1 /* inftrees.h -- header to use inftrees.c

     2  * Copyright (C) 1995-2005 Mark Adler

     3  * For conditions of distribution and use, see copyright notice in zlib.h

     4  */

     5 

     6 /* WARNING: this file should *not* be used by applications. It is

     7    part of the implementation of the compression library and is

     8    subject to change. Applications should only use zlib.h.

     9  */

    10 

    11 /* Structure for decoding tables.  Each entry provides either the

    12    information needed to do the operation requested by the code that

    13    indexed that table entry, or it provides a pointer to another

    14    table that indexes more bits of the code.  op indicates whether

    15    the entry is a pointer to another table, a literal, a length or

    16    distance, an end-of-block, or an invalid code.  For a table

    17    pointer, the low four bits of op is the number of index bits of

    18    that table.  For a length or distance, the low four bits of op

    19    is the number of extra bits to get after the code.  bits is

    20    the number of bits in this code or part of the code to drop off

    21    of the bit buffer.  val is the actual byte to output in the case

    22    of a literal, the base length or distance, or the offset from

    23    the current table to the next table.  Each entry is four bytes. */

    24 typedef struct {

    25     unsigned char op;           /* operation, extra bits, table bits */

    26     unsigned char bits;         /* bits in this part of the code */

    27     unsigned short val;         /* offset in table or code value */

    28 } code;

    29 

    30 /* op values as set by inflate_table():

    31     00000000 - literal

    32     0000tttt - table link, tttt != 0 is the number of table index bits

    33     0001eeee - length or distance, eeee is the number of extra bits

    34     01100000 - end of block

    35     01000000 - invalid code

    36  */

    37 

    38 /* Maximum size of dynamic tree.  The maximum found in a long but non-

    39    exhaustive search was 1444 code structures (852 for length/literals

    40    and 592 for distances, the latter actually the result of an

    41    exhaustive search).  The true maximum is not known, but the value

    42    below is more than safe. */

    43 #define ENOUGH 2048

    44 #define MAXD 592

    45 

    46 /* Type of code to build for inftable() */

    47 typedef enum {

    48     CODES,

    49     LENS,

    50     DISTS

    51 } codetype;

    52 

    53 extern int inflate_table OF((codetype type, unsigned short FAR *lens,

    54                              unsigned codes, code FAR * FAR *table,

    55                              unsigned FAR *bits, unsigned short FAR *work));