| /* inftrees.h -- header to use inftrees.c |
| * Copyright (C) 1995-2005, 2010 Mark Adler |
| * For conditions of distribution and use, see copyright notice in zlib.h |
| */ |
| |
| #ifndef INFTREES_H |
| #define INFTREES_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 |
| 0001eeee - 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 |
| 1444, which is the sum of 852 for literal/length codes and 592 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 30 6 15" for distance codes returns 592. |
| The initial root table size (9 or 6) is found in the fifth argument of the |
| inflate_table() calls in inflate.c and infback.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 592 |
| #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS) |
| |
| /* Type of code to build for inflate_table() */ |
| typedef enum { |
| CODES, |
| LENS, |
| DISTS |
| } codetype; |
| |
| int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens, |
| unsigned codes, code FAR * FAR *table, |
| unsigned FAR *bits, unsigned short FAR *work)); |
| |
| #endif /* INFTREES_H_ */ |