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old_flsystem/类库/Update/ZIP/BZip2/BZip2InputStream.cs

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2022-09-20 03:10:29 +00:00
// BZip2InputStream.cs
//
// Copyright (C) 2001 Mike Krueger
//
// 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 System.IO;
using ICSharpCode.SharpZipLib.Checksums;
namespace ICSharpCode.SharpZipLib.BZip2
{
/// <summary>
/// An input stream that decompresses files in the BZip2 format
/// </summary>
public class BZip2InputStream : Stream
{
#region Constants
const int START_BLOCK_STATE = 1;
const int RAND_PART_A_STATE = 2;
const int RAND_PART_B_STATE = 3;
const int RAND_PART_C_STATE = 4;
const int NO_RAND_PART_A_STATE = 5;
const int NO_RAND_PART_B_STATE = 6;
const int NO_RAND_PART_C_STATE = 7;
#endregion
#region Constructors
/// <summary>
/// Construct instance for reading from stream
/// </summary>
/// <param name="stream">Data source</param>
public BZip2InputStream(Stream stream)
{
// init arrays
for (int i = 0; i < BZip2Constants.GroupCount; ++i)
{
limit[i] = new int[BZip2Constants.MaximumAlphaSize];
baseArray[i] = new int[BZip2Constants.MaximumAlphaSize];
perm[i] = new int[BZip2Constants.MaximumAlphaSize];
}
BsSetStream(stream);
Initialize();
InitBlock();
SetupBlock();
}
#endregion
/// <summary>
/// Get/set flag indicating ownership of underlying stream.
/// When the flag is true <see cref="Close"></see> will close the underlying stream also.
/// </summary>
public bool IsStreamOwner
{
get { return isStreamOwner; }
set { isStreamOwner = value; }
}
#region Stream Overrides
/// <summary>
/// Gets a value indicating if the stream supports reading
/// </summary>
public override bool CanRead
{
get {
return baseStream.CanRead;
}
}
/// <summary>
/// Gets a value indicating whether the current stream supports seeking.
/// </summary>
public override bool CanSeek {
get {
return baseStream.CanSeek;
}
}
/// <summary>
/// Gets a value indicating whether the current stream supports writing.
/// This property always returns false
/// </summary>
public override bool CanWrite {
get {
return false;
}
}
/// <summary>
/// Gets the length in bytes of the stream.
/// </summary>
public override long Length {
get {
return baseStream.Length;
}
}
/// <summary>
/// Gets or sets the streams position.
/// Setting the position is not supported and will throw a NotSupportException
/// </summary>
/// <exception cref="NotSupportedException">Any attempt to set the position</exception>
public override long Position {
get {
return baseStream.Position;
}
set {
throw new NotSupportedException("BZip2InputStream position cannot be set");
}
}
/// <summary>
/// Flushes the stream.
/// </summary>
public override void Flush()
{
if (baseStream != null) {
baseStream.Flush();
}
}
/// <summary>
/// Set the streams position. This operation is not supported and will throw a NotSupportedException
/// </summary>
/// <param name="offset">A byte offset relative to the <paramref name="origin"/> parameter.</param>
/// <param name="origin">A value of type <see cref="SeekOrigin"/> indicating the reference point used to obtain the new position.</param>
/// <returns>The new position of the stream.</returns>
/// <exception cref="NotSupportedException">Any access</exception>
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException("BZip2InputStream Seek not supported");
}
/// <summary>
/// Sets the length of this stream to the given value.
/// This operation is not supported and will throw a NotSupportedExceptionortedException
/// </summary>
/// <param name="value">The new length for the stream.</param>
/// <exception cref="NotSupportedException">Any access</exception>
public override void SetLength(long value)
{
throw new NotSupportedException("BZip2InputStream SetLength not supported");
}
/// <summary>
/// Writes a block of bytes to this stream using data from a buffer.
/// This operation is not supported and will throw a NotSupportedException
/// </summary>
/// <param name="buffer">The buffer to source data from.</param>
/// <param name="offset">The offset to start obtaining data from.</param>
/// <param name="count">The number of bytes of data to write.</param>
/// <exception cref="NotSupportedException">Any access</exception>
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException("BZip2InputStream Write not supported");
}
/// <summary>
/// Writes a byte to the current position in the file stream.
/// This operation is not supported and will throw a NotSupportedException
/// </summary>
/// <param name="value">The value to write.</param>
/// <exception cref="NotSupportedException">Any access</exception>
public override void WriteByte(byte value)
{
throw new NotSupportedException("BZip2InputStream WriteByte not supported");
}
/// <summary>
/// Read a sequence of bytes and advances the read position by one byte.
