1 /* Inflate deflated data
3 Copyright (C) 1997-1999, 2002, 2006, 2009 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
19 /* Not copyrighted 1992 by Mark Adler
20 version c10p1, 10 January 1993 */
22 /* You can do whatever you like with this source file, though I would
23 prefer that if you modify it and redistribute it that you include
24 comments to that effect with your name and the date. Thank you.
25 [The history has been moved to the file ChangeLog.]
29 Inflate deflated (PKZIP's method 8 compressed) data. The compression
30 method searches for as much of the current string of bytes (up to a
31 length of 258) in the previous 32K bytes. If it doesn't find any
32 matches (of at least length 3), it codes the next byte. Otherwise, it
33 codes the length of the matched string and its distance backwards from
34 the current position. There is a single Huffman code that codes both
35 single bytes (called "literals") and match lengths. A second Huffman
36 code codes the distance information, which follows a length code. Each
37 length or distance code actually represents a base value and a number
38 of "extra" (sometimes zero) bits to get to add to the base value. At
39 the end of each deflated block is a special end-of-block (EOB) literal/
40 length code. The decoding process is basically: get a literal/length
41 code; if EOB then done; if a literal, emit the decoded byte; if a
42 length then get the distance and emit the referred-to bytes from the
43 sliding window of previously emitted data.
45 There are (currently) three kinds of inflate blocks: stored, fixed, and
46 dynamic. The compressor deals with some chunk of data at a time, and
47 decides which method to use on a chunk-by-chunk basis. A chunk might
48 typically be 32K or 64K. If the chunk is uncompressible, then the
49 "stored" method is used. In this case, the bytes are simply stored as
50 is, eight bits per byte, with none of the above coding. The bytes are
51 preceded by a count, since there is no longer an EOB code.
53 If the data is compressible, then either the fixed or dynamic methods
54 are used. In the dynamic method, the compressed data is preceded by
55 an encoding of the literal/length and distance Huffman codes that are
56 to be used to decode this block. The representation is itself Huffman
57 coded, and so is preceded by a description of that code. These code
58 descriptions take up a little space, and so for small blocks, there is
59 a predefined set of codes, called the fixed codes. The fixed method is
60 used if the block codes up smaller that way (usually for quite small
61 chunks), otherwise the dynamic method is used. In the latter case, the
62 codes are customized to the probabilities in the current block, and so
63 can code it much better than the pre-determined fixed codes.
65 The Huffman codes themselves are decoded using a multi-level table
66 lookup, in order to maximize the speed of decoding plus the speed of
67 building the decoding tables. See the comments below that precede the
68 lbits and dbits tuning parameters.
73 Notes beyond the 1.93a appnote.txt:
75 1. Distance pointers never point before the beginning of the output
77 2. Distance pointers can point back across blocks, up to 32k away.
78 3. There is an implied maximum of 7 bits for the bit length table and
79 15 bits for the actual data.
80 4. If only one code exists, then it is encoded using one bit. (Zero
81 would be more efficient, but perhaps a little confusing.) If two
82 codes exist, they are coded using one bit each (0 and 1).
83 5. There is no way of sending zero distance codes--a dummy must be
84 sent if there are none. (History: a pre 2.0 version of PKZIP would
85 store blocks with no distance codes, but this was discovered to be
86 too harsh a criterion.) Valid only for 1.93a. 2.04c does allow
87 zero distance codes, which is sent as one code of zero bits in
89 6. There are up to 286 literal/length codes. Code 256 represents the
90 end-of-block. Note however that the static length tree defines
91 288 codes just to fill out the Huffman codes. Codes 286 and 287
92 cannot be used though, since there is no length base or extra bits
93 defined for them. Similarly, there are up to 30 distance codes.
94 However, static trees define 32 codes (all 5 bits) to fill out the
95 Huffman codes, but the last two had better not show up in the data.
96 7. Unzip can check dynamic Huffman blocks for complete code sets.
97 The exception is that a single code would not be complete (see #4).
98 8. The five bits following the block type is really the number of
99 literal codes sent minus 257.
