1 /* inflate.c -- Not copyrighted 1992 by Mark Adler
2 version c10p1, 10 January 1993 */
4 /* You can do whatever you like with this source file, though I would
5 prefer that if you modify it and redistribute it that you include
6 comments to that effect with your name and the date. Thank you.
7 [The history has been moved to the file ChangeLog.]
11 Inflate deflated (PKZIP's method 8 compressed) data. The compression
12 method searches for as much of the current string of bytes (up to a
13 length of 258) in the previous 32K bytes. If it doesn't find any
14 matches (of at least length 3), it codes the next byte. Otherwise, it
15 codes the length of the matched string and its distance backwards from
16 the current position. There is a single Huffman code that codes both
17 single bytes (called "literals") and match lengths. A second Huffman
18 code codes the distance information, which follows a length code. Each
19 length or distance code actually represents a base value and a number
20 of "extra" (sometimes zero) bits to get to add to the base value. At
21 the end of each deflated block is a special end-of-block (EOB) literal/
22 length code. The decoding process is basically: get a literal/length
23 code; if EOB then done; if a literal, emit the decoded byte; if a
24 length then get the distance and emit the referred-to bytes from the
25 sliding window of previously emitted data.
27 There are (currently) three kinds of inflate blocks: stored, fixed, and
28 dynamic. The compressor deals with some chunk of data at a time, and
29 decides which method to use on a chunk-by-chunk basis. A chunk might
30 typically be 32K or 64K. If the chunk is uncompressible, then the
31 "stored" method is used. In this case, the bytes are simply stored as
32 is, eight bits per byte, with none of the above coding. The bytes are
33 preceded by a count, since there is no longer an EOB code.
35 If the data is compressible, then either the fixed or dynamic methods
36 are used. In the dynamic method, the compressed data is preceded by
37 an encoding of the literal/length and distance Huffman codes that are
38 to be used to decode this block. The representation is itself Huffman
39 coded, and so is preceded by a description of that code. These code
40 descriptions take up a little space, and so for small blocks, there is
41 a predefined set of codes, called the fixed codes. The fixed method is
42 used if the block codes up smaller that way (usually for quite small
43 chunks), otherwise the dynamic method is used. In the latter case, the
44 codes are customized to the probabilities in the current block, and so
45 can code it much better than the pre-determined fixed codes.
47 The Huffman codes themselves are decoded using a mutli-level table
48 lookup, in order to maximize the speed of decoding plus the speed of
49 building the decoding tables. See the comments below that precede the
50 lbits and dbits tuning parameters.
55 Notes beyond the 1.93a appnote.txt:
57 1. Distance pointers never point before the beginning of the output
59 2. Distance pointers can point back across blocks, up to 32k away.
60 3. There is an implied maximum of 7 bits for the bit length table and
61 15 bits for the actual data.
62 4. If only one code exists, then it is encoded using one bit. (Zero
63 would be more efficient, but perhaps a little confusing.) If two
64 codes exist, they are coded using one bit each (0 and 1).
65 5. There is no way of sending zero distance codes--a dummy must be
66 sent if there are none. (History: a pre 2.0 version of PKZIP would
67 store blocks with no distance codes, but this was discovered to be
68 too harsh a criterion.) Valid only for 1.93a. 2.04c does allow
69 zero distance codes, which is sent as one code of zero bits in
71 6. There are up to 286 literal/length codes. Code 256 represents the
72 end-of-block. Note however that the static length tree defines
73 288 codes just to fill out the Huffman codes. Codes 286 and 287
74 cannot be used though, since there is no length base or extra bits
75 defined for them. Similarly, there are up to 30 distance codes.
76 However, static trees define 32 codes (all 5 bits) to fill out the
77 Huffman codes, but the last two had better not show up in the data.
78 7. Unzip can check dynamic Huffman blocks for complete code sets.
79 The exception is that a single code would not be complete (see #4).
80 8. The five bits following the block type is really the number of
81 literal codes sent minus 257.
82 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
83 (1+6+6). Therefore, to output three times the length, you output
84 three codes (1+1+1), whereas to output four times the same length,
85 you only need two codes (1+3). Hmm.
