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1da177e4 LT |
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 <linux/zutil.h> | |
7 | #include "inftrees.h" | |
8 | #include "infutil.h" | |
9 | ||
10 | static const char inflate_copyright[] __attribute_used__ = | |
11 | " inflate 1.1.3 Copyright 1995-1998 Mark Adler "; | |
12 | /* | |
13 | If you use the zlib library in a product, an acknowledgment is welcome | |
14 | in the documentation of your product. If for some reason you cannot | |
15 | include such an acknowledgment, I would appreciate that you keep this | |
16 | copyright string in the executable of your product. | |
17 | */ | |
18 | struct internal_state; | |
19 | ||
20 | /* simplify the use of the inflate_huft type with some defines */ | |
21 | #define exop word.what.Exop | |
22 | #define bits word.what.Bits | |
23 | ||
24 | ||
25 | static int huft_build ( | |
26 | uInt *, /* code lengths in bits */ | |
27 | uInt, /* number of codes */ | |
28 | uInt, /* number of "simple" codes */ | |
29 | const uInt *, /* list of base values for non-simple codes */ | |
30 | const uInt *, /* list of extra bits for non-simple codes */ | |
31 | inflate_huft **, /* result: starting table */ | |
32 | uInt *, /* maximum lookup bits (returns actual) */ | |
33 | inflate_huft *, /* space for trees */ | |
34 | uInt *, /* hufts used in space */ | |
35 | uInt * ); /* space for values */ | |
36 | ||
37 | /* Tables for deflate from PKZIP's appnote.txt. */ | |
38 | static const uInt cplens[31] = { /* Copy lengths for literal codes 257..285 */ | |
39 | 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, | |
40 | 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; | |
41 | /* see note #13 above about 258 */ | |
42 | static const uInt cplext[31] = { /* Extra bits for literal codes 257..285 */ | |
43 | 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, | |
44 | 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 112, 112}; /* 112==invalid */ | |
45 | static const uInt cpdist[30] = { /* Copy offsets for distance codes 0..29 */ | |
46 | 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, | |
47 | 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, | |
48 | 8193, 12289, 16385, 24577}; | |
49 | static const uInt cpdext[30] = { /* Extra bits for distance codes */ | |
50 | 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, | |
51 | 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, | |
52 | 12, 12, 13, 13}; | |
53 | ||
54 | /* | |
55 | Huffman code decoding is performed using a multi-level table lookup. | |
56 | The fastest way to decode is to simply build a lookup table whose | |
57 | size is determined by the longest code. However, the time it takes | |
58 | to build this table can also be a factor if the data being decoded | |
59 | is not very long. The most common codes are necessarily the | |
60 | shortest codes, so those codes dominate the decoding time, and hence | |
61 | the speed. The idea is you can have a shorter table that decodes the | |
62 | shorter, more probable codes, and then point to subsidiary tables for | |
63 | the longer codes. The time it costs to decode the longer codes is | |
64 | then traded against the time it takes to make longer tables. | |
65 | ||
66 | This results of this trade are in the variables lbits and dbits | |
67 | below. lbits is the number of bits the first level table for literal/ | |
68 | length codes can decode in one step, and dbits is the same thing for | |
69 | the distance codes. Subsequent tables are also less than or equal to | |
70 | those sizes. These values may be adjusted either when all of the | |
71 | codes are shorter than that, in which case the longest code length in | |
72 | bits is used, or when the shortest code is *longer* than the requested | |
73 | table size, in which case the length of the shortest code in bits is | |
74 | used. | |
75 | ||
76 | There are two different values for the two tables, since they code a | |
77 | different number of possibilities each. The literal/length table | |
