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1654
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1 /* inflate.h -- internal inflate state definition |
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2 * Copyright (C) 1995-2003 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 #ifdef GUNZIP |
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23 FLAGS, /* i: waiting for method and flags (gzip) */ |
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24 TIME, /* i: waiting for modification time (gzip) */ |
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25 OS, /* i: waiting for extra flags and operating system (gzip) */ |
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26 EXLEN, /* i: waiting for extra length (gzip) */ |
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27 EXTRA, /* i: waiting for extra bytes (gzip) */ |
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28 NAME, /* i: waiting for end of file name (gzip) */ |
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29 COMMENT, /* i: waiting for end of comment (gzip) */ |
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30 HCRC, /* i: waiting for header crc (gzip) */ |
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31 #endif |
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32 DICTID, /* i: waiting for dictionary check value */ |
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33 DICT, /* waiting for inflateSetDictionary() call */ |
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34 TYPE, /* i: waiting for type bits, including last-flag bit */ |
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35 TYPEDO, /* i: same, but skip check to exit inflate on new block */ |
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36 STORED, /* i: waiting for stored size (length and complement) */ |
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37 COPY, /* i/o: waiting for input or output to copy stored block */ |
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38 TABLE, /* i: waiting for dynamic block table lengths */ |
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39 LENLENS, /* i: waiting for code length code lengths */ |
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40 CODELENS, /* i: waiting for length/lit and distance code lengths */ |
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41 LEN, /* i: waiting for length/lit 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 #ifdef GUNZIP |
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49 LENGTH, /* i: waiting for 32-bit length (gzip) */ |
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50 #endif |
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51 DONE, /* finished check, done -- remain here until reset */ |
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52 BAD, /* got a data error -- remain here until reset */ |
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53 MEM, /* got an inflate() memory error -- remain here until reset */ |
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54 SYNC /* looking for synchronization bytes to restart inflate() */ |
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55 } inflate_mode; |
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56 |
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57 /* |
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58 State transitions between above modes - |
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59 |
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60 (most modes can go to the BAD or MEM mode -- not shown for clarity) |
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61 |
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62 Process header: |
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63 HEAD -> (gzip) or (zlib) |
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64 (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME |
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65 NAME -> COMMENT -> HCRC -> TYPE |
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66 (zlib) -> DICTID or TYPE |
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67 DICTID -> DICT -> TYPE |
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68 Read deflate blocks: |
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69 TYPE -> STORED or TABLE or LEN or CHECK |
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70 STORED -> COPY -> TYPE |
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71 TABLE -> LENLENS -> CODELENS -> LEN |
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72 Read deflate codes: |
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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 7K 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 long check; /* protected copy of check value */ |
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88 unsigned long total; /* protected copy of output count */ |
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89 /* sliding window */ |
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90 unsigned wbits; /* log base 2 of requested window size */ |
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91 unsigned wsize; /* window size or zero if not using window */ |
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92 unsigned whave; /* valid bytes in the window */ |
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93 unsigned write; /* window write index */ |
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94 unsigned char FAR *window; /* allocated sliding window, if needed */ |
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95 /* bit accumulator */ |
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96 unsigned long hold; /* input bit accumulator */ |
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97 unsigned bits; /* number of bits in "in" */ |
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98 /* for string and stored block copying */ |
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99 unsigned length; /* literal or length of data to copy */ |
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100 unsigned offset; /* distance back to copy string from */ |
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101 /* for table and code decoding */ |
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102 unsigned extra; /* extra bits needed */ |
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103 /* fixed and dynamic code tables */ |
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104 code const FAR *lencode; /* starting table for length/literal codes */ |
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105 code const FAR *distcode; /* starting table for distance codes */ |
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106 unsigned lenbits; /* index bits for lencode */ |
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107 unsigned distbits; /* index bits for distcode */ |
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108 /* dynamic table building */ |
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109 unsigned ncode; /* number of code length code lengths */ |
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110 unsigned nlen; /* number of length code lengths */ |
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111 unsigned ndist; /* number of distance code lengths */ |
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112 unsigned have; /* number of code lengths in lens[] */ |
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113 code FAR *next; /* next available space in codes[] */ |
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114 unsigned short lens[320]; /* temporary storage for code lengths */ |
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115 unsigned short work[288]; /* work area for code table building */ |
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116 code codes[ENOUGH]; /* space for code tables */ |
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117 }; |