86 10. In the tree reconstruction algorithm, Code = Code + Increment
87 only if BitLength(i) is not zero. (Pretty obvious.)
88 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19)
89 12. Note: length code 284 can represent 227-258, but length code 285
90 really is 258. The last length deserves its own, short code
91 since it gets used a lot in very redundant files. The length
92 258 is special since 258 - 3 (the min match length) is 255.
93 13. The literal/length and distance code bit lengths are read as a
94 single stream of lengths. It is possible (and advantageous) for
95 a repeat code (16, 17, or 18) to go across the boundary between
96 the two sets of lengths.
100 static char rcsid
[] = "$Id$";
108 typedef unsigned char uch
;
109 typedef unsigned short ush
;
110 typedef unsigned int ulg
;
112 #define memzero(a, b) memset(a, 0, b)
114 /* 32k sliding window */
116 static unsigned char *window
= 0;
117 static unsigned int inptr
= 0; /* index of next byte to be processed in inbuf */
118 static unsigned int outcnt
= 0; /* bytes in output buffer */
119 static const unsigned char *inbuf
= 0;
120 static unsigned char *outbuf
= 0;
122 #define get_byte() (inbuf[inptr++])
124 static void flush_window()
127 memcpy(outbuf
, window
, outcnt
);
135 #define printf dprintf
136 #define fprintf(a,b) printf(b)
138 #if defined(STDC_HEADERS) || !defined(NO_STDLIB_H)
142 /*#include "gzip.h"*/
145 /* Huffman code lookup table entry--this entry is four bytes for machines
146 that have 16-bit pointers (e.g. PC's in the small or medium model).
147 Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16
148 means that v is a literal, 16 < e < 32 means that v is a pointer to
149 the next table, which codes e - 16 bits, and lastly e == 99 indicates
150 an unused code. If a code with e == 99 is looked up, this implies an
151 error in the data. */
153 uch e
; /* number of extra bits or operation */
154 uch b
; /* number of bits in this code or subcode */
156 ush n
; /* literal, length base, or distance base */
157 struct huft
*t
; /* pointer to next level of table */
162 /* Function prototypes */
163 int huft_build
OF((unsigned *, unsigned, unsigned, ush
*, ush
*,
164 struct huft
**, int *));
165 int huft_free
OF((struct huft
*));
167 static int inflate_codes
OF((struct huft
*, struct huft
*, int, int));
168 static int inflate_stored
OF((void));
169 static int inflate_fixed
OF((void));
170 static int inflate_dynamic
OF((void));
171 static int inflate_block
OF((int *));
172 static int inflate
OF((void));
175 /* The inflate algorithm uses a sliding 32K byte window on the uncompressed
176 stream to find repeated byte strings. This is implemented here as a
177 circular buffer. The index is updated simply by incrementing and then
178 and'ing with 0x7fff (32K-1). */
179 /* It is left to other modules to supply the 32K area. It is assumed
180 to be usable as if it were declared "uch slide[32768];" or as just
181 "uch *slide;" and then malloc'ed in the latter case. The definition
182 must be in unzip.h, included above. */
183 /* unsigned wp; current position in slide */
185 #define flush_output(w) (wp=(w),flush_window())
187 /* Tables for deflate from PKZIP's appnote.txt. */
188 static unsigned border
[] = { /* Order of the bit length code lengths */
189 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
190 static ush cplens
[] = { /* Copy lengths for literal codes 257..285 */
191 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
192 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
193 /* note: see note #13 above about the 258 in this list. */
194 static ush cplext
[] = { /* Extra bits for literal codes 257..285 */
195 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
196 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */
197 static ush cpdist
[] = { /* Copy offsets for distance codes 0..29 */
198 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
199 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
200 8193, 12289, 16385, 24577};
201 static ush cpdext
[] = { /* Extra bits for distance codes */
202 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
203 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
208 /* Macros for inflate() bit peeking and grabbing.