78 | codes 286 possible values, or in a flat code, a little over eight | |
79 | bits. The distance table codes 30 possible values, or a little less | |
80 | than five bits, flat. The optimum values for speed end up being | |
81 | about one bit more than those, so lbits is 8+1 and dbits is 5+1. | |
82 | The optimum values may differ though from machine to machine, and | |
83 | possibly even between compilers. Your mileage may vary. | |
84 | */ | |
85 | ||
86 | ||
87 | /* If BMAX needs to be larger than 16, then h and x[] should be uLong. */ | |
88 | #define BMAX 15 /* maximum bit length of any code */ | |
89 | ||
90 | static int huft_build( | |
91 | uInt *b, /* code lengths in bits (all assumed <= BMAX) */ | |
92 | uInt n, /* number of codes (assumed <= 288) */ | |
93 | uInt s, /* number of simple-valued codes (0..s-1) */ | |
94 | const uInt *d, /* list of base values for non-simple codes */ | |
95 | const uInt *e, /* list of extra bits for non-simple codes */ | |
96 | inflate_huft **t, /* result: starting table */ | |
97 | uInt *m, /* maximum lookup bits, returns actual */ | |
98 | inflate_huft *hp, /* space for trees */ | |
99 | uInt *hn, /* hufts used in space */ | |
100 | uInt *v /* working area: values in order of bit length */ | |
101 | ) | |
102 | /* Given a list of code lengths and a maximum table size, make a set of | |
103 | tables to decode that set of codes. Return Z_OK on success, Z_BUF_ERROR | |
104 | if the given code set is incomplete (the tables are still built in this | |
105 | case), Z_DATA_ERROR if the input is invalid (an over-subscribed set of | |
106 | lengths), or Z_MEM_ERROR if not enough memory. */ | |
107 | { | |
108 | ||
109 | uInt a; /* counter for codes of length k */ | |
110 | uInt c[BMAX+1]; /* bit length count table */ | |
111 | uInt f; /* i repeats in table every f entries */ | |
112 | int g; /* maximum code length */ | |
113 | int h; /* table level */ | |
114 | register uInt i; /* counter, current code */ | |
115 | register uInt j; /* counter */ | |
116 | register int k; /* number of bits in current code */ | |
117 | int l; /* bits per table (returned in m) */ | |
118 | uInt mask; /* (1 << w) - 1, to avoid cc -O bug on HP */ | |
119 | register uInt *p; /* pointer into c[], b[], or v[] */ | |
120 | inflate_huft *q; /* points to current table */ | |
121 | struct inflate_huft_s r; /* table entry for structure assignment */ | |
122 | inflate_huft *u[BMAX]; /* table stack */ | |
123 | register int w; /* bits before this table == (l * h) */ | |
124 | uInt x[BMAX+1]; /* bit offsets, then code stack */ | |
125 | uInt *xp; /* pointer into x */ | |
126 | int y; /* number of dummy codes added */ | |
127 | uInt z; /* number of entries in current table */ | |
128 | ||
129 | ||
130 | /* Generate counts for each bit length */ | |
131 | p = c; | |
132 | #define C0 *p++ = 0; | |
133 | #define C2 C0 C0 C0 C0 | |
134 | #define C4 C2 C2 C2 C2 | |
135 | C4 /* clear c[]--assume BMAX+1 is 16 */ | |
136 | p = b; i = n; | |
137 | do { | |
138 | c[*p++]++; /* assume all entries <= BMAX */ | |
139 | } while (--i); | |
140 | if (c[0] == n) /* null input--all zero length codes */ | |
141 | { | |
142 | *t = NULL; | |
143 | *m = 0; | |
c231c7db | 144 | return Z_OK; |
1da177e4 LT |
145 | } |
146 | ||
147 | ||
148 | /* Find minimum and maximum length, bound *m by those */ | |
149 | l = *m; | |
150 | for (j = 1; j <= BMAX; j++) | |
151 | if (c[j]) | |
152 | break; | |
153 | k = j; /* minimum code length */ | |
154 | if ((uInt)l < j) | |
155 | l = j; | |
156 | for (i = BMAX; i; i--) | |
157 | if (c[i]) | |
158 | break; | |
159 | g = i; /* maximum code length */ | |
160 | if ((uInt)l > i) | |
161 | l = i; | |
162 | *m = l; | |
163 | ||
164 | ||
165 | /* Adjust last length count to fill out codes, if needed */ | |
166 | for (y = 1 << j; j < i; j++, y <<= 1) | |
167 | if ((y -= c[j]) < 0) | |
168 | return Z_DATA_ERROR; | |
169 | if ((y -= c[i]) < 0) | |
170 | return Z_DATA_ERROR; | |
171 | c[i] += y; | |
172 | ||
173 | ||
174 | /* Generate starting offsets into the value table for each length */ | |
