source: SVN/cambria/redboot/packages/services/compress/zlib/current/src/deflate.h @ 1

Last change on this file since 1 was 1, checked in by Tim Harvey, 2 years ago

restored latest version of files from server backup

Signed-off-by: Tim Harvey <tharvey@…>

File size: 11.7 KB
Line 
1/* deflate.h -- internal compression state
2 * Copyright (C) 1995-2002 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 BUSY_STATE   113
53#define FINISH_STATE 666
54/* Stream status */
55
56
57/* Data structure describing a single value and its code string. */
58typedef struct ct_data_s {
59    union {
60        ush  freq;       /* frequency count */
61        ush  code;       /* bit string */
62    } fc;
63    union {
64        ush  dad;        /* father node in Huffman tree */
65        ush  len;        /* length of bit string */
66    } dl;
67} FAR ct_data;
68
69#define Freq fc.freq
70#define Code fc.code
71#define Dad  dl.dad
72#define Len  dl.len
73
74typedef struct static_tree_desc_s  static_tree_desc;
75
76typedef struct tree_desc_s {
77    ct_data *dyn_tree;           /* the dynamic tree */
78    int     max_code;            /* largest code with non zero frequency */
79    static_tree_desc *stat_desc; /* the corresponding static tree */
80} FAR tree_desc;
81
82typedef ush Pos;
83typedef Pos FAR Posf;
84typedef unsigned IPos;
85
86/* A Pos is an index in the character window. We use short instead of int to
87 * save space in the various tables. IPos is used only for parameter passing.
88 */
89
90typedef struct internal_state {
91    z_streamp strm;      /* pointer back to this zlib stream */
92    int   status;        /* as the name implies */
93    Bytef *pending_buf;  /* output still pending */
94    ulg   pending_buf_size; /* size of pending_buf */
95    Bytef *pending_out;  /* next pending byte to output to the stream */
96    int   pending;       /* nb of bytes in the pending buffer */
97    int   wrap;          /* bit 0 true for zlib, bit 1 true for gzip */
98    Byte  data_type;     /* UNKNOWN, BINARY or ASCII */
99    Byte  method;        /* STORED (for zip only) or DEFLATED */
100    int   last_flush;    /* value of flush param for previous deflate call */
101
102                /* used by deflate.c: */
103
104    uInt  w_size;        /* LZ77 window size (32K by default) */
105    uInt  w_bits;        /* log2(w_size)  (8..16) */
106    uInt  w_mask;        /* w_size - 1 */
107
108    Bytef *window;
109    /* Sliding window. Input bytes are read into the second half of the window,
110     * and move to the first half later to keep a dictionary of at least wSize
111     * bytes. With this organization, matches are limited to a distance of
112     * wSize-MAX_MATCH bytes, but this ensures that IO is always
113     * performed with a length multiple of the block size. Also, it limits
114     * the window size to 64K, which is quite useful on MSDOS.
115     * To do: use the user input buffer as sliding window.
116     */
117
118    ulg window_size;
119    /* Actual size of window: 2*wSize, except when the user input buffer
120     * is directly used as sliding window.
121     */
122
123    Posf *prev;
124    /* Link to older string with same hash index. To limit the size of this
125     * array to 64K, this link is maintained only for the last 32K strings.
126     * An index in this array is thus a window index modulo 32K.
127     */
128
129    Posf *head; /* Heads of the hash chains or NIL. */
130
131    uInt  ins_h;          /* hash index of string to be inserted */
132    uInt  hash_size;      /* number of elements in hash table */
133    uInt  hash_bits;      /* log2(hash_size) */
134    uInt  hash_mask;      /* hash_size-1 */
135
136    uInt  hash_shift;
137    /* Number of bits by which ins_h must be shifted at each input
138     * step. It must be such that after MIN_MATCH steps, the oldest
139     * byte no longer takes part in the hash key, that is:
140     *   hash_shift * MIN_MATCH >= hash_bits
141     */
142
143    long block_start;
144    /* Window position at the beginning of the current output block. Gets
145     * negative when the window is moved backwards.
146     */
147
148    uInt match_length;           /* length of best match */
149    IPos prev_match;             /* previous match */
150    int match_available;         /* set if previous match exists */
151    uInt strstart;               /* start of string to insert */
152    uInt match_start;            /* start of matching string */
153    uInt lookahead;              /* number of valid bytes ahead in window */
154
155    uInt prev_length;
156    /* Length of the best match at previous step. Matches not greater than this
157     * are discarded. This is used in the lazy match evaluation.
158     */
159
160    uInt max_chain_length;
161    /* To speed up deflation, hash chains are never searched beyond this
