// 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 PdfSharp.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.<br/>
/// Author of the original java version: John Leuner
/// </summary>
internal class OutputWindow
{
#region Constants
const int WindowSize = 1 << 15;
const int WindowMask = WindowSize - 1;
#endregion
#region Instance Fields
byte[] window = new byte[WindowSize]; //The window is 2^15 bytes
int windowEnd;
int windowFilled;
#endregion
/// <summary>
/// Write a byte to this output window
/// </summary>
/// <param name="value">value to write</param>
/// <exception cref="InvalidOperationException">
/// if window is full
/// </exception>
public void Write(int value)
{
if (windowFilled++ == WindowSize)
{
throw new InvalidOperationException("Window full");
}
window[windowEnd++] = (byte)value;
windowEnd &= WindowMask;
}
private void SlowRepeat(int repStart, int length, int distance)
{
while (length-- > 0)
{
window[windowEnd++] = window[repStart++];
windowEnd &= WindowMask;
repStart &= WindowMask;
}
}
/// <summary>
/// Append a byte pattern already in the window itself
/// </summary>
/// <param name="length">length of pattern to copy</param>
/// <param name="distance">distance from end of window pattern occurs</param>
/// <exception cref="InvalidOperationException">
/// If the repeated data overflows the window
/// </exception>
public void Repeat(int length, int distance)
{
if ((windowFilled += length) > WindowSize)
{
throw new InvalidOperationException("Window full");
}
int repStart = (windowEnd - distance) & WindowMask;
int border = WindowSize - length;
if ((repStart <= border) && (windowEnd < border))
{
if (length <= distance)
{
System.Array.Copy(window, repStart, window, windowEnd, length);
windowEnd += length;
}
else
{
// We have to copy manually, since the repeat pattern overlaps.
while (length-- > 0)
{
window[windowEnd++] = window[repStart++];
}
}
}
else
{
SlowRepeat(repStart, length, distance);
}
}
/// <summary>
/// Copy from input manipulator to internal window
/// </summary>
/// <param name="input">source of data</param>
/// <param name="length">length of data to copy</param>
/// <returns>the number of bytes copied</returns>
public int CopyStored(StreamManipulator input, int length)
{
length = Math.Min(Math.Min(length, WindowSize - windowFilled), input.AvailableBytes);
int copied;
int tailLen = WindowSize - windowEnd;
if (length > tailLen)
{
copied = input.CopyBytes(window, windowEnd, tailLen);
if (copied == tailLen)
{
copied += input.CopyBytes(window, 0, length - tailLen);
}
}
else
{
copied = input.CopyBytes(window, windowEnd, length);
}
windowEnd = (windowEnd + copied) & WindowMask;
windowFilled += copied;
return copied;
}
/// <summary>
/// Copy dictionary to window
/// </summary>
/// <param name="dictionary">source dictionary</param>
/// <param name="offset">offset of start in source dictionary</param>
/// <param name="length">length of dictionary</param>
/// <exception cref="InvalidOperationException">
/// If window isnt empty
/// </exception>
public void CopyDict(byte[] dictionary, int offset, int length)
{
if (dictionary == null)
{
throw new ArgumentNullException("dictionary");
}
if (windowFilled > 0)
{
throw new InvalidOperationException();
}
if (length > WindowSize)
{
offset += length - WindowSize;
length = WindowSize;
}
System.Array.Copy(dictionary, offset, window, 0, length);
windowEnd = length & WindowMask;
}
/// <summary>
/// Get remaining unfilled space in window
/// </summary>
/// <returns>Number of bytes left in window</returns>
public int GetFreeSpace()
{
return WindowSize - windowFilled;
}
/// <summary>
/// Get bytes available for output in window
/// </summary>
/// <returns>Number of bytes filled</returns>
public int GetAvailable()
{
return windowFilled;
}
/// <summary>
/// Copy contents of window to output
/// </summary>
/// <param name="output">buffer to copy to</param>
/// <param name="offset">offset to start at</param>
/// <param name="len">number of bytes to count</param>
/// <returns>The number of bytes copied</returns>
/// <exception cref="InvalidOperationException">
/// If a window underflow occurs
/// </exception>
public int CopyOutput(byte[] output, int offset, int len)
{
int copyEnd = windowEnd;
if (len > windowFilled)
{
len = windowFilled;
}
else
{
copyEnd = (windowEnd - windowFilled + len) & WindowMask;
}
int copied = len;
int tailLen = len - copyEnd;
if (tailLen > 0)
{
System.Array.Copy(window, WindowSize - tailLen, output, offset, tailLen);
offset += tailLen;
len = copyEnd;
}
System.Array.Copy(window, copyEnd - len, output, offset, len);
windowFilled -= copied;
if (windowFilled < 0)
{
throw new InvalidOperationException();
}
return copied;
}
/// <summary>
/// Reset by clearing window so <see cref="GetAvailable">GetAvailable</see> returns 0
/// </summary>
public void Reset()
{
windowFilled = windowEnd = 0;
}
}
}