source: trunk/sys/libz/inflate.h @ 1

Last change on this file since 1 was 1, checked in by alain, 5 years ago

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File size: 5.8 KB
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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
4 */
5
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.
9 */
10
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. */
15#ifndef NO_GZIP
16#  define GUNZIP
17#endif
18
19/* Possible inflate modes between inflate() calls */
20typedef enum {
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() */
51} inflate_mode;
52
53/*
54    State transitions between above modes -
55
56    (most modes can go to the BAD or MEM mode -- not shown for clarity)
57
58    Process header:
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
64    Read deflate blocks:
65            TYPE -> STORED or TABLE or LEN or CHECK
66            STORED -> COPY -> TYPE
67            TABLE -> LENLENS -> CODELENS -> LEN
68    Read deflate codes:
69                LEN -> LENEXT or LIT or TYPE
70                LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
71                LIT -> LEN
72    Process trailer:
73        CHECK -> LENGTH -> DONE
74 */
75
76/* state maintained between inflate() calls.  Approximately 7K bytes. */
77struct 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 */
87        /* sliding window */
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 */
93        /* bit accumulator */
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 */
115};
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