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
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.
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. */
19 /* Possible inflate modes between inflate() calls */
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() */
54 State transitions between above modes -
56 (most modes can go to the BAD or MEM mode -- not shown for clarity)
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
65 TYPE -> STORED or TABLE or LEN or CHECK
66 STORED -> COPY -> TYPE
67 TABLE -> LENLENS -> CODELENS -> LEN
69 LEN -> LENEXT or LIT or TYPE
70 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
73 CHECK -> LENGTH -> DONE
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 */
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 */
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 */