alpar@9: /* inftrees.h -- header to use inftrees.c
alpar@9:  * Copyright (C) 1995-2005, 2010 Mark Adler
alpar@9:  * For conditions of distribution and use, see copyright notice in zlib.h
alpar@9:  */
alpar@9: 
alpar@9: /* WARNING: this file should *not* be used by applications. It is
alpar@9:    part of the implementation of the compression library and is
alpar@9:    subject to change. Applications should only use zlib.h.
alpar@9:  */
alpar@9: 
alpar@9: /* Structure for decoding tables.  Each entry provides either the
alpar@9:    information needed to do the operation requested by the code that
alpar@9:    indexed that table entry, or it provides a pointer to another
alpar@9:    table that indexes more bits of the code.  op indicates whether
alpar@9:    the entry is a pointer to another table, a literal, a length or
alpar@9:    distance, an end-of-block, or an invalid code.  For a table
alpar@9:    pointer, the low four bits of op is the number of index bits of
alpar@9:    that table.  For a length or distance, the low four bits of op
alpar@9:    is the number of extra bits to get after the code.  bits is
alpar@9:    the number of bits in this code or part of the code to drop off
alpar@9:    of the bit buffer.  val is the actual byte to output in the case
alpar@9:    of a literal, the base length or distance, or the offset from
alpar@9:    the current table to the next table.  Each entry is four bytes. */
alpar@9: typedef struct {
alpar@9:     unsigned char op;           /* operation, extra bits, table bits */
alpar@9:     unsigned char bits;         /* bits in this part of the code */
alpar@9:     unsigned short val;         /* offset in table or code value */
alpar@9: } code;
alpar@9: 
alpar@9: /* op values as set by inflate_table():
alpar@9:     00000000 - literal
alpar@9:     0000tttt - table link, tttt != 0 is the number of table index bits
alpar@9:     0001eeee - length or distance, eeee is the number of extra bits
alpar@9:     01100000 - end of block
alpar@9:     01000000 - invalid code
alpar@9:  */
alpar@9: 
alpar@9: /* Maximum size of the dynamic table.  The maximum number of code structures is
alpar@9:    1444, which is the sum of 852 for literal/length codes and 592 for distance
alpar@9:    codes.  These values were found by exhaustive searches using the program
alpar@9:    examples/enough.c found in the zlib distribtution.  The arguments to that
alpar@9:    program are the number of symbols, the initial root table size, and the
alpar@9:    maximum bit length of a code.  "enough 286 9 15" for literal/length codes
alpar@9:    returns returns 852, and "enough 30 6 15" for distance codes returns 592.
alpar@9:    The initial root table size (9 or 6) is found in the fifth argument of the
alpar@9:    inflate_table() calls in inflate.c and infback.c.  If the root table size is
alpar@9:    changed, then these maximum sizes would be need to be recalculated and
alpar@9:    updated. */
alpar@9: #define ENOUGH_LENS 852
alpar@9: #define ENOUGH_DISTS 592
alpar@9: #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
alpar@9: 
alpar@9: /* Type of code to build for inflate_table() */
alpar@9: typedef enum {
alpar@9:     CODES,
alpar@9:     LENS,
alpar@9:     DISTS
alpar@9: } codetype;
alpar@9: 
alpar@9: int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens,
alpar@9:                              unsigned codes, code FAR * FAR *table,
alpar@9:                              unsigned FAR *bits, unsigned short FAR *work));