1aaf4ece6Schristos /* inftree9.h -- header to use inftree9.c 2c3423655Schristos * Copyright (C) 1995-2008 Mark Adler 3aaf4ece6Schristos * For conditions of distribution and use, see copyright notice in zlib.h 4aaf4ece6Schristos */ 5aaf4ece6Schristos 6aaf4ece6Schristos /* WARNING: this file should *not* be used by applications. It is 7aaf4ece6Schristos part of the implementation of the compression library and is 8aaf4ece6Schristos subject to change. Applications should only use zlib.h. 9aaf4ece6Schristos */ 10aaf4ece6Schristos 11aaf4ece6Schristos /* Structure for decoding tables. Each entry provides either the 12aaf4ece6Schristos information needed to do the operation requested by the code that 13aaf4ece6Schristos indexed that table entry, or it provides a pointer to another 14aaf4ece6Schristos table that indexes more bits of the code. op indicates whether 15aaf4ece6Schristos the entry is a pointer to another table, a literal, a length or 16aaf4ece6Schristos distance, an end-of-block, or an invalid code. For a table 17aaf4ece6Schristos pointer, the low four bits of op is the number of index bits of 18aaf4ece6Schristos that table. For a length or distance, the low four bits of op 19aaf4ece6Schristos is the number of extra bits to get after the code. bits is 20aaf4ece6Schristos the number of bits in this code or part of the code to drop off 21aaf4ece6Schristos of the bit buffer. val is the actual byte to output in the case 22aaf4ece6Schristos of a literal, the base length or distance, or the offset from 23aaf4ece6Schristos the current table to the next table. Each entry is four bytes. */ 24aaf4ece6Schristos typedef struct { 25aaf4ece6Schristos unsigned char op; /* operation, extra bits, table bits */ 26aaf4ece6Schristos unsigned char bits; /* bits in this part of the code */ 27aaf4ece6Schristos unsigned short val; /* offset in table or code value */ 28aaf4ece6Schristos } code; 29aaf4ece6Schristos 30aaf4ece6Schristos /* op values as set by inflate_table(): 31aaf4ece6Schristos 00000000 - literal 32aaf4ece6Schristos 0000tttt - table link, tttt != 0 is the number of table index bits 33aaf4ece6Schristos 100eeeee - length or distance, eeee is the number of extra bits 34aaf4ece6Schristos 01100000 - end of block 35aaf4ece6Schristos 01000000 - invalid code 36aaf4ece6Schristos */ 37aaf4ece6Schristos 38c3423655Schristos /* Maximum size of the dynamic table. The maximum number of code structures is 39c3423655Schristos 1446, which is the sum of 852 for literal/length codes and 594 for distance 40c3423655Schristos codes. These values were found by exhaustive searches using the program 41ec47cc4bSchristos examples/enough.c found in the zlib distribution. The arguments to that 42c3423655Schristos program are the number of symbols, the initial root table size, and the 43c3423655Schristos maximum bit length of a code. "enough 286 9 15" for literal/length codes 44*b175d1c2Schristos returns 852, and "enough 32 6 15" for distance codes returns 594. The 45*b175d1c2Schristos initial root table size (9 or 6) is found in the fifth argument of the 46c3423655Schristos inflate_table() calls in infback9.c. If the root table size is changed, 47c3423655Schristos then these maximum sizes would be need to be recalculated and updated. */ 48c3423655Schristos #define ENOUGH_LENS 852 49c3423655Schristos #define ENOUGH_DISTS 594 50c3423655Schristos #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS) 51aaf4ece6Schristos 52c3423655Schristos /* Type of code to build for inflate_table9() */ 53aaf4ece6Schristos typedef enum { 54aaf4ece6Schristos CODES, 55aaf4ece6Schristos LENS, 56aaf4ece6Schristos DISTS 57aaf4ece6Schristos } codetype; 58aaf4ece6Schristos 59*b175d1c2Schristos extern int inflate_table9(codetype type, unsigned short FAR *lens, 60aaf4ece6Schristos unsigned codes, code FAR * FAR *table, 61*b175d1c2Schristos unsigned FAR *bits, unsigned short FAR *work); 62