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