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