212 x = b & mask_bits[j];
215 where NEEDBITS makes sure that b has at least j bits in it, and
216 DUMPBITS removes the bits from b. The macros use the variable k
217 for the number of bits in b. Normally, b and k are register
218 variables for speed, and are initialized at the beginning of a
219 routine that uses these macros from a global bit buffer and count.
221 If we assume that EOB will be the longest code, then we will never
222 ask for bits with NEEDBITS that are beyond the end of the stream.
223 So, NEEDBITS should not read any more bytes than are needed to
224 meet the request. Then no bytes need to be "returned" to the buffer
225 at the end of the last block.
227 However, this assumption is not true for fixed blocks--the EOB code
228 is 7 bits, but the other literal/length codes can be 8 or 9 bits.
229 (The EOB code is shorter than other codes because fixed blocks are
230 generally short. So, while a block always has an EOB, many other
231 literal/length codes have a significantly lower probability of
232 showing up at all.) However, by making the first table have a
233 lookup of seven bits, the EOB code will be found in that first
234 lookup, and so will not require that too many bits be pulled from
238 ulg bb
= 0; /* bit buffer */
239 unsigned bk
= 0; /* bits in bit buffer */
243 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
244 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
249 # define NEXTBYTE() \
250 (decrypt ? (cc = get_byte(), zdecode(cc), cc) : get_byte())
252 # define NEXTBYTE() (uch)get_byte()
254 #define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}}
255 #define DUMPBITS(n) {b>>=(n);k-=(n);}
259 Huffman code decoding is performed using a multi-level table lookup.
260 The fastest way to decode is to simply build a lookup table whose
261 size is determined by the longest code. However, the time it takes
262 to build this table can also be a factor if the data being decoded
263 is not very long. The most common codes are necessarily the
264 shortest codes, so those codes dominate the decoding time, and hence
265 the speed. The idea is you can have a shorter table that decodes the
266 shorter, more probable codes, and then point to subsidiary tables for
267 the longer codes. The time it costs to decode the longer codes is
268 then traded against the time it takes to make longer tables.
270 This results of this trade are in the variables lbits and dbits
271 below. lbits is the number of bits the first level table for literal/
272 length codes can decode in one step, and dbits is the same thing for
273 the distance codes. Subsequent tables are also less than or equal to
274 those sizes. These values may be adjusted either when all of the
275 codes are shorter than that, in which case the longest code length in
276 bits is used, or when the shortest code is *longer* than the requested
277 table size, in which case the length of the shortest code in bits is
280 There are two different values for the two tables, since they code a
281 different number of possibilities each. The literal/length table
282 codes 286 possible values, or in a flat code, a little over eight
283 bits. The distance table codes 30 possible values, or a little less
284 than five bits, flat. The optimum values for speed end up being
285 about one bit more than those, so lbits is 8+1 and dbits is 5+1.
286 The optimum values may differ though from machine to machine, and
287 possibly even between compilers. Your mileage may vary.
291 int lbits
= 9; /* bits in base literal/length lookup table */
292 int dbits
= 6; /* bits in base distance lookup table */
