1
2
3
4#define Assert(err, str)
5#define Trace(dummy)
6#define Tracev(dummy)
7#define Tracecv(err, dummy)
8#define Tracevv(dummy)
9
10
11
12#define LENGTH_CODES 29
13/* number of length codes, not counting the special END_BLOCK code */
14
15#define LITERALS  256
16/* number of literal bytes 0..255 */
17
18#define L_CODES (LITERALS+1+LENGTH_CODES)
19/* number of Literal or Length codes, including the END_BLOCK code */
20
21#define D_CODES   30
22/* number of distance codes */
23
24#define BL_CODES  19
25/* number of codes used to transfer the bit lengths */
26
27#define HEAP_SIZE (2*L_CODES+1)
28/* maximum heap size */
29
30#define MAX_BITS 15
31/* All codes must not exceed MAX_BITS bits */
32
33#define INIT_STATE    42
34#define BUSY_STATE   113
35#define FINISH_STATE 666
36/* Stream status */
37
38
39/* Data structure describing a single value and its code string. */
40typedef struct ct_data_s {
41    union {
42        ush  freq;       /* frequency count */
43        ush  code;       /* bit string */
44    } fc;
45    union {
46        ush  dad;        /* father node in Huffman tree */
47        ush  len;        /* length of bit string */
48    } dl;
49} ct_data;
50
51#define Freq fc.freq
52#define Code fc.code
53#define Dad  dl.dad
54#define Len  dl.len
55
56typedef struct static_tree_desc_s  static_tree_desc;
57
58typedef struct tree_desc_s {
59    ct_data *dyn_tree;           /* the dynamic tree */
60    int     max_code;            /* largest code with non zero frequency */
61    static_tree_desc *stat_desc; /* the corresponding static tree */
62} tree_desc;
63
64typedef ush Pos;
65typedef unsigned IPos;
66
67/* A Pos is an index in the character window. We use short instead of int to
68 * save space in the various tables. IPos is used only for parameter passing.
69 */
70
71typedef struct deflate_state {
72    z_streamp strm;      /* pointer back to this zlib stream */
73    int   status;        /* as the name implies */
74    Byte *pending_buf;   /* output still pending */
75    ulg   pending_buf_size; /* size of pending_buf */
76    Byte *pending_out;   /* next pending byte to output to the stream */
77    int   pending;       /* nb of bytes in the pending buffer */
78    int   noheader;      /* suppress zlib header and adler32 */
79    Byte  data_type;     /* UNKNOWN, BINARY or ASCII */
80    Byte  method;        /* STORED (for zip only) or DEFLATED */
81    int   last_flush;    /* value of flush param for previous deflate call */
82
83                /* used by deflate.c: */
84
85    uInt  w_size;        /* LZ77 window size (32K by default) */
86    uInt  w_bits;        /* log2(w_size)  (8..16) */
87    uInt  w_mask;        /* w_size - 1 */
88
89    Byte *window;
90    /* Sliding window. Input bytes are read into the second half of the window,
91     * and move to the first half later to keep a dictionary of at least wSize
92     * bytes. With this organization, matches are limited to a distance of
93     * wSize-MAX_MATCH bytes, but this ensures that IO is always
94     * performed with a length multiple of the block size. Also, it limits
95     * the window size to 64K, which is quite useful on MSDOS.
96     * To do: use the user input buffer as sliding window.
97     */
98
99    ulg window_size;
100    /* Actual size of window: 2*wSize, except when the user input buffer
101     * is directly used as sliding window.
102     */
103
104    Pos *prev;
105    /* Link to older string with same hash index. To limit the size of this
106     * array to 64K, this link is maintained only for the last 32K strings.
107     * An index in this array is thus a window index modulo 32K.
108     */
109
110    Pos *head; /* Heads of the hash chains or NIL. */
111
112    uInt  ins_h;          /* hash index of string to be inserted */
113    uInt  hash_size;      /* number of elements in hash table */
114    uInt  hash_bits;      /* log2(hash_size) */
115    uInt  hash_mask;      /* hash_size-1 */
116
117    uInt  hash_shift;
118    /* Number of bits by which ins_h must be shifted at each input
119     * step. It must be such that after MIN_MATCH steps, the oldest
120     * byte no longer takes part in the hash key, that is:
121     *   hash_shift * MIN_MATCH >= hash_bits
122     */
123
124    long block_start;
125    /* Window position at the beginning of the current output block. Gets
126     * negative when the window is moved backwards.
