Posf * head
Definition: deflate.h:134
uInt max_chain_length
Definition: deflate.h:165
struct tree_desc_s d_desc
Definition: deflate.h:197
uInt max_lazy_match
Definition: deflate.h:171
int last_eob_len
Definition: deflate.h:242
ush bl_count[MAX_BITS+1]
Definition: deflate.h:200
gz_headerp gzhead
Definition: deflate.h:102
uInt matches
Definition: deflate.h:241
int block_start
Definition: deflate.h:148
uInt pending
Definition: deflate.h:100
int match_available
Definition: deflate.h:155
uInt match_start
Definition: deflate.h:157
int heap[2 *L_CODES+1]
Definition: deflate.h:203
struct ct_data_s dyn_ltree[HEAP_SIZE]
Definition: deflate.h:192
Bytef * pending_buf
Definition: deflate.h:97
uInt hash_shift
Definition: deflate.h:141
uchf * sym_buf
Definition: deflate.h:214
int max_code
Definition: deflate.h:82
ct_data * dyn_tree
Definition: deflate.h:81
static_tree_desc * stat_desc
Definition: deflate.h:83