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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 #pragma ident	"@(#)inflate.h	1.1	07/03/22 SMI"
      7 
      8 /* WARNING: this file should *not* be used by applications. It is
      9    part of the implementation of the compression library and is
     10    subject to change. Applications should only use zlib.h.
     11  */
     12 
     13 /* define NO_GZIP when compiling if you want to disable gzip header and
     14    trailer decoding by inflate().  NO_GZIP would be used to avoid linking in
     15    the crc code when it is not needed.  For shared libraries, gzip decoding
     16    should be left enabled. */
     17 #ifndef NO_GZIP
     18 #  define GUNZIP
     19 #endif
     20 
     21 /* Possible inflate modes between inflate() calls */
     22 typedef enum {
     23     HEAD,       /* i: waiting for magic header */
     24     FLAGS,      /* i: waiting for method and flags (gzip) */
     25     TIME,       /* i: waiting for modification time (gzip) */
     26     OS,         /* i: waiting for extra flags and operating system (gzip) */
     27     EXLEN,      /* i: waiting for extra length (gzip) */
     28     EXTRA,      /* i: waiting for extra bytes (gzip) */
     29     NAME,       /* i: waiting for end of file name (gzip) */
     30     COMMENT,    /* i: waiting for end of comment (gzip) */
     31     HCRC,       /* i: waiting for header crc (gzip) */
     32     DICTID,     /* i: waiting for dictionary check value */
     33     DICT,       /* waiting for inflateSetDictionary() call */
     34         TYPE,       /* i: waiting for type bits, including last-flag bit */
     35         TYPEDO,     /* i: same, but skip check to exit inflate on new block */
     36         STORED,     /* i: waiting for stored size (length and complement) */
     37         COPY,       /* i/o: waiting for input or output to copy stored block */
     38         TABLE,      /* i: waiting for dynamic block table lengths */
     39         LENLENS,    /* i: waiting for code length code lengths */
     40         CODELENS,   /* i: waiting for length/lit and distance code lengths */
     41             LEN,        /* i: waiting for length/lit code */
     42             LENEXT,     /* i: waiting for length extra bits */
     43             DIST,       /* i: waiting for distance code */
     44             DISTEXT,    /* i: waiting for distance extra bits */
     45             MATCH,      /* o: waiting for output space to copy string */
     46             LIT,        /* o: waiting for output space to write literal */
     47     CHECK,      /* i: waiting for 32-bit check value */
     48     LENGTH,     /* i: waiting for 32-bit length (gzip) */
     49     DONE,       /* finished check, done -- remain here until reset */
     50     BAD,        /* got a data error -- remain here until reset */
     51     MEM,        /* got an inflate() memory error -- remain here until reset */
     52     SYNC        /* looking for synchronization bytes to restart inflate() */
     53 } inflate_mode;
     54 
     55 /*
     56     State transitions between above modes -
     57 
     58     (most modes can go to the BAD or MEM mode -- not shown for clarity)
     59 
     60     Process header:
     61         HEAD -> (gzip) or (zlib)
     62         (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME
     63         NAME -> COMMENT -> HCRC -> TYPE
     64         (zlib) -> DICTID or TYPE
     65         DICTID -> DICT -> TYPE
     66     Read deflate blocks:
     67             TYPE -> STORED or TABLE or LEN or CHECK
     68             STORED -> COPY -> TYPE
     69             TABLE -> LENLENS -> CODELENS -> LEN
     70     Read deflate codes:
     71                 LEN -> LENEXT or LIT or TYPE
     72                 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
     73                 LIT -> LEN
     74     Process trailer:
     75         CHECK -> LENGTH -> DONE
     76  */
     77 
     78 /* state maintained between inflate() calls.  Approximately 7K bytes. */
     79 struct inflate_state {
     80     inflate_mode mode;          /* current inflate mode */
     81     int last;                   /* true if processing last block */
     82     int wrap;                   /* bit 0 true for zlib, bit 1 true for gzip */
     83     int havedict;               /* true if dictionary provided */
     84     int flags;                  /* gzip header method and flags (0 if zlib) */
     85     unsigned dmax;              /* zlib header max distance (INFLATE_STRICT) */
     86     unsigned long check;        /* protected copy of check value */
     87     unsigned long total;        /* protected copy of output count */
     88     gz_headerp head;            /* where to save gzip header information */
     89         /* sliding window */
     90     unsigned wbits;             /* log base 2 of requested window size */
     91     unsigned wsize;             /* window size or zero if not using window */
     92     unsigned whave;             /* valid bytes in the window */
     93     unsigned write;             /* window write index */
     94     unsigned char FAR *window;  /* allocated sliding window, if needed */
     95         /* bit accumulator */
     96     unsigned long hold;         /* input bit accumulator */
     97     unsigned bits;              /* number of bits in "in" */
     98         /* for string and stored block copying */
     99     unsigned length;            /* literal or length of data to copy */
    100     unsigned offset;            /* distance back to copy string from */
    101         /* for table and code decoding */
    102     unsigned extra;             /* extra bits needed */
    103         /* fixed and dynamic code tables */
    104     code const FAR *lencode;    /* starting table for length/literal codes */
    105     code const FAR *distcode;   /* starting table for distance codes */
    106     unsigned lenbits;           /* index bits for lencode */
    107     unsigned distbits;          /* index bits for distcode */
    108         /* dynamic table building */
    109     unsigned ncode;             /* number of code length code lengths */
    110     unsigned nlen;              /* number of length code lengths */
    111     unsigned ndist;             /* number of distance code lengths */
    112     unsigned have;              /* number of code lengths in lens[] */
    113     code FAR *next;             /* next available space in codes[] */
    114     unsigned short lens[320];   /* temporary storage for code lengths */
    115     unsigned short work[288];   /* work area for code table building */
    116     code codes[ENOUGH];         /* space for code tables */
    117 };
    118