c62d2810 |
1 | /* inftrees.c -- generate Huffman trees for efficient decoding |
2 | * Copyright (C) 1995-2002 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 1.1.4 Copyright 1995-2002 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), or Z_DATA_ERROR if the input is invalid. */ |
108 | { |
109 | |
110 | uInt a; /* counter for codes of length k */ |
111 | uInt c[BMAX+1]; /* bit length count table */ |
112 | uInt f; /* i repeats in table every f entries */ |
113 | int g; /* maximum code length */ |
114 | int h; /* table level */ |
115 | register uInt i; /* counter, current code */ |
116 | register uInt j; /* counter */ |
117 | register int k; /* number of bits in current code */ |
118 | int l; /* bits per table (returned in m) */ |
119 | uInt mask; /* (1 << w) - 1, to avoid cc -O bug on HP */ |
120 | register uIntf *p; /* pointer into c[], b[], or v[] */ |
121 | inflate_huft *q; /* points to current table */ |
122 | struct inflate_huft_s r; /* table entry for structure assignment */ |
123 | inflate_huft *u[BMAX]; /* table stack */ |
124 | register int w; /* bits before this table == (l * h) */ |
125 | uInt x[BMAX+1]; /* bit offsets, then code stack */ |
126 | uIntf *xp; /* pointer into x */ |
127 | int y; /* number of dummy codes added */ |
128 | uInt z; /* number of entries in current table */ |
129 | |
130 | |
131 | /* Generate counts for each bit length */ |
132 | p = c; |
133 | #define C0 *p++ = 0; |
134 | #define C2 C0 C0 C0 C0 |
135 | #define C4 C2 C2 C2 C2 |
136 | C4 /* clear c[]--assume BMAX+1 is 16 */ |
137 | p = b; i = n; |
138 | do { |
139 | c[*p++]++; /* assume all entries <= BMAX */ |
140 | } while (--i); |
141 | if (c[0] == n) /* null input--all zero length codes */ |
142 | { |
143 | *t = (inflate_huft *)Z_NULL; |
144 | *m = 0; |
145 | return Z_OK; |
146 | } |
147 | |
148 | |
149 | /* Find minimum and maximum length, bound *m by those */ |
150 | l = *m; |
151 | for (j = 1; j <= BMAX; j++) |
152 | if (c[j]) |
153 | break; |
154 | k = j; /* minimum code length */ |
155 | if ((uInt)l < j) |
156 | l = j; |
157 | for (i = BMAX; i; i--) |
158 | if (c[i]) |
159 | break; |
160 | g = i; /* maximum code length */ |
161 | if ((uInt)l > i) |
162 | l = i; |
163 | *m = l; |
164 | |
165 | |
166 | /* Adjust last length count to fill out codes, if needed */ |
167 | for (y = 1 << j; j < i; j++, y <<= 1) |
168 | if ((y -= c[j]) < 0) |
169 | return Z_DATA_ERROR; |
170 | if ((y -= c[i]) < 0) |
171 | return Z_DATA_ERROR; |
172 | c[i] += y; |
173 | |
174 | |
175 | /* Generate starting offsets into the value table for each length */ |
176 | x[1] = j = 0; |
177 | p = c + 1; xp = x + 2; |
178 | while (--i) { /* note that i == g from above */ |
179 | *xp++ = (j += *p++); |
180 | } |
181 | |
182 | |
183 | /* Make a table of values in order of bit lengths */ |
184 | p = b; i = 0; |
185 | do { |
186 | if ((j = *p++) != 0) |
187 | v[x[j]++] = i; |
188 | } while (++i < n); |
189 | n = x[g]; /* set n to length of v */ |
190 | |
191 | |
192 | /* Generate the Huffman codes and for each, make the table entries */ |
193 | x[0] = i = 0; /* first Huffman code is zero */ |
194 | p = v; /* grab values in bit order */ |
195 | h = -1; /* no tables yet--level -1 */ |
196 | w = -l; /* bits decoded == (l * h) */ |
197 | u[0] = (inflate_huft *)Z_NULL; /* just to keep compilers happy */ |
198 | q = (inflate_huft *)Z_NULL; /* ditto */ |
199 | z = 0; /* ditto */ |
200 | |
201 | /* go through the bit lengths (k already is bits in shortest code) */ |
202 | for (; k <= g; k++) |
203 | { |
204 | a = c[k]; |
205 | while (a--) |
206 | { |
207 | /* here i is the Huffman code of length k bits for value *p */ |
208 | /* make tables up to required level */ |
209 | while (k > w + l) |
210 | { |
211 | h++; |
212 | w += l; /* previous table always l bits */ |
213 | |
