1#ifndef INFTREES_H_
2#define INFTREES_H_
3
4/* inftrees.h -- header to use inftrees.c
5 * Copyright (C) 1995-2005, 2010 Mark Adler
6 * For conditions of distribution and use, see copyright notice in zlib.h
7 */
8
9/* WARNING: this file should *not* be used by applications. It is
10 part of the implementation of the compression library and is
11 subject to change. Applications should only use zlib.h.
12 */
13
14/* Structure for decoding tables. Each entry provides either the
15 information needed to do the operation requested by the code that
16 indexed that table entry, or it provides a pointer to another
17 table that indexes more bits of the code. op indicates whether
18 the entry is a pointer to another table, a literal, a length or
19 distance, an end-of-block, or an invalid code. For a table
20 pointer, the low four bits of op is the number of index bits of
21 that table. For a length or distance, the low four bits of op
22 is the number of extra bits to get after the code. bits is
23 the number of bits in this code or part of the code to drop off
24 of the bit buffer. val is the actual byte to output in the case
25 of a literal, the base length or distance, or the offset from
26 the current table to the next table. Each entry is four bytes. */
27typedef struct {
28 unsigned char op; /* operation, extra bits, table bits */
29 unsigned char bits; /* bits in this part of the code */
30 uint16_t val; /* offset in table or code value */
31} code;
32
33/* op values as set by inflate_table():
34 00000000 - literal
35 0000tttt - table link, tttt != 0 is the number of table index bits
36 0001eeee - length or distance, eeee is the number of extra bits
37 01100000 - end of block
38 01000000 - invalid code
39 */
40
41/* Maximum size of the dynamic table. The maximum number of code structures is
42 1444, which is the sum of 852 for literal/length codes and 592 for distance
43 codes. These values were found by exhaustive searches using the program
44 examples/enough.c found in the zlib distributions. The arguments to that
45 program are the number of symbols, the initial root table size, and the
46 maximum bit length of a code. "enough 286 9 15" for literal/length codes
47 returns returns 852, and "enough 30 6 15" for distance codes returns 592.
48 The initial root table size (9 or 6) is found in the fifth argument of the
49 inflate_table() calls in inflate.c and infback.c. If the root table size is
50 changed, then these maximum sizes would be need to be recalculated and
51 updated. */
52#define ENOUGH_LENS 852
53#define ENOUGH_DISTS 592
54#define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
55
56/* Type of code to build for inflate_table() */
57typedef enum {
58 CODES,
59 LENS,
60 DISTS
61} codetype;
62
63int Z_INTERNAL zng_inflate_table (codetype type, uint16_t *lens, unsigned codes,
64 code * *table, unsigned *bits, uint16_t *work);
65
66#endif /* INFTREES_H_ */
67