inflate.h (5916B)
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 /* 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: waiting for input or output to copy stored block */ 36 TABLE, /* i: waiting for dynamic block table lengths */ 37 LENLENS, /* i: waiting for code length code lengths */ 38 CODELENS, /* i: waiting for length/lit and distance code lengths */ 39 LEN, /* i: waiting for length/lit code */ 40 LENEXT, /* i: waiting for length extra bits */ 41 DIST, /* i: waiting for distance code */ 42 DISTEXT, /* i: waiting for distance extra bits */ 43 MATCH, /* o: waiting for output space to copy string */ 44 LIT, /* o: waiting for output space to write literal */ 45 CHECK, /* i: waiting for 32-bit check value */ 46 LENGTH, /* i: waiting for 32-bit length (gzip) */ 47 DONE, /* finished check, done -- remain here until reset */ 48 BAD, /* got a data error -- remain here until reset */ 49 MEM, /* got an inflate() memory error -- remain here until reset */ 50 SYNC /* looking for synchronization bytes to restart inflate() */ 51 } inflate_mode; 52 53 /* 54 State transitions between above modes - 55 56 (most modes can go to the BAD or MEM mode -- not shown for clarity) 57 58 Process header: 59 HEAD -> (gzip) or (zlib) 60 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME 61 NAME -> COMMENT -> HCRC -> TYPE 62 (zlib) -> DICTID or TYPE 63 DICTID -> DICT -> TYPE 64 Read deflate blocks: 65 TYPE -> STORED or TABLE or LEN or CHECK 66 STORED -> COPY -> TYPE 67 TABLE -> LENLENS -> CODELENS -> LEN 68 Read deflate codes: 69 LEN -> LENEXT or LIT or TYPE 70 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN 71 LIT -> LEN 72 Process trailer: 73 CHECK -> LENGTH -> DONE 74 */ 75 76 /* state maintained between inflate() calls. Approximately 7K bytes. */ 77 struct inflate_state { 78 inflate_mode mode; /* current inflate mode */ 79 int last; /* true if processing last block */ 80 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ 81 int havedict; /* true if dictionary provided */ 82 int flags; /* gzip header method and flags (0 if zlib) */ 83 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */ 84 unsigned long check; /* protected copy of check value */ 85 unsigned long total; /* protected copy of output count */ 86 gz_headerp head; /* where to save gzip header information */ 87 /* sliding window */ 88 unsigned wbits; /* log base 2 of requested window size */ 89 unsigned wsize; /* window size or zero if not using window */ 90 unsigned whave; /* valid bytes in the window */ 91 unsigned write; /* window write index */ 92 unsigned char FAR *window; /* allocated sliding window, if needed */ 93 /* bit accumulator */ 94 unsigned long hold; /* input bit accumulator */ 95 unsigned bits; /* number of bits in "in" */ 96 /* for string and stored block copying */ 97 unsigned length; /* literal or length of data to copy */ 98 unsigned offset; /* distance back to copy string from */ 99 /* for table and code decoding */ 100 unsigned extra; /* extra bits needed */ 101 /* fixed and dynamic code tables */ 102 code const FAR *lencode; /* starting table for length/literal codes */ 103 code const FAR *distcode; /* starting table for distance codes */ 104 unsigned lenbits; /* index bits for lencode */ 105 unsigned distbits; /* index bits for distcode */ 106 /* dynamic table building */ 107 unsigned ncode; /* number of code length code lengths */ 108 unsigned nlen; /* number of length code lengths */ 109 unsigned ndist; /* number of distance code lengths */ 110 unsigned have; /* number of code lengths in lens[] */ 111 code FAR *next; /* next available space in codes[] */ 112 unsigned short lens[320]; /* temporary storage for code lengths */ 113 unsigned short work[288]; /* work area for code table building */ 114 code codes[ENOUGH]; /* space for code tables */ 115 };