175 | x[1] = j = 0; | |
176 | p = c + 1; xp = x + 2; | |
177 | while (--i) { /* note that i == g from above */ | |
178 | *xp++ = (j += *p++); | |
179 | } | |
180 | ||
181 | ||
182 | /* Make a table of values in order of bit lengths */ | |
183 | p = b; i = 0; | |
184 | do { | |
185 | if ((j = *p++) != 0) | |
186 | v[x[j]++] = i; | |
187 | } while (++i < n); | |
188 | n = x[g]; /* set n to length of v */ | |
189 | ||
190 | ||
191 | /* Generate the Huffman codes and for each, make the table entries */ | |
192 | x[0] = i = 0; /* first Huffman code is zero */ | |
193 | p = v; /* grab values in bit order */ | |
194 | h = -1; /* no tables yet--level -1 */ | |
195 | w = -l; /* bits decoded == (l * h) */ | |
196 | u[0] = NULL; /* just to keep compilers happy */ | |
197 | q = NULL; /* ditto */ | |
198 | z = 0; /* ditto */ | |
199 | ||
200 | /* go through the bit lengths (k already is bits in shortest code) */ | |
201 | for (; k <= g; k++) | |
202 | { | |
203 | a = c[k]; | |
204 | while (a--) | |
205 | { | |
206 | /* here i is the Huffman code of length k bits for value *p */ | |
207 | /* make tables up to required level */ | |
208 | while (k > w + l) | |
209 | { | |
210 | h++; | |
211 | w += l; /* previous table always l bits */ | |
212 | ||
213 | /* compute minimum size table less than or equal to l bits */ | |
214 | z = g - w; | |
215 | z = z > (uInt)l ? l : z; /* table size upper limit */ | |
216 | if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */ | |
217 | { /* too few codes for k-w bit table */ | |
218 | f -= a + 1; /* deduct codes from patterns left */ | |
219 | xp = c + k; | |
220 | if (j < z) | |
221 | while (++j < z) /* try smaller tables up to z bits */ | |
222 | { | |
223 | if ((f <<= 1) <= *++xp) | |
224 | break; /* enough codes to use up j bits */ | |
225 | f -= *xp; /* else deduct codes from patterns */ | |
226 | } | |
227 | } | |
228 | z = 1 << j; /* table entries for j-bit table */ | |
229 | ||
230 | /* allocate new table */ | |
231 | if (*hn + z > MANY) /* (note: doesn't matter for fixed) */ | |
232 | return Z_DATA_ERROR; /* overflow of MANY */ | |
233 | u[h] = q = hp + *hn; | |
234 | *hn += z; | |
235 | ||
236 | /* connect to last table, if there is one */ | |
237 | if (h) | |
238 | { | |
239 | x[h] = i; /* save pattern for backing up */ | |
240 | r.bits = (Byte)l; /* bits to dump before this table */ | |
241 | r.exop = (Byte)j; /* bits in this table */ | |
242 | j = i >> (w - l); | |
243 | r.base = (uInt)(q - u[h-1] - j); /* offset to this table */ | |
244 | u[h-1][j] = r; /* connect to last table */ | |
245 | } | |
246 | else | |
247 | *t = q; /* first table is returned result */ | |
248 | } | |
249 | ||
250 | /* set up table entry in r */ | |
251 | r.bits = (Byte)(k - w); | |
252 | if (p >= v + n) | |
253 | r.exop = 128 + 64; /* out of values--invalid code */ | |
254 | else if (*p < s) | |
255 | { | |
256 | r.exop = (Byte)(*p < 256 ? 0 : 32 + 64); /* 256 is end-of-block */ | |
257 | r.base = *p++; /* simple code is just the value */ | |
258 | } | |
259 | else | |
260 | { | |
261 | r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */ | |
262 | r.base = d[*p++ - s]; | |
263 | } | |
264 | ||
265 | /* fill code-like entries with r */ | |
266 | f = 1 << (k - w); | |
267 | for (j = i >> w; j < z; j += f) | |
268 | q[j] = r; | |
269 | ||
270 | /* backwards increment the k-bit code i */ | |
271 | for (j = 1 << (k - 1); i & j; j >>= 1) | |
272 | i ^= j; | |
273 | i ^= j; | |
274 | ||
275 | /* backup over finished tables */ | |
276 | mask = (1 << w) - 1; /* needed on HP, cc -O bug */ | |
277 | while ((i & mask) != x[h]) | |
278 | { | |
279 | h--; /* don't need to update q */ | |
280 | w -= l; | |
281 | mask = (1 << w) - 1; | |
282 | } | |
283 | } | |
284 | } | |
285 | ||
286 | ||
287 | /* Return Z_BUF_ERROR if we were given an incomplete table */ | |
288 | return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK; | |
289 | } | |
290 | ||
291 | ||
292 | int zlib_inflate_trees_bits( | |
293 | uInt *c, /* 19 code lengths */ | |
