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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 }; |
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