162     * length.  A higher limit improves compression ratio but degrades the
163     * speed.
164     */
165
166    uInt max_lazy_match;
167    /* Attempt to find a better match only when the current match is strictly
168     * smaller than this value. This mechanism is used only for compression
169     * levels >= 4.
170     */
171#   define max_insert_length  max_lazy_match
172    /* Insert new strings in the hash table only if the match length is not
173     * greater than this length. This saves time but degrades compression.
174     * max_insert_length is used only for compression levels <= 3.
175     */
176
177    int level;    /* compression level (1..9) */
178    int strategy; /* favor or force Huffman coding*/
179
180    uInt good_match;
181    /* Use a faster search when the previous match is longer than this */
182
183    int nice_match; /* Stop searching when current match exceeds this */
184
185                /* used by trees.c: */
186    /* Didn't use ct_data typedef below to supress compiler warning */
187    struct ct_data_s dyn_ltree[HEAP_SIZE];   /* literal and length tree */
188    struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
189    struct ct_data_s bl_tree[2*BL_CODES+1];  /* Huffman tree for bit lengths */
190
191    struct tree_desc_s l_desc;               /* desc. for literal tree */
192    struct tree_desc_s d_desc;               /* desc. for distance tree */
193    struct tree_desc_s bl_desc;              /* desc. for bit length tree */
194
195    ush bl_count[MAX_BITS+1];
196    /* number of codes at each bit length for an optimal tree */
197
198    int heap[2*L_CODES+1];      /* heap used to build the Huffman trees */
199    int heap_len;               /* number of elements in the heap */
200    int heap_max;               /* element of largest frequency */
201    /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
202     * The same heap array is used to build all trees.
203     */
204
205    uch depth[2*L_CODES+1];
206    /* Depth of each subtree used as tie breaker for trees of equal frequency
207     */
208
209    uchf *l_buf;          /* buffer for literals or lengths */
210
211    uInt  lit_bufsize;
212    /* Size of match buffer for literals/lengths.  There are 4 reasons for
213     * limiting lit_bufsize to 64K:
214     *   - frequencies can be kept in 16 bit counters
215     *   - if compression is not successful for the first block, all input
216     *     data is still in the window so we can still emit a stored block even
217     *     when input comes from standard input.  (This can also be done for
218     *     all blocks if lit_bufsize is not greater than 32K.)
219     *   - if compression is not successful for a file smaller than 64K, we can
220     *     even emit a stored file instead of a stored block (saving 5 bytes).
221     *     This is applicable only for zip (not gzip or zlib).
222     *   - creating new Huffman trees less frequently may not provide fast
223     *     adaptation to changes in the input data statistics. (Take for
224     *     example a binary file with poorly compressible code followed by
225     *     a highly compressible string table.) Smaller buffer sizes give
226     *     fast adaptation but have of course the overhead of transmitting
227     *     trees more frequently.
228     *   - I can't count above 4
229     */
230
231    uInt last_lit;      /* running index in l_buf */
232
233    ushf *d_buf;
234    /* Buffer for distances. To simplify the code, d_buf and l_buf have
235     * the same number of elements. To use different lengths, an extra flag
236     * array would be necessary.
237     */
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 */
277void _tr_init         OF((deflate_state *s));
278int  _tr_tally        OF((deflate_state *s, unsigned dist, unsigned lc));
279void _tr_flush_block  OF((deflate_state *s, charf *buf, ulg stored_len,
280                          int eof));
281void _tr_align        OF((deflate_state *s));
282void _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->d_buf[s->last_lit] = 0; \
306    s->l_buf[s->last_lit++] = cc; \
307    s->dyn_ltree[cc].Freq++; \
308    flush = (s->last_lit == s->lit_bufsize-1); \
309   }
310# define _tr_tally_dist(s, distance, length, flush) \
311  { uch len = (length); \
312    ush dist = (distance); \
313    s->d_buf[s->last_lit] = dist; \
314    s->l_buf[s->last_lit++] = len; \
315    dist--; \
316    s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
317    s->dyn_dtree[d_code(dist)].Freq++; \
318    flush = (s->last_lit == s->lit_bufsize-1); \
319  }
320#else
321# define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
322# define _tr_tally_dist(s, distance, length, flush) \
323              flush = _tr_tally(s, distance, length)
324#endif
325
326#endif /* DEFLATE_H */
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