214 | /* compute minimum size table less than or equal to l bits */ |
215 | z = g - w; |
216 | z = z > (uInt)l ? l : z; /* table size upper limit */ |
217 | if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */ |
218 | { /* too few codes for k-w bit table */ |
219 | f -= a + 1; /* deduct codes from patterns left */ |
220 | xp = c + k; |
221 | if (j < z) |
222 | while (++j < z) /* try smaller tables up to z bits */ |
223 | { |
224 | if ((f <<= 1) <= *++xp) |
225 | break; /* enough codes to use up j bits */ |
226 | f -= *xp; /* else deduct codes from patterns */ |
227 | } |
228 | } |
229 | z = 1 << j; /* table entries for j-bit table */ |
230 | |
231 | /* allocate new table */ |
232 | if (*hn + z > MANY) /* (note: doesn't matter for fixed) */ |
233 | return Z_DATA_ERROR; /* overflow of MANY */ |
234 | u[h] = q = hp + *hn; |
235 | *hn += z; |
236 | |
237 | /* connect to last table, if there is one */ |
238 | if (h) |
239 | { |
240 | x[h] = i; /* save pattern for backing up */ |
241 | r.bits = (Byte)l; /* bits to dump before this table */ |
242 | r.exop = (Byte)j; /* bits in this table */ |
243 | j = i >> (w - l); |
244 | r.base = (uInt)(q - u[h-1] - j); /* offset to this table */ |
245 | u[h-1][j] = r; /* connect to last table */ |
246 | } |
247 | else |
248 | *t = q; /* first table is returned result */ |
249 | } |
250 | |
251 | /* set up table entry in r */ |
252 | r.bits = (Byte)(k - w); |
253 | if (p >= v + n) |
254 | r.exop = 128 + 64; /* out of values--invalid code */ |
255 | else if (*p < s) |
256 | { |
257 | r.exop = (Byte)(*p < 256 ? 0 : 32 + 64); /* 256 is end-of-block */ |
258 | r.base = *p++; /* simple code is just the value */ |
259 | } |
260 | else |
261 | { |
262 | r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */ |
263 | r.base = d[*p++ - s]; |
264 | } |
265 | |
266 | /* fill code-like entries with r */ |
267 | f = 1 << (k - w); |
268 | for (j = i >> w; j < z; j += f) |
269 | q[j] = r; |
270 | |
271 | /* backwards increment the k-bit code i */ |
272 | for (j = 1 << (k - 1); i & j; j >>= 1) |
273 | i ^= j; |
274 | i ^= j; |
275 | |
276 | /* backup over finished tables */ |
277 | mask = (1 << w) - 1; /* needed on HP, cc -O bug */ |
278 | while ((i & mask) != x[h]) |
279 | { |
280 | h--; /* don't need to update q */ |
281 | w -= l; |
282 | mask = (1 << w) - 1; |
283 | } |
284 | } |
285 | } |
286 | |
287 | |
288 | /* Return Z_BUF_ERROR if we were given an incomplete table */ |
289 | return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK; |
290 | } |
291 | |
292 | |
293 | int inflate_trees_bits(c, bb, tb, hp, z) |
294 | uIntf *c; /* 19 code lengths */ |
295 | uIntf *bb; /* bits tree desired/actual depth */ |
296 | inflate_huft * FAR *tb; /* bits tree result */ |
297 | inflate_huft *hp; /* space for trees */ |
298 | z_streamp z; /* for messages */ |
299 | { |
300 | int r; |
301 | uInt hn = 0; /* hufts used in space */ |
302 | uIntf *v; /* work area for huft_build */ |
303 | |
304 | if ((v = (uIntf*)ZALLOC(z, 19, sizeof(uInt))) == Z_NULL) |
305 | return Z_MEM_ERROR; |
306 | r = huft_build(c, 19, 19, (uIntf*)Z_NULL, (uIntf*)Z_NULL, |
307 | tb, bb, hp, &hn, v); |
308 | if (r == Z_DATA_ERROR) |
309 | z->msg = (char*)"oversubscribed dynamic bit lengths tree"; |
310 | else if (r == Z_BUF_ERROR || *bb == 0) |
311 | { |
312 | z->msg = (char*)"incomplete dynamic bit lengths tree"; |
313 | r = Z_DATA_ERROR; |
314 | } |
315 | ZFREE(z, v); |
316 | return r; |
317 | } |
318 | |
319 | |
320 | int inflate_trees_dynamic(nl, nd, c, bl, bd, tl, td, hp, z) |
321 | uInt nl; /* number of literal/length codes */ |
322 | uInt nd; /* number of distance codes */ |
323 | uIntf *c; /* that many (total) code lengths */ |
324 | uIntf *bl; /* literal desired/actual bit depth */ |
325 | uIntf *bd; /* distance desired/actual bit depth */ |
326 | inflate_huft * FAR *tl; /* literal/length tree result */ |
