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 #include "inftrees.h"
15
16 /* Possible inflate modes between inflate() calls */
17 typedef enum {
18 HEAD, /* i: waiting for magic header */
19 FLAGS, /* i: waiting for method and flags (gzip) */
20 TIME, /* i: waiting for modification time (gzip) */
21 OS, /* i: waiting for extra flags and operating system (gzip) */
22 EXLEN, /* i: waiting for extra length (gzip) */
23 EXTRA, /* i: waiting for extra bytes (gzip) */
24 NAME, /* i: waiting for end of file name (gzip) */
25 COMMENT, /* i: waiting for end of comment (gzip) */
26 HCRC, /* i: waiting for header crc (gzip) */
27 DICTID, /* i: waiting for dictionary check value */
28 DICT, /* waiting for inflateSetDictionary() call */
29 TYPE, /* i: waiting for type bits, including last-flag bit */
30 TYPEDO, /* i: same, but skip check to exit inflate on new block */
31 STORED, /* i: waiting for stored size (length and complement) */
32 COPY, /* i/o: waiting for input or output to copy stored block */
33 TABLE, /* i: waiting for dynamic block table lengths */
34 LENLENS, /* i: waiting for code length code lengths */
35 CODELENS, /* i: waiting for length/lit and distance code lengths */
36 LEN, /* i: waiting for length/lit code */
37 LENEXT, /* i: waiting for length extra bits */
38 DIST, /* i: waiting for distance code */
39 DISTEXT, /* i: waiting for distance extra bits */
40 MATCH, /* o: waiting for output space to copy string */
41 LIT, /* o: waiting for output space to write literal */
42 CHECK, /* i: waiting for 32-bit check value */
43 LENGTH, /* i: waiting for 32-bit length (gzip) */
44 DONE, /* finished check, done -- remain here until reset */
45 BAD, /* got a data error -- remain here until reset */
46 MEM, /* got an inflate() memory error -- remain here until reset */
47 SYNC /* looking for synchronization bytes to restart inflate() */
48 } inflate_mode;
49
50 /*
51 State transitions between above modes -
52
53 (most modes can go to the BAD or MEM mode -- not shown for clarity)
54
55 Process header:
56 HEAD -> (gzip) or (zlib)
57 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME
58 NAME -> COMMENT -> HCRC -> TYPE
59 (zlib) -> DICTID or TYPE
60 DICTID -> DICT -> TYPE
61 Read deflate blocks:
62 TYPE -> STORED or TABLE or LEN or CHECK
63 STORED -> COPY -> TYPE
64 TABLE -> LENLENS -> CODELENS -> LEN
65 Read deflate codes:
66 LEN -> LENEXT or LIT or TYPE
67 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
68 LIT -> LEN
69 Process trailer:
70 CHECK -> LENGTH -> DONE
71 */
72
73 /* state maintained between inflate() calls. Approximately 7K bytes. */
74 struct inflate_state {
75 inflate_mode mode; /* current inflate mode */
76 int last; /* true if processing last block */
77 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
78 int havedict; /* true if dictionary provided */
79 int flags; /* gzip header method and flags (0 if zlib) */
80 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
81 unsigned long check; /* protected copy of check value */
82 unsigned long total; /* protected copy of output count */
83 /* gz_headerp head; */ /* where to save gzip header information */
84 /* sliding window */
85 unsigned wbits; /* log base 2 of requested window size */
86 unsigned wsize; /* window size or zero if not using window */
87 unsigned whave; /* valid bytes in the window */
88 unsigned write; /* window write index */
89 unsigned char *window; /* allocated sliding window, if needed */
90 /* bit accumulator */
91 unsigned long hold; /* input bit accumulator */
92 unsigned bits; /* number of bits in "in" */
93 /* for string and stored block copying */
94 unsigned length; /* literal or length of data to copy */
95 unsigned offset; /* distance back to copy string from */
96 /* for table and code decoding */
97 unsigned extra; /* extra bits needed */
98 /* fixed and dynamic code tables */
99 code const *lencode; /* starting table for length/literal codes */
100 code const *distcode; /* starting table for distance codes */
101 unsigned lenbits; /* index bits for lencode */
102 unsigned distbits; /* index bits for distcode */
103 /* dynamic table building */
104 unsigned ncode; /* number of code length code lengths */
105 unsigned nlen; /* number of length code lengths */
106 unsigned ndist; /* number of distance code lengths */
107 unsigned have; /* number of code lengths in lens[] */
108 code *next; /* next available space in codes[] */
109 unsigned short lens[320]; /* temporary storage for code lengths */
110 unsigned short work[288]; /* work area for code table building */
111 code codes[ENOUGH]; /* space for code tables */
112 };
113
114 /* Reverse the bytes in a 32-bit value */
115 #define REVERSE(q) \
116 ((((q) >> 24) & 0xff) + (((q) >> 8) & 0xff00) + \
117 (((q) & 0xff00) << 8) + (((q) & 0xff) << 24))
118
119 #endif
120
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