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1 /* inflate.h -- internal inflate state definition
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2 * Copyright (C) 1995-2009 Mark Adler
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3 * For conditions of distribution and use, see copyright notice in zlib.h
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4 */
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5
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6 /* WARNING: this file should *not* be used by applications. It is
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7 part of the implementation of the compression library and is
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8 subject to change. Applications should only use zlib.h.
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9 */
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10
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11 /* define NO_GZIP when compiling if you want to disable gzip header and
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12 trailer decoding by inflate(). NO_GZIP would be used to avoid linking in
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13 the crc code when it is not needed. For shared libraries, gzip decoding
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14 should be left enabled. */
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15 #ifndef NO_GZIP
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16 # define GUNZIP
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17 #endif
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18
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19 /* Possible inflate modes between inflate() calls */
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20 typedef enum {
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21 HEAD, /* i: waiting for magic header */
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22 FLAGS, /* i: waiting for method and flags (gzip) */
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23 TIME, /* i: waiting for modification time (gzip) */
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24 OS, /* i: waiting for extra flags and operating system (gzip) */
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25 EXLEN, /* i: waiting for extra length (gzip) */
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26 EXTRA, /* i: waiting for extra bytes (gzip) */
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27 NAME, /* i: waiting for end of file name (gzip) */
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28 COMMENT, /* i: waiting for end of comment (gzip) */
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29 HCRC, /* i: waiting for header crc (gzip) */
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30 DICTID, /* i: waiting for dictionary check value */
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31 DICT, /* waiting for inflateSetDictionary() call */
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32 TYPE, /* i: waiting for type bits, including last-flag bit */
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33 TYPEDO, /* i: same, but skip check to exit inflate on new block */
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34 STORED, /* i: waiting for stored size (length and complement) */
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35 COPY_, /* i/o: same as COPY below, but only first time in */
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36 COPY, /* i/o: waiting for input or output to copy stored block */
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37 TABLE, /* i: waiting for dynamic block table lengths */
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38 LENLENS, /* i: waiting for code length code lengths */
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39 CODELENS, /* i: waiting for length/lit and distance code lengths */
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40 LEN_, /* i: same as LEN below, but only first time in */
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41 LEN, /* i: waiting for length/lit/eob code */
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42 LENEXT, /* i: waiting for length extra bits */
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43 DIST, /* i: waiting for distance code */
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44 DISTEXT, /* i: waiting for distance extra bits */
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45 MATCH, /* o: waiting for output space to copy string */
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46 LIT, /* o: waiting for output space to write literal */
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47 CHECK, /* i: waiting for 32-bit check value */
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48 LENGTH, /* i: waiting for 32-bit length (gzip) */
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49 DONE, /* finished check, done -- remain here until reset */
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50 BAD, /* got a data error -- remain here until reset */
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51 MEM, /* got an inflate() memory error -- remain here until reset */
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52 SYNC /* looking for synchronization bytes to restart inflate() */
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53 } inflate_mode;
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54
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55 /*
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56 State transitions between above modes -
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57
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58 (most modes can go to BAD or MEM on error -- not shown for clarity)
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59
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60 Process header:
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61 HEAD -> (gzip) or (zlib) or (raw)
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62 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
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63 HCRC -> TYPE
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64 (zlib) -> DICTID or TYPE
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65 DICTID -> DICT -> TYPE
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66 (raw) -> TYPEDO
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67 Read deflate blocks:
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68 TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
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69 STORED -> COPY_ -> COPY -> TYPE
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70 TABLE -> LENLENS -> CODELENS -> LEN_
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71 LEN_ -> LEN
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72 Read deflate codes in fixed or dynamic block:
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73 LEN -> LENEXT or LIT or TYPE
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74 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
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75 LIT -> LEN
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76 Process trailer:
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77 CHECK -> LENGTH -> DONE
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78 */
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79
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80 /* state maintained between inflate() calls. Approximately 10K bytes. */
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81 struct inflate_state {
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82 inflate_mode mode; /* current inflate mode */
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83 int last; /* true if processing last block */
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84 int wrap; /* bit 0 true for zlib, bit 1 true for gzip */
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85 int havedict; /* true if dictionary provided */
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86 int flags; /* gzip header method and flags (0 if zlib) */
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87 unsigned dmax; /* zlib header max distance (INFLATE_STRICT) */
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88 unsigned long check; /* protected copy of check value */
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89 unsigned long total; /* protected copy of output count */
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90 gz_headerp head; /* where to save gzip header information */
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91 /* sliding window */
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92 unsigned wbits; /* log base 2 of requested window size */
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93 unsigned wsize; /* window size or zero if not using window */
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94 unsigned whave; /* valid bytes in the window */
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95 unsigned wnext; /* window write index */
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96 unsigned char FAR *window; /* allocated sliding window, if needed */
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97 /* bit accumulator */
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98 unsigned long hold; /* input bit accumulator */
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99 unsigned bits; /* number of bits in "in" */
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100 /* for string and stored block copying */
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101 unsigned length; /* literal or length of data to copy */
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102 unsigned offset; /* distance back to copy string from */
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103 /* for table and code decoding */
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104 unsigned extra; /* extra bits needed */
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105 /* fixed and dynamic code tables */
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106 code const FAR *lencode; /* starting table for length/literal codes */
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107 code const FAR *distcode; /* starting table for distance codes */
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108 unsigned lenbits; /* index bits for lencode */
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109 unsigned distbits; /* index bits for distcode */
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110 /* dynamic table building */
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111 unsigned ncode; /* number of code length code lengths */
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112 unsigned nlen; /* number of length code lengths */
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113 unsigned ndist; /* number of distance code lengths */
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114 unsigned have; /* number of code lengths in lens[] */
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115 code FAR *next; /* next available space in codes[] */
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116 unsigned short lens[320]; /* temporary storage for code lengths */
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117 unsigned short work[288]; /* work area for code table building */
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118 code codes[ENOUGH]; /* space for code tables */
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119 int sane; /* if false, allow invalid distance too far */
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120 int back; /* bits back of last unprocessed length/lit */
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121 unsigned was; /* initial length of match */
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122 };
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