1 /*
 2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 3  *
 4  * This code is free software; you can redistribute it and/or modify it
 5  * under the terms of the GNU General Public License version 2 only, as
 6  * published by the Free Software Foundation.  Oracle designates this
 7  * particular file as subject to the "Classpath" exception as provided
 8  * by Oracle in the LICENSE file that accompanied this code.
 9  *
10  * This code is distributed in the hope that it will be useful, but WITHOUT
11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13  * version 2 for more details (a copy is included in the LICENSE file that
14  * accompanied this code).
15  *
16  * You should have received a copy of the GNU General Public License version
17  * 2 along with this work; if not, write to the Free Software Foundation,
18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19  *
20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21  * or visit www.oracle.com if you need additional information or have any
22  * questions.
23  */
24 
25 /* inftrees.h -- header to use inftrees.c
26  * Copyright (C) 1995-2005, 2010 Mark Adler
27  * For conditions of distribution and use, see copyright notice in zlib.h
28  */
29 
30 /* WARNING: this file should *not* be used by applications. It is
31    part of the implementation of the compression library and is
32    subject to change. Applications should only use zlib.h.
33  */
34 
35 /* Structure for decoding tables.  Each entry provides either the
36    information needed to do the operation requested by the code that
37    indexed that table entry, or it provides a pointer to another
38    table that indexes more bits of the code.  op indicates whether
39    the entry is a pointer to another table, a literal, a length or
40    distance, an end-of-block, or an invalid code.  For a table
41    pointer, the low four bits of op is the number of index bits of
42    that table.  For a length or distance, the low four bits of op
43    is the number of extra bits to get after the code.  bits is
44    the number of bits in this code or part of the code to drop off
45    of the bit buffer.  val is the actual byte to output in the case
46    of a literal, the base length or distance, or the offset from
47    the current table to the next table.  Each entry is four bytes. */
48 typedef struct {
49     unsigned char op;           /* operation, extra bits, table bits */
50     unsigned char bits;         /* bits in this part of the code */
51     unsigned short val;         /* offset in table or code value */
52 } code;
53 
54 /* op values as set by inflate_table():
55     00000000 - literal
56     0000tttt - table link, tttt != 0 is the number of table index bits
57     0001eeee - length or distance, eeee is the number of extra bits
58     01100000 - end of block
59     01000000 - invalid code
60  */
61 
62 /* Maximum size of the dynamic table.  The maximum number of code structures is
63    1444, which is the sum of 852 for literal/length codes and 592 for distance
64    codes.  These values were found by exhaustive searches using the program
65    examples/enough.c found in the zlib distribution.  The arguments to that
66    program are the number of symbols, the initial root table size, and the
67    maximum bit length of a code.  "enough 286 9 15" for literal/length codes
68    returns 852, and "enough 30 6 15" for distance codes returns 592. The
69    initial root table size (9 or 6) is found in the fifth argument of the
70    inflate_table() calls in inflate.c and infback.c.  If the root table size is
71    changed, then these maximum sizes would be need to be recalculated and
72    updated. */
73 #define ENOUGH_LENS 852
74 #define ENOUGH_DISTS 592
75 #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
76 
77 /* Type of code to build for inflate_table() */
78 typedef enum {
79     CODES,
80     LENS,
81     DISTS
82 } codetype;
83 
84 int ZLIB_INTERNAL inflate_table(codetype type, unsigned short FAR *lens,
85                                 unsigned codes, code FAR * FAR *table,
86                                 unsigned FAR *bits, unsigned short FAR *work);