1 /* $OpenBSD: inftrees.h,v 1.8 2005/07/20 15:56:46 millert Exp $ */
2 /* inftrees.h -- header to use inftrees.c
3 * Copyright (C) 1995-2005 Mark Adler
4 * For conditions of distribution and use, see copyright notice in zlib.h
5 */
6
7 /* WARNING: this file should *not* be used by applications. It is
8 part of the implementation of the compression library and is
9 subject to change. Applications should only use zlib.h.
10 */
11
12 /* Structure for decoding tables. Each entry provides either the
13 information needed to do the operation requested by the code that
14 indexed that table entry, or it provides a pointer to another
15 table that indexes more bits of the code. op indicates whether
16 the entry is a pointer to another table, a literal, a length or
17 distance, an end-of-block, or an invalid code. For a table
18 pointer, the low four bits of op is the number of index bits of
19 that table. For a length or distance, the low four bits of op
20 is the number of extra bits to get after the code. bits is
21 the number of bits in this code or part of the code to drop off
22 of the bit buffer. val is the actual byte to output in the case
23 of a literal, the base length or distance, or the offset from
24 the current table to the next table. Each entry is four bytes. */
25 typedef struct {
26 unsigned char op; /* operation, extra bits, table bits */
27 unsigned char bits; /* bits in this part of the code */
28 unsigned short val; /* offset in table or code value */
29 } code;
30
31 /* op values as set by inflate_table():
32 00000000 - literal
33 0000tttt - table link, tttt != 0 is the number of table index bits
34 0001eeee - length or distance, eeee is the number of extra bits
35 01100000 - end of block
36 01000000 - invalid code
37 */
38
39 /* Maximum size of dynamic tree. The maximum found in a long but non-
40 exhaustive search was 1444 code structures (852 for length/literals
41 and 592 for distances, the latter actually the result of an
42 exhaustive search). The true maximum is not known, but the value
43 below is more than safe. */
44 #define ENOUGH 2048
45 #define MAXD 592
46
47 /* Type of code to build for inftable() */
48 typedef enum {
49 CODES,
50 LENS,
51 DISTS
52 } codetype;
53
54 extern int inflate_table OF((codetype type, unsigned short FAR *lens,
55 unsigned codes, code FAR * FAR *table,
56 unsigned FAR *bits, unsigned short FAR *work));