xref: /openbmc/linux/lib/zlib_inflate/inflate.h (revision 12619610)
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