100 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
101 (1+6+6). Therefore, to output three times the length, you output
102 three codes (1+1+1), whereas to output four times the same length,
103 you only need two codes (1+3). Hmm.
104 10. In the tree reconstruction algorithm, Code = Code + Increment
105 only if BitLength(i) is not zero. (Pretty obvious.)
106 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19)
107 12. Note: length code 284 can represent 227-258, but length code 285
108 really is 258. The last length deserves its own, short code
109 since it gets used a lot in very redundant files. The length
110 258 is special since 258 - 3 (the min match length) is 255.
111 13. The literal/length and distance code bit lengths are read as a
112 single stream of lengths. It is possible (and advantageous) for
113 a repeat code (16, 17, or 18) to go across the boundary between
114 the two sets of lengths.
125 /* Huffman code lookup table entry--this entry is four bytes for machines
126 that have 16-bit pointers (e.g. PC's in the small or medium model).
127 Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16
128 means that v is a literal, 16 < e < 32 means that v is a pointer to
129 the next table, which codes e - 16 bits, and lastly e == 99 indicates
130 an unused code. If a code with e == 99 is looked up, this implies an
131 error in the data. */
133 uch e; /* number of extra bits or operation */
134 uch b; /* number of bits in this code or subcode */
136 ush n; /* literal, length base, or distance base */
137 struct huft *t; /* pointer to next level of table */
142 /* Function prototypes */
143 int huft_build OF((unsigned *, unsigned, unsigned, ush *, ush *,
144 struct huft **, int *));
145 int huft_free OF((struct huft *));
146 int inflate_codes OF((struct huft *, struct huft *, int, int));
147 int inflate_stored OF((void));
148 int inflate_fixed OF((void));
149 int inflate_dynamic OF((void));
150 int inflate_block OF((int *));
151 int inflate OF((void));
154 /* The inflate algorithm uses a sliding 32K byte window on the uncompressed
155 stream to find repeated byte strings. This is implemented here as a
156 circular buffer. The index is updated simply by incrementing and then
157 and'ing with 0x7fff (32K-1). */
158 /* It is left to other modules to supply the 32K area. It is assumed
159 to be usable as if it were declared "uch slide[32768];" or as just
160 "uch *slide;" and then malloc'ed in the latter case. The definition
161 must be in unzip.h, included above. */
162 /* unsigned wp; current position in slide */
164 #define flush_output(w) (wp=(w),flush_window())
166 /* Tables for deflate from PKZIP's appnote.txt. */
167 static unsigned border[] = { /* Order of the bit length code lengths */
168 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
169 static ush cplens[] = { /* Copy lengths for literal codes 257..285 */
170 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
171 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
172 /* note: see note #13 above about the 258 in this list. */
173 static ush cplext[] = { /* Extra bits for literal codes 257..285 */
174 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
175 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */
176 static ush cpdist[] = { /* Copy offsets for distance codes 0..29 */
177 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
178 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
179 8193, 12289, 16385, 24577};
180 static ush cpdext[] = { /* Extra bits for distance codes */
181 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
182 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
187 /* Macros for inflate() bit peeking and grabbing.
191 x = b & mask_bits[j];
194 where NEEDBITS makes sure that b has at least j bits in it, and
195 DUMPBITS removes the bits from b. The macros use the variable k
196 for the number of bits in b. Normally, b and k are register
197 variables for speed, and are initialized at the beginning of a
198 routine that uses these macros from a global bit buffer and count.
199 The macros also use the variable w, which is a cached copy of wp.
201 If we assume that EOB will be the longest code, then we will never
202 ask for bits with NEEDBITS that are beyond the end of the stream.
203 So, NEEDBITS should not read any more bytes than are needed to
204 meet the request. Then no bytes need to be "returned" to the buffer
205 at the end of the last block.
207 However, this assumption is not true for fixed blocks--the EOB code
208 is 7 bits, but the other literal/length codes can be 8 or 9 bits.
