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  1. /* inflate.h -- internal inflate state definition
  2.  * Copyright (C) 1995-2009 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. /* define NO_GZIP when compiling if you want to disable gzip header and
  12.    trailer decoding by inflate().  NO_GZIP would be used to avoid linking in
  13.    the crc code when it is not needed.  For shared libraries, gzip decoding
  14.    should be left enabled. */
  15. #ifndef NO_GZIP
  16. #  define GUNZIP
  17. #endif
  18.  
  19. /* Possible inflate modes between inflate() calls */
  20. typedef enum {
  21.     HEAD,       /* i: waiting for magic header */
  22.     FLAGS,      /* i: waiting for method and flags (gzip) */
  23.     TIME,       /* i: waiting for modification time (gzip) */
  24.     OS,         /* i: waiting for extra flags and operating system (gzip) */
  25.     EXLEN,      /* i: waiting for extra length (gzip) */
  26.     EXTRA,      /* i: waiting for extra bytes (gzip) */
  27.     NAME,       /* i: waiting for end of file name (gzip) */
  28.     COMMENT,    /* i: waiting for end of comment (gzip) */
  29.     HCRC,       /* i: waiting for header crc (gzip) */
  30.     DICTID,     /* i: waiting for dictionary check value */
  31.     DICT,       /* waiting for inflateSetDictionary() call */
  32.         TYPE,       /* i: waiting for type bits, including last-flag bit */
  33.         TYPEDO,     /* i: same, but skip check to exit inflate on new block */
  34.         STORED,     /* i: waiting for stored size (length and complement) */
  35.         COPY_,      /* i/o: same as COPY below, but only first time in */
  36.         COPY,       /* i/o: waiting for input or output to copy stored block */
  37.         TABLE,      /* i: waiting for dynamic block table lengths */
  38.         LENLENS,    /* i: waiting for code length code lengths */
  39.         CODELENS,   /* i: waiting for length/lit and distance code lengths */
  40.             LEN_,       /* i: same as LEN below, but only first time in */
  41.             LEN,        /* i: waiting for length/lit/eob 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 BAD or MEM on error -- not shown for clarity)
  59.  
  60.     Process header:
  61.         HEAD -> (gzip) or (zlib) or (raw)
  62.         (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
  63.                   HCRC -> TYPE
  64.         (zlib) -> DICTID or TYPE
  65.         DICTID -> DICT -> TYPE
  66.         (raw) -> TYPEDO
  67.     Read deflate blocks:
  68.             TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
  69.             STORED -> COPY_ -> COPY -> TYPE
  70.             TABLE -> LENLENS -> CODELENS -> LEN_
  71.             LEN_ -> LEN
  72.     Read deflate codes in fixed or dynamic block:
  73.                 LEN -> LENEXT or LIT or TYPE
  74.                 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
  75.                 LIT -> LEN
  76.     Process trailer:
  77.         CHECK -> LENGTH -> DONE
  78.  */
  79.  
  80. /* state maintained between inflate() calls.  Approximately 10K bytes. */
  81. struct inflate_state {
  82.     inflate_mode mode;          /* current inflate mode */
  83.     int last;                   /* true if processing last block */
  84.     int wrap;                   /* bit 0 true for zlib, bit 1 true for gzip */
  85.     int havedict;               /* true if dictionary provided */
  86.     int flags;                  /* gzip header method and flags (0 if zlib) */
  87.     unsigned dmax;              /* zlib header max distance (INFLATE_STRICT) */
  88.     unsigned long check;        /* protected copy of check value */
  89.     unsigned long total;        /* protected copy of output count */
  90.     gz_headerp head;            /* where to save gzip header information */
  91.         /* sliding window */
  92.     unsigned wbits;             /* log base 2 of requested window size */
  93.     unsigned wsize;             /* window size or zero if not using window */
  94.     unsigned whave;             /* valid bytes in the window */
  95.     unsigned wnext;             /* window write index */
  96.     unsigned char FAR *window;  /* allocated sliding window, if needed */
  97.         /* bit accumulator */
  98.     unsigned long hold;         /* input bit accumulator */
  99.     unsigned bits;              /* number of bits in "in" */
  100.         /* for string and stored block copying */
  101.     unsigned length;            /* literal or length of data to copy */
  102.     unsigned offset;            /* distance back to copy string from */
  103.         /* for table and code decoding */
  104.     unsigned extra;             /* extra bits needed */
  105.         /* fixed and dynamic code tables */
  106.     code const FAR *lencode;    /* starting table for length/literal codes */
  107.     code const FAR *distcode;   /* starting table for distance codes */
  108.     unsigned lenbits;           /* index bits for lencode */
  109.     unsigned distbits;          /* index bits for distcode */
  110.         /* dynamic table building */
  111.     unsigned ncode;             /* number of code length code lengths */
  112.     unsigned nlen;              /* number of length code lengths */
  113.     unsigned ndist;             /* number of distance code lengths */
  114.     unsigned have;              /* number of code lengths in lens[] */
  115.     code FAR *next;             /* next available space in codes[] */
  116.     unsigned short lens[320];   /* temporary storage for code lengths */
  117.     unsigned short work[288];   /* work area for code table building */
  118.     code codes[ENOUGH];         /* space for code tables */
  119.     int sane;                   /* if false, allow invalid distance too far */
  120.     int back;                   /* bits back of last unprocessed length/lit */
  121.     unsigned was;               /* initial length of match */
  122. };
  123.