|
0
|
1 /* inftrees.c -- generate Huffman trees for efficient decoding
|
|
|
2 * Copyright (C) 1995-1998 Mark Adler
|
|
|
3 * For conditions of distribution and use, see copyright notice in zlib.h
|
|
|
4 */
|
|
|
5
|
|
|
6 #include "zutil.h"
|
|
|
7 #include "inftrees.h"
|
|
|
8
|
|
|
9 #if !defined(BUILDFIXED) && !defined(STDC)
|
|
|
10 # define BUILDFIXED /* non ANSI compilers may not accept inffixed.h */
|
|
|
11 #endif
|
|
|
12
|
|
|
13 const char inflate_copyright[] =
|
|
|
14 " inflate 1.1.3 Copyright 1995-1998 Mark Adler ";
|
|
|
15 /*
|
|
|
16 If you use the zlib library in a product, an acknowledgment is welcome
|
|
|
17 in the documentation of your product. If for some reason you cannot
|
|
|
18 include such an acknowledgment, I would appreciate that you keep this
|
|
|
19 copyright string in the executable of your product.
|
|
|
20 */
|
|
|
21 struct internal_state {int dummy;}; /* for buggy compilers */
|
|
|
22
|
|
|
23 /* simplify the use of the inflate_huft type with some defines */
|
|
|
24 #define exop word.what.Exop
|
|
|
25 #define bits word.what.Bits
|
|
|
26
|
|
|
27
|
|
|
28 local int huft_build OF((
|
|
|
29 uIntf *, /* code lengths in bits */
|
|
|
30 uInt, /* number of codes */
|
|
|
31 uInt, /* number of "simple" codes */
|
|
|
32 const uIntf *, /* list of base values for non-simple codes */
|
|
|
33 const uIntf *, /* list of extra bits for non-simple codes */
|
|
|
34 inflate_huft * FAR*,/* result: starting table */
|
|
|
35 uIntf *, /* maximum lookup bits (returns actual) */
|
|
|
36 inflate_huft *, /* space for trees */
|
|
|
37 uInt *, /* hufts used in space */
|
|
|
38 uIntf * )); /* space for values */
|
|
|
39
|
|
|
40 /* Tables for deflate from PKZIP's appnote.txt. */
|
|
|
41 local const uInt cplens[31] = { /* Copy lengths for literal codes 257..285 */
|
|
|
42 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
|
|
|
43 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
|
|
|
44 /* see note #13 above about 258 */
|
|
|
45 local const uInt cplext[31] = { /* Extra bits for literal codes 257..285 */
|
|
|
46 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
|
|
|
47 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 112, 112}; /* 112==invalid */
|
|
|
48 local const uInt cpdist[30] = { /* Copy offsets for distance codes 0..29 */
|
|
|
49 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
|
|
|
50 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
|
|
|
51 8193, 12289, 16385, 24577};
|
|
|
52 local const uInt cpdext[30] = { /* Extra bits for distance codes */
|
|
|
53 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
|
|
|
54 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
|
|
|
55 12, 12, 13, 13};
|
|
|
56
|
|
|
57 /*
|
|
|
58 Huffman code decoding is performed using a multi-level table lookup.
|
|
|
59 The fastest way to decode is to simply build a lookup table whose
|
|
|
60 size is determined by the longest code. However, the time it takes
|
|
|
61 to build this table can also be a factor if the data being decoded
|
|
|
62 is not very long. The most common codes are necessarily the
|
|
|
63 shortest codes, so those codes dominate the decoding time, and hence
|
|
|
64 the speed. The idea is you can have a shorter table that decodes the
|
|
|
65 shorter, more probable codes, and then point to subsidiary tables for
|
|
|
66 the longer codes. The time it costs to decode the longer codes is
|
|
|
67 then traded against the time it takes to make longer tables.