294 | uInt *bb, /* bits tree desired/actual depth */ | |
295 | inflate_huft **tb, /* bits tree result */ | |
296 | inflate_huft *hp, /* space for trees */ | |
297 | z_streamp z /* for messages */ | |
298 | ) | |
299 | { | |
300 | int r; | |
301 | uInt hn = 0; /* hufts used in space */ | |
302 | uInt *v; /* work area for huft_build */ | |
303 | ||
304 | v = WS(z)->tree_work_area_1; | |
305 | r = huft_build(c, 19, 19, NULL, NULL, tb, bb, hp, &hn, v); | |
306 | if (r == Z_DATA_ERROR) | |
307 | z->msg = (char*)"oversubscribed dynamic bit lengths tree"; | |
308 | else if (r == Z_BUF_ERROR || *bb == 0) | |
309 | { | |
310 | z->msg = (char*)"incomplete dynamic bit lengths tree"; | |
311 | r = Z_DATA_ERROR; | |
312 | } | |
313 | return r; | |
314 | } | |
315 | ||
316 | int zlib_inflate_trees_dynamic( | |
317 | uInt nl, /* number of literal/length codes */ | |
318 | uInt nd, /* number of distance codes */ | |
319 | uInt *c, /* that many (total) code lengths */ | |
320 | uInt *bl, /* literal desired/actual bit depth */ | |
321 | uInt *bd, /* distance desired/actual bit depth */ | |
322 | inflate_huft **tl, /* literal/length tree result */ | |
323 | inflate_huft **td, /* distance tree result */ | |
324 | inflate_huft *hp, /* space for trees */ | |
325 | z_streamp z /* for messages */ | |
326 | ) | |
327 | { | |
328 | int r; | |
329 | uInt hn = 0; /* hufts used in space */ | |
330 | uInt *v; /* work area for huft_build */ | |
331 | ||
332 | /* allocate work area */ | |
333 | v = WS(z)->tree_work_area_2; | |
334 | ||
335 | /* build literal/length tree */ | |
336 | r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v); | |
337 | if (r != Z_OK || *bl == 0) | |
338 | { | |
339 | if (r == Z_DATA_ERROR) | |
340 | z->msg = (char*)"oversubscribed literal/length tree"; | |
341 | else if (r != Z_MEM_ERROR) | |
342 | { | |
343 | z->msg = (char*)"incomplete literal/length tree"; | |
344 | r = Z_DATA_ERROR; | |
345 | } | |
346 | return r; | |
347 | } | |
348 | ||
349 | /* build distance tree */ | |
350 | r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v); | |
351 | if (r != Z_OK || (*bd == 0 && nl > 257)) | |
352 | { | |
353 | if (r == Z_DATA_ERROR) | |
354 | z->msg = (char*)"oversubscribed distance tree"; | |
355 | else if (r == Z_BUF_ERROR) { | |
356 | #ifdef PKZIP_BUG_WORKAROUND | |
357 | r = Z_OK; | |
358 | } | |
359 | #else | |
360 | z->msg = (char*)"incomplete distance tree"; | |
361 | r = Z_DATA_ERROR; | |
362 | } | |
363 | else if (r != Z_MEM_ERROR) | |
364 | { | |
365 | z->msg = (char*)"empty distance tree with lengths"; | |
366 | r = Z_DATA_ERROR; | |
367 | } | |
368 | return r; | |
369 | #endif | |
370 | } | |
371 | ||
372 | /* done */ | |
373 | return Z_OK; | |
374 | } | |
375 | ||
376 | ||
377 | int zlib_inflate_trees_fixed( | |
378 | uInt *bl, /* literal desired/actual bit depth */ | |
379 | uInt *bd, /* distance desired/actual bit depth */ | |
380 | inflate_huft **tl, /* literal/length tree result */ | |
381 | inflate_huft **td, /* distance tree result */ | |
382 | inflate_huft *hp, /* space for trees */ | |
383 | z_streamp z /* for memory allocation */ | |
384 | ) | |
385 | { | |
386 | int i; /* temporary variable */ | |
387 | unsigned l[288]; /* length list for huft_build */ | |
388 | uInt *v; /* work area for huft_build */ | |
389 | ||
390 | /* set up literal table */ | |
391 | for (i = 0; i < 144; i++) | |
392 | l[i] = 8; | |
393 | for (; i < 256; i++) | |
394 | l[i] = 9; | |
395 | for (; i < 280; i++) | |
396 | l[i] = 7; | |
397 | for (; i < 288; i++) /* make a complete, but wrong code set */ | |
398 | l[i] = 8; | |
399 | *bl = 9; | |
400 | v = WS(z)->tree_work_area_1; | |
401 | if ((i = huft_build(l, 288, 257, cplens, cplext, tl, bl, hp, &i, v)) != 0) | |
402 | return i; | |
403 | ||
404 | /* set up distance table */ | |
405 | for (i = 0; i < 30; i++) /* make an incomplete code set */ | |
406 | l[i] = 5; | |
407 | *bd = 5; | |
408 | if ((i = huft_build(l, 30, 0, cpdist, cpdext, td, bd, hp, &i, v)) > 1) | |
409 | return i; | |
410 | ||
411 | return Z_OK; | |
412 | } |