209 (The EOB code is shorter than other codes because fixed blocks are
210 generally short. So, while a block always has an EOB, many other
211 literal/length codes have a significantly lower probability of
212 showing up at all.) However, by making the first table have a
213 lookup of seven bits, the EOB code will be found in that first
214 lookup, and so will not require that too many bits be pulled from
218 ulg bb; /* bit buffer */
219 unsigned bk; /* bits in bit buffer */
223 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
224 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
227 #define GETBYTE() (inptr < insize ? inbuf[inptr++] : (wp = w, fill_inbuf(0)))
231 # define NEXTBYTE() \
232 (decrypt ? (cc = GETBYTE(), zdecode(cc), cc) : GETBYTE())
234 # define NEXTBYTE() (uch)GETBYTE()
236 #define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}}
237 #define DUMPBITS(n) {b>>=(n);k-=(n);}
241 Huffman code decoding is performed using a multi-level table lookup.
242 The fastest way to decode is to simply build a lookup table whose
243 size is determined by the longest code. However, the time it takes
244 to build this table can also be a factor if the data being decoded
245 is not very long. The most common codes are necessarily the
246 shortest codes, so those codes dominate the decoding time, and hence
247 the speed. The idea is you can have a shorter table that decodes the
248 shorter, more probable codes, and then point to subsidiary tables for
249 the longer codes. The time it costs to decode the longer codes is
250 then traded against the time it takes to make longer tables.
252 This results of this trade are in the variables lbits and dbits
253 below. lbits is the number of bits the first level table for literal/
254 length codes can decode in one step, and dbits is the same thing for
255 the distance codes. Subsequent tables are also less than or equal to
256 those sizes. These values may be adjusted either when all of the
257 codes are shorter than that, in which case the longest code length in
258 bits is used, or when the shortest code is *longer* than the requested
259 table size, in which case the length of the shortest code in bits is
262 There are two different values for the two tables, since they code a
263 different number of possibilities each. The literal/length table
264 codes 286 possible values, or in a flat code, a little over eight
265 bits. The distance table codes 30 possible values, or a little less
266 than five bits, flat. The optimum values for speed end up being
267 about one bit more than those, so lbits is 8+1 and dbits is 5+1.
268 The optimum values may differ though from machine to machine, and
269 possibly even between compilers. Your mileage may vary.
273 int lbits = 9; /* bits in base literal/length lookup table */
274 int dbits = 6; /* bits in base distance lookup table */
277 /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
278 #define BMAX 16 /* maximum bit length of any code (16 for explode) */
279 #define N_MAX 288 /* maximum number of codes in any set */
282 unsigned hufts; /* track memory usage */
285 int huft_build(b, n, s, d, e, t, m)
286 unsigned *b; /* code lengths in bits (all assumed <= BMAX) */
287 unsigned n; /* number of codes (assumed <= N_MAX) */
288 unsigned s; /* number of simple-valued codes (0..s-1) */
289 ush *d; /* list of base values for non-simple codes */
290 ush *e; /* list of extra bits for non-simple codes */
291 struct huft **t; /* result: starting table */
292 int *m; /* maximum lookup bits, returns actual */
293 /* Given a list of code lengths and a maximum table size, make a set of
294 tables to decode that set of codes. Return zero on success, one if
295 the given code set is incomplete (the tables are still built in this
296 case), two if the input is invalid (all zero length codes or an
297 oversubscribed set of lengths), and three if not enough memory. */
299 unsigned a; /* counter for codes of length k */
300 unsigned c[BMAX+1]; /* bit length count table */
301 unsigned f; /* i repeats in table every f entries */
302 int g; /* maximum code length */
303 int h; /* table level */
304 register unsigned i; /* counter, current code */
305 register unsigned j; /* counter */
306 register int k; /* number of bits in current code */
307 int l; /* bits per table (returned in m) */
308 register unsigned *p; /* pointer into c[], b[], or v[] */
309 register struct huft *q; /* points to current table */
310 struct huft r; /* table entry for structure assignment */