/// </summary>
/// <param name="buffer">Array of bytes to store values in</param>
/// <param name="offset">Offset in array to begin storing data</param>
/// <param name="count">The maximum number of bytes to read</param>
/// <returns>The total number of bytes read into the buffer. This might be less
/// than the number of bytes requested if that number of bytes are not
/// currently available or zero if the end of the stream is reached.
/// </returns>
public override int Read(byte[] buffer, int offset, int count)
{
if ( buffer == null )
{
throw new ArgumentNullException("buffer");
}
for (int i = 0; i < count; ++i) {
int rb = ReadByte();
if (rb == -1) {
return i;
}
buffer[offset + i] = (byte)rb;
}
return count;
}
/// <summary>
/// Closes the stream, releasing any associated resources.
/// </summary>
public override void Close()
{
if ( IsStreamOwner && (baseStream != null) ) {
baseStream.Close();
}
}
/// <summary>
/// Read a byte from stream advancing position
/// </summary>
/// <returns>byte read or -1 on end of stream</returns>
public override int ReadByte()
{
if (streamEnd)
{
return -1; // ok
}
int retChar = currentChar;
switch (currentState)
{
case RAND_PART_B_STATE:
SetupRandPartB();
break;
case RAND_PART_C_STATE:
SetupRandPartC();
break;
case NO_RAND_PART_B_STATE:
SetupNoRandPartB();
break;
case NO_RAND_PART_C_STATE:
SetupNoRandPartC();
break;
case START_BLOCK_STATE:
case NO_RAND_PART_A_STATE:
case RAND_PART_A_STATE:
break;
default:
break;
}
return retChar;
}
#endregion
void MakeMaps()
{
nInUse = 0;
for (int i = 0; i < 256; ++i) {
if (inUse[i]) {
seqToUnseq[nInUse] = (byte)i;
unseqToSeq[i] = (byte)nInUse;
nInUse++;
}
}
}
void Initialize()
{
char magic1 = BsGetUChar();
char magic2 = BsGetUChar();
char magic3 = BsGetUChar();
char magic4 = BsGetUChar();
if (magic1 != 'B' || magic2 != 'Z' || magic3 != 'h' || magic4 < '1' || magic4 > '9') {
streamEnd = true;
return;
}
SetDecompressStructureSizes(magic4 - '0');
computedCombinedCRC = 0;
}
void InitBlock()
{
char magic1 = BsGetUChar();
char magic2 = BsGetUChar();
char magic3 = BsGetUChar();
char magic4 = BsGetUChar();
char magic5 = BsGetUChar();
char magic6 = BsGetUChar();
if (magic1 == 0x17 && magic2 == 0x72 && magic3 == 0x45 && magic4 == 0x38 && magic5 == 0x50 && magic6 == 0x90) {
Complete();
return;
}
if (magic1 != 0x31 || magic2 != 0x41 || magic3 != 0x59 || magic4 != 0x26 || magic5 != 0x53 || magic6 != 0x59) {
BadBlockHeader();
streamEnd = true;
return;
}
storedBlockCRC = BsGetInt32();
blockRandomised = (BsR(1) == 1);
GetAndMoveToFrontDecode();
mCrc.Reset();
currentState = START_BLOCK_STATE;
}
void EndBlock()
{
computedBlockCRC = (int)mCrc.Value;
// -- A bad CRC is considered a fatal error. --
if (storedBlockCRC != computedBlockCRC) {
CrcError();
}
// 1528150659
computedCombinedCRC = ((computedCombinedCRC << 1) & 0xFFFFFFFF) | (computedCombinedCRC >> 31);
computedCombinedCRC = computedCombinedCRC ^ (uint)computedBlockCRC;
}
void Complete()
{
storedCombinedCRC = BsGetInt32();
if (storedCombinedCRC != (int)computedCombinedCRC) {
CrcError();
}
streamEnd = true;
}
void BsSetStream(Stream stream)
{
baseStream = stream;
bsLive = 0;
bsBuff = 0;
}
void FillBuffer()
{
int thech = 0;
try {
thech = baseStream.ReadByte();
} catch (Exception) {
CompressedStreamEOF();
}
if (thech == -1) {
CompressedStreamEOF();
}
bsBuff = (bsBuff << 8) | (thech & 0xFF);
bsLive += 8;
}
int BsR(int n)
{
while (bsLive < n) {
FillBuffer();
