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 */
17typedef 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. */
74struct 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