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// InflaterDynHeader.cs
// Copyright (C) 2001 Mike Krueger
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module. An independent module is a module which is not derived from
// or based on this library. If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
using System;
using ICSharpCode.SharpZipLib.Zip.Compression.Streams;
namespace ICSharpCode.SharpZipLib.Zip.Compression
{
class InflaterDynHeader
{
const int LNUM = 0;
const int DNUM = 1;
const int BLNUM = 2;
const int BLLENS = 3;
const int LENS = 4;
const int REPS = 5;
static readonly int[] repMin = { 3, 3, 11 };
static readonly int[] repBits = { 2, 3, 7 };
byte[] blLens;
byte[] litdistLens;
InflaterHuffmanTree blTree;
int mode;
int lnum, dnum, blnum, num;
int repSymbol;
byte lastLen;
int ptr;
static readonly int[] BL_ORDER =
{ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
public InflaterDynHeader()
{
}
public bool Decode(StreamManipulator input)
{
decode_loop:
for (;;) {
switch (mode) {
case LNUM:
lnum = input.PeekBits(5);
if (lnum < 0) {
return false;
}
lnum += 257;
input.DropBits(5);
// System.err.println("LNUM: "+lnum);
mode = DNUM;
goto case DNUM; // fall through
case DNUM:
dnum = input.PeekBits(5);
if (dnum < 0) {
return false;
}
dnum++;
input.DropBits(5);
// System.err.println("DNUM: "+dnum);
num = lnum+dnum;
litdistLens = new byte[num];
mode = BLNUM;
goto case BLNUM; // fall through
case BLNUM:
blnum = input.PeekBits(4);
if (blnum < 0) {
return false;
}
blnum += 4;
input.DropBits(4);
blLens = new byte[19];
ptr = 0;
// System.err.println("BLNUM: "+blnum);
mode = BLLENS;
goto case BLLENS; // fall through
case BLLENS:
while (ptr < blnum) {
int len = input.PeekBits(3);
if (len < 0) {
return false;
}
input.DropBits(3);
// System.err.println("blLens["+BL_ORDER[ptr]+"]: "+len);
blLens[BL_ORDER[ptr]] = (byte) len;
ptr++;
}
blTree = new InflaterHuffmanTree(blLens);
blLens = null;
ptr = 0;
mode = LENS;
goto case LENS; // fall through
case LENS:
{
int symbol;
while (((symbol = blTree.GetSymbol(input)) & ~15) == 0) {
/* Normal case: symbol in [0..15] */
// System.err.println("litdistLens["+ptr+"]: "+symbol);
litdistLens[ptr++] = lastLen = (byte)symbol;
if (ptr == num) {
/* Finished */
return true;
}
}
/* need more input ? */
if (symbol < 0) {
return false;
}
/* otherwise repeat code */
if (symbol >= 17) {
/* repeat zero */
// System.err.println("repeating zero");
lastLen = 0;
} else {
if (ptr == 0) {
throw new Exception();
}
}
repSymbol = symbol-16;
}
mode = REPS;
goto case REPS; // fall through
case REPS:
{
int bits = repBits[repSymbol];
int count = input.PeekBits(bits);
if (count < 0) {
return false;
}
input.DropBits(bits);
count += repMin[repSymbol];
// System.err.println("litdistLens repeated: "+count);
if (ptr + count > num) {
throw new Exception();
}
while (count-- > 0) {
litdistLens[ptr++] = lastLen;
}
if (ptr == num) {
/* Finished */
return true;
}
}
mode = LENS;
goto decode_loop;
}
}
}
public InflaterHuffmanTree BuildLitLenTree()
{
byte[] litlenLens = new byte[lnum];
Array.Copy(litdistLens, 0, litlenLens, 0, lnum);
return new InflaterHuffmanTree(litlenLens);
}
public InflaterHuffmanTree BuildDistTree()
{
byte[] distLens = new byte[dnum];
Array.Copy(litdistLens, lnum, distLens, 0, dnum);
return new InflaterHuffmanTree(distLens);
}
}
}
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