|
|
|
68
|
|
|
69 This results of this trade are in the variables lbits and dbits
|
|
|
70 below. lbits is the number of bits the first level table for literal/
|
|
|
71 length codes can decode in one step, and dbits is the same thing for
|
|
|
72 the distance codes. Subsequent tables are also less than or equal to
|
|
|
73 those sizes. These values may be adjusted either when all of the
|
|
|
74 codes are shorter than that, in which case the longest code length in
|
|
|
75 bits is used, or when the shortest code is *longer* than the requested
|
|
|
76 table size, in which case the length of the shortest code in bits is
|
|
|
77 used.
|
|
|
78
|
|
|
79 There are two different values for the two tables, since they code a
|
|
|
80 different number of possibilities each. The literal/length table
|
|
|
81 codes 286 possible values, or in a flat code, a little over eight
|
|
|
82 bits. The distance table codes 30 possible values, or a little less
|
|
|
83 than five bits, flat. The optimum values for speed end up being
|
|
|
84 about one bit more than those, so lbits is 8+1 and dbits is 5+1.
|
|
|
85 The optimum values may differ though from machine to machine, and
|
|
|
86 possibly even between compilers. Your mileage may vary.
|
|
|
87 */
|
|
|
88
|
|
|
89
|
|
|
90 /* If BMAX needs to be larger than 16, then h and x[] should be uLong. */
|
|
|
91 #define BMAX 15 /* maximum bit length of any code */
|
|
|
92
|
|
|
93 local int huft_build(b, n, s, d, e, t, m, hp, hn, v)
|
|
|
94 uIntf *b; /* code lengths in bits (all assumed <= BMAX) */
|
|
|
95 uInt n; /* number of codes (assumed <= 288) */
|
|
|
96 uInt s; /* number of simple-valued codes (0..s-1) */
|
|
|
97 const uIntf *d; /* list of base values for non-simple codes */
|
|
|
98 const uIntf *e; /* list of extra bits for non-simple codes */
|
|
|
99 inflate_huft * FAR *t; /* result: starting table */
|
|
|
100 uIntf *m; /* maximum lookup bits, returns actual */
|
|
|
101 inflate_huft *hp; /* space for trees */
|
|
|
102 uInt *hn; /* hufts used in space */
|
|
|
103 uIntf *v; /* working area: values in order of bit length */
|
|
|
104 /* Given a list of code lengths and a maximum table size, make a set of
|
|
|
105 tables to decode that set of codes. Return Z_OK on success, Z_BUF_ERROR
|
|
|
106 if the given code set is incomplete (the tables are still built in this
|
|
|
107 case), Z_DATA_ERROR if the input is invalid (an over-subscribed set of
|
|
|
108 lengths), or Z_MEM_ERROR if not enough memory. */
|
|
|
109 {
|
|
|
110
|
|
|
111 uInt a; /* counter for codes of length k */
|
|
|
112 uInt c[BMAX+1]; /* bit length count table */
|
|
|
113 uInt f; /* i repeats in table every f entries */
|
|
|
114 int g; /* maximum code length */
|
|
|
115 int h; /* table level */
|
|
|
116 register uInt i; /* counter, current code */
|
|
|
117 register uInt j; /* counter */
|
|
|