311 struct huft *u[BMAX]; /* table stack */
312 unsigned v[N_MAX]; /* values in order of bit length */
313 register int w; /* bits before this table == (l * h) */
314 unsigned x[BMAX+1]; /* bit offsets, then code stack */
315 unsigned *xp; /* pointer into x */
316 int y; /* number of dummy codes added */
317 unsigned z; /* number of entries in current table */
320 /* Generate counts for each bit length */
321 memzero(c, sizeof(c));
324 Tracecv(*p, (stderr, (n-i >= ' ' && n-i <= '~' ? "%c %d\n" : "0x%x %d\n"),
326 c[*p]++; /* assume all entries <= BMAX */
327 p++; /* Can't combine with above line (Solaris bug) */
329 if (c[0] == n) /* null input--all zero length codes */
331 q = (struct huft *) malloc (3 * sizeof *q);
335 q[0].v.t = (struct huft *) NULL;
336 q[1].e = 99; /* invalid code marker */
338 q[2].e = 99; /* invalid code marker */
346 /* Find minimum and maximum length, bound *m by those */
348 for (j = 1; j <= BMAX; j++)
351 k = j; /* minimum code length */
354 for (i = BMAX; i; i--)
357 g = i; /* maximum code length */
363 /* Adjust last length count to fill out codes, if needed */
364 for (y = 1 << j; j < i; j++, y <<= 1)
366 return 2; /* bad input: more codes than bits */
372 /* Generate starting offsets into the value table for each length */
374 p = c + 1; xp = x + 2;
375 while (--i) { /* note that i == g from above */
380 /* Make a table of values in order of bit lengths */
386 n = x[g]; /* set n to length of v */
389 /* Generate the Huffman codes and for each, make the table entries */
390 x[0] = i = 0; /* first Huffman code is zero */
391 p = v; /* grab values in bit order */
392 h = -1; /* no tables yet--level -1 */
393 w = -l; /* bits decoded == (l * h) */
394 u[0] = (struct huft *)NULL; /* just to keep compilers happy */
395 q = (struct huft *)NULL; /* ditto */
398 /* go through the bit lengths (k already is bits in shortest code) */
404 /* here i is the Huffman code of length k bits for value *p */
405 /* make tables up to required level */
409 w += l; /* previous table always l bits */
411 /* compute minimum size table less than or equal to l bits */
412 z = (z = g - w) > (unsigned)l ? l : z; /* upper limit on table size */
413 if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */
414 { /* too few codes for k-w bit table */
415 f -= a + 1; /* deduct codes from patterns left */
418 while (++j < z) /* try smaller tables up to z bits */
420 if ((f <<= 1) <= *++xp)
421 break; /* enough codes to use up j bits */
422 f -= *xp; /* else deduct codes from patterns */
425 z = 1 << j; /* table entries for j-bit table */
427 /* allocate and link in new table */
428 if ((q = (struct huft *)malloc((z + 1)*sizeof(struct huft))) ==
433 return 3; /* not enough memory */
435 hufts += z + 1; /* track memory usage */
436 *t = q + 1; /* link to list for huft_free() */
437 *(t = &(q->v.t)) = (struct huft *)NULL;
438 u[h] = ++q; /* table starts after link */
440 /* connect to last table, if there is one */
443 x[h] = i; /* save pattern for backing up */
444 r.b = (uch)l; /* bits to dump before this table */
445 r.e = (uch)(16 + j); /* bits in this table */
446 r.v.t = q; /* pointer to this table */
447 j = i >> (w - l); /* (get around Turbo C bug) */
448 u[h-1][j] = r; /* connect to last table */
452 /* set up table entry in r */
455 r.e = 99; /* out of values--invalid code */
458 r.e = (uch)(*p < 256 ? 16 : 15); /* 256 is end-of-block code */
459 r.v.n = (ush)(*p); /* simple code is just the value */
460 p++; /* one compiler does not like *p++ */
464 r.e = (uch)e[*p - s]; /* non-simple--look up in lists */
468 /* fill code-like entries with r */
470 for (j = i >> w; j < z; j += f)
473 /* backwards increment the k-bit code i */
474 for (j = 1 << (k - 1); i & j; j >>= 1)
478 /* backup over finished tables */
479 while ((i & ((1 << w) - 1)) != x[h])
481 h--; /* don't need to update q */
488 /* Return true (1) if we were given an incomplete table */
489 return y != 0 && g != 1;
495 struct huft *t; /* table to free */
496 /* Free the malloc'ed tables built by huft_build(), which makes a linked
497 list of the tables it made, with the links in a dummy first entry of
500 register struct huft *p, *q;
503 /* Go through linked list, freeing from the malloced (t[-1]) address. */
505 while (p != (struct huft *)NULL)
515 int inflate_codes(tl, td, bl, bd)
516 struct huft *tl, *td; /* literal/length and distance decoder tables */
517 int bl, bd; /* number of bits decoded by tl[] and td[] */
518 /* inflate (decompress) the codes in a deflated (compressed) block.
