| [1096] | 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 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 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));
|
|---|
