inftrees.h 2.3 KB

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  1. /* inftrees.h -- header to use inftrees.c
  2. * Copyright (C) 1995-2005 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. /* Structure for decoding tables. Each entry provides either the
  10. information needed to do the operation requested by the code that
  11. indexed that table entry, or it provides a pointer to another
  12. table that indexes more bits of the code. op indicates whether
  13. the entry is a pointer to another table, a literal, a length or
  14. distance, an end-of-block, or an invalid code. For a table
  15. pointer, the low four bits of op is the number of index bits of
  16. that table. For a length or distance, the low four bits of op
  17. is the number of extra bits to get after the code. bits is
  18. the number of bits in this code or part of the code to drop off
  19. of the bit buffer. val is the actual byte to output in the case
  20. of a literal, the base length or distance, or the offset from
  21. the current table to the next table. Each entry is four bytes. */
  22. typedef struct {
  23. unsigned char op; /* operation, extra bits, table bits */
  24. unsigned char bits; /* bits in this part of the code */
  25. unsigned short val; /* offset in table or code value */
  26. } code;
  27. /* op values as set by inflate_table():
  28. 00000000 - literal
  29. 0000tttt - table link, tttt != 0 is the number of table index bits
  30. 0001eeee - length or distance, eeee is the number of extra bits
  31. 01100000 - end of block
  32. 01000000 - invalid code
  33. */
  34. /* Maximum size of dynamic tree. The maximum found in a long but non-
  35. exhaustive search was 1444 code structures (852 for length/literals
  36. and 592 for distances, the latter actually the result of an
  37. exhaustive search). The true maximum is not known, but the value
  38. below is more than safe. */
  39. #define ENOUGH 2048
  40. #define MAXD 592
  41. /* Type of code to build for inftable() */
  42. typedef enum {
  43. CODES,
  44. LENS,
  45. DISTS
  46. } codetype;
  47. extern int inflate_table OF((codetype type, unsigned short FAR *lens,
  48. unsigned codes, code FAR * FAR *table,
  49. unsigned FAR *bits, unsigned short FAR *work));