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
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 /* Possible inflate modes between inflate() calls */
13 HEAD, /* i: waiting for magic header */
14 FLAGS, /* i: waiting for method and flags (gzip) */
15 TIME, /* i: waiting for modification time (gzip) */
16 OS, /* i: waiting for extra flags and operating system (gzip) */
17 EXLEN, /* i: waiting for extra length (gzip) */
18 EXTRA, /* i: waiting for extra bytes (gzip) */
19 NAME, /* i: waiting for end of file name (gzip) */
20 COMMENT, /* i: waiting for end of comment (gzip) */
21 HCRC, /* i: waiting for header crc (gzip) */
22 DICTID, /* i: waiting for dictionary check value */
23 DICT, /* waiting for inflateSetDictionary() call */
24 TYPE, /* i: waiting for type bits, including last-flag bit */
25 TYPEDO, /* i: same, but skip check to exit inflate on new block */
26 STORED, /* i: waiting for stored size (length and complement) */
27 COPY_, /* i/o: same as COPY below, but only first time in */
28 COPY, /* i/o: waiting for input or output to copy stored block */
29 TABLE, /* i: waiting for dynamic block table lengths */
30 LENLENS, /* i: waiting for code length code lengths */
31 CODELENS, /* i: waiting for length/lit and distance code lengths */
32 LEN_, /* i: same as LEN below, but only first time in */
33 LEN, /* i: waiting for length/lit/eob code */
34 LENEXT, /* i: waiting for length extra bits */
35 DIST, /* i: waiting for distance code */
36 DISTEXT, /* i: waiting for distance extra bits */
37 MATCH, /* o: waiting for output space to copy string */
38 LIT, /* o: waiting for output space to write literal */
39 CHECK, /* i: waiting for 32-bit check value */
40 LENGTH, /* i: waiting for 32-bit length (gzip) */
41 DONE, /* finished check, done -- remain here until reset */
42 BAD, /* got a data error -- remain here until reset */
43 MEM, /* got an inflate() memory error -- remain here until reset */
44 SYNC /* looking for synchronization bytes to restart inflate() */
48 State transitions between above modes -
50 (most modes can go to BAD or MEM on error -- not shown for clarity)
53 HEAD -> (gzip) or (zlib) or (raw)
54 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
56 (zlib) -> DICTID or TYPE
57 DICTID -> DICT -> TYPE
60 TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
61 STORED -> COPY_ -> COPY -> TYPE
62 TABLE -> LENLENS -> CODELENS -> LEN_
64 Read deflate codes in fixed or dynamic block:
65 LEN -> LENEXT or LIT or TYPE
66 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
69 CHECK -> LENGTH -> DONE
72 /* state maintained between inflate() calls. Approximately 10K bytes. */
73 struct inflate_state {
74 inflate_mode mode; /* current inflate mode */
75 int last; /* true if processing last block */
76 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
77 int havedict; /* true if dictionary provided */
78 int flags; /* gzip header method and flags (0 if zlib) */
79 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
80 unsigned long check; /* protected copy of check value */
81 unsigned long total; /* protected copy of output count */
83 unsigned wbits; /* log base 2 of requested window size */
84 unsigned wsize; /* window size or zero if not using window */
85 unsigned whave; /* valid bytes in the window */
86 unsigned wnext; /* window write index */
87 unsigned char FAR *window; /* allocated sliding window, if needed */
89 unsigned long hold; /* input bit accumulator */
90 unsigned bits; /* number of bits in "in" */
91 /* for string and stored block copying */
92 unsigned length; /* literal or length of data to copy */
93 unsigned offset; /* distance back to copy string from */
94 /* for table and code decoding */
95 unsigned extra; /* extra bits needed */
96 /* fixed and dynamic code tables */
97 code const FAR *lencode; /* starting table for length/literal codes */
98 code const FAR *distcode; /* starting table for distance codes */
99 unsigned lenbits; /* index bits for lencode */
100 unsigned distbits; /* index bits for distcode */
101 /* dynamic table building */
102 unsigned ncode; /* number of code length code lengths */
103 unsigned nlen; /* number of length code lengths */
104 unsigned ndist; /* number of distance code lengths */
105 unsigned have; /* number of code lengths in lens[] */
106 code FAR *next; /* next available space in codes[] */
107 unsigned short lens[320]; /* temporary storage for code lengths */
108 unsigned short work[288]; /* work area for code table building */
109 code codes[ENOUGH]; /* space for code tables */
110 int sane; /* if false, allow invalid distance too far */
111 int back; /* bits back of last unprocessed length/lit */
112 unsigned was; /* initial length of match */