inflate.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2018, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */
 
/* WARNING: this file should *not* be used by applications. It is
   part of the implementation of the compression library and is
   subject to change. Applications should only use zlib.h.
 */
 
/* define NO_GZIP when compiling if you want to disable gzip header and
   trailer decoding by inflate().  NO_GZIP would be used to avoid linking in
   the crc code when it is not needed.  For shared libraries, gzip decoding
   should be left enabled. */
#ifndef NO_GZIP
#define GUNZIP
#endif
 
/* Possible inflate modes between inflate() calls */
typedef enum {
        HEAD, /* i: waiting for magic header */
        FLAGS, /* i: waiting for method and flags (gzip) */
        TIME, /* i: waiting for modification time (gzip) */
        OS, /* i: waiting for extra flags and operating system (gzip) */
        EXLEN, /* i: waiting for extra length (gzip) */
        EXTRA, /* i: waiting for extra bytes (gzip) */
        NAME, /* i: waiting for end of file name (gzip) */
        COMMENT, /* i: waiting for end of comment (gzip) */
        HCRC, /* i: waiting for header crc (gzip) */
        DICTID, /* i: waiting for dictionary check value */
        DICT, /* waiting for inflateSetDictionary() call */
        TYPE, /* i: waiting for type bits, including last-flag bit */
        TYPEDO, /* i: same, but skip check to exit inflate on new block */
        STORED, /* i: waiting for stored size (length and complement) */
        COPY, /* i/o: waiting for input or output to copy stored block */
        TABLE, /* i: waiting for dynamic block table lengths */
        LENLENS, /* i: waiting for code length code lengths */
        CODELENS, /* i: waiting for length/lit and distance code lengths */
        LEN, /* i: waiting for length/lit code */
        LENEXT, /* i: waiting for length extra bits */
        DIST, /* i: waiting for distance code */
        DISTEXT, /* i: waiting for distance extra bits */
        MATCH, /* o: waiting for output space to copy string */
        LIT, /* o: waiting for output space to write literal */
        CHECK, /* i: waiting for 32-bit check value */
        LENGTH, /* i: waiting for 32-bit length (gzip) */
        DONE, /* finished check, done -- remain here until reset */
        BAD, /* got a data error -- remain here until reset */
        MEM, /* got an inflate() memory error -- remain here until reset */
        SYNC /* looking for synchronization bytes to restart inflate() */
} inflate_mode;
 
/*
        State transitions between above modes -
 
        (most modes can go to the BAD or MEM mode -- not shown for clarity)
 
        Process header:
                HEAD -> (gzip) or (zlib)
                (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME
                NAME -> COMMENT -> HCRC -> TYPE
                (zlib) -> DICTID or TYPE
                DICTID -> DICT -> TYPE
        Read deflate blocks:
                        TYPE -> STORED or TABLE or LEN or CHECK
                        STORED -> COPY -> TYPE
                        TABLE -> LENLENS -> CODELENS -> LEN
        Read deflate codes:
                                LEN -> LENEXT or LIT or TYPE
                                LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
                                LIT -> LEN
        Process trailer:
                CHECK -> LENGTH -> DONE
 */
 
/* state maintained between inflate() calls.  Approximately 7K bytes. */
struct inflate_state
{
        inflate_mode mode; /* current inflate mode */
        int last; /* true if processing last block */
        int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
        int havedict; /* true if dictionary provided */
        int flags; /* gzip header method and flags (0 if zlib) */
        unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
        unsigned long check; /* protected copy of check value */
        unsigned long total; /* protected copy of output count */
        gz_headerp head; /* where to save gzip header information */
        /* sliding window */
        unsigned wbits; /* log base 2 of requested window size */
        unsigned wsize; /* window size or zero if not using window */
        unsigned whave; /* valid bytes in the window */
        unsigned write; /* window write index */
        unsigned char FAR* window; /* allocated sliding window, if needed */
        /* bit accumulator */
        unsigned long hold; /* input bit accumulator */
        unsigned bits; /* number of bits in "in" */
        /* for string and stored block copying */
        unsigned length; /* literal or length of data to copy */
        unsigned offset; /* distance back to copy string from */
        /* for table and code decoding */
        unsigned extra; /* extra bits needed */
        /* fixed and dynamic code tables */
        code const FAR* lencode; /* starting table for length/literal codes */
        code const FAR* distcode; /* starting table for distance codes */
        unsigned lenbits; /* index bits for lencode */
        unsigned distbits; /* index bits for distcode */
        /* dynamic table building */
        unsigned ncode; /* number of code length code lengths */
        unsigned nlen; /* number of length code lengths */
        unsigned ndist; /* number of distance code lengths */
        unsigned have; /* number of code lengths in lens[] */
        code FAR* next; /* next available space in codes[] */
        unsigned short lens[320]; /* temporary storage for code lengths */
        unsigned short work[288]; /* work area for code table building */
        code codes[ENOUGH]; /* space for code tables */
};