1: /* deflate.h -- internal compression state
2: * Copyright (C) 1995-2012 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: deflate.h,v 1.1.1.2 2013/10/14 07:51:14 misho Exp $ */
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 Buf_size 16
52: /* size of bit buffer in bi_buf */
53:
54: #define INIT_STATE 42
55: #define EXTRA_STATE 69
56: #define NAME_STATE 73
57: #define COMMENT_STATE 91
58: #define HCRC_STATE 103
59: #define BUSY_STATE 113
60: #define FINISH_STATE 666
61: /* Stream status */
62:
63:
64: /* Data structure describing a single value and its code string. */
65: typedef struct ct_data_s {
66: union {
67: ush freq; /* frequency count */
68: ush code; /* bit string */
69: } fc;
70: union {
71: ush dad; /* father node in Huffman tree */
72: ush len; /* length of bit string */
73: } dl;
74: } FAR ct_data;
75:
76: #define Freq fc.freq
77: #define Code fc.code
78: #define Dad dl.dad
79: #define Len dl.len
80:
81: typedef struct static_tree_desc_s static_tree_desc;
82:
83: typedef struct tree_desc_s {
84: ct_data *dyn_tree; /* the dynamic tree */
85: int max_code; /* largest code with non zero frequency */
86: static_tree_desc *stat_desc; /* the corresponding static tree */
87: } FAR tree_desc;
88:
89: typedef ush Pos;
90: typedef Pos FAR Posf;
91: typedef unsigned IPos;
92:
93: /* A Pos is an index in the character window. We use short instead of int to
94: * save space in the various tables. IPos is used only for parameter passing.
95: */
96:
97: typedef struct internal_state {
98: z_streamp strm; /* pointer back to this zlib stream */
99: int status; /* as the name implies */
100: Bytef *pending_buf; /* output still pending */
101: ulg pending_buf_size; /* size of pending_buf */
102: Bytef *pending_out; /* next pending byte to output to the stream */
103: uInt pending; /* nb of bytes in the pending buffer */
104: int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
105: gz_headerp gzhead; /* gzip header information to write */
106: uInt gzindex; /* where in extra, name, or comment */
107: Byte method; /* can only be DEFLATED */
108: int last_flush; /* value of flush param for previous deflate call */
109:
110: /* used by deflate.c: */
111:
112: uInt w_size; /* LZ77 window size (32K by default) */
113: uInt w_bits; /* log2(w_size) (8..16) */
114: uInt w_mask; /* w_size - 1 */
115:
116: Bytef *window;
117: /* Sliding window. Input bytes are read into the second half of the window,
118: * and move to the first half later to keep a dictionary of at least wSize
119: * bytes. With this organization, matches are limited to a distance of
120: * wSize-MAX_MATCH bytes, but this ensures that IO is always
121: * performed with a length multiple of the block size. Also, it limits
122: * the window size to 64K, which is quite useful on MSDOS.
123: * To do: use the user input buffer as sliding window.
124: */
125:
126: ulg window_size;
127: /* Actual size of window: 2*wSize, except when the user input buffer
128: * is directly used as sliding window.
129: */
130:
131: Posf *prev;
132: /* Link to older string with same hash index. To limit the size of this
133: * array to 64K, this link is maintained only for the last 32K strings.
134: * An index in this array is thus a window index modulo 32K.
135: */
136:
137: Posf *head; /* Heads of the hash chains or NIL. */
138:
139: uInt ins_h; /* hash index of string to be inserted */
140: uInt hash_size; /* number of elements in hash table */
141: uInt hash_bits; /* log2(hash_size) */
142: uInt hash_mask; /* hash_size-1 */
143:
144: uInt hash_shift;
145: /* Number of bits by which ins_h must be shifted at each input
146: * step. It must be such that after MIN_MATCH steps, the oldest
147: * byte no longer takes part in the hash key, that is:
148: * hash_shift * MIN_MATCH >= hash_bits
149: */
150:
151: long block_start;
152: /* Window position at the beginning of the current output block. Gets
153: * negative when the window is moved backwards.
