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1/* inflate.h -- internal inflate state definition
2 * Copyright (C) 1995-2003 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_GUNZIP when compiling if you want to disable gzip header and
12 trailer decoding by inflate(). NO_GUNZIP 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_GUNZIP
16# define GUNZIP
17#endif
18
19/* Possible inflate modes between inflate() calls */
20typedef enum {
21 HEAD, /* i: waiting for magic header */
22#ifdef GUNZIP
23 FLAGS, /* i: waiting for method and flags (gzip) */
24 TIME, /* i: waiting for modification time (gzip) */
25 OS, /* i: waiting for extra flags and operating system (gzip) */
26 EXLEN, /* i: waiting for extra length (gzip) */
27 EXTRA, /* i: waiting for extra bytes (gzip) */
28 NAME, /* i: waiting for end of file name (gzip) */
29 COMMENT, /* i: waiting for end of comment (gzip) */
30 HCRC, /* i: waiting for header crc (gzip) */
31#endif
32 DICTID, /* i: waiting for dictionary check value */
33 DICT, /* waiting for inflateSetDictionary() call */
34 TYPE, /* i: waiting for type bits, including last-flag bit */
35 STORED, /* i: waiting for stored size (length and complement) */
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: waiting for length/lit code */
41 LENEXT, /* i: waiting for length extra bits */
42 DIST, /* i: waiting for distance code */
43 DISTEXT, /* i: waiting for distance extra bits */
44 MATCH, /* o: waiting for output space to copy string */
45 LIT, /* o: waiting for output space to write literal */
46 CHECK, /* i: waiting for 32-bit check value */
47#ifdef GUNZIP
48 LENGTH, /* i: waiting for 32-bit length (gzip) */
49#endif
50 DONE, /* finished check, done -- remain here until reset */
51 BAD, /* got a data error -- remain here until reset */
52 MEM, /* got an inflate() memory error -- remain here until reset */
53 SYNC /* looking for synchronization bytes to restart inflate() */
54} inflate_mode;
55
56/*
57 State transitions between above modes -
58
59 (most modes can go to the BAD or MEM mode -- not shown for clarity)
60
61 Process header:
62 HEAD -> (gzip) or (zlib)
63 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME
64 NAME -> COMMENT -> HCRC -> TYPE
65 (zlib) -> DICTID or TYPE
66 DICTID -> DICT -> TYPE
67 Read deflate blocks:
68 TYPE -> STORED or TABLE or LEN or CHECK
69 STORED -> COPY -> TYPE
70 TABLE -> LENLENS -> CODELENS -> LEN
71 Read deflate codes:
72 LEN -> LENEXT or LIT or TYPE
73 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
74 LIT -> LEN
75 Process trailer:
76 CHECK -> LENGTH -> DONE
77 */
78
79/* state maintained between inflate() calls. Approximately 7K bytes. */
80struct inflate_state {
81 inflate_mode mode; /* current inflate mode */
82 int last; /* true if processing last block */
83 int wrap; /* true to process header and trailer */
84 int havedict; /* true if dictionary provided */
85 int flags; /* gzip header method and flags (0 if zlib) */
86 unsigned long check; /* protected copy of check value */
87 unsigned long total; /* protected copy of output count */
88 /* sliding window */
89 unsigned wbits; /* log base 2 of requested window size */
90 unsigned wsize; /* window size or zero if not using 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};