|
|
/* inftree9.h -- header to use inftree9.c
* Copyright (C) 1995-2008 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h */
/* WARNING: this file should *not* be used by applications. It is
part of the implementation of the compression library and is subject to change. Applications should only use zlib.h. */
/* Structure for decoding tables. Each entry provides either the
information needed to do the operation requested by the code that indexed that table entry, or it provides a pointer to another table that indexes more bits of the code. op indicates whether the entry is a pointer to another table, a literal, a length or distance, an end-of-block, or an invalid code. For a table pointer, the low four bits of op is the number of index bits of that table. For a length or distance, the low four bits of op is the number of extra bits to get after the code. bits is the number of bits in this code or part of the code to drop off of the bit buffer. val is the actual byte to output in the case of a literal, the base length or distance, or the offset from the current table to the next table. Each entry is four bytes. */typedef struct { unsigned char op; /* operation, extra bits, table bits */ unsigned char bits; /* bits in this part of the code */ unsigned short val; /* offset in table or code value */} code;
/* op values as set by inflate_table():
00000000 - literal 0000tttt - table link, tttt != 0 is the number of table index bits 100eeeee - length or distance, eeee is the number of extra bits 01100000 - end of block 01000000 - invalid code */
/* Maximum size of the dynamic table. The maximum number of code structures is
1446, which is the sum of 852 for literal/length codes and 594 for distance codes. These values were found by exhaustive searches using the program examples/enough.c found in the zlib distribtution. The arguments to that program are the number of symbols, the initial root table size, and the maximum bit length of a code. "enough 286 9 15" for literal/length codes returns returns 852, and "enough 32 6 15" for distance codes returns 594. The initial root table size (9 or 6) is found in the fifth argument of the inflate_table() calls in infback9.c. If the root table size is changed, then these maximum sizes would be need to be recalculated and updated. */#define ENOUGH_LENS 852
#define ENOUGH_DISTS 594
#define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
/* Type of code to build for inflate_table9() */typedef enum { CODES, LENS, DISTS} codetype;
extern int inflate_table9 OF((codetype type, unsigned short FAR *lens, unsigned codes, code FAR * FAR *table, unsigned FAR *bits, unsigned short FAR *work));
|
