1*b8382935SToomas Soome /* inftrees.h -- header to use inftrees.c 2*b8382935SToomas Soome * Copyright (C) 1995-2005, 2010 Mark Adler 3*b8382935SToomas Soome * For conditions of distribution and use, see copyright notice in zlib.h 4*b8382935SToomas Soome */ 5*b8382935SToomas Soome 6*b8382935SToomas Soome /* WARNING: this file should *not* be used by applications. It is 7*b8382935SToomas Soome part of the implementation of the compression library and is 8*b8382935SToomas Soome subject to change. Applications should only use zlib.h. 9*b8382935SToomas Soome */ 10*b8382935SToomas Soome 11*b8382935SToomas Soome /* Structure for decoding tables. Each entry provides either the 12*b8382935SToomas Soome information needed to do the operation requested by the code that 13*b8382935SToomas Soome indexed that table entry, or it provides a pointer to another 14*b8382935SToomas Soome table that indexes more bits of the code. op indicates whether 15*b8382935SToomas Soome the entry is a pointer to another table, a literal, a length or 16*b8382935SToomas Soome distance, an end-of-block, or an invalid code. For a table 17*b8382935SToomas Soome pointer, the low four bits of op is the number of index bits of 18*b8382935SToomas Soome that table. For a length or distance, the low four bits of op 19*b8382935SToomas Soome is the number of extra bits to get after the code. bits is 20*b8382935SToomas Soome the number of bits in this code or part of the code to drop off 21*b8382935SToomas Soome of the bit buffer. val is the actual byte to output in the case 22*b8382935SToomas Soome of a literal, the base length or distance, or the offset from 23*b8382935SToomas Soome the current table to the next table. Each entry is four bytes. */ 24*b8382935SToomas Soome typedef struct { 25*b8382935SToomas Soome unsigned char op; /* operation, extra bits, table bits */ 26*b8382935SToomas Soome unsigned char bits; /* bits in this part of the code */ 27*b8382935SToomas Soome unsigned short val; /* offset in table or code value */ 28*b8382935SToomas Soome } code; 29*b8382935SToomas Soome 30*b8382935SToomas Soome /* op values as set by inflate_table(): 31*b8382935SToomas Soome 00000000 - literal 32*b8382935SToomas Soome 0000tttt - table link, tttt != 0 is the number of table index bits 33*b8382935SToomas Soome 0001eeee - length or distance, eeee is the number of extra bits 34*b8382935SToomas Soome 01100000 - end of block 35*b8382935SToomas Soome 01000000 - invalid code 36*b8382935SToomas Soome */ 37*b8382935SToomas Soome 38*b8382935SToomas Soome /* Maximum size of the dynamic table. The maximum number of code structures is 39*b8382935SToomas Soome 1444, which is the sum of 852 for literal/length codes and 592 for distance 40*b8382935SToomas Soome codes. These values were found by exhaustive searches using the program 41*b8382935SToomas Soome examples/enough.c found in the zlib distribtution. The arguments to that 42*b8382935SToomas Soome program are the number of symbols, the initial root table size, and the 43*b8382935SToomas Soome maximum bit length of a code. "enough 286 9 15" for literal/length codes 44*b8382935SToomas Soome returns returns 852, and "enough 30 6 15" for distance codes returns 592. 45*b8382935SToomas Soome The initial root table size (9 or 6) is found in the fifth argument of the 46*b8382935SToomas Soome inflate_table() calls in inflate.c and infback.c. If the root table size is 47*b8382935SToomas Soome changed, then these maximum sizes would be need to be recalculated and 48*b8382935SToomas Soome updated. */ 49*b8382935SToomas Soome #define ENOUGH_LENS 852 50*b8382935SToomas Soome #define ENOUGH_DISTS 592 51*b8382935SToomas Soome #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS) 52*b8382935SToomas Soome 53*b8382935SToomas Soome /* Type of code to build for inflate_table() */ 54*b8382935SToomas Soome typedef enum { 55*b8382935SToomas Soome CODES, 56*b8382935SToomas Soome LENS, 57*b8382935SToomas Soome DISTS 58*b8382935SToomas Soome } codetype; 59*b8382935SToomas Soome 60*b8382935SToomas Soome int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens, 61*b8382935SToomas Soome unsigned codes, code FAR * FAR *table, 62*b8382935SToomas Soome unsigned FAR *bits, unsigned short FAR *work)); 63