00001 /* inftrees.h -- header to use inftrees.c 00002 * Copyright (C) 1995-2003 Mark Adler 00003 * For conditions of distribution and use, see copyright notice in zlib.h 00004 */ 00005 00006 /* WARNING: this file should *not* be used by applications. It is 00007 part of the implementation of the compression library and is 00008 subject to change. Applications should only use zlib.h. 00009 */ 00010 00011 /* Structure for decoding tables. Each entry provides either the 00012 information needed to do the operation requested by the code that 00013 indexed that table entry, or it provides a pointer to another 00014 table that indexes more bits of the code. op indicates whether 00015 the entry is a pointer to another table, a literal, a length or 00016 distance, an end-of-block, or an invalid code. For a table 00017 pointer, the low four bits of op is the number of index bits of 00018 that table. For a length or distance, the low four bits of op 00019 is the number of extra bits to get after the code. bits is 00020 the number of bits in this code or part of the code to drop off 00021 of the bit buffer. val is the actual byte to output in the case 00022 of a literal, the base length or distance, or the offset from 00023 the current table to the next table. Each entry is four bytes. */ 00024 typedef struct { 00025 unsigned char op; /* operation, extra bits, table bits */ 00026 unsigned char bits; /* bits in this part of the code */ 00027 unsigned short val; /* offset in table or code value */ 00028 } code; 00029 00030 /* op values as set by inflate_table(): 00031 00000000 - literal 00032 0000tttt - table link, tttt != 0 is the number of table index bits 00033 0001eeee - length or distance, eeee is the number of extra bits 00034 01100000 - end of block 00035 01000000 - invalid code 00036 */ 00037 00038 /* Maximum size of dynamic tree. The maximum found in a long but non- 00039 exhaustive search was 1004 code structures (850 for length/literals 00040 and 154 for distances, the latter actually the result of an 00041 exhaustive search). The true maximum is not known, but the value 00042 below is more than safe. */ 00043 #define ENOUGH 1440 00044 #define MAXD 154 00045 00046 /* Type of code to build for inftable() */ 00047 typedef enum { 00048 CODES, 00049 LENS, 00050 DISTS 00051 } codetype; 00052 00053 extern int inflate_table OF((codetype type, unsigned short FAR *lens, 00054 unsigned codes, code FAR * FAR *table, 00055 unsigned FAR *bits, unsigned short FAR *work));
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