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v 3.1.0

    1: /* inftrees.h -- header to use inftrees.c
    2:  * Copyright (C) 1995-2005, 2010 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 the dynamic table.  The maximum number of code structures is
   39:    1444, which is the sum of 852 for literal/length codes and 592 for distance
   40:    codes.  These values were found by exhaustive searches using the program
   41:    examples/enough.c found in the zlib distribtution.  The arguments to that
   42:    program are the number of symbols, the initial root table size, and the
   43:    maximum bit length of a code.  "enough 286 9 15" for literal/length codes
   44:    returns returns 852, and "enough 30 6 15" for distance codes returns 592.
   45:    The initial root table size (9 or 6) is found in the fifth argument of the
   46:    inflate_table() calls in inflate.c and infback.c.  If the root table size is
   47:    changed, then these maximum sizes would be need to be recalculated and
   48:    updated. */
   49: #define ENOUGH_LENS 852
   50: #define ENOUGH_DISTS 592
   51: #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
   52: 
   53: /* Type of code to build for inflate_table() */
   54: typedef enum {
   55:     CODES,
   56:     LENS,
   57:     DISTS
   58: } codetype;
   59: 
   60: int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens,
   61:                              unsigned codes, code FAR * FAR *table,
   62:                              unsigned FAR *bits, unsigned short FAR *work));