295 /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
296 #define BMAX 16 /* maximum bit length of any code (16 for explode) */
297 #define N_MAX 288 /* maximum number of codes in any set */
300 unsigned hufts
= 0; /* track memory usage */
303 int huft_build(b
, n
, s
, d
, e
, t
, m
)
304 unsigned *b
; /* code lengths in bits (all assumed <= BMAX) */
305 unsigned n
; /* number of codes (assumed <= N_MAX) */
306 unsigned s
; /* number of simple-valued codes (0..s-1) */
307 ush
*d
; /* list of base values for non-simple codes */
308 ush
*e
; /* list of extra bits for non-simple codes */
309 struct huft
**t
; /* result: starting table */
310 int *m
; /* maximum lookup bits, returns actual */
311 /* Given a list of code lengths and a maximum table size, make a set of
312 tables to decode that set of codes. Return zero on success, one if
313 the given code set is incomplete (the tables are still built in this
314 case), two if the input is invalid (all zero length codes or an
315 oversubscribed set of lengths), and three if not enough memory. */
317 unsigned a
; /* counter for codes of length k */
318 unsigned c
[BMAX
+1]; /* bit length count table */
319 unsigned f
; /* i repeats in table every f entries */
320 int g
; /* maximum code length */
321 int h
; /* table level */
322 register unsigned i
; /* counter, current code */
323 register unsigned j
; /* counter */
324 register int k
; /* number of bits in current code */
325 int l
; /* bits per table (returned in m) */
326 register unsigned *p
; /* pointer into c[], b[], or v[] */
327 register struct huft
*q
; /* points to current table */
328 struct huft r
; /* table entry for structure assignment */
329 struct huft
*u
[BMAX
]; /* table stack */
330 unsigned v
[N_MAX
]; /* values in order of bit length */
331 register int w
; /* bits before this table == (l * h) */
332 unsigned x
[BMAX
+1]; /* bit offsets, then code stack */
333 unsigned *xp
; /* pointer into x */
334 int y
; /* number of dummy codes added */
335 unsigned z
; /* number of entries in current table */
338 /* Generate counts for each bit length */
339 memzero(c
, sizeof(c
));
342 Tracecv(*p
, (stderr
, (n
-i
>= ' ' && n
-i
<= '~' ? "%c %d\n" : "0x%x %d\n"),
344 c
[*p
]++; /* assume all entries <= BMAX */
345 p
++; /* Can't combine with above line (Solaris bug) */
347 if (c
[0] == n
) /* null input--all zero length codes */
349 *t
= (struct huft
*)NULL
;
355 /* Find minimum and maximum length, bound *m by those */
357 for (j
= 1; j
<= BMAX
; j
++)
360 k
= j
; /* minimum code length */
363 for (i
= BMAX
; i
; i
--)
366 g
= i
; /* maximum code length */
372 /* Adjust last length count to fill out codes, if needed */
373 for (y
= 1 << j
; j
< i
; j
++, y
<<= 1)
375 return 2; /* bad input: more codes than bits */
381 /* Generate starting offsets into the value table for each length */
383 p
= c
+ 1; xp
= x
+ 2;
384 while (--i
) { /* note that i == g from above */
389 /* Make a table of values in order of bit lengths */
397 /* Generate the Huffman codes and for each, make the table entries */
398 x
[0] = i
= 0; /* first Huffman code is zero */
399 p
= v
; /* grab values in bit order */
400 h
= -1; /* no tables yet--level -1 */
401 w
= -l
; /* bits decoded == (l * h) */
402 u
[0] = (struct huft
*)NULL
; /* just to keep compilers happy */
403 q
= (struct huft
*)NULL
; /* ditto */
406 /* go through the bit lengths (k already is bits in shortest code) */
412 /* here i is the Huffman code of length k bits for value *p */
413 /* make tables up to required level */
417 w
+= l
; /* previous table always l bits */
419 /* compute minimum size table less than or equal to l bits */
420 z
