/[pcsx2_0.9.7]/trunk/3rdparty/zlib/inftrees.h
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Revision 31 - (hide annotations) (download)
Tue Sep 7 03:24:11 2010 UTC (10 years, 4 months ago) by william
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committing r3113 initial commit again...
1 william 31 /* 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 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 distribtution. 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     extern int inflate_table OF((codetype type, unsigned short FAR *lens,
61     unsigned codes, code FAR * FAR *table,
62     unsigned FAR *bits, unsigned short FAR *work));

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