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 */
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 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
53/* Type of code to build for inflate_table() */
54typedef enum {
55    CODES,
56    LENS,
57    DISTS
58} codetype;
60int 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));