inflate.h 5.8 KB

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