154: */
155:
156: uInt match_length; /* length of best match */
157: IPos prev_match; /* previous match */
158: int match_available; /* set if previous match exists */
159: uInt strstart; /* start of string to insert */
160: uInt match_start; /* start of matching string */
161: uInt lookahead; /* number of valid bytes ahead in window */
162:
163: uInt prev_length;
164: /* Length of the best match at previous step. Matches not greater than this
165: * are discarded. This is used in the lazy match evaluation.
166: */
167:
168: uInt max_chain_length;
169: /* To speed up deflation, hash chains are never searched beyond this
170: * length. A higher limit improves compression ratio but degrades the
171: * speed.
172: */
173:
174: uInt max_lazy_match;
175: /* Attempt to find a better match only when the current match is strictly
176: * smaller than this value. This mechanism is used only for compression
177: * levels >= 4.
178: */
179: # define max_insert_length max_lazy_match
180: /* Insert new strings in the hash table only if the match length is not
181: * greater than this length. This saves time but degrades compression.
182: * max_insert_length is used only for compression levels <= 3.
183: */
184:
185: int level; /* compression level (1..9) */
186: int strategy; /* favor or force Huffman coding*/
187:
188: uInt good_match;
189: /* Use a faster search when the previous match is longer than this */
190:
191: int nice_match; /* Stop searching when current match exceeds this */
192:
193: /* used by trees.c: */
194: /* Didn't use ct_data typedef below to suppress compiler warning */
195: struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */
196: struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
197: struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */
198:
199: struct tree_desc_s l_desc; /* desc. for literal tree */
200: struct tree_desc_s d_desc; /* desc. for distance tree */
201: struct tree_desc_s bl_desc; /* desc. for bit length tree */
202:
203: ush bl_count[MAX_BITS+1];
204: /* number of codes at each bit length for an optimal tree */
205:
206: int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */
207: int heap_len; /* number of elements in the heap */
208: int heap_max; /* element of largest frequency */
209: /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
210: * The same heap array is used to build all trees.
211: */
212:
213: uch depth[2*L_CODES+1];
214: /* Depth of each subtree used as tie breaker for trees of equal frequency
215: */
216:
217: uchf *l_buf; /* buffer for literals or lengths */
218:
219: uInt lit_bufsize;
220: /* Size of match buffer for literals/lengths. There are 4 reasons for
221: * limiting lit_bufsize to 64K:
222: * - frequencies can be kept in 16 bit counters
223: * - if compression is not successful for the first block, all input
224: * data is still in the window so we can still emit a stored block even
225: * when input comes from standard input. (This can also be done for
226: * all blocks if lit_bufsize is not greater than 32K.)
227: * - if compression is not successful for a file smaller than 64K, we can
228: * even emit a stored file instead of a stored block (saving 5 bytes).
229: * This is applicable only for zip (not gzip or zlib).
230: * - creating new Huffman trees less frequently may not provide fast
231: * adaptation to changes in the input data statistics. (Take for
232: * example a binary file with poorly compressible code followed by
233: * a highly compressible string table.) Smaller buffer sizes give
234: * fast adaptation but have of course the overhead of transmitting
235: * trees more frequently.
236: * - I can't count above 4
237: */
238:
239: uInt last_lit; /* running index in l_buf */
240:
241: ushf *d_buf;
242: /* Buffer for distances. To simplify the code, d_buf and l_buf have
243: * the same number of elements. To use different lengths, an extra flag
244: * array would be necessary.
