lib/zlib_inflate/inflate.h

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