519 Return an error code or zero if it all goes ok. */
521 register unsigned e; /* table entry flag/number of extra bits */
522 unsigned n, d; /* length and index for copy */
523 unsigned w; /* current window position */
524 struct huft *t; /* pointer to table entry */
525 unsigned ml, md; /* masks for bl and bd bits */
526 register ulg b; /* bit buffer */
527 register unsigned k; /* number of bits in bit buffer */
530 /* make local copies of globals */
531 b = bb; /* initialize bit buffer */
533 w = wp; /* initialize window position */
535 /* inflate the coded data */
536 ml = mask_bits[bl]; /* precompute masks for speed */
538 for (;;) /* do until end of block */
540 NEEDBITS((unsigned)bl)
541 if ((e = (t = tl + ((unsigned)b & ml))->e) > 16)
548 } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16);
550 if (e == 16) /* then it's a literal */
552 slide[w++] = (uch)t->v.n;
553 Tracevv((stderr, "%c", slide[w-1]));
560 else /* it's an EOB or a length */
562 /* exit if end of block */
566 /* get length of block to copy */
568 n = t->v.n + ((unsigned)b & mask_bits[e]);
571 /* decode distance of block to copy */
572 NEEDBITS((unsigned)bd)
573 if ((e = (t = td + ((unsigned)b & md))->e) > 16)
580 } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16);
583 d = w - t->v.n - ((unsigned)b & mask_bits[e]);
585 Tracevv((stderr,"\\[%d,%d]", w-d, n));
589 n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e);
590 #if !defined(NOMEMCPY) && !defined(DEBUG)
591 if (w - d >= e) /* (this test assumes unsigned comparison) */
593 memcpy(slide + w, slide + d, e);
597 else /* do it slow to avoid memcpy() overlap */
598 #endif /* !NOMEMCPY */
600 slide[w++] = slide[d++];
601 Tracevv((stderr, "%c", slide[w-1]));
613 /* restore the globals from the locals */
614 wp = w; /* restore global window pointer */
615 bb = b; /* restore global bit buffer */
625 /* "decompress" an inflated type 0 (stored) block. */
627 unsigned n; /* number of bytes in block */
628 unsigned w; /* current window position */
629 register ulg b; /* bit buffer */
630 register unsigned k; /* number of bits in bit buffer */
633 /* make local copies of globals */
634 b = bb; /* initialize bit buffer */
636 w = wp; /* initialize window position */
639 /* go to byte boundary */
644 /* get the length and its complement */
646 n = ((unsigned)b & 0xffff);
649 if (n != (unsigned)((~b) & 0xffff))
650 return 1; /* error in compressed data */
654 /* read and output the compressed data */
668 /* restore the globals from the locals */
669 wp = w; /* restore global window pointer */
670 bb = b; /* restore global bit buffer */
678 /* decompress an inflated type 1 (fixed Huffman codes) block. We should
679 either replace this with a custom decoder, or at least precompute the
682 int i; /* temporary variable */
683 struct huft *tl; /* literal/length code table */
684 struct huft *td; /* distance code table */
685 int bl; /* lookup bits for tl */
686 int bd; /* lookup bits for td */
687 unsigned l[288]; /* length list for huft_build */
690 /* set up literal table */
691 for (i = 0; i < 144; i++)
697 for (; i < 288; i++) /* make a complete, but wrong code set */
700 if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0)
704 /* set up distance table */
705 for (i = 0; i < 30; i++) /* make an incomplete code set */
708 if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1)
715 /* decompress until an end-of-block code */
716 if (inflate_codes(tl, td, bl, bd))
720 /* free the decoding tables, return */
728 int inflate_dynamic()
729 /* decompress an inflated type 2 (dynamic Huffman codes) block. */
731 int i; /* temporary variables */
733 unsigned l; /* last length */