127     */
128
129    uInt match_length;           /* length of best match */
130    IPos prev_match;             /* previous match */
131    int match_available;         /* set if previous match exists */
132    uInt strstart;               /* start of string to insert */
133    uInt match_start;            /* start of matching string */
134    uInt lookahead;              /* number of valid bytes ahead in window */
135
136    uInt prev_length;
137    /* Length of the best match at previous step. Matches not greater than this
138     * are discarded. This is used in the lazy match evaluation.
139     */
140
141    uInt max_chain_length;
142    /* To speed up deflation, hash chains are never searched beyond this
143     * length.  A higher limit improves compression ratio but degrades the
144     * speed.
145     */
146
147    uInt max_lazy_match;
148    /* Attempt to find a better match only when the current match is strictly
149     * smaller than this value. This mechanism is used only for compression
150     * levels >= 4.
151     */
152#   define max_insert_length  max_lazy_match
153    /* Insert new strings in the hash table only if the match length is not
154     * greater than this length. This saves time but degrades compression.
155     * max_insert_length is used only for compression levels <= 3.
156     */
157
158    int level;    /* compression level (1..9) */
159    int strategy; /* favor or force Huffman coding*/
160
161    uInt good_match;
162    /* Use a faster search when the previous match is longer than this */
163
164    int nice_match; /* Stop searching when current match exceeds this */
165
166                /* used by trees.c: */
167    /* Didn't use ct_data typedef below to supress compiler warning */
168    struct ct_data_s dyn_ltree[HEAP_SIZE];   /* literal and length tree */
169    struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
170    struct ct_data_s bl_tree[2*BL_CODES+1];  /* Huffman tree for bit lengths */
171
172    struct tree_desc_s l_desc;               /* desc. for literal tree */
173    struct tree_desc_s d_desc;               /* desc. for distance tree */
174    struct tree_desc_s bl_desc;              /* desc. for bit length tree */
175
176    ush bl_count[MAX_BITS+1];
177    /* number of codes at each bit length for an optimal tree */
178
179    int heap[2*L_CODES+1];      /* heap used to build the Huffman trees */
180    int heap_len;               /* number of elements in the heap */
181    int heap_max;               /* element of largest frequency */
182    /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
183     * The same heap array is used to build all trees.
184     */
185
186    uch depth[2*L_CODES+1];
187    /* Depth of each subtree used as tie breaker for trees of equal frequency
188     */
189
190    uch *l_buf;          /* buffer for literals or lengths */
191
192    uInt  lit_bufsize;
193    /* Size of match buffer for literals/lengths.  There are 4 reasons for
194     * limiting lit_bufsize to 64K:
195     *   - frequencies can be kept in 16 bit counters
196     *   - if compression is not successful for the first block, all input
197     *     data is still in the window so we can still emit a stored block even
198     *     when input comes from standard input.  (This can also be done for
199     *     all blocks if lit_bufsize is not greater than 32K.)
200     *   - if compression is not successful for a file smaller than 64K, we can
201     *     even emit a stored file instead of a stored block (saving 5 bytes).
202     *     This is applicable only for zip (not gzip or zlib).
203     *   - creating new Huffman trees less frequently may not provide fast
204     *     adaptation to changes in the input data statistics. (Take for
205     *     example a binary file with poorly compressible code followed by
206     *     a highly compressible string table.) Smaller buffer sizes give
207     *     fast adaptation but have of course the overhead of transmitting
208     *     trees more frequently.
209     *   - I can't count above 4
210     */
211
212    uInt last_lit;      /* running index in l_buf */
213
214    ush *d_buf;
215    /* Buffer for distances. To simplify the code, d_buf and l_buf have
216     * the same number of elements. To use different lengths, an extra flag
217     * array would be necessary.
