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e6153040 | 1 | /* inflate.h -- internal inflate state definition |
2 | * Copyright (C) 1995-2009 Mark Adler | |
3 | * For conditions of distribution and use, see copyright notice in zlib.h | |
4 | */ | |
5 | ||
6 | /* WARNING: this file should *not* be used by applications. It is | |
7 | part of the implementation of the compression library and is | |
8 | subject to change. Applications should only use zlib.h. | |
9 | */ | |
10 | ||
11 | /* define NO_GZIP when compiling if you want to disable gzip header and | |
12 | trailer decoding by inflate(). NO_GZIP would be used to avoid linking in | |
13 | the crc code when it is not needed. For shared libraries, gzip decoding | |
14 | should be left enabled. */ | |
15 | #ifndef NO_GZIP | |
16 | # define GUNZIP | |
17 | #endif | |
18 | ||
19 | /* Possible inflate modes between inflate() calls */ | |
20 | typedef enum { | |
21 | HEAD, /* i: waiting for magic header */ | |
22 | FLAGS, /* i: waiting for method and flags (gzip) */ | |
23 | TIME, /* i: waiting for modification time (gzip) */ | |
24 | OS, /* i: waiting for extra flags and operating system (gzip) */ | |
25 | EXLEN, /* i: waiting for extra length (gzip) */ | |
26 | EXTRA, /* i: waiting for extra bytes (gzip) */ | |
27 | NAME, /* i: waiting for end of file name (gzip) */ | |
28 | COMMENT, /* i: waiting for end of comment (gzip) */ | |
29 | HCRC, /* i: waiting for header crc (gzip) */ | |
30 | DICTID, /* i: waiting for dictionary check value */ | |
31 | DICT, /* waiting for inflateSetDictionary() call */ | |
32 | TYPE, /* i: waiting for type bits, including last-flag bit */ | |
33 | TYPEDO, /* i: same, but skip check to exit inflate on new block */ | |
34 | STORED, /* i: waiting for stored size (length and complement) */ | |
35 | COPY_, /* i/o: same as COPY below, but only first time in */ | |
36 | COPY, /* i/o: waiting for input or output to copy stored block */ | |
37 | TABLE, /* i: waiting for dynamic block table lengths */ | |
38 | LENLENS, /* i: waiting for code length code lengths */ | |
39 | CODELENS, /* i: waiting for length/lit and distance code lengths */ | |
40 | LEN_, /* i: same as LEN below, but only first time in */ | |
41 | LEN, /* i: waiting for length/lit/eob code */ | |
42 | LENEXT, /* i: waiting for length extra bits */ | |
43 | DIST, /* i: waiting for distance code */ | |
44 | DISTEXT, /* i: waiting for distance extra bits */ | |
45 | MATCH, /* o: waiting for output space to copy string */ | |
46 | LIT, /* o: waiting for output space to write literal */ | |
47 | CHECK, /* i: waiting for 32-bit check value */ | |
48 | LENGTH, /* i: waiting for 32-bit length (gzip) */ | |
49 | DONE, /* finished check, done -- remain here until reset */ | |
50 | BAD, /* got a data error -- remain here until reset */ | |
51 | MEM, /* got an inflate() memory error -- remain here until reset */ | |
52 | SYNC /* looking for synchronization bytes to restart inflate() */ | |
53 | } inflate_mode; | |
54 | ||
55 | /* | |
56 | State transitions between above modes - | |
57 | ||
58 | (most modes can go to BAD or MEM on error -- not shown for clarity) | |
59 | ||
60 | Process header: | |
61 | HEAD -> (gzip) or (zlib) or (raw) | |
62 | (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT -> | |
63 | HCRC -> TYPE | |
64 | (zlib) -> DICTID or TYPE | |
65 | DICTID -> DICT -> TYPE | |
66 | (raw) -> TYPEDO | |
67 | Read deflate blocks: | |
68 | TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK | |
69 | STORED -> COPY_ -> COPY -> TYPE | |
70 | TABLE -> LENLENS -> CODELENS -> LEN_ | |
71 | LEN_ -> LEN | |
72 | Read deflate codes in fixed or dynamic block: | |
73 | LEN -> LENEXT or LIT or TYPE | |
74 | LENEXT -> DIST -> DISTEXT -> MATCH -> LEN | |
75 | LIT -> LEN | |
76 | Process trailer: | |
77 | CHECK -> LENGTH -> DONE | |
78 | */ | |
79 | ||
80 | /* state maintained between inflate() calls. Approximately 10K bytes. */ | |
81 | struct inflate_state { | |
82 | inflate_mode mode; /* current inflate mode */ | |
83 | int last; /* true if processing last block */ | |
84 | int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ | |
85 | int havedict; /* true if dictionary provided */ | |
86 | int flags; /* gzip header method and flags (0 if zlib) */ | |
87 | unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */ | |
88 | unsigned long check; /* protected copy of check value */ | |
89 | unsigned long total; /* protected copy of output count */ | |
90 | gz_headerp head; /* where to save gzip header information */ | |
91 | /* sliding window */ | |
92 | unsigned wbits; /* log base 2 of requested window size */ | |
93 | unsigned wsize; /* window size or zero if not using window */ | |
94 | unsigned whave; /* valid bytes in the window */ | |
95 | unsigned wnext; /* window write index */ | |
96 | unsigned char FAR *window; /* allocated sliding window, if needed */ | |
97 | /* bit accumulator */ | |
98 | unsigned long hold; /* input bit accumulator */ | |
99 | unsigned bits; /* number of bits in "in" */ | |
100 | /* for string and stored block copying */ | |
101 | unsigned length; /* literal or length of data to copy */ | |
102 | unsigned offset; /* distance back to copy string from */ | |
103 | /* for table and code decoding */ | |
104 | unsigned extra; /* extra bits needed */ | |
105 | /* fixed and dynamic code tables */ | |
106 | code const FAR *lencode; /* starting table for length/literal codes */ | |
107 | code const FAR *distcode; /* starting table for distance codes */ | |
108 | unsigned lenbits; /* index bits for lencode */ | |
109 | unsigned distbits; /* index bits for distcode */ | |
110 | /* dynamic table building */ | |
111 | unsigned ncode; /* number of code length code lengths */ | |
112 | unsigned nlen; /* number of length code lengths */ | |
113 | unsigned ndist; /* number of distance code lengths */ | |
114 | unsigned have; /* number of code lengths in lens[] */ | |
115 | code FAR *next; /* next available space in codes[] */ | |
116 | unsigned short lens[320]; /* temporary storage for code lengths */ | |
117 | unsigned short work[288]; /* work area for code table building */ | |
118 | code codes[ENOUGH]; /* space for code tables */ | |
119 | int sane; /* if false, allow invalid distance too far */ | |
120 | int back; /* bits back of last unprocessed length/lit */ | |
121 | unsigned was; /* initial length of match */ | |
122 | }; |