118 register int k; /* number of bits in current code */
|
|
|
119 int l; /* bits per table (returned in m) */
|
|
|
120 uInt mask; /* (1 << w) - 1, to avoid cc -O bug on HP */
|
|
|
121 register uIntf *p; /* pointer into c[], b[], or v[] */
|
|
|
122 inflate_huft *q; /* points to current table */
|
|
|
123 struct inflate_huft_s r; /* table entry for structure assignment */
|
|
|
124 inflate_huft *u[BMAX]; /* table stack */
|
|
|
125 register int w; /* bits before this table == (l * h) */
|
|
|
126 uInt x[BMAX+1]; /* bit offsets, then code stack */
|
|
|
127 uIntf *xp; /* pointer into x */
|
|
|
128 int y; /* number of dummy codes added */
|
|
|
129 uInt z; /* number of entries in current table */
|
|
|
130
|
|
|
131
|
|
|
132 /* Generate counts for each bit length */
|
|
|
133 p = c;
|
|
|
134 #define C0 *p++ = 0;
|
|
|
135 #define C2 C0 C0 C0 C0
|
|
|
136 #define C4 C2 C2 C2 C2
|
|
|
137 C4 /* clear c[]--assume BMAX+1 is 16 */
|
|
|
138 p = b; i = n;
|
|
|
139 do {
|
|
|
140 c[*p++]++; /* assume all entries <= BMAX */
|
|
|
141 } while (--i);
|
|
|
142 if (c[0] == n) /* null input--all zero length codes */
|
|
|
143 {
|
|
|
144 *t = (inflate_huft *)Z_NULL;
|
|
|
145 *m = 0;
|
|
|
146 return Z_OK;
|
|
|
147 }
|
|
|
148
|
|
|
149
|
|
|
150 /* Find minimum and maximum length, bound *m by those */
|
|
|
151 l = *m;
|
|
|
152 for (j = 1; j <= BMAX; j++)
|
|
|
153 if (c[j])
|
|
|
154 break;
|
|
|
155 k = j; /* minimum code length */
|
|
|
156 if ((uInt)l < j)
|
|
|
157 l = j;
|
|
|
158 for (i = BMAX; i; i--)
|
|
|
159 if (c[i])
|
|
|
160 break;
|
|
|
161 g = i; /* maximum code length */
|
|
|
162 if ((uInt)l > i)
|
|
|
163 l = i;
|
|
|
164 *m = l;
|
|
|
165
|
|
|
166
|
|
|
167 /* Adjust last length count to fill out codes, if needed */
|
|
|
168 for (y = 1 << j; j < i; j++, y <<= 1)
|
|
|
169 if ((y -= c[j]) < 0)
|
|
|
170 return Z_DATA_ERROR;
|
|
|
171 if ((y -= c[i]) < 0)
|
|
|
172 return Z_DATA_ERROR;
|
|
|
173 c[i] += y;
|
|
|
174
|
|
|
175
|
|
|
176 /* Generate starting offsets into the value table for each length */
|
|
|
177 x[1] = j = 0;
|
|
|
178 p = c + 1; xp = x + 2;
|
|
|
179 while (--i) { /* note that i == g from above */
|
|
|
180 *xp++ = (j += *p++);
|
|
|
181 }
|
|
|
182
|
|
|
183
|
|
|
184 /* Make a table of values in order of bit lengths */
|
|
|
185 p = b; i = 0;
|
|
|
186 do {
|
|
|
187 if ((j = *p++) != 0)
|
|
|
188 v[x[j]++] = i;
|
|
|
189 } while (++i < n);
|
|
|
190 n = x[g]; /* set n to length of v */
|
|
|
191
|
|
|
192
|
|
|
193 /* Generate the Huffman codes and for each, make the table entries */
|
|
|
194 x[0] = i = 0; /* first Huffman code is zero */
|
|
|
195 p = v; /* grab values in bit order */
|
|
|
196 h = -1; /* no tables yet--level -1 */
|
|
|
197 w = -l; /* bits decoded == (l * h) */
|
|
|
198 u[0] = (inflate_huft *)Z_NULL; /* just to keep compilers happy */
|
|
|
199 q = (inflate_huft *)Z_NULL; /* ditto */