327 | inflate_huft * FAR *td; /* distance tree result */ |
328 | inflate_huft *hp; /* space for trees */ |
329 | z_streamp z; /* for messages */ |
330 | { |
331 | int r; |
332 | uInt hn = 0; /* hufts used in space */ |
333 | uIntf *v; /* work area for huft_build */ |
334 | |
335 | /* allocate work area */ |
336 | if ((v = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL) |
337 | return Z_MEM_ERROR; |
338 | |
339 | /* build literal/length tree */ |
340 | r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v); |
341 | if (r != Z_OK || *bl == 0) |
342 | { |
343 | if (r == Z_DATA_ERROR) |
344 | z->msg = (char*)"oversubscribed literal/length tree"; |
345 | else if (r != Z_MEM_ERROR) |
346 | { |
347 | z->msg = (char*)"incomplete literal/length tree"; |
348 | r = Z_DATA_ERROR; |
349 | } |
350 | ZFREE(z, v); |
351 | return r; |
352 | } |
353 | |
354 | /* build distance tree */ |
355 | r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v); |
356 | if (r != Z_OK || (*bd == 0 && nl > 257)) |
357 | { |
358 | if (r == Z_DATA_ERROR) |
359 | z->msg = (char*)"oversubscribed distance tree"; |
360 | else if (r == Z_BUF_ERROR) { |
361 | #ifdef PKZIP_BUG_WORKAROUND |
362 | r = Z_OK; |
363 | } |
364 | #else |
365 | z->msg = (char*)"incomplete distance tree"; |
366 | r = Z_DATA_ERROR; |
367 | } |
368 | else if (r != Z_MEM_ERROR) |
369 | { |
370 | z->msg = (char*)"empty distance tree with lengths"; |
371 | r = Z_DATA_ERROR; |
372 | } |
373 | ZFREE(z, v); |
374 | return r; |
375 | #endif |
376 | } |
377 | |
378 | /* done */ |
379 | ZFREE(z, v); |
380 | return Z_OK; |
381 | } |
382 | |
383 | |
384 | /* build fixed tables only once--keep them here */ |
385 | #ifdef BUILDFIXED |
386 | local int fixed_built = 0; |
387 | #define FIXEDH 544 /* number of hufts used by fixed tables */ |
388 | local inflate_huft fixed_mem[FIXEDH]; |
389 | local uInt fixed_bl; |
390 | local uInt fixed_bd; |
391 | local inflate_huft *fixed_tl; |
392 | local inflate_huft *fixed_td; |
393 | #else |
394 | #include "inffixed.h" |
395 | #endif |
396 | |
397 | |
398 | int inflate_trees_fixed(bl, bd, tl, td, z) |
399 | uIntf *bl; /* literal desired/actual bit depth */ |
400 | uIntf *bd; /* distance desired/actual bit depth */ |
401 | inflate_huft * FAR *tl; /* literal/length tree result */ |
402 | inflate_huft * FAR *td; /* distance tree result */ |
403 | z_streamp z; /* for memory allocation */ |
404 | { |
405 | #ifdef BUILDFIXED |
406 | /* build fixed tables if not already */ |
407 | if (!fixed_built) |
408 | { |
409 | int k; /* temporary variable */ |
410 | uInt f = 0; /* number of hufts used in fixed_mem */ |
411 | uIntf *c; /* length list for huft_build */ |
412 | uIntf *v; /* work area for huft_build */ |
413 | |
414 | /* allocate memory */ |
415 | if ((c = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL) |
416 | return Z_MEM_ERROR; |
417 | if ((v = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL) |
418 | { |
419 | ZFREE(z, c); |
420 | return Z_MEM_ERROR; |
421 | } |
422 | |
423 | /* literal table */ |
424 | for (k = 0; k < 144; k++) |
425 | c[k] = 8; |
426 | for (; k < 256; k++) |
427 | c[k] = 9; |
428 | for (; k < 280; k++) |
429 | c[k] = 7; |
430 | for (; k < 288; k++) |
431 | c[k] = 8; |
432 | fixed_bl = 9; |
433 | huft_build(c, 288, 257, cplens, cplext, &fixed_tl, &fixed_bl, |
434 | fixed_mem, &f, v); |
435 | |
436 | /* distance table */ |
437 | for (k = 0; k < 30; k++) |
438 | c[k] = 5; |
439 | fixed_bd = 5; |
440 | huft_build(c, 30, 0, cpdist, cpdext, &fixed_td, &fixed_bd, |
441 | fixed_mem, &f, v); |
442 | |
443 | /* done */ |
444 | ZFREE(z, v); |
445 | ZFREE(z, c); |
446 | fixed_built = 1; |
447 | } |
448 | #endif |
449 | *bl = fixed_bl; |
450 | *bd = fixed_bd; |
451 | *tl = fixed_tl; |
452 | *td = fixed_td; |
453 | return Z_OK; |
454 | } |