RTEMS
6.1-rc5
Loading...
Searching...
No Matches
cpukit
compression
zlib
inftrees.h
1
/* inftrees.h -- header to use inftrees.c
2
* Copyright (C) 1995-2005, 2010 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 the dynamic table. The maximum number of code structures is
39
1444, which is the sum of 852 for literal/length codes and 592 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 30 6 15" for distance codes returns 592.
45
The initial root table size (9 or 6) is found in the fifth argument of the
46
inflate_table() calls in inflate.c and infback.c. If the root table size is
47
changed, then these maximum sizes would be need to be recalculated and
48
updated. */
49
#define ENOUGH_LENS 852
50
#define ENOUGH_DISTS 592
51
#define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
52
53
/* Type of code to build for inflate_table() */
54
typedef
enum
{
55
CODES,
56
LENS,
57
DISTS
58
} codetype;
59
60
int
ZLIB_INTERNAL inflate_table OF((codetype type,
unsigned
short
FAR *lens,
61
unsigned
codes,
code
FAR * FAR *table,
62
unsigned
FAR *bits,
unsigned
short
FAR *work));
code
Definition:
inftrees.h:24
Generated by
1.9.6