cannam@89: /* inftree9.h -- header to use inftree9.c
cannam@89:  * Copyright (C) 1995-2008 Mark Adler
cannam@89:  * For conditions of distribution and use, see copyright notice in zlib.h
cannam@89:  */
cannam@89: 
cannam@89: /* WARNING: this file should *not* be used by applications. It is
cannam@89:    part of the implementation of the compression library and is
cannam@89:    subject to change. Applications should only use zlib.h.
cannam@89:  */
cannam@89: 
cannam@89: /* Structure for decoding tables.  Each entry provides either the
cannam@89:    information needed to do the operation requested by the code that
cannam@89:    indexed that table entry, or it provides a pointer to another
cannam@89:    table that indexes more bits of the code.  op indicates whether
cannam@89:    the entry is a pointer to another table, a literal, a length or
cannam@89:    distance, an end-of-block, or an invalid code.  For a table
cannam@89:    pointer, the low four bits of op is the number of index bits of
cannam@89:    that table.  For a length or distance, the low four bits of op
cannam@89:    is the number of extra bits to get after the code.  bits is
cannam@89:    the number of bits in this code or part of the code to drop off
cannam@89:    of the bit buffer.  val is the actual byte to output in the case
cannam@89:    of a literal, the base length or distance, or the offset from
cannam@89:    the current table to the next table.  Each entry is four bytes. */
cannam@89: typedef struct {
cannam@89:     unsigned char op;           /* operation, extra bits, table bits */
cannam@89:     unsigned char bits;         /* bits in this part of the code */
cannam@89:     unsigned short val;         /* offset in table or code value */
cannam@89: } code;
cannam@89: 
cannam@89: /* op values as set by inflate_table():
cannam@89:     00000000 - literal
cannam@89:     0000tttt - table link, tttt != 0 is the number of table index bits
cannam@89:     100eeeee - length or distance, eeee is the number of extra bits
cannam@89:     01100000 - end of block
cannam@89:     01000000 - invalid code
cannam@89:  */
cannam@89: 
cannam@89: /* Maximum size of the dynamic table.  The maximum number of code structures is
cannam@89:    1446, which is the sum of 852 for literal/length codes and 594 for distance
cannam@89:    codes.  These values were found by exhaustive searches using the program
cannam@89:    examples/enough.c found in the zlib distribtution.  The arguments to that
cannam@89:    program are the number of symbols, the initial root table size, and the
cannam@89:    maximum bit length of a code.  "enough 286 9 15" for literal/length codes
cannam@89:    returns returns 852, and "enough 32 6 15" for distance codes returns 594.
cannam@89:    The initial root table size (9 or 6) is found in the fifth argument of the
cannam@89:    inflate_table() calls in infback9.c.  If the root table size is changed,
cannam@89:    then these maximum sizes would be need to be recalculated and updated. */
cannam@89: #define ENOUGH_LENS 852
cannam@89: #define ENOUGH_DISTS 594
cannam@89: #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
cannam@89: 
cannam@89: /* Type of code to build for inflate_table9() */
cannam@89: typedef enum {
cannam@89:     CODES,
cannam@89:     LENS,
cannam@89:     DISTS
cannam@89: } codetype;
cannam@89: 
cannam@89: extern int inflate_table9 OF((codetype type, unsigned short FAR *lens,
cannam@89:                              unsigned codes, code FAR * FAR *table,
cannam@89:                              unsigned FAR *bits, unsigned short FAR *work));