1*4a5d661aSToomas Soome /* inftrees.h -- header to use inftrees.c 2*4a5d661aSToomas Soome * Copyright (C) 1995-2005, 2010 Mark Adler 3*4a5d661aSToomas Soome * For conditions of distribution and use, see copyright notice in zlib.h 4*4a5d661aSToomas Soome */ 5*4a5d661aSToomas Soome 6*4a5d661aSToomas Soome /* WARNING: this file should *not* be used by applications. It is 7*4a5d661aSToomas Soome part of the implementation of the compression library and is 8*4a5d661aSToomas Soome subject to change. Applications should only use zlib.h. 9*4a5d661aSToomas Soome */ 10*4a5d661aSToomas Soome 11*4a5d661aSToomas Soome /* Structure for decoding tables. Each entry provides either the 12*4a5d661aSToomas Soome information needed to do the operation requested by the code that 13*4a5d661aSToomas Soome indexed that table entry, or it provides a pointer to another 14*4a5d661aSToomas Soome table that indexes more bits of the code. op indicates whether 15*4a5d661aSToomas Soome the entry is a pointer to another table, a literal, a length or 16*4a5d661aSToomas Soome distance, an end-of-block, or an invalid code. For a table 17*4a5d661aSToomas Soome pointer, the low four bits of op is the number of index bits of 18*4a5d661aSToomas Soome that table. For a length or distance, the low four bits of op 19*4a5d661aSToomas Soome is the number of extra bits to get after the code. bits is 20*4a5d661aSToomas Soome the number of bits in this code or part of the code to drop off 21*4a5d661aSToomas Soome of the bit buffer. val is the actual byte to output in the case 22*4a5d661aSToomas Soome of a literal, the base length or distance, or the offset from 23*4a5d661aSToomas Soome the current table to the next table. Each entry is four bytes. */ 24*4a5d661aSToomas Soome typedef struct { 25*4a5d661aSToomas Soome unsigned char op; /* operation, extra bits, table bits */ 26*4a5d661aSToomas Soome unsigned char bits; /* bits in this part of the code */ 27*4a5d661aSToomas Soome unsigned short val; /* offset in table or code value */ 28*4a5d661aSToomas Soome } code; 29*4a5d661aSToomas Soome 30*4a5d661aSToomas Soome /* op values as set by inflate_table(): 31*4a5d661aSToomas Soome 00000000 - literal 32*4a5d661aSToomas Soome 0000tttt - table link, tttt != 0 is the number of table index bits 33*4a5d661aSToomas Soome 0001eeee - length or distance, eeee is the number of extra bits 34*4a5d661aSToomas Soome 01100000 - end of block 35*4a5d661aSToomas Soome 01000000 - invalid code 36*4a5d661aSToomas Soome */ 37*4a5d661aSToomas Soome 38*4a5d661aSToomas Soome /* Maximum size of the dynamic table. The maximum number of code structures is 39*4a5d661aSToomas Soome 1444, which is the sum of 852 for literal/length codes and 592 for distance 40*4a5d661aSToomas Soome codes. These values were found by exhaustive searches using the program 41*4a5d661aSToomas Soome examples/enough.c found in the zlib distribtution. The arguments to that 42*4a5d661aSToomas Soome program are the number of symbols, the initial root table size, and the 43*4a5d661aSToomas Soome maximum bit length of a code. "enough 286 9 15" for literal/length codes 44*4a5d661aSToomas Soome returns returns 852, and "enough 30 6 15" for distance codes returns 592. 45*4a5d661aSToomas Soome The initial root table size (9 or 6) is found in the fifth argument of the 46*4a5d661aSToomas Soome inflate_table() calls in inflate.c and infback.c. If the root table size is 47*4a5d661aSToomas Soome changed, then these maximum sizes would be need to be recalculated and 48*4a5d661aSToomas Soome updated. */ 49*4a5d661aSToomas Soome #define ENOUGH_LENS 852 50*4a5d661aSToomas Soome #define ENOUGH_DISTS 592 51*4a5d661aSToomas Soome #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS) 52*4a5d661aSToomas Soome 53*4a5d661aSToomas Soome /* Type of code to build for inflate_table() */ 54*4a5d661aSToomas Soome typedef enum { 55*4a5d661aSToomas Soome CODES, 56*4a5d661aSToomas Soome LENS, 57*4a5d661aSToomas Soome DISTS 58*4a5d661aSToomas Soome } codetype; 59*4a5d661aSToomas Soome 60*4a5d661aSToomas Soome int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens, 61*4a5d661aSToomas Soome unsigned codes, code FAR * FAR *table, 62*4a5d661aSToomas Soome unsigned FAR *bits, unsigned short FAR *work)); 63