|
|
|
200 z = 0; /* ditto */
|
|
|
201
|
|
|
202 /* go through the bit lengths (k already is bits in shortest code) */
|
|
|
203 for (; k <= g; k++)
|
|
|
204 {
|
|
|
205 a = c[k];
|
|
|
206 while (a--)
|
|
|
207 {
|
|
|
208 /* here i is the Huffman code of length k bits for value *p */
|
|
|
209 /* make tables up to required level */
|
|
|
210 while (k > w + l)
|
|
|
211 {
|
|
|
212 h++;
|
|
|
213 w += l; /* previous table always l bits */
|
|
|
214
|
|
|
215 /* compute minimum size table less than or equal to l bits */
|
|
|
216 z = g - w;
|
|
|
217 z = z > (uInt)l ? l : z; /* table size upper limit */
|
|
|
218 if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */
|
|
|
219 { /* too few codes for k-w bit table */
|
|
|
220 f -= a + 1; /* deduct codes from patterns left */
|
|
|
221 xp = c + k;
|
|
|
222 if (j < z)
|
|
|
223 while (++j < z) /* try smaller tables up to z bits */
|
|
|
224 {
|
|
|
225 if ((f <<= 1) <= *++xp)
|
|
|
226 break; /* enough codes to use up j bits */
|
|
|
227 f -= *xp; /* else deduct codes from patterns */
|
|
|
228 }
|
|
|
229 }
|
|
|
230 z = 1 << j; /* table entries for j-bit table */
|
|
|
231
|
|
|
232 /* allocate new table */
|
|
|
233 if (*hn + z > MANY) /* (note: doesn't matter for fixed) */
|
|
|
234 return Z_MEM_ERROR; /* not enough memory */
|
|
|
235 u[h] = q = hp + *hn;
|
|
|
236 *hn += z;
|
|
|
237
|
|
|
238 /* connect to last table, if there is one */
|
|
|
239 if (h)
|
|
|
240 {
|
|
|
241 x[h] = i; /* save pattern for backing up */
|
|
|
242 r.bits = (Byte)l; /* bits to dump before this table */
|
|
|
243 r.exop = (Byte)j; /* bits in this table */
|
|
|
244 j = i >> (w - l);
|
|
|
245 r.base = (uInt)(q - u[h-1] - j); /* offset to this table */
|
|
|
246 u[h-1][j] = r; /* connect to last table */
|
|
|
247 }
|
|
|
248 else
|
|
|
249 *t = q; /* first table is returned result */
|
|
|
250 }
|
|
|
251
|
|
|
252 /* set up table entry in r */
|
|
|
253 r.bits = (Byte)(k - w);
|
|
|
254 if (p >= v + n)
|
|
|
255 r.exop = 128 + 64; /* out of values--invalid code */
|
|
|
256 else if (*p < s)
|
|
|
257 {
|
|
|
258 r.exop = (Byte)(*p < 256 ? 0 : 32 + 64); /* 256 is end-of-block */
|
|
|
259 r.base = *p++; /* simple code is just the value */
|
|
|
260 }
|
|
|
261 else
|
|
|
262 {
|
|
|
263 r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */
|
|
|
264 r.base = d[*p++ - s];
|
|
|
265 }
|
|
|
266
|
|
|
267 /* fill code-like entries with r */
|
|
|
268 f = 1 << (k - w);
|
|
|
269 for (j = i >> w; j < z; j += f)
|
|
|
270 q[j] = r;
|
|
|
271
|
|
|
272 /* backwards increment the k-bit code i */
|
|
|
273 for (j = 1 << (k - 1); i & j; j >>= 1)
|
|
|
274 i ^= j;
|
|
|
275 i ^= j;
|
|
|
276
|
|
|
277 /* backup over finished tables */
|
|
|
278 mask = (1 << w) - 1; /* needed on HP, cc -O bug */
|
|
|
279 while ((i & mask) != x[h])
|
|
|
280 {
|
|
|
281 h--; /* don't need to update q */
