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/*
* Copyright 2010 Phil Burk, Mobileer Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.jsyn.io;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* FIFO that implements AudioInputStream, AudioOutputStream interfaces. This can be used to send
* audio data between different threads. The reads or writes may or may not wait based on flags.
*
* @author Phil Burk (C) 2010 Mobileer Inc
*/
public class AudioFifo implements AudioInputStream, AudioOutputStream {
// These indices run double the FIFO size so that we can tell empty from full.
private volatile int readIndex;
private volatile int writeIndex;
private volatile double[] buffer;
// Used to mask the index into range when accessing the buffer array.
private int accessMask;
// Used to mask the index so it wraps around.
private int sizeMask;
private boolean writeWaitEnabled = true;
private boolean readWaitEnabled = true;
private volatile boolean mOpen = true;
final Lock lock = new ReentrantLock();
final Condition notFull = lock.newCondition();
final Condition notEmpty = lock.newCondition();
/**
* @param size Number of doubles in the FIFO. Must be a power of 2. Eg. 1024.
*/
public void allocate(int size) {
if (!isPowerOfTwo(size)) {
throw new IllegalArgumentException("Size must be a power of two.");
}
buffer = new double[size];
accessMask = size - 1;
sizeMask = (size * 2) - 1;
}
public int size() {
return buffer.length;
}
public static boolean isPowerOfTwo(int size) {
return ((size & (size - 1)) == 0);
}
/** How many samples are available for reading without blocking? */
@Override
public int available() {
return (writeIndex - readIndex) & sizeMask;
}
@Override
public void close() {
// Tell any thread that is waiting that the FIFO is closed.
mOpen = false;
lock.lock();
notEmpty.signal();
notFull.signal();
lock.unlock();
}
@Override
public double read() {
double value = Double.NaN;
if (readWaitEnabled) {
lock.lock();
try {
while (mOpen && available() < 1) {
try {
notEmpty.await();
} catch (InterruptedException e) {
return Double.NaN;
}
}
if (mOpen) {
value = readOneInternal();
}
} finally {
lock.unlock();
}
} else {
if (mOpen && readIndex != writeIndex) {
value = readOneInternal();
}
}
if (writeWaitEnabled) {
lock.lock();
notFull.signal();
lock.unlock();
}
return value;
}
private double readOneInternal() {
double value = buffer[readIndex & accessMask];
readIndex = (readIndex + 1) & sizeMask;
return value;
}
@Override
public void write(double value) {
if (writeWaitEnabled) {
lock.lock();
try {
while (mOpen && available() == buffer.length)
{
try {
notFull.await();
} catch (InterruptedException e) {
return; // Silently fail
}
}
if (mOpen) {
writeOneInternal(value);
}
} finally {
lock.unlock();
}
} else {
if (available() != buffer.length) {
writeOneInternal(value);
}
}
if (readWaitEnabled) {
lock.lock();
notEmpty.signal();
lock.unlock();
}
}
private void writeOneInternal(double value) {
buffer[writeIndex & accessMask] = value;
writeIndex = (writeIndex + 1) & sizeMask;
}
@Override
public int read(double[] buffer) {
return read(buffer, 0, buffer.length);
}
@Override
public int read(double[] buffer, int start, int count) {
if (!mOpen) {
return 0;
}
if (!readWaitEnabled) {
count = Math.min(available(), count);
}
int numRead = 0;
for (int i = 0; mOpen && i < count; i++) {
double value = read();
if (Double.isNaN(value)) break;
buffer[i + start] = value;
numRead++;
}
return numRead;
}
@Override
public void write(double[] buffer) {
write(buffer, 0, buffer.length);
}
@Override
public void write(double[] buffer, int start, int count) {
for (int i = 0; i < count; i++) {
write(buffer[i + start]);
}
}
/** If true then a subsequent write call will wait if there is no room to write. */
public void setWriteWaitEnabled(boolean enabled) {
writeWaitEnabled = enabled;
}
/** If true then a subsequent read call will wait if there is no data to read. */
public void setReadWaitEnabled(boolean enabled) {
readWaitEnabled = enabled;
}
public boolean isWriteWaitEnabled() {
return writeWaitEnabled;
}
public boolean isReadWaitEnabled() {
return readWaitEnabled;
}
}
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