= (z
= g
- w
) > (unsigned)l
? (unsigned)l
: z
; /* upper limit on table size */
421 if ((f
= 1 << (j
= k
- w
)) > a
+ 1) /* try a k-w bit table */
422 { /* too few codes for k-w bit table */
423 f
-= a
+ 1; /* deduct codes from patterns left */
425 while (++j
< z
) /* try smaller tables up to z bits */
427 if ((f
<<= 1) <= *++xp
)
428 break; /* enough codes to use up j bits */
429 f
-= *xp
; /* else deduct codes from patterns */
432 z
= 1 << j
; /* table entries for j-bit table */
434 /* allocate and link in new table */
435 if ((q
= (struct huft
*)malloc((z
+ 1)*sizeof(struct huft
))) ==
440 return 3; /* not enough memory */
442 hufts
+= z
+ 1; /* track memory usage */
443 *t
= q
+ 1; /* link to list for huft_free() */
444 *(t
= &(q
->v
.t
)) = (struct huft
*)NULL
;
445 u
[h
] = ++q
; /* table starts after link */
447 /* connect to last table, if there is one */
450 x
[h
] = i
; /* save pattern for backing up */
451 r
.b
= (uch
)l
; /* bits to dump before this table */
452 r
.e
= (uch
)(16 + j
); /* bits in this table */
453 r
.v
.t
= q
; /* pointer to this table */
454 j
= i
>> (w
- l
); /* (get around Turbo C bug) */
455 u
[h
-1][j
] = r
; /* connect to last table */
459 /* set up table entry in r */
462 r
.e
= 99; /* out of values--invalid code */
465 r
.e
= (uch
)(*p
< 256 ? 16 : 15); /* 256 is end-of-block code */
466 r
.v
.n
= (ush
)(*p
); /* simple code is just the value */
467 p
++; /* one compiler does not like *p++ */
471 r
.e
= (uch
)e
[*p
- s
]; /* non-simple--look up in lists */
475 /* fill code-like entries with r */
477 for (j
= i
>> w
; j
< z
; j
+= f
)
480 /* backwards increment the k-bit code i */
481 for (j
= 1 << (k
- 1); i
& j
; j
>>= 1)
485 /* backup over finished tables */
486 while ((i
& ((1 << w
) - 1)) != x
[h
])
488 h
--; /* don't need to update q */
495 /* Return true (1) if we were given an incomplete table */
496 return y
!= 0 && g
!= 1;
502 struct huft
*t
; /* table to free */
503 /* Free the malloc'ed tables built by huft_build(), which makes a linked
504 list of the tables it made, with the links in a dummy first entry of
507 register struct huft
*p
, *q
;
510 /* Go through linked list, freeing from the malloced (t[-1]) address. */
512 while (p
!= (struct huft
*)NULL
)
522 static int inflate_codes(tl
, td
, bl
, bd
)
523 struct huft
*tl
, *td
; /* literal/length and distance decoder tables */
524 int bl
, bd
; /* number of bits decoded by tl[] and td[] */
525 /* inflate (decompress) the codes in a deflated (compressed) block.
526 Return an error code or zero if it all goes ok. */
528 register unsigned e
; /* table entry flag/number of extra bits */
529 unsigned n
, d
; /* length and index for copy */
530 unsigned w
; /* current window position */
531 struct huft
*t
; /* pointer to table entry */
532 unsigned ml
, md
; /* masks for bl and bd bits */
533 register ulg b
; /* bit buffer */
534 register unsigned k
; /* number of bits in bit buffer */
537 /* make local copies of globals */
538 b
= bb
; /* initialize bit buffer */
540 w
= wp
; /* initialize window position */
542 /* inflate the coded data */
543 ml
= mask_bits
[bl
]; /* precompute masks for speed */
545 for (;;) /* do until end of block */
547 NEEDBITS((unsigned)bl
)
548 if ((e
= (t
= tl
+ ((unsigned)b
& ml
))->e
) > 16)
555 } while ((e
= (t
= t
->v
.t
+ ((unsigned)b
& mask_bits
[e
]))->e
) > 16);
557 if (e
== 16) /* then it's a literal */
559 slide
[w
++] = (uch
)t
->v
.n
;
560 Tracevv((stderr
, "%c", slide
[w
-1]));
567 else /* it's an EOB or a length */
569 /* exit if end of block */
573 /* get length of block to copy */
575 n
= t
->v
.n
+ ((unsigned)b
& mask_bits
[e
]);
