cc68a136 |
1 | /* inflate.h -- internal inflate state definition |
2 | * Copyright (C) 1995-2004 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: waiting for input or output to copy stored block */ |
36 | TABLE, /* i: waiting for dynamic block table lengths */ |
37 | LENLENS, /* i: waiting for code length code lengths */ |
38 | CODELENS, /* i: waiting for length/lit and distance code lengths */ |
39 | LEN, /* i: waiting for length/lit code */ |
40 | LENEXT, /* i: waiting for length extra bits */ |
41 | DIST, /* i: waiting for distance code */ |
42 | DISTEXT, /* i: waiting for distance extra bits */ |
43 | MATCH, /* o: waiting for output space to copy string */ |
44 | LIT, /* o: waiting for output space to write literal */ |
45 | CHECK, /* i: waiting for 32-bit check value */ |
46 | LENGTH, /* i: waiting for 32-bit length (gzip) */ |
47 | DONE, /* finished check, done -- remain here until reset */ |
48 | BAD, /* got a data error -- remain here until reset */ |
49 | MEM, /* got an inflate() memory error -- remain here until reset */ |
50 | SYNC /* looking for synchronization bytes to restart inflate() */ |
51 | } inflate_mode; |
52 | |
53 | /* |
54 | State transitions between above modes - |
55 | |
56 | (most modes can go to the BAD or MEM mode -- not shown for clarity) |
57 | |
58 | Process header: |
59 | HEAD -> (gzip) or (zlib) |
60 | (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME |
61 | NAME -> COMMENT -> HCRC -> TYPE |
62 | (zlib) -> DICTID or TYPE |
63 | DICTID -> DICT -> TYPE |
64 | Read deflate blocks: |
65 | TYPE -> STORED or TABLE or LEN or CHECK |
66 | STORED -> COPY -> TYPE |
67 | TABLE -> LENLENS -> CODELENS -> LEN |
68 | Read deflate codes: |
69 | LEN -> LENEXT or LIT or TYPE |
70 | LENEXT -> DIST -> DISTEXT -> MATCH -> LEN |
71 | LIT -> LEN |
72 | Process trailer: |
73 | CHECK -> LENGTH -> DONE |
74 | */ |
75 | |
76 | /* state maintained between inflate() calls. Approximately 7K bytes. */ |
77 | struct inflate_state { |
78 | inflate_mode mode; /* current inflate mode */ |
79 | int last; /* true if processing last block */ |
80 | int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ |
81 | int havedict; /* true if dictionary provided */ |
82 | int flags; /* gzip header method and flags (0 if zlib) */ |
83 | unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */ |
84 | unsigned long check; /* protected copy of check value */ |
85 | unsigned long total; /* protected copy of output count */ |
86 | gz_headerp head; /* where to save gzip header information */ |
87 | /* sliding window */ |
88 | unsigned wbits; /* log base 2 of requested window size */ |
89 | unsigned wsize; /* window size or zero if not using window */ |
90 | unsigned whave; /* valid bytes in the window */ |
91 | unsigned write; /* window write index */ |
92 | unsigned char FAR *window; /* allocated sliding window, if needed */ |
93 | /* bit accumulator */ |
94 | unsigned long hold; /* input bit accumulator */ |
95 | unsigned bits; /* number of bits in "in" */ |
96 | /* for string and stored block copying */ |
97 | unsigned length; /* literal or length of data to copy */ |
98 | unsigned offset; /* distance back to copy string from */ |
99 | /* for table and code decoding */ |
100 | unsigned extra; /* extra bits needed */ |
101 | /* fixed and dynamic code tables */ |
102 | code const FAR *lencode; /* starting table for length/literal codes */ |
103 | code const FAR *distcode; /* starting table for distance codes */ |
104 | unsigned lenbits; /* index bits for lencode */ |
105 | unsigned distbits; /* index bits for distcode */ |
106 | /* dynamic table building */ |
107 | unsigned ncode; /* number of code length code lengths */ |
108 | unsigned nlen; /* number of length code lengths */ |
109 | unsigned ndist; /* number of distance code lengths */ |
110 | unsigned have; /* number of code lengths in lens[] */ |
111 | code FAR *next; /* next available space in codes[] */ |
112 | unsigned short lens[320]; /* temporary storage for code lengths */ |
113 | unsigned short work[288]; /* work area for code table building */ |
114 | code codes[ENOUGH]; /* space for code tables */ |
115 | }; |