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// OutputWindow.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;
namespace ICSharpCode.SharpZipLib.Zip.Compression.Streams
{
/// <summary>
/// Contains the output from the Inflation process.
/// We need to have a window so that we can refer backwards into the output stream
/// to repeat stuff.
///
/// author of the original java version : John Leuner
/// </summary>
public class OutputWindow
{
private static int WINDOW_SIZE = 1 << 15;
private static int WINDOW_MASK = WINDOW_SIZE - 1;
private byte[] window = new byte[WINDOW_SIZE]; //The window is 2^15 bytes
private int windowEnd = 0;
private int windowFilled = 0;
public void Write(int abyte)
{
if (windowFilled++ == WINDOW_SIZE) {
throw new InvalidOperationException("Window full");
}
window[windowEnd++] = (byte) abyte;
windowEnd &= WINDOW_MASK;
}
private void SlowRepeat(int repStart, int len, int dist)
{
while (len-- > 0) {
window[windowEnd++] = window[repStart++];
windowEnd &= WINDOW_MASK;
repStart &= WINDOW_MASK;
}
}
public void Repeat(int len, int dist)
{
if ((windowFilled += len) > WINDOW_SIZE) {
throw new InvalidOperationException("Window full");
}
int rep_start = (windowEnd - dist) & WINDOW_MASK;
int border = WINDOW_SIZE - len;
if (rep_start <= border && windowEnd < border) {
if (len <= dist) {
System.Array.Copy(window, rep_start, window, windowEnd, len);
windowEnd += len;
} else {
/* We have to copy manually, since the repeat pattern overlaps.
*/
while (len-- > 0) {
window[windowEnd++] = window[rep_start++];
}
}
} else {
SlowRepeat(rep_start, len, dist);
}
}
public int CopyStored(StreamManipulator input, int len)
{
len = Math.Min(Math.Min(len, WINDOW_SIZE - windowFilled), input.AvailableBytes);
int copied;
int tailLen = WINDOW_SIZE - windowEnd;
if (len > tailLen) {
copied = input.CopyBytes(window, windowEnd, tailLen);
if (copied == tailLen) {
copied += input.CopyBytes(window, 0, len - tailLen);
}
} else {
copied = input.CopyBytes(window, windowEnd, len);
}
windowEnd = (windowEnd + copied) & WINDOW_MASK;
windowFilled += copied;
return copied;
}
public void CopyDict(byte[] dict, int offset, int len)
{
if (windowFilled > 0) {
throw new InvalidOperationException();
}
if (len > WINDOW_SIZE) {
offset += len - WINDOW_SIZE;
len = WINDOW_SIZE;
}
System.Array.Copy(dict, offset, window, 0, len);
windowEnd = len & WINDOW_MASK;
}
public int GetFreeSpace()
{
return WINDOW_SIZE - windowFilled;
}
public int GetAvailable()
{
return windowFilled;
}
public int CopyOutput(byte[] output, int offset, int len)
{
int copy_end = windowEnd;
if (len > windowFilled) {
len = windowFilled;
} else {
copy_end = (windowEnd - windowFilled + len) & WINDOW_MASK;
}
int copied = len;
int tailLen = len - copy_end;
if (tailLen > 0) {
System.Array.Copy(window, WINDOW_SIZE - tailLen, output, offset, tailLen);
offset += tailLen;
len = copy_end;
}
System.Array.Copy(window, copy_end - len, output, offset, len);
windowFilled -= copied;
if (windowFilled < 0) {
throw new InvalidOperationException();
}
return copied;
}
public void Reset()
{
windowFilled = windowEnd = 0;
}
}
}
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