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/* inflate.h -- internal inflate state definition |
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* Copyright (C) 1995-2009 Mark Adler |
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* For conditions of distribution and use, see copyright notice in zlib.h |
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*/ |
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|
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/* WARNING: this file should *not* be used by applications. It is |
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part of the implementation of the compression library and is |
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subject to change. Applications should only use zlib.h. |
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*/ |
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|
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/* define NO_GZIP when compiling if you want to disable gzip header and |
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trailer decoding by inflate(). NO_GZIP would be used to avoid linking in |
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the crc code when it is not needed. For shared libraries, gzip decoding |
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should be left enabled. */ |
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#ifndef NO_GZIP |
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# define GUNZIP |
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#endif |
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|
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/* Possible inflate modes between inflate() calls */ |
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typedef enum { |
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HEAD, /* i: waiting for magic header */ |
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FLAGS, /* i: waiting for method and flags (gzip) */ |
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TIME, /* i: waiting for modification time (gzip) */ |
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OS, /* i: waiting for extra flags and operating system (gzip) */ |
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EXLEN, /* i: waiting for extra length (gzip) */ |
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EXTRA, /* i: waiting for extra bytes (gzip) */ |
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NAME, /* i: waiting for end of file name (gzip) */ |
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COMMENT, /* i: waiting for end of comment (gzip) */ |
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HCRC, /* i: waiting for header crc (gzip) */ |
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DICTID, /* i: waiting for dictionary check value */ |
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DICT, /* waiting for inflateSetDictionary() call */ |
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TYPE, /* i: waiting for type bits, including last-flag bit */ |
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TYPEDO, /* i: same, but skip check to exit inflate on new block */ |
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STORED, /* i: waiting for stored size (length and complement) */ |
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COPY_, /* i/o: same as COPY below, but only first time in */ |
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COPY, /* i/o: waiting for input or output to copy stored block */ |
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TABLE, /* i: waiting for dynamic block table lengths */ |
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LENLENS, /* i: waiting for code length code lengths */ |
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CODELENS, /* i: waiting for length/lit and distance code lengths */ |
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LEN_, /* i: same as LEN below, but only first time in */ |
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LEN, /* i: waiting for length/lit/eob code */ |
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LENEXT, /* i: waiting for length extra bits */ |
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DIST, /* i: waiting for distance code */ |
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DISTEXT, /* i: waiting for distance extra bits */ |
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MATCH, /* o: waiting for output space to copy string */ |
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LIT, /* o: waiting for output space to write literal */ |
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CHECK, /* i: waiting for 32-bit check value */ |
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LENGTH, /* i: waiting for 32-bit length (gzip) */ |
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DONE, /* finished check, done -- remain here until reset */ |
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BAD, /* got a data error -- remain here until reset */ |
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MEM, /* got an inflate() memory error -- remain here until reset */ |
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SYNC /* looking for synchronization bytes to restart inflate() */ |
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} inflate_mode; |
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|
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/* |
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State transitions between above modes - |
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|
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(most modes can go to BAD or MEM on error -- not shown for clarity) |
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|
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Process header: |
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HEAD -> (gzip) or (zlib) or (raw) |
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(gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT -> |
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HCRC -> TYPE |
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(zlib) -> DICTID or TYPE |
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DICTID -> DICT -> TYPE |
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(raw) -> TYPEDO |
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Read deflate blocks: |
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TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK |
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STORED -> COPY_ -> COPY -> TYPE |
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TABLE -> LENLENS -> CODELENS -> LEN_ |
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LEN_ -> LEN |
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Read deflate codes in fixed or dynamic block: |
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LEN -> LENEXT or LIT or TYPE |
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LENEXT -> DIST -> DISTEXT -> MATCH -> LEN |
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LIT -> LEN |
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Process trailer: |
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CHECK -> LENGTH -> DONE |
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*/ |
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|
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/* state maintained between inflate() calls. Approximately 10K bytes. */ |
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struct inflate_state { |
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inflate_mode mode; /* current inflate mode */ |
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int last; /* true if processing last block */ |
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int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ |
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int havedict; /* true if dictionary provided */ |
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int flags; /* gzip header method and flags (0 if zlib) */ |
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unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */ |
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unsigned long check; /* protected copy of check value */ |
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unsigned long total; /* protected copy of output count */ |
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gz_headerp head; /* where to save gzip header information */ |
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/* sliding window */ |
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unsigned wbits; /* log base 2 of requested window size */ |
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unsigned wsize; /* window size or zero if not using window */ |
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unsigned whave; /* valid bytes in the window */ |
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unsigned wnext; /* window write index */ |
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unsigned char FAR *window; /* allocated sliding window, if needed */ |
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/* bit accumulator */ |
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unsigned long hold; /* input bit accumulator */ |
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unsigned bits; /* number of bits in "in" */ |
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/* for string and stored block copying */ |
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unsigned length; /* literal or length of data to copy */ |
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unsigned offset; /* distance back to copy string from */ |
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/* for table and code decoding */ |
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unsigned extra; /* extra bits needed */ |
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/* fixed and dynamic code tables */ |
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code const FAR *lencode; /* starting table for length/literal codes */ |
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code const FAR *distcode; /* starting table for distance codes */ |
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unsigned lenbits; /* index bits for lencode */ |
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unsigned distbits; /* index bits for distcode */ |
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/* dynamic table building */ |
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unsigned ncode; /* number of code length code lengths */ |
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unsigned nlen; /* number of length code lengths */ |
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unsigned ndist; /* number of distance code lengths */ |
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unsigned have; /* number of code lengths in lens[] */ |
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code FAR *next; /* next available space in codes[] */ |
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unsigned short lens[320]; /* temporary storage for code lengths */ |
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unsigned short work[288]; /* work area for code table building */ |
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code codes[ENOUGH]; /* space for code tables */ |
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int sane; /* if false, allow invalid distance too far */ |
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int back; /* bits back of last unprocessed length/lit */ |
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unsigned was; /* initial length of match */ |
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}; |
