source: trunk/sys/libz/inftrees.h @ 63

Last change on this file since 63 was 1, checked in by alain, 7 years ago

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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 */
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 */
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. */
24typedef 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;
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 */
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
46/* Type of code to build for inftable() */
47typedef enum {
48    CODES,
49    LENS,
50    DISTS
51} codetype;
53extern 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));
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