1*b3be2f66SJerome Forissier /* inftrees.h -- header to use inftrees.c 2*b3be2f66SJerome Forissier * Copyright (C) 1995-2005, 2010 Mark Adler 3*b3be2f66SJerome Forissier * For conditions of distribution and use, see copyright notice in zlib.h 4*b3be2f66SJerome Forissier */ 5*b3be2f66SJerome Forissier 6*b3be2f66SJerome Forissier /* WARNING: this file should *not* be used by applications. It is 7*b3be2f66SJerome Forissier part of the implementation of the compression library and is 8*b3be2f66SJerome Forissier subject to change. Applications should only use zlib.h. 9*b3be2f66SJerome Forissier */ 10*b3be2f66SJerome Forissier 11*b3be2f66SJerome Forissier /* Structure for decoding tables. Each entry provides either the 12*b3be2f66SJerome Forissier information needed to do the operation requested by the code that 13*b3be2f66SJerome Forissier indexed that table entry, or it provides a pointer to another 14*b3be2f66SJerome Forissier table that indexes more bits of the code. op indicates whether 15*b3be2f66SJerome Forissier the entry is a pointer to another table, a literal, a length or 16*b3be2f66SJerome Forissier distance, an end-of-block, or an invalid code. For a table 17*b3be2f66SJerome Forissier pointer, the low four bits of op is the number of index bits of 18*b3be2f66SJerome Forissier that table. For a length or distance, the low four bits of op 19*b3be2f66SJerome Forissier is the number of extra bits to get after the code. bits is 20*b3be2f66SJerome Forissier the number of bits in this code or part of the code to drop off 21*b3be2f66SJerome Forissier of the bit buffer. val is the actual byte to output in the case 22*b3be2f66SJerome Forissier of a literal, the base length or distance, or the offset from 23*b3be2f66SJerome Forissier the current table to the next table. Each entry is four bytes. */ 24*b3be2f66SJerome Forissier typedef struct { 25*b3be2f66SJerome Forissier unsigned char op; /* operation, extra bits, table bits */ 26*b3be2f66SJerome Forissier unsigned char bits; /* bits in this part of the code */ 27*b3be2f66SJerome Forissier unsigned short val; /* offset in table or code value */ 28*b3be2f66SJerome Forissier } code; 29*b3be2f66SJerome Forissier 30*b3be2f66SJerome Forissier /* op values as set by inflate_table(): 31*b3be2f66SJerome Forissier 00000000 - literal 32*b3be2f66SJerome Forissier 0000tttt - table link, tttt != 0 is the number of table index bits 33*b3be2f66SJerome Forissier 0001eeee - length or distance, eeee is the number of extra bits 34*b3be2f66SJerome Forissier 01100000 - end of block 35*b3be2f66SJerome Forissier 01000000 - invalid code 36*b3be2f66SJerome Forissier */ 37*b3be2f66SJerome Forissier 38*b3be2f66SJerome Forissier /* Maximum size of the dynamic table. The maximum number of code structures is 39*b3be2f66SJerome Forissier 1444, which is the sum of 852 for literal/length codes and 592 for distance 40*b3be2f66SJerome Forissier codes. These values were found by exhaustive searches using the program 41*b3be2f66SJerome Forissier examples/enough.c found in the zlib distribtution. The arguments to that 42*b3be2f66SJerome Forissier program are the number of symbols, the initial root table size, and the 43*b3be2f66SJerome Forissier maximum bit length of a code. "enough 286 9 15" for literal/length codes 44*b3be2f66SJerome Forissier returns returns 852, and "enough 30 6 15" for distance codes returns 592. 45*b3be2f66SJerome Forissier The initial root table size (9 or 6) is found in the fifth argument of the 46*b3be2f66SJerome Forissier inflate_table() calls in inflate.c and infback.c. If the root table size is 47*b3be2f66SJerome Forissier changed, then these maximum sizes would be need to be recalculated and 48*b3be2f66SJerome Forissier updated. */ 49*b3be2f66SJerome Forissier #define ENOUGH_LENS 852 50*b3be2f66SJerome Forissier #define ENOUGH_DISTS 592 51*b3be2f66SJerome Forissier #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS) 52*b3be2f66SJerome Forissier 53*b3be2f66SJerome Forissier /* Type of code to build for inflate_table() */ 54*b3be2f66SJerome Forissier typedef enum { 55*b3be2f66SJerome Forissier CODES, 56*b3be2f66SJerome Forissier LENS, 57*b3be2f66SJerome Forissier DISTS 58*b3be2f66SJerome Forissier } codetype; 59*b3be2f66SJerome Forissier 60*b3be2f66SJerome Forissier int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens, 61*b3be2f66SJerome Forissier unsigned codes, code FAR * FAR *table, 62*b3be2f66SJerome Forissier unsigned FAR *bits, unsigned short FAR *work)); 63