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
112