1221b1638SMasahiro Yamada /* inftrees.h -- header to use inftrees.c 2221b1638SMasahiro Yamada * Copyright (C) 1995-2005, 2010 Mark Adler 3221b1638SMasahiro Yamada * For conditions of distribution and use, see copyright notice in zlib.h 4221b1638SMasahiro Yamada */ 5221b1638SMasahiro Yamada 6221b1638SMasahiro Yamada /* WARNING: this file should *not* be used by applications. It is 7221b1638SMasahiro Yamada part of the implementation of the compression library and is 8221b1638SMasahiro Yamada subject to change. Applications should only use zlib.h. 9221b1638SMasahiro Yamada */ 10221b1638SMasahiro Yamada 11221b1638SMasahiro Yamada /* Structure for decoding tables. Each entry provides either the 12221b1638SMasahiro Yamada information needed to do the operation requested by the code that 13221b1638SMasahiro Yamada indexed that table entry, or it provides a pointer to another 14221b1638SMasahiro Yamada table that indexes more bits of the code. op indicates whether 15221b1638SMasahiro Yamada the entry is a pointer to another table, a literal, a length or 16221b1638SMasahiro Yamada distance, an end-of-block, or an invalid code. For a table 17221b1638SMasahiro Yamada pointer, the low four bits of op is the number of index bits of 18221b1638SMasahiro Yamada that table. For a length or distance, the low four bits of op 19221b1638SMasahiro Yamada is the number of extra bits to get after the code. bits is 20221b1638SMasahiro Yamada the number of bits in this code or part of the code to drop off 21221b1638SMasahiro Yamada of the bit buffer. val is the actual byte to output in the case 22221b1638SMasahiro Yamada of a literal, the base length or distance, or the offset from 23221b1638SMasahiro Yamada the current table to the next table. Each entry is four bytes. */ 24221b1638SMasahiro Yamada typedef struct { 25221b1638SMasahiro Yamada unsigned char op; /* operation, extra bits, table bits */ 26221b1638SMasahiro Yamada unsigned char bits; /* bits in this part of the code */ 27221b1638SMasahiro Yamada unsigned short val; /* offset in table or code value */ 28221b1638SMasahiro Yamada } code; 29221b1638SMasahiro Yamada 30221b1638SMasahiro Yamada /* op values as set by inflate_table(): 31221b1638SMasahiro Yamada 00000000 - literal 32221b1638SMasahiro Yamada 0000tttt - table link, tttt != 0 is the number of table index bits 33221b1638SMasahiro Yamada 0001eeee - length or distance, eeee is the number of extra bits 34221b1638SMasahiro Yamada 01100000 - end of block 35221b1638SMasahiro Yamada 01000000 - invalid code 36221b1638SMasahiro Yamada */ 37221b1638SMasahiro Yamada 38221b1638SMasahiro Yamada /* Maximum size of the dynamic table. The maximum number of code structures is 39221b1638SMasahiro Yamada 1444, which is the sum of 852 for literal/length codes and 592 for distance 40221b1638SMasahiro Yamada codes. These values were found by exhaustive searches using the program 41a194255dSDaniel Boulby examples/enough.c found in the zlib distribution. The arguments to that 42221b1638SMasahiro Yamada program are the number of symbols, the initial root table size, and the 43221b1638SMasahiro Yamada maximum bit length of a code. "enough 286 9 15" for literal/length codes 44221b1638SMasahiro Yamada returns returns 852, and "enough 30 6 15" for distance codes returns 592. 45221b1638SMasahiro Yamada The initial root table size (9 or 6) is found in the fifth argument of the 46221b1638SMasahiro Yamada inflate_table() calls in inflate.c and infback.c. If the root table size is 47221b1638SMasahiro Yamada changed, then these maximum sizes would be need to be recalculated and 48221b1638SMasahiro Yamada updated. */ 49221b1638SMasahiro Yamada #define ENOUGH_LENS 852 50221b1638SMasahiro Yamada #define ENOUGH_DISTS 592 51221b1638SMasahiro Yamada #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS) 52221b1638SMasahiro Yamada 53221b1638SMasahiro Yamada /* Type of code to build for inflate_table() */ 54221b1638SMasahiro Yamada typedef enum { 55221b1638SMasahiro Yamada CODES, 56221b1638SMasahiro Yamada LENS, 57221b1638SMasahiro Yamada DISTS 58221b1638SMasahiro Yamada } codetype; 59221b1638SMasahiro Yamada 60*fd39217aSManish Pandey int ZLIB_INTERNAL inflate_table(codetype type, unsigned short FAR *lens, 61221b1638SMasahiro Yamada unsigned codes, code FAR * FAR *table, 62*fd39217aSManish Pandey unsigned FAR *bits, unsigned short FAR *work); 63