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First entry of Paradise Server 2.9 patch 10 Beta
author darius
date Sat, 06 Dec 1997 04:37:18 +0000
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9:331055a97a9d 10:1040ca591f2e
1 /* inftrees.c -- generate Huffman trees for efficient decoding
2 * Copyright (C) 1995 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 struct internal_state {int dummy;}; /* for buggy compilers */
10
11 /* simplify the use of the inflate_huft type with some defines */
12 #define base more.Base
13 #define next more.Next
14 #define exop word.what.Exop
15 #define bits word.what.Bits
16
17
18 local int huft_build OF((
19 uIntf *, /* code lengths in bits */
20 uInt, /* number of codes */
21 uInt, /* number of "simple" codes */
22 uIntf *, /* list of base values for non-simple codes */
23 uIntf *, /* list of extra bits for non-simple codes */
24 inflate_huft * FAR*,/* result: starting table */
25 uIntf *, /* maximum lookup bits (returns actual) */
26 z_stream *)); /* for zalloc function */
27
28 local voidpf falloc OF((
29 voidpf, /* opaque pointer (not used) */
30 uInt, /* number of items */
31 uInt)); /* size of item */
32
33 local void ffree OF((
34 voidpf q, /* opaque pointer (not used) */
35 voidpf p)); /* what to free (not used) */
36
37 /* Tables for deflate from PKZIP's appnote.txt. */
38 local uInt cplens[] = { /* 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 /* actually lengths - 2; also see note #13 above about 258 */
42 local uInt cplext[] = { /* 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, 192, 192}; /* 192==invalid */
45 local uInt cpdist[] = { /* 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 local uInt cpdext[] = { /* 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 #define N_MAX 288 /* maximum number of codes in any set */
90
91 #ifdef DEBUG
92 uInt inflate_hufts;
93 #endif
94
95 local int huft_build(b, n, s, d, e, t, m, zs)
96 uIntf *b; /* code lengths in bits (all assumed <= BMAX) */
97 uInt n; /* number of codes (assumed <= N_MAX) */
98 uInt s; /* number of simple-valued codes (0..s-1) */
99 uIntf *d; /* list of base values for non-simple codes */
100 uIntf *e; /* list of extra bits for non-simple codes */
101 inflate_huft * FAR *t; /* result: starting table */
102 uIntf *m; /* maximum lookup bits, returns actual */
103 z_stream *zs; /* for zalloc function */
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 (all zero length codes or an
108 over-subscribed set of 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 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 uInt v[N_MAX]; /* values in order of bit length */
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
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 = (z = g - w) > (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 and link in new table */
231 if ((q = (inflate_huft *)ZALLOC
232 (zs,z + 1,sizeof(inflate_huft))) == Z_NULL)
233 {
234 if (h)
235 inflate_trees_free(u[0], zs);
236 return Z_MEM_ERROR; /* not enough memory */
237 }
238 #ifdef DEBUG
239 inflate_hufts += z + 1;
240 #endif
241 *t = q + 1; /* link to list for huft_free() */
242 *(t = &(q->next)) = Z_NULL;
243 u[h] = ++q; /* table starts after link */
244
245 /* connect to last table, if there is one */
246 if (h)
247 {
248 x[h] = i; /* save pattern for backing up */
249 r.bits = (Byte)l; /* bits to dump before this table */
250 r.exop = (Byte)j; /* bits in this table */
251 r.next = q; /* pointer to this table */
252 j = i >> (w - l); /* (get around Turbo C bug) */
253 u[h-1][j] = r; /* connect to last table */
254 }
255 }
256
257 /* set up table entry in r */
258 r.bits = (Byte)(k - w);
259 if (p >= v + n)
260 r.exop = 128 + 64; /* out of values--invalid code */
261 else if (*p < s)
262 {
263 r.exop = (Byte)(*p < 256 ? 0 : 32 + 64); /* 256 is end-of-block */
264 r.base = *p++; /* simple code is just the value */
265 }
266 else
267 {
268 r.exop = (Byte)e[*p - s] + 16 + 64; /* non-simple--look up in lists */
269 r.base = d[*p++ - s];
270 }
271
272 /* fill code-like entries with r */
273 f = 1 << (k - w);
274 for (j = i >> w; j < z; j += f)
275 q[j] = r;
276
277 /* backwards increment the k-bit code i */
278 for (j = 1 << (k - 1); i & j; j >>= 1)
279 i ^= j;
280 i ^= j;
281
282 /* backup over finished tables */
283 while ((i & ((1 << w) - 1)) != x[h])
284 {
285 h--; /* don't need to update q */
286 w -= l;
287 }
288 }
289 }
290
291
292 /* Return Z_BUF_ERROR if we were given an incomplete table */
293 return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
294 }
295
296
297 int inflate_trees_bits(c, bb, tb, z)
