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/*
* TCircularBuffer.java
*
* This file is part of Tritonus: http://www.tritonus.org/
*/
/*
* Copyright (c) 1999 by Matthias Pfisterer
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library 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 Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
/*
|<--- this code is formatted to fit into 80 columns --->|
*/
package org.tritonus.share;
import org.tritonus.share.TDebug;
public class TCircularBuffer
{
private boolean m_bBlockingRead;
private boolean m_bBlockingWrite;
private byte[] m_abData;
private int m_nSize;
private long m_lReadPos;
private long m_lWritePos;
private Trigger m_trigger;
private boolean m_bOpen;
public TCircularBuffer(int nSize, boolean bBlockingRead, boolean bBlockingWrite, Trigger trigger)
{
m_bBlockingRead = bBlockingRead;
m_bBlockingWrite = bBlockingWrite;
m_nSize = nSize;
m_abData = new byte[m_nSize];
m_lReadPos = 0;
m_lWritePos = 0;
m_trigger = trigger;
m_bOpen = true;
}
public void close()
{
m_bOpen = false;
// TODO: call notify() ?
}
private boolean isOpen()
{
return m_bOpen;
}
public int availableRead()
{
return (int) (m_lWritePos - m_lReadPos);
}
public int availableWrite()
{
return m_nSize - availableRead();
}
private int getReadPos()
{
return (int) (m_lReadPos % m_nSize);
}
private int getWritePos()
{
return (int) (m_lWritePos % m_nSize);
}
public int read(byte[] abData)
{
return read(abData, 0, abData.length);
}
public int read(byte[] abData, int nOffset, int nLength)
{
if (TDebug.TraceCircularBuffer)
{
TDebug.out(">TCircularBuffer.read(): called.");
dumpInternalState();
}
if (! isOpen())
{
if (availableRead() > 0)
{
nLength = Math.min(nLength, availableRead());
if (TDebug.TraceCircularBuffer) { TDebug.out("reading rest in closed buffer, length: " + nLength); }
}
else
{
if (TDebug.TraceCircularBuffer) { TDebug.out("< not open. returning -1."); }
return -1;
}
}
synchronized (this)
{
if (m_trigger != null && availableRead() < nLength)
{
if (TDebug.TraceCircularBuffer) { TDebug.out("executing trigger."); }
m_trigger.execute();
}
if (!m_bBlockingRead)
{
nLength = Math.min(availableRead(), nLength);
}
int nRemainingBytes = nLength;
while (nRemainingBytes > 0)
{
while (availableRead() == 0)
{
try
{
wait();
}
catch (InterruptedException e)
{
if (TDebug.TraceAllExceptions)
{
TDebug.out(e);
}
}
}
int nAvailable = Math.min(availableRead(), nRemainingBytes);
while (nAvailable > 0)
{
int nToRead = Math.min(nAvailable, m_nSize - getReadPos());
System.arraycopy(m_abData, getReadPos(), abData, nOffset, nToRead);
m_lReadPos += nToRead;
nOffset += nToRead;
nAvailable -= nToRead;
nRemainingBytes -= nToRead;
}
notifyAll();
}
if (TDebug.TraceCircularBuffer)
{
TDebug.out("After read:");
dumpInternalState();
TDebug.out("< completed. Read " + nLength + " bytes");
}
return nLength;
}
}
public int write(byte[] abData)
{
return write(abData, 0, abData.length);
}
public int write(byte[] abData, int nOffset, int nLength)
{
if (TDebug.TraceCircularBuffer)
{
TDebug.out(">TCircularBuffer.write(): called; nLength: " + nLength);
dumpInternalState();
}
synchronized (this)
{
if (TDebug.TraceCircularBuffer) { TDebug.out("entered synchronized block."); }
if (!m_bBlockingWrite)
{
nLength = Math.min(availableWrite(), nLength);
}
int nRemainingBytes = nLength;
while (nRemainingBytes > 0)
{
while (availableWrite() == 0)
{
try
{
wait();
}
catch (InterruptedException e)
{
if (TDebug.TraceAllExceptions)
{
TDebug.out(e);
}
}
}
int nAvailable = Math.min(availableWrite(), nRemainingBytes);
while (nAvailable > 0)
{
int nToWrite = Math.min(nAvailable, m_nSize - getWritePos());
//TDebug.out("src buf size= " + abData.length + ", offset = " + nOffset + ", dst buf size=" + m_abData.length + " write pos=" + getWritePos() + " len=" + nToWrite);
System.arraycopy(abData, nOffset, m_abData, getWritePos(), nToWrite);
m_lWritePos += nToWrite;
nOffset += nToWrite;
nAvailable -= nToWrite;
nRemainingBytes -= nToWrite;
}
notifyAll();
}
if (TDebug.TraceCircularBuffer)
{
TDebug.out("After write:");
dumpInternalState();
TDebug.out("< completed. Wrote "+nLength+" bytes");
}
return nLength;
}
}
private void dumpInternalState()
{
TDebug.out("m_lReadPos = " + m_lReadPos + " ^= "+getReadPos());
TDebug.out("m_lWritePos = " + m_lWritePos + " ^= "+getWritePos());
TDebug.out("availableRead() = " + availableRead());
TDebug.out("availableWrite() = " + availableWrite());
}
public static interface Trigger
{
public void execute();
}
}
/*** TCircularBuffer.java ***/
|