}
int v = (bsBuff >> (bsLive - n)) & ((1 << n) - 1);
bsLive -= n;
return v;
}
char BsGetUChar()
{
return (char)BsR(8);
}
int BsGetIntVS(int numBits)
{
return BsR(numBits);
}
int BsGetInt32()
{
int result = BsR(8);
result = (result << 8) | BsR(8);
result = (result << 8) | BsR(8);
result = (result << 8) | BsR(8);
return result;
}
void RecvDecodingTables()
{
char[][] len = new char[BZip2Constants.GroupCount][];
for (int i = 0; i < BZip2Constants.GroupCount; ++i) {
len[i] = new char[BZip2Constants.MaximumAlphaSize];
}
bool[] inUse16 = new bool[16];
//--- Receive the mapping table ---
for (int i = 0; i < 16; i++) {
inUse16[i] = (BsR(1) == 1);
}
for (int i = 0; i < 16; i++) {
if (inUse16[i]) {
for (int j = 0; j < 16; j++) {
inUse[i * 16 + j] = (BsR(1) == 1);
}
} else {
for (int j = 0; j < 16; j++) {
inUse[i * 16 + j] = false;
}
}
}
MakeMaps();
int alphaSize = nInUse + 2;
//--- Now the selectors ---
int nGroups = BsR(3);
int nSelectors = BsR(15);
for (int i = 0; i < nSelectors; i++) {
int j = 0;
while (BsR(1) == 1) {
j++;
}
selectorMtf[i] = (byte)j;
}
//--- Undo the MTF values for the selectors. ---
byte[] pos = new byte[BZip2Constants.GroupCount];
for (int v = 0; v < nGroups; v++) {
pos[v] = (byte)v;
}
for (int i = 0; i < nSelectors; i++) {
int v = selectorMtf[i];
byte tmp = pos[v];
while (v > 0) {
pos[v] = pos[v - 1];
v--;
}
pos[0] = tmp;
selector[i] = tmp;
}
//--- Now the coding tables ---
for (int t = 0; t < nGroups; t++) {
int curr = BsR(5);
for (int i = 0; i < alphaSize; i++) {
while (BsR(1) == 1) {
if (BsR(1) == 0) {
curr++;
} else {
curr--;
}
}
len[t][i] = (char)curr;
}
}
//--- Create the Huffman decoding tables ---
for (int t = 0; t < nGroups; t++) {
int minLen = 32;
int maxLen = 0;
for (int i = 0; i < alphaSize; i++) {
maxLen = Math.Max(maxLen, len[t][i]);
minLen = Math.Min(minLen, len[t][i]);
}
HbCreateDecodeTables(limit[t], baseArray[t], perm[t], len[t], minLen, maxLen, alphaSize);
minLens[t] = minLen;
}
}
void GetAndMoveToFrontDecode()
{
byte[] yy = new byte[256];
int nextSym;
int limitLast = BZip2Constants.BaseBlockSize * blockSize100k;
origPtr = BsGetIntVS(24);
RecvDecodingTables();
int EOB = nInUse+1;
int groupNo = -1;
int groupPos = 0;
/*--
Setting up the unzftab entries here is not strictly
necessary, but it does save having to do it later
in a separate pass, and so saves a block's worth of
cache misses.
--*/
for (int i = 0; i <= 255; i++) {
unzftab[i] = 0;
}
for (int i = 0; i <= 255; i++) {
yy[i] = (byte)i;
}
last = -1;
if (groupPos == 0) {
groupNo++;
groupPos = BZip2Constants.GroupSize;
}
groupPos--;
int zt = selector[groupNo];
int zn = minLens[zt];
int zvec = BsR(zn);
int zj;
while (zvec > limit[zt][zn]) {
if (zn > 20) { // the longest code
throw new BZip2Exception("Bzip data error");
}
zn++;
while (bsLive < 1) {
FillBuffer();
}
zj = (bsBuff >> (bsLive-1)) & 1;
bsLive--;
zvec = (zvec << 1) | zj;
}
if (zvec - baseArray[zt][zn] < 0 || zvec - baseArray[zt][zn] >= BZip2Constants.MaximumAlphaSize) {
throw new BZip2Exception("Bzip data error");
}
nextSym = perm[zt][zvec - baseArray[zt][zn]];
while (true) {
if (nextSym == EOB) {
break;
}
if (nextSym == BZip2Constants.RunA || nextSym == BZip2Constants.RunB) {
int s = -1;
int n = 1;
do {
if (nextSym == BZip2Constants.RunA) {
s += (0 + 1) * n;
} else if (nextSym == BZip2Constants.RunB) {
s += (1 + 1) * n;
}
n <<= 1;
if (groupPos == 0) {
groupNo++;
groupPos = BZip2Constants.GroupSize;
}
groupPos--;
