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