|
|
|
282 w -= l;
|
|
|
283 mask = (1 << w) - 1;
|
|
|
284 }
|
|
|
285 }
|
|
|
286 }
|
|
|
287
|
|
|
288
|
|
|
289 /* Return Z_BUF_ERROR if we were given an incomplete table */
|
|
|
290 return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
|
|
|
291 }
|
|
|
292
|
|
|
293
|
|
|
294 int inflate_trees_bits(c, bb, tb, hp, z)
|
|
|
295 uIntf *c; /* 19 code lengths */
|
|
|
296 uIntf *bb; /* bits tree desired/actual depth */
|
|
|
297 inflate_huft * FAR *tb; /* bits tree result */
|
|
|
298 inflate_huft *hp; /* space for trees */
|
|
|
299 z_streamp z; /* for messages */
|
|
|
300 {
|
|
|
301 int r;
|
|
|
302 uInt hn = 0; /* hufts used in space */
|
|
|
303 uIntf *v; /* work area for huft_build */
|
|
|
304
|
|
|
305 if ((v = (uIntf*)ZALLOC(z, 19, sizeof(uInt))) == Z_NULL)
|
|
|
306 return Z_MEM_ERROR;
|
|
|
307 r = huft_build(c, 19, 19, (uIntf*)Z_NULL, (uIntf*)Z_NULL,
|
|
|
308 tb, bb, hp, &hn, v);
|
|
|
309 if (r == Z_DATA_ERROR)
|
|
|
310 z->msg = (char*)"oversubscribed dynamic bit lengths tree";
|
|
|
311 else if (r == Z_BUF_ERROR || *bb == 0)
|
|
|
312 {
|
|
|
313 z->msg = (char*)"incomplete dynamic bit lengths tree";
|
|
|
314 r = Z_DATA_ERROR;
|
|
|
315 }
|
|
|
316 ZFREE(z, v);
|
|
|
317 return r;
|
|
|
318 }
|
|
|
319
|
|
|
320
|
|
|
321 int inflate_trees_dynamic(nl, nd, c, bl, bd, tl, td, hp, z)
|
|
|
322 uInt nl; /* number of literal/length codes */
|
|
|
323 uInt nd; /* number of distance codes */
|
|
|
324 uIntf *c; /* that many (total) code lengths */
|
|
|
325 uIntf *bl; /* literal desired/actual bit depth */
|
|
|
326 uIntf *bd; /* distance desired/actual bit depth */
|
|
|
327 inflate_huft * FAR *tl; /* literal/length tree result */
|
|
|
328 inflate_huft * FAR *td; /* distance tree result */
|
|
|
329 inflate_huft *hp; /* space for trees */
|
|
|
330 z_streamp z; /* for messages */
|
|
|
331 {
|
|
|
332 int r;
|
|
|
333 uInt hn = 0; /* hufts used in space */
|
|
|
334 uIntf *v; /* work area for huft_build */
|
|
|
335
|
|
|
336 /* allocate work area */
|
|
|
337 if ((v = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
|
|
|
338 return Z_MEM_ERROR;
|
|
|
339
|
|
|
340 /* build literal/length tree */
|
|
|
341 r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v);
|
|
|
342 if (r != Z_OK || *bl == 0)
|
|
|
343 {
|
|
|
344 if (r == Z_DATA_ERROR)
|
|
|
345 z->msg = (char*)"oversubscribed literal/length tree";
|
|
|
346 else if (r != Z_MEM_ERROR)
|
|
|
347 {
|
|
|
348 z->msg = (char*)"incomplete literal/length tree";
|
|
|
349 r = Z_DATA_ERROR;
|
|
|
350 }
|
|
|
351 ZFREE(z, v);
|
|
|
352 return r;
|
|
|
353 }
|
|
|
354
|
|
|
355 /* build distance tree */
|
|
|
356 r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v);
|
|
|
357 if (r != Z_OK || (*bd == 0 && nl > 257))
|
|
|
358 {
|
|
|
359 if (r == Z_DATA_ERROR)
|
|
|
360 z->msg = (char*)"oversubscribed distance tree";
|
|
|