734 unsigned m; /* mask for bit lengths table */
735 unsigned n; /* number of lengths to get */
736 unsigned w; /* current window position */
737 struct huft *tl; /* literal/length code table */
738 struct huft *td; /* distance code table */
739 int bl; /* lookup bits for tl */
740 int bd; /* lookup bits for td */
741 unsigned nb; /* number of bit length codes */
742 unsigned nl; /* number of literal/length codes */
743 unsigned nd; /* number of distance codes */
744 #ifdef PKZIP_BUG_WORKAROUND
745 unsigned ll[288+32]; /* literal/length and distance code lengths */
747 unsigned ll[286+30]; /* literal/length and distance code lengths */
749 register ulg b; /* bit buffer */
750 register unsigned k; /* number of bits in bit buffer */
753 /* make local bit buffer */
759 /* read in table lengths */
761 nl = 257 + ((unsigned)b & 0x1f); /* number of literal/length codes */
764 nd = 1 + ((unsigned)b & 0x1f); /* number of distance codes */
767 nb = 4 + ((unsigned)b & 0xf); /* number of bit length codes */
769 #ifdef PKZIP_BUG_WORKAROUND
770 if (nl > 288 || nd > 32)
772 if (nl > 286 || nd > 30)
774 return 1; /* bad lengths */
777 /* read in bit-length-code lengths */
778 for (j = 0; j < nb; j++)
781 ll[border[j]] = (unsigned)b & 7;
788 /* build decoding table for trees--single level, 7 bit lookup */
790 if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0)
794 return i; /* incomplete code set */
797 if (tl == NULL) /* Grrrhhh */
800 /* read in literal and distance code lengths */
804 while ((unsigned)i < n)
806 NEEDBITS((unsigned)bl)
807 j = (td = tl + ((unsigned)b & m))->b;
810 if (j < 16) /* length of code in bits (0..15) */
811 ll[i++] = l = j; /* save last length in l */
812 else if (j == 16) /* repeat last length 3 to 6 times */
815 j = 3 + ((unsigned)b & 3);
817 if ((unsigned)i + j > n)
822 else if (j == 17) /* 3 to 10 zero length codes */
825 j = 3 + ((unsigned)b & 7);
827 if ((unsigned)i + j > n)
833 else /* j == 18: 11 to 138 zero length codes */
836 j = 11 + ((unsigned)b & 0x7f);
838 if ((unsigned)i + j > n)
847 /* free decoding table for trees */
851 /* restore the global bit buffer */
856 /* build the decoding tables for literal/length and distance codes */
858 if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0)
861 Trace ((stderr, " incomplete literal tree\n"));
864 return i; /* incomplete code set */
867 if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0)
870 Trace ((stderr, " incomplete distance tree\n"));
871 #ifdef PKZIP_BUG_WORKAROUND
878 return i; /* incomplete code set */
884 /* decompress until an end-of-block code */
885 int err = inflate_codes(tl, td, bl, bd) ? 1 : 0;
887 /* free the decoding tables */
898 int *e; /* last block flag */
899 /* decompress an inflated block */
901 unsigned t; /* block type */
902 unsigned w; /* current window position */
903 register ulg b; /* bit buffer */
904 register unsigned k; /* number of bits in bit buffer */
907 /* make local bit buffer */
913 /* read in last block bit */
919 /* read in block type */
925 /* restore the global bit buffer */
930 /* inflate that block type */
932 return inflate_dynamic();
934 return inflate_stored();
936 return inflate_fixed();
946 /* decompress an inflated entry */
948 int e; /* last block flag */
949 int r; /* result code */
950 unsigned h; /* maximum struct huft's malloc'ed */
953 /* initialize window, bit buffer */
959 /* decompress until the last block */
963 if ((r = inflate_block(&e)) != 0)
969 /* Undo too much lookahead. The next read will be byte aligned so we
970 * can discard unused bits in the last meaningful byte.
977 /* flush out slide */
982 Trace ((stderr, "<%u> ", h));