zt = selector[groupNo];
zn = minLens[zt];
zvec = BsR(zn);
while (zvec > limit[zt][zn]) {
zn++;
while (bsLive < 1) {
FillBuffer();
}
zj = (bsBuff >> (bsLive - 1)) & 1;
bsLive--;
zvec = (zvec << 1) | zj;
}
nextSym = perm[zt][zvec - baseArray[zt][zn]];
} while (nextSym == BZip2Constants.RunA || nextSym == BZip2Constants.RunB);
s++;
byte ch = seqToUnseq[yy[0]];
unzftab[ch] += s;
while (s > 0) {
last++;
ll8[last] = ch;
s--;
}
if (last >= limitLast) {
BlockOverrun();
}
continue;
} else {
last++;
if (last >= limitLast) {
BlockOverrun();
}
byte tmp = yy[nextSym - 1];
unzftab[seqToUnseq[tmp]]++;
ll8[last] = seqToUnseq[tmp];
for (int j = nextSym-1; j > 0; --j) {
yy[j] = yy[j - 1];
}
yy[0] = tmp;
if (groupPos == 0) {
groupNo++;
groupPos = BZip2Constants.GroupSize;
}
groupPos--;
zt = selector[groupNo];
zn = minLens[zt];
zvec = BsR(zn);
while (zvec > limit[zt][zn]) {
zn++;
while (bsLive < 1) {
FillBuffer();
}
zj = (bsBuff >> (bsLive-1)) & 1;
bsLive--;
zvec = (zvec << 1) | zj;
}
nextSym = perm[zt][zvec - baseArray[zt][zn]];
continue;
}
}
}
void SetupBlock()
{
int[] cftab = new int[257];
cftab[0] = 0;
Array.Copy(unzftab, 0, cftab, 1, 256);
for (int i = 1; i <= 256; i++) {
cftab[i] += cftab[i - 1];
}
for (int i = 0; i <= last; i++) {
byte ch = ll8[i];
tt[cftab[ch]] = i;
cftab[ch]++;
}
cftab = null;
tPos = tt[origPtr];
count = 0;
i2 = 0;
ch2 = 256; /*-- not a char and not EOF --*/
if (blockRandomised) {
rNToGo = 0;
rTPos = 0;
SetupRandPartA();
} else {
SetupNoRandPartA();
}
}
void SetupRandPartA()
{
if (i2 <= last) {
chPrev = ch2;
ch2 = ll8[tPos];
tPos = tt[tPos];
if (rNToGo == 0) {
rNToGo = BZip2Constants.RandomNumbers[rTPos];
rTPos++;
if (rTPos == 512) {
rTPos = 0;
}
}
rNToGo--;
ch2 ^= (int)((rNToGo == 1) ? 1 : 0);
i2++;
currentChar = ch2;
currentState = RAND_PART_B_STATE;
mCrc.Update(ch2);
} else {
EndBlock();
InitBlock();
SetupBlock();
}
}
void SetupNoRandPartA()
{
if (i2 <= last) {
chPrev = ch2;
ch2 = ll8[tPos];
tPos = tt[tPos];
i2++;
currentChar = ch2;
currentState = NO_RAND_PART_B_STATE;
mCrc.Update(ch2);
} else {
EndBlock();
InitBlock();
SetupBlock();
}
}
void SetupRandPartB()
{
if (ch2 != chPrev) {
currentState = RAND_PART_A_STATE;
count = 1;
SetupRandPartA();
} else {
count++;
if (count >= 4) {
z = ll8[tPos];
tPos = tt[tPos];
if (rNToGo == 0) {
rNToGo = BZip2Constants.RandomNumbers[rTPos];
rTPos++;
if (rTPos == 512) {
rTPos = 0;
}
}
rNToGo--;
z ^= (byte)((rNToGo == 1) ? 1 : 0);
j2 = 0;
currentState = RAND_PART_C_STATE;
SetupRandPartC();
} else {
currentState = RAND_PART_A_STATE;
SetupRandPartA();
}
}
}
void SetupRandPartC()
{
if (j2 < (int)z) {
currentChar = ch2;
mCrc.Update(ch2);
j2++;
} else {
currentState = RAND_PART_A_STATE;
i2++;
count = 0;
SetupRandPartA();
}
}
void SetupNoRandPartB()
{
if (ch2 != chPrev) {
currentState = NO_RAND_PART_A_STATE;
count = 1;
SetupNoRandPartA();
} else {
count++;
if (count >= 4) {
z = ll8[tPos];
tPos = tt[tPos];
currentState = NO_RAND_PART_C_STATE;
j2 = 0;
SetupNoRandPartC();
} else {
currentState = NO_RAND_PART_A_STATE;
SetupNoRandPartA();
}
}
}
void SetupNoRandPartC()
{
if (j2 < (int)z) {
currentChar = ch2;
mCrc.Update(ch2);
j2++;
} else {
currentState = NO_RAND_PART_A_STATE;
i2++;
count = 0;
SetupNoRandPartA();
}
}
void SetDecompressStructureSizes(int newSize100k)
{
if (!(0 <= newSize100k && newSize100k <= 9 && 0 <= blockSize100k && blockSize100k <= 9)) {
throw new BZip2Exception("Invalid block size");
}
blockSize100k = newSize100k;