578 /* decode distance of block to copy */
579 NEEDBITS((unsigned)bd
)
580 if ((e
= (t
= td
+ ((unsigned)b
& md
))->e
) > 16)
587 } while ((e
= (t
= t
->v
.t
+ ((unsigned)b
& mask_bits
[e
]))->e
) > 16);
590 d
= w
- t
->v
.n
- ((unsigned)b
& mask_bits
[e
]);
592 Tracevv((stderr
,"\\[%d,%d]", w
-d
, n
));
596 n
-= (e
= (e
= WSIZE
- ((d
&= WSIZE
-1) > w
? d
: w
)) > n
? n
: e
);
597 #if !defined(NOMEMCPY) && !defined(DEBUG)
598 if (w
- d
>= e
) /* (this test assumes unsigned comparison) */
600 memcpy(slide
+ w
, slide
+ d
, e
);
604 else /* do it slow to avoid memcpy() overlap */
605 #endif /* !NOMEMCPY */
607 slide
[w
++] = slide
[d
++];
608 Tracevv((stderr
, "%c", slide
[w
-1]));
620 /* restore the globals from the locals */
621 wp
= w
; /* restore global window pointer */
622 bb
= b
; /* restore global bit buffer */
631 static int inflate_stored()
632 /* "decompress" an inflated type 0 (stored) block. */
634 unsigned n
; /* number of bytes in block */
635 unsigned w
; /* current window position */
636 register ulg b
; /* bit buffer */
637 register unsigned k
; /* number of bits in bit buffer */
640 /* make local copies of globals */
641 b
= bb
; /* initialize bit buffer */
643 w
= wp
; /* initialize window position */
646 /* go to byte boundary */
651 /* get the length and its complement */
653 n
= ((unsigned)b
& 0xffff);
656 if (n
!= (unsigned)((~b
) & 0xffff))
657 return 1; /* error in compressed data */
661 /* read and output the compressed data */
675 /* restore the globals from the locals */
676 wp
= w
; /* restore global window pointer */
677 bb
= b
; /* restore global bit buffer */
684 static int inflate_fixed()
685 /* decompress an inflated type 1 (fixed Huffman codes) block. We should
686 either replace this with a custom decoder, or at least precompute the
689 int i
; /* temporary variable */
690 struct huft
*tl
; /* literal/length code table */
691 struct huft
*td
; /* distance code table */
692 int bl
; /* lookup bits for tl */
693 int bd
; /* lookup bits for td */
694 unsigned l
[288]; /* length list for huft_build */
697 /* set up literal table */
698 for (i
= 0; i
< 144; i
++)
704 for (; i
< 288; i
++) /* make a complete, but wrong code set */
707 if ((i
= huft_build(l
, 288, 257, cplens
, cplext
, &tl
, &bl
)) != 0)
711 /* set up distance table */
712 for (i
= 0; i
< 30; i
++) /* make an incomplete code set */
715 if ((i
= huft_build(l
, 30, 0, cpdist
, cpdext
, &td
, &bd
)) > 1)
722 /* decompress until an end-of-block code */
723 if (inflate_codes(tl
, td
, bl
, bd
))
727 /* free the decoding tables, return */
735 static int inflate_dynamic()
736 /* decompress an inflated type 2 (dynamic Huffman codes) block. */
738 int i
; /* temporary variables */
740 unsigned l
; /* last length */
741 unsigned m
; /* mask for bit lengths table */
742 unsigned n
; /* number of lengths to get */
743 struct huft
*tl
; /* literal/length code table */
744 struct huft
*td
; /* distance code table */
745 int bl
; /* lookup bits for tl */
746 int bd
; /* lookup bits for td */
747 unsigned nb
; /* number of bit length codes */
748 unsigned nl
; /* number of literal/length codes */
749 unsigned nd
; /* number of distance codes */
750 #ifdef PKZIP_BUG_WORKAROUND
751 unsigned ll
[288+32]; /* literal/length and distance code lengths */
753 unsigned ll
[286+30]; /* literal/length and distance code lengths */
755 register ulg b
; /* bit buffer */
756 register unsigned k
; /* number of bits in bit buffer */
759 /* make local bit buffer */
764 /* read in table lengths */
766 nl
= 257 + ((unsigned)b
& 0x1f); /* number of literal/length codes */
769 nd
= 1 + ((unsigned)b
& 0x1f); /* number of distance codes */
