1 #ifndef INFLATE_H
2 #define INFLATE_H
3
4 /* inflate.h -- internal inflate state definition
5 * Copyright (C) 1995-2004 Mark Adler
6 * For conditions of distribution and use, see copyright notice in zlib.h
7 */
8
9 /* WARNING: this file should *not* be used by applications. It is
10 part of the implementation of the compression library and is
11 subject to change. Applications should only use zlib.h.
12 */
13
14 /* Possible inflate modes between inflate() calls */
15 typedef enum {
16 HEAD, /* i: waiting for magic header */
17 FLAGS, /* i: waiting for method and flags (gzip) */
18 TIME, /* i: waiting for modification time (gzip) */
19 OS, /* i: waiting for extra flags and operating system (gzip) */
20 EXLEN, /* i: waiting for extra length (gzip) */
21 EXTRA, /* i: waiting for extra bytes (gzip) */
22 NAME, /* i: waiting for end of file name (gzip) */
23 COMMENT, /* i: waiting for end of comment (gzip) */
24 HCRC, /* i: waiting for header crc (gzip) */
25 DICTID, /* i: waiting for dictionary check value */
26 DICT, /* waiting for inflateSetDictionary() call */
27 TYPE, /* i: waiting for type bits, including last-flag bit */
28 TYPEDO, /* i: same, but skip check to exit inflate on new block */
29 STORED, /* i: waiting for stored size (length and complement) */
30 COPY, /* i/o: waiting for input or output to copy stored block */
31 TABLE, /* i: waiting for dynamic block table lengths */
32 LENLENS, /* i: waiting for code length code lengths */
33 CODELENS, /* i: waiting for length/lit and distance code lengths */
34 LEN, /* i: waiting for length/lit code */
35 LENEXT, /* i: waiting for length extra bits */
36 DIST, /* i: waiting for distance code */
37 DISTEXT, /* i: waiting for distance extra bits */
38 MATCH, /* o: waiting for output space to copy string */
39 LIT, /* o: waiting for output space to write literal */
40 CHECK, /* i: waiting for 32-bit check value */
41 LENGTH, /* i: waiting for 32-bit length (gzip) */
42 DONE, /* finished check, done -- remain here until reset */
43 BAD, /* got a data error -- remain here until reset */
44 MEM, /* got an inflate() memory error -- remain here until reset */
45 SYNC /* looking for synchronization bytes to restart inflate() */
46 } inflate_mode;
47
48 /*
49 State transitions between above modes -
50
51 (most modes can go to the BAD or MEM mode -- not shown for clarity)
52
53 Process header:
54 HEAD -> (gzip) or (zlib)
55 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME
56 NAME -> COMMENT -> HCRC -> TYPE
57 (zlib) -> DICTID or TYPE
58 DICTID -> DICT -> TYPE
59 Read deflate blocks:
60 TYPE -> STORED or TABLE or LEN or CHECK
61 STORED -> COPY -> TYPE
62 TABLE -> LENLENS -> CODELENS -> LEN
63 Read deflate codes:
64 LEN -> LENEXT or LIT or TYPE
65 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
66 LIT -> LEN
67 Process trailer:
68 CHECK -> LENGTH -> DONE
69 */
70
71 /* state maintained between inflate() calls. Approximately 7K bytes. */
72 struct inflate_state {
73 inflate_mode mode; /* current inflate mode */
74 int last; /* true if processing last block */
75 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
76 int havedict; /* true if dictionary provided */
77 int flags; /* gzip header method and flags (0 if zlib) */
78 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
79 unsigned long check; /* protected copy of check value */
80 unsigned long total; /* protected copy of output count */
81 /* gz_headerp head; */ /* where to save gzip header information */
82 /* sliding window */
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 write; /* window write index */
87 unsigned char *window; /* allocated sliding window, if needed */
88 /* bit accumulator */
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 *lencode; /* starting table for length/literal codes */
98 code const *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 *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 };
111 #endif