298 uIntf *c; /* 19 code lengths */
299 uIntf *bb; /* bits tree desired/actual depth */
300 inflate_huft * FAR *tb; /* bits tree result */
301 z_stream *z; /* for zfree function */
302 {
303 int r;
304
305 r = huft_build(c, 19, 19, (uIntf*)Z_NULL, (uIntf*)Z_NULL, tb, bb, z);
306 if (r == Z_DATA_ERROR)
307 z->msg = "oversubscribed dynamic bit lengths tree";
308 else if (r == Z_BUF_ERROR)
309 {
310 inflate_trees_free(*tb, z);
311 z->msg = "incomplete dynamic bit lengths tree";
312 r = Z_DATA_ERROR;
313 }
314 return r;
315 }
316
317
318 int inflate_trees_dynamic(nl, nd, c, bl, bd, tl, td, z)
319 uInt nl; /* number of literal/length codes */
320 uInt nd; /* number of distance codes */
321 uIntf *c; /* that many (total) code lengths */
322 uIntf *bl; /* literal desired/actual bit depth */
323 uIntf *bd; /* distance desired/actual bit depth */
324 inflate_huft * FAR *tl; /* literal/length tree result */
325 inflate_huft * FAR *td; /* distance tree result */
326 z_stream *z; /* for zfree function */
327 {
328 int r;
329
330 /* build literal/length tree */
331 if ((r = huft_build(c, nl, 257, cplens, cplext, tl, bl, z)) != Z_OK)
332 {
333 if (r == Z_DATA_ERROR)
334 z->msg = "oversubscribed literal/length tree";
335 else if (r == Z_BUF_ERROR)
336 {
337 inflate_trees_free(*tl, z);
338 z->msg = "incomplete literal/length tree";
339 r = Z_DATA_ERROR;
340 }
341 return r;
342 }
343
344 /* build distance tree */
345 if ((r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, z)) != Z_OK)
346 {
347 if (r == Z_DATA_ERROR)
348 z->msg = "oversubscribed literal/length tree";
349 else if (r == Z_BUF_ERROR) {
350 #ifdef PKZIP_BUG_WORKAROUND
351 r = Z_OK;
352 }
353 #else
354 inflate_trees_free(*td, z);
355 z->msg = "incomplete literal/length tree";
356 r = Z_DATA_ERROR;
357 }
358 inflate_trees_free(*tl, z);
359 return r;
360 #endif
361 }
362
363 /* done */
364 return Z_OK;
365 }
366
367
368 /* build fixed tables only once--keep them here */
369 local int fixed_lock = 0;
370 local int fixed_built = 0;
371 #define FIXEDH 530 /* number of hufts used by fixed tables */
372 local uInt fixed_left = FIXEDH;
373 local inflate_huft fixed_mem[FIXEDH];
374 local uInt fixed_bl;
375 local uInt fixed_bd;
376 local inflate_huft *fixed_tl;
377 local inflate_huft *fixed_td;
378
379
380 local voidpf falloc(q, n, s)
381 voidpf q; /* opaque pointer (not used) */
382 uInt n; /* number of items */
383 uInt s; /* size of item */
384 {
385 Assert(s == sizeof(inflate_huft) && n <= fixed_left,
386 "inflate_trees falloc overflow");
387 if (q) s++; /* to make some compilers happy */
388 fixed_left -= n;
389 return (voidpf)(fixed_mem + fixed_left);
390 }
391
392
393 local void ffree(q, p)
394 voidpf q;
395 voidpf p;
396 {
397 Assert(0, "inflate_trees ffree called!");
398 if (q) q = p; /* to make some compilers happy */
399 }
400
401
402 int inflate_trees_fixed(bl, bd, tl, td)
403 uIntf *bl; /* literal desired/actual bit depth */
404 uIntf *bd; /* distance desired/actual bit depth */
405 inflate_huft * FAR *tl; /* literal/length tree result */
406 inflate_huft * FAR *td; /* distance tree result */
407 {
408 /* build fixed tables if not built already--lock out other instances */
409 while (++fixed_lock > 1)
410 fixed_lock--;
411 if (!fixed_built)
412 {
413 int k; /* temporary variable */
414 unsigned c[288]; /* length list for huft_build */
415 z_stream z; /* for falloc function */
416
417 /* set up fake z_stream for memory routines */
418 z.zalloc = falloc;
419 z.zfree = ffree;
420 z.opaque = Z_NULL;
421
422 /* literal table */
423 for (k = 0; k < 144; k++)
424 c[k] = 8;
425 for (; k < 256; k++)
426 c[k] = 9;
427 for (; k < 280; k++)
428 c[k] = 7;
429 for (; k < 288; k++)
430 c[k] = 8;
431 fixed_bl = 7;
432 huft_build(c, 288, 257, cplens, cplext, &fixed_tl, &fixed_bl, &z);
433
434 /* distance table */
435 for (k = 0; k < 30; k++)
436 c[k] = 5;
437 fixed_bd = 5;
438 huft_build(c, 30, 0, cpdist, cpdext, &fixed_td, &fixed_bd, &z);
439
440 /* done */
441 fixed_built = 1;
442 }
443 fixed_lock--;
444 *bl = fixed_bl;
445 *bd = fixed_bd;
446 *tl = fixed_tl;
447 *td = fixed_td;
448 return Z_OK;
449 }
450
451
452 int inflate_trees_free(t, z)
453 inflate_huft *t; /* table to free */
454 z_stream *z; /* for zfree function */
455 /* Free the malloc'ed tables built by huft_build(), which makes a linked
456 list of the tables it made, with the links in a dummy first entry of
457 each table. */
458 {
459 register inflate_huft *p, *q;
460
461 /* Go through linked list, freeing from the malloced (t[-1]) address. */
462 p = t;
463 while (p != Z_NULL)
464 {
465 q = (--p)->next;
466 ZFREE(z,p);
467 p = q;
468 }
469 return Z_OK;
470 }