772 nb
= 4 + ((unsigned)b
& 0xf); /* number of bit length codes */
774 #ifdef PKZIP_BUG_WORKAROUND
775 if (nl
> 288 || nd
> 32)
777 if (nl
> 286 || nd
> 30)
779 return 1; /* bad lengths */
782 /* read in bit-length-code lengths */
783 for (j
= 0; j
< nb
; j
++)
786 ll
[border
[j
]] = (unsigned)b
& 7;
793 /* build decoding table for trees--single level, 7 bit lookup */
795 if ((i
= huft_build(ll
, 19, 19, NULL
, NULL
, &tl
, &bl
)) != 0)
799 return i
; /* incomplete code set */
803 /* read in literal and distance code lengths */
807 while ((unsigned)i
< n
)
809 NEEDBITS((unsigned)bl
)
810 j
= (td
= tl
+ ((unsigned)b
& m
))->b
;
813 if (j
< 16) /* length of code in bits (0..15) */
814 ll
[i
++] = l
= j
; /* save last length in l */
815 else if (j
== 16) /* repeat last length 3 to 6 times */
818 j
= 3 + ((unsigned)b
& 3);
820 if ((unsigned)i
+ j
> n
)
825 else if (j
== 17) /* 3 to 10 zero length codes */
828 j
= 3 + ((unsigned)b
& 7);
830 if ((unsigned)i
+ j
> n
)
836 else /* j == 18: 11 to 138 zero length codes */
839 j
= 11 + ((unsigned)b
& 0x7f);
841 if ((unsigned)i
+ j
> n
)
850 /* free decoding table for trees */
854 /* restore the global bit buffer */
859 /* build the decoding tables for literal/length and distance codes */
861 if ((i
= huft_build(ll
, nl
, 257, cplens
, cplext
, &tl
, &bl
)) != 0)
864 fprintf(stderr
, " incomplete literal tree\n");
867 return i
; /* incomplete code set */
870 if ((i
= huft_build(ll
+ nl
, nd
, 0, cpdist
, cpdext
, &td
, &bd
)) != 0)
873 fprintf(stderr
, " incomplete distance tree\n");
874 #ifdef PKZIP_BUG_WORKAROUND
881 return i
; /* incomplete code set */
886 /* decompress until an end-of-block code */
887 if (inflate_codes(tl
, td
, bl
, bd
))
891 /* free the decoding tables, return */
899 static int inflate_block(e
)
900 int *e
; /* last block flag */
901 /* decompress an inflated block */
903 unsigned t
; /* block type */
904 register ulg b
; /* bit buffer */
905 register unsigned k
; /* number of bits in bit buffer */
908 /* make local bit buffer */
913 /* read in last block bit */
919 /* read in block type */
925 /* restore the global bit buffer */
929 /* inflate that block type */
931 return inflate_dynamic();
933 return inflate_stored();
935 return inflate_fixed();
945 /* decompress an inflated entry */
947 int e
; /* last block flag */
948 int r
; /* result code */
949 unsigned h
; /* maximum struct huft's malloc'ed */
952 /* initialize window, bit buffer */
958 /* decompress until the last block */
962 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 */
983 //fprintf("<%d> ", h);
988 static ulg crc32tab
[0x100] = { 0, };
990 static void inittab()
993 for (i
=0;i
<0x100;i
++) {
996 c
= (c
& 1) ? ((c
>> 1) ^ 0xedb88320) : (c
>> 1);
1002 static ulg
crc32(uch
*buff
, int len
)
1009 c
= (c
>> 8) ^ crc32tab
[(c
^ *(buff
++)) & 0xff];
1010 return c
^ 0xffffffff;
1013 ulg
gunzip(const uch
*in
, uch
*out
, uch
*inflate_buf
)
1015 if (in
[2] != 8) panic("Unsupported compression method");
1016 if (in
[3] & 0xe3) panic("Unsupported gzip format");
1018 inbuf
= in
+ 10; /* skip header */
1019 if (in
[3] & 4) inbuf
+= in
[10] + in
[11] * 0x100;
1020 if (in
[3] & 8) while (*(inbuf
++) != 0) ; /* skip original file name */
1021 if (in
[3] & 0x10) while (*(inbuf
++) != 0) ; /* skip file comment */
1023 outbuf
= out
; inptr
= 0; outcnt
= 0;
1024 window
= inflate_buf
;
1026 if (inflate()) panic("Error inflating file");
1030 if ((ulg
)(outbuf
- out
) != *(ulg
*)(inbuf
+ 4))
1031 panic("Invalid size %d != %d\n", outbuf
- out
, *(ulg
*)(inbuf
+ 4));
1033 if (crc32(out
, outbuf
- out
) != *(ulg
*)inbuf
)
1036 return outbuf
- out
;