Ruby: ext/zlib/zlib-1.2.13/contrib/infback9/inftree9.h Source File

Ruby 3.0.5p211 (2022-11-24 revision ba5cf0f7c52d4d35cc6a173c89eda98ceffa2dcf)

inftree9.h
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1/* inftree9.h -- header to use inftree9.c
2 * Copyright (C) 1995-2008 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 100eeeee - 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 the dynamic table. The maximum number of code structures is
39 1446, which is the sum of 852 for literal/length codes and 594 for distance
40 codes. These values were found by exhaustive searches using the program
41 examples/enough.c found in the zlib distribution. The arguments to that
42 program are the number of symbols, the initial root table size, and the
43 maximum bit length of a code. "enough 286 9 15" for literal/length codes
44 returns returns 852, and "enough 32 6 15" for distance codes returns 594.
45 The initial root table size (9 or 6) is found in the fifth argument of the
46 inflate_table() calls in infback9.c. If the root table size is changed,
47 then these maximum sizes would be need to be recalculated and updated. */
48#define ENOUGH_LENS 852
49#define ENOUGH_DISTS 594
50#define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
51
52/* Type of code to build for inflate_table9() */
53 typedef enum {
54 CODES,
55 LENS,
56 DISTS
57} codetype;
58
59 extern int inflate_table9 OF((codetype type, unsigned short FAR *lens,
60 unsigned codes, code FAR * FAR *table,
61 unsigned FAR *bits, unsigned short FAR *work));
bits
int bits(struct state *s, int need)
Definition: blast.c:72
inflate_table9
int inflate_table9(codetype type, unsigned short FAR *lens, unsigned codes, code FAR *FAR *table, unsigned FAR *bits, unsigned short FAR *work)
Definition: inftree9.c:32
codetype
codetype
Definition: inftree9.h:53
CODES
@ CODES
Definition: inftree9.h:54
LENS
@ LENS
Definition: inftree9.h:55
DISTS
@ DISTS
Definition: inftree9.h:56
codes
int codes(struct state *s, const struct huffman *lencode, const struct huffman *distcode)
Definition: puff.c:436
code
Definition: inftree9.h:24
code::op
unsigned char op
Definition: inftree9.h:25
code::bits
unsigned char bits
Definition: inftree9.h:26
code::val
unsigned short val
Definition: inftree9.h:27
OF
#define OF(args)
Definition: zconf.h:293
FAR
#define FAR
Definition: zconf.h:393