218     */
219
220    ulg opt_len;        /* bit length of current block with optimal trees */
221    ulg static_len;     /* bit length of current block with static trees */
222    ulg compressed_len; /* total bit length of compressed file */
223    uInt matches;       /* number of string matches in current block */
224    int last_eob_len;   /* bit length of EOB code for last block */
225
226#ifdef DEBUG_ZLIB
227    ulg bits_sent;      /* bit length of the compressed data */
228#endif
229
230    ush bi_buf;
231    /* Output buffer. bits are inserted starting at the bottom (least
232     * significant bits).
233     */
234    int bi_valid;
235    /* Number of valid bits in bi_buf.  All bits above the last valid bit
236     * are always zero.
237     */
238
239} deflate_state;
240
241typedef struct deflate_workspace {
242    /* State memory for the deflator */
243    deflate_state deflate_memory;
244    Byte window_memory[2 * (1 << MAX_WBITS)];
245    Pos prev_memory[1 << MAX_WBITS];
246    Pos head_memory[1 << (MAX_MEM_LEVEL + 7)];
247    char overlay_memory[(1 << (MAX_MEM_LEVEL + 6)) * (sizeof(ush)+2)];
248} deflate_workspace;
249
250/* Output a byte on the stream.
251 * IN assertion: there is enough room in pending_buf.
252 */
253#define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}
254
255
256#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
257/* Minimum amount of lookahead, except at the end of the input file.
258 * See deflate.c for comments about the MIN_MATCH+1.
259 */
260
261#define MAX_DIST(s)  ((s)->w_size-MIN_LOOKAHEAD)
262/* In order to simplify the code, particularly on 16 bit machines, match
263 * distances are limited to MAX_DIST instead of WSIZE.
264 */
265
266        /* in trees.c */
267void zlib_tr_init         (deflate_state *s);
268int  zlib_tr_tally        (deflate_state *s, unsigned dist, unsigned lc);
269ulg  zlib_tr_flush_block  (deflate_state *s, char *buf, ulg stored_len,
270			   int eof);
271void zlib_tr_align        (deflate_state *s);
272void zlib_tr_stored_block (deflate_state *s, char *buf, ulg stored_len,
273			   int eof);
274void zlib_tr_stored_type_only (deflate_state *);
275
276
277/* ===========================================================================
278 * Output a short LSB first on the stream.
279 * IN assertion: there is enough room in pendingBuf.
280 */
281#define put_short(s, w) { \
282    put_byte(s, (uch)((w) & 0xff)); \
283    put_byte(s, (uch)((ush)(w) >> 8)); \
284}
285
286/* ===========================================================================
287 * Reverse the first len bits of a code, using straightforward code (a faster
288 * method would use a table)
289 * IN assertion: 1 <= len <= 15
290 */
291static inline unsigned bi_reverse(unsigned code, /* the value to invert */
292				  int len)       /* its bit length */
293{
294    register unsigned res = 0;
295    do {
296        res |= code & 1;
297        code >>= 1, res <<= 1;
298    } while (--len > 0);
299    return res >> 1;
300}
301
302/* ===========================================================================
303 * Flush the bit buffer, keeping at most 7 bits in it.
304 */
305static inline void bi_flush(deflate_state *s)
306{
307    if (s->bi_valid == 16) {
308        put_short(s, s->bi_buf);
309        s->bi_buf = 0;
310        s->bi_valid = 0;
311    } else if (s->bi_valid >= 8) {
312        put_byte(s, (Byte)s->bi_buf);
313        s->bi_buf >>= 8;
314        s->bi_valid -= 8;
315    }
316}
317
318/* ===========================================================================
319 * Flush the bit buffer and align the output on a byte boundary
320 */
321static inline void bi_windup(deflate_state *s)
322{
323    if (s->bi_valid > 8) {
324        put_short(s, s->bi_buf);
325    } else if (s->bi_valid > 0) {
326        put_byte(s, (Byte)s->bi_buf);
327    }
328    s->bi_buf = 0;
329    s->bi_valid = 0;
330#ifdef DEBUG_ZLIB
331    s->bits_sent = (s->bits_sent+7) & ~7;
332#endif
333}
334