1*9573673dSchristos /* inftrees.h -- header to use inftrees.c 2*9573673dSchristos * Copyright (C) 1995-2005, 2010 Mark Adler 3*9573673dSchristos * For conditions of distribution and use, see copyright notice in zlib.h 4*9573673dSchristos */ 5*9573673dSchristos 6*9573673dSchristos /* WARNING: this file should *not* be used by applications. It is 7*9573673dSchristos part of the implementation of the compression library and is 8*9573673dSchristos subject to change. Applications should only use zlib.h. 9*9573673dSchristos */ 10*9573673dSchristos 11*9573673dSchristos /* Structure for decoding tables. Each entry provides either the 12*9573673dSchristos information needed to do the operation requested by the code that 13*9573673dSchristos indexed that table entry, or it provides a pointer to another 14*9573673dSchristos table that indexes more bits of the code. op indicates whether 15*9573673dSchristos the entry is a pointer to another table, a literal, a length or 16*9573673dSchristos distance, an end-of-block, or an invalid code. For a table 17*9573673dSchristos pointer, the low four bits of op is the number of index bits of 18*9573673dSchristos that table. For a length or distance, the low four bits of op 19*9573673dSchristos is the number of extra bits to get after the code. bits is 20*9573673dSchristos the number of bits in this code or part of the code to drop off 21*9573673dSchristos of the bit buffer. val is the actual byte to output in the case 22*9573673dSchristos of a literal, the base length or distance, or the offset from 23*9573673dSchristos the current table to the next table. Each entry is four bytes. */ 24*9573673dSchristos typedef struct { 25*9573673dSchristos unsigned char op; /* operation, extra bits, table bits */ 26*9573673dSchristos unsigned char bits; /* bits in this part of the code */ 27*9573673dSchristos unsigned short val; /* offset in table or code value */ 28*9573673dSchristos } code; 29*9573673dSchristos 30*9573673dSchristos /* op values as set by inflate_table(): 31*9573673dSchristos 00000000 - literal 32*9573673dSchristos 0000tttt - table link, tttt != 0 is the number of table index bits 33*9573673dSchristos 0001eeee - length or distance, eeee is the number of extra bits 34*9573673dSchristos 01100000 - end of block 35*9573673dSchristos 01000000 - invalid code 36*9573673dSchristos */ 37*9573673dSchristos 38*9573673dSchristos /* Maximum size of the dynamic table. The maximum number of code structures is 39*9573673dSchristos 1444, which is the sum of 852 for literal/length codes and 592 for distance 40*9573673dSchristos codes. These values were found by exhaustive searches using the program 41*9573673dSchristos examples/enough.c found in the zlib distribtution. The arguments to that 42*9573673dSchristos program are the number of symbols, the initial root table size, and the 43*9573673dSchristos maximum bit length of a code. "enough 286 9 15" for literal/length codes 44*9573673dSchristos returns returns 852, and "enough 30 6 15" for distance codes returns 592. 45*9573673dSchristos The initial root table size (9 or 6) is found in the fifth argument of the 46*9573673dSchristos inflate_table() calls in inflate.c and infback.c. If the root table size is 47*9573673dSchristos changed, then these maximum sizes would be need to be recalculated and 48*9573673dSchristos updated. */ 49*9573673dSchristos #define ENOUGH_LENS 852 50*9573673dSchristos #define ENOUGH_DISTS 592 51*9573673dSchristos #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS) 52*9573673dSchristos 53*9573673dSchristos /* Type of code to build for inflate_table() */ 54*9573673dSchristos typedef enum { 55*9573673dSchristos CODES, 56*9573673dSchristos LENS, 57*9573673dSchristos DISTS 58*9573673dSchristos } codetype; 59*9573673dSchristos 60*9573673dSchristos int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens, 61*9573673dSchristos unsigned codes, code FAR * FAR *table, 62*9573673dSchristos unsigned FAR *bits, unsigned short FAR *work)); 63