common/dist/zlib/inftrees.h

   1 /*      $NetBSD: inftrees.h,v 1.1.1.1 2006/01/14 20:10:31 christos Exp $        */
   2
   3 /* inftrees.h -- header to use inftrees.c
   4  * Copyright (C) 1995-2005 Mark Adler
   5  * For conditions of distribution and use, see copyright notice in zlib.h
   6  */
   7
   8 /* WARNING: this file should *not* be used by applications. It is
   9    part of the implementation of the compression library and is
  10    subject to change. Applications should only use zlib.h.
  11  */
  12
  13 /* Structure for decoding tables.  Each entry provides either the
  14    information needed to do the operation requested by the code that
  15    indexed that table entry, or it provides a pointer to another
  16    table that indexes more bits of the code.  op indicates whether
  17    the entry is a pointer to another table, a literal, a length or
  18    distance, an end-of-block, or an invalid code.  For a table
  19    pointer, the low four bits of op is the number of index bits of
  20    that table.  For a length or distance, the low four bits of op
  21    is the number of extra bits to get after the code.  bits is
  22    the number of bits in this code or part of the code to drop off
  23    of the bit buffer.  val is the actual byte to output in the case
  24    of a literal, the base length or distance, or the offset from
  25    the current table to the next table.  Each entry is four bytes. */
  26 typedef struct {
  27     unsigned char op;           /* operation, extra bits, table bits */
  28     unsigned char bits;         /* bits in this part of the code */
  29     unsigned short val;         /* offset in table or code value */
  30 } code;
  31
  32 /* op values as set by inflate_table():
  33     00000000 - literal
  34     0000tttt - table link, tttt != 0 is the number of table index bits
  35     0001eeee - length or distance, eeee is the number of extra bits
  36     01100000 - end of block
  37     01000000 - invalid code
  38  */
  39
  40 /* Maximum size of dynamic tree.  The maximum found in a long but non-
  41    exhaustive search was 1444 code structures (852 for length/literals
  42    and 592 for distances, the latter actually the result of an
  43    exhaustive search).  The true maximum is not known, but the value
  44    below is more than safe. */
  45 #define ENOUGH 2048
  46 #define MAXD 592
  47
  48 /* Type of code to build for inftable() */
  49 typedef enum {
  50     CODES,
  51     LENS,
  52     DISTS
  53 } codetype;
  54
  55 extern int inflate_table OF((codetype type, unsigned short FAR *lens,
  56                              unsigned codes, code FAR * FAR *table,
  57                              unsigned FAR *bits, unsigned short FAR *work));