245: */
246:
247: ulg opt_len; /* bit length of current block with optimal trees */
248: ulg static_len; /* bit length of current block with static trees */
249: uInt matches; /* number of string matches in current block */
250: uInt insert; /* bytes at end of window left to insert */
251:
252: #ifdef DEBUG
253: ulg compressed_len; /* total bit length of compressed file mod 2^32 */
254: ulg bits_sent; /* bit length of compressed data sent mod 2^32 */
255: #endif
256:
257: ush bi_buf;
258: /* Output buffer. bits are inserted starting at the bottom (least
259: * significant bits).
260: */
261: int bi_valid;
262: /* Number of valid bits in bi_buf. All bits above the last valid bit
263: * are always zero.
264: */
265:
266: ulg high_water;
267: /* High water mark offset in window for initialized bytes -- bytes above
268: * this are set to zero in order to avoid memory check warnings when
269: * longest match routines access bytes past the input. This is then
270: * updated to the new high water mark.
271: */
272:
273: } FAR deflate_state;
274:
275: /* Output a byte on the stream.
276: * IN assertion: there is enough room in pending_buf.
277: */
278: #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}
279:
280:
281: #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
282: /* Minimum amount of lookahead, except at the end of the input file.
283: * See deflate.c for comments about the MIN_MATCH+1.
284: */
285:
286: #define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD)
287: /* In order to simplify the code, particularly on 16 bit machines, match
288: * distances are limited to MAX_DIST instead of WSIZE.
289: */
290:
291: #define WIN_INIT MAX_MATCH
292: /* Number of bytes after end of data in window to initialize in order to avoid
293: memory checker errors from longest match routines */
294:
295: /* in trees.c */
296: void ZLIB_INTERNAL _tr_init OF((deflate_state *s));
297: int ZLIB_INTERNAL _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc));
298: void ZLIB_INTERNAL _tr_flush_block OF((deflate_state *s, charf *buf,
299: ulg stored_len, int last));
300: void ZLIB_INTERNAL _tr_flush_bits OF((deflate_state *s));
301: void ZLIB_INTERNAL _tr_align OF((deflate_state *s));
302: void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf,
303: ulg stored_len, int last));
304:
305: #define d_code(dist) \
306: ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])
307: /* Mapping from a distance to a distance code. dist is the distance - 1 and
308: * must not have side effects. _dist_code[256] and _dist_code[257] are never
309: * used.
310: */
311:
312: #ifndef DEBUG
313: /* Inline versions of _tr_tally for speed: */
314:
315: #if defined(GEN_TREES_H) || !defined(STDC)
316: extern uch ZLIB_INTERNAL _length_code[];
317: extern uch ZLIB_INTERNAL _dist_code[];
318: #else
319: extern const uch ZLIB_INTERNAL _length_code[];
320: extern const uch ZLIB_INTERNAL _dist_code[];
321: #endif
322:
323: # define _tr_tally_lit(s, c, flush) \
324: { uch cc = (c); \
325: s->d_buf[s->last_lit] = 0; \
326: s->l_buf[s->last_lit++] = cc; \
327: s->dyn_ltree[cc].Freq++; \
328: flush = (s->last_lit == s->lit_bufsize-1); \
329: }
330: # define _tr_tally_dist(s, distance, length, flush) \
331: { uch len = (length); \
332: ush dist = (distance); \
333: s->d_buf[s->last_lit] = dist; \
334: s->l_buf[s->last_lit++] = len; \
335: dist--; \
336: s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
337: s->dyn_dtree[d_code(dist)].Freq++; \
338: flush = (s->last_lit == s->lit_bufsize-1); \
339: }
340: #else
341: # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
342: # define _tr_tally_dist(s, distance, length, flush) \
343: flush = _tr_tally(s, distance, length)
344: #endif
345:
346: #endif /* DEFLATE_H */
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>
![[BACK]](/icons/cvsweb/back.gif){kind=icon}
Return to deflate.h CVS log ![[TXT]](/icons/cvsweb/text.gif){kind=icon}
![[DIR]](/icons/cvsweb/dir.gif){kind=icon}
Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / rsync / zlib