if (newSize100k == 0) {
return;
}
int n = BZip2Constants.BaseBlockSize * newSize100k;
ll8 = new byte[n];
tt = new int[n];
}
static void CompressedStreamEOF()
{
throw new EndOfStreamException("BZip2 input stream end of compressed stream");
}
static void BlockOverrun()
{
throw new BZip2Exception("BZip2 input stream block overrun");
}
static void BadBlockHeader()
{
throw new BZip2Exception("BZip2 input stream bad block header");
}
static void CrcError()
{
throw new BZip2Exception("BZip2 input stream crc error");
}
static void HbCreateDecodeTables(int[] limit, int[] baseArray, int[] perm, char[] length, int minLen, int maxLen, int alphaSize)
{
int pp = 0;
for (int i = minLen; i <= maxLen; ++i)
{
for (int j = 0; j < alphaSize; ++j)
{
if (length[j] == i)
{
perm[pp] = j;
++pp;
}
}
}
for (int i = 0; i < BZip2Constants.MaximumCodeLength; i++)
{
baseArray[i] = 0;
}
for (int i = 0; i < alphaSize; i++)
{
++baseArray[length[i] + 1];
}
for (int i = 1; i < BZip2Constants.MaximumCodeLength; i++)
{
baseArray[i] += baseArray[i - 1];
}
for (int i = 0; i < BZip2Constants.MaximumCodeLength; i++)
{
limit[i] = 0;
}
int vec = 0;
for (int i = minLen; i <= maxLen; i++)
{
vec += (baseArray[i + 1] - baseArray[i]);
limit[i] = vec - 1;
vec <<= 1;
}
for (int i = minLen + 1; i <= maxLen; i++)
{
baseArray[i] = ((limit[i - 1] + 1) << 1) - baseArray[i];
}
}
#region Instance Fields
/*--
index of the last char in the block, so
the block size == last + 1.
--*/
int last;
/*--
index in zptr[] of original string after sorting.
--*/
int origPtr;
/*--
always: in the range 0 .. 9.
The current block size is 100000 * this number.
--*/
int blockSize100k;
bool blockRandomised;
int bsBuff;
int bsLive;
IChecksum mCrc = new StrangeCRC();
bool[] inUse = new bool[256];
int nInUse;
byte[] seqToUnseq = new byte[256];
byte[] unseqToSeq = new byte[256];
byte[] selector = new byte[BZip2Constants.MaximumSelectors];
byte[] selectorMtf = new byte[BZip2Constants.MaximumSelectors];
int[] tt;
byte[] ll8;
/*--
freq table collected to save a pass over the data
during decompression.
--*/
int[] unzftab = new int[256];
int[][] limit = new int[BZip2Constants.GroupCount][];
int[][] baseArray = new int[BZip2Constants.GroupCount][];
int[][] perm = new int[BZip2Constants.GroupCount][];
int[] minLens = new int[BZip2Constants.GroupCount];
Stream baseStream;
bool streamEnd;
int currentChar = -1;
int currentState = START_BLOCK_STATE;
int storedBlockCRC, storedCombinedCRC;
int computedBlockCRC;
uint computedCombinedCRC;
int count, chPrev, ch2;
int tPos;
int rNToGo;
int rTPos;
int i2, j2;
byte z;
bool isStreamOwner = true;
#endregion
}
}
/* This file was derived from a file containing this license:
*
* This file is a part of bzip2 and/or libbzip2, a program and
* library for lossless, block-sorting data compression.
*
* Copyright (C) 1996-1998 Julian R Seward. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. The origin of this software must not be misrepresented; you must
* not claim that you wrote the original software. If you use this
* software in a product, an acknowledgment in the product
* documentation would be appreciated but is not required.
*
* 3. Altered source versions must be plainly marked as such, and must
* not be misrepresented as being the original software.
*
* 4. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Java version ported by Keiron Liddle, Aftex Software <keiron@aftexsw.com> 1999-2001
*/