361 else if (r == Z_BUF_ERROR) {
|
|
|
362 #ifdef PKZIP_BUG_WORKAROUND
|
|
|
363 r = Z_OK;
|
|
|
364 }
|
|
|
365 #else
|
|
|
366 z->msg = (char*)"incomplete distance tree";
|
|
|
367 r = Z_DATA_ERROR;
|
|
|
368 }
|
|
|
369 else if (r != Z_MEM_ERROR)
|
|
|
370 {
|
|
|
371 z->msg = (char*)"empty distance tree with lengths";
|
|
|
372 r = Z_DATA_ERROR;
|
|
|
373 }
|
|
|
374 ZFREE(z, v);
|
|
|
375 return r;
|
|
|
376 #endif
|
|
|
377 }
|
|
|
378
|
|
|
379 /* done */
|
|
|
380 ZFREE(z, v);
|
|
|
381 return Z_OK;
|
|
|
382 }
|
|
|
383
|
|
|
384
|
|
|
385 /* build fixed tables only once--keep them here */
|
|
|
386 #ifdef BUILDFIXED
|
|
|
387 local int fixed_built = 0;
|
|
|
388 #define FIXEDH 544 /* number of hufts used by fixed tables */
|
|
|
389 local inflate_huft fixed_mem[FIXEDH];
|
|
|
390 local uInt fixed_bl;
|
|
|
391 local uInt fixed_bd;
|
|
|
392 local inflate_huft *fixed_tl;
|
|
|
393 local inflate_huft *fixed_td;
|
|
|
394 #else
|
|
|
395 #include "inffixed.h"
|
|
|
396 #endif
|
|
|
397
|
|
|
398
|
|
|
399 int inflate_trees_fixed(bl, bd, tl, td, z)
|
|
|
400 uIntf *bl; /* literal desired/actual bit depth */
|
|
|
401 uIntf *bd; /* distance desired/actual bit depth */
|
|
|
402 inflate_huft * FAR *tl; /* literal/length tree result */
|
|
|
403 inflate_huft * FAR *td; /* distance tree result */
|
|
|
404 z_streamp z; /* for memory allocation */
|
|
|
405 {
|
|
|
406 #ifdef BUILDFIXED
|
|
|
407 /* build fixed tables if not already */
|
|
|
408 if (!fixed_built)
|
|
|
409 {
|
|
|
410 int k; /* temporary variable */
|
|
|
411 uInt f = 0; /* number of hufts used in fixed_mem */
|
|
|
412 uIntf *c; /* length list for huft_build */
|
|
|
413 uIntf *v; /* work area for huft_build */
|
|
|
414
|
|
|
415 /* allocate memory */
|
|
|
416 if ((c = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
|
|
|
417 return Z_MEM_ERROR;
|
|
|
418 if ((v = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
|
|
|
419 {
|
|
|
420 ZFREE(z, c);
|
|
|
421 return Z_MEM_ERROR;
|
|
|
422 }
|
|
|
423
|
|
|
424 /* literal table */
|
|
|
425 for (k = 0; k < 144; k++)
|
|
|
426 c[k] = 8;
|
|
|
427 for (; k < 256; k++)
|
|
|
428 c[k] = 9;
|
|
|
429 for (; k < 280; k++)
|
|
|
430 c[k] = 7;
|
|
|
431 for (; k < 288; k++)
|
|
|
432 c[k] = 8;
|
|
|
433 fixed_bl = 9;
|
|
|
434 huft_build(c, 288, 257, cplens, cplext, &fixed_tl, &fixed_bl,
|
|
|
435 fixed_mem, &f, v);
|
|
|
436
|
|
|
437 /* distance table */
|
|
|
438 for (k = 0; k < 30; k++)
|
|
|
439 c[k] = 5;
|
|
|
440 fixed_bd = 5;
|
|
|
441 huft_build(c, 30, 0, cpdist, cpdext, &fixed_td, &fixed_bd,
|
|
|
442 fixed_mem, &f, v);
|
|
|
443
|
|
|
444 /* done */
|
|
|
445 ZFREE(z, v);
|
|
|
446 ZFREE(z, c);
|
|
|
447 fixed_built = 1;
|
|
|
448 }
|
|
|
449 #endif
|
|
|
450 *bl = fixed_bl;
|
|
|
451 *bd = fixed_bd;
|
|
|
452 *tl = fixed_tl;
|
|
|
453 *td = fixed_td;
|
|
|
454 return Z_OK;
|
|
|
455 }
|
