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diff --git a/src/java/com/jogamp/openal/util/SimpleSineSynth.java b/src/java/com/jogamp/openal/util/SimpleSineSynth.java
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+/**
+ * Copyright 2023 JogAmp Community. 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. Redistributions in binary form must reproduce the above copyright notice, this list
+ *       of conditions and the following disclaimer in the documentation and/or other materials
+ *       provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``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 JogAmp Community OR
+ * CONTRIBUTORS 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.
+ *
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+package com.jogamp.openal.util;
+
+import java.nio.ByteBuffer;
+import java.nio.FloatBuffer;
+
+import com.jogamp.common.av.AudioFormat;
+import com.jogamp.common.av.AudioSink;
+import com.jogamp.common.nio.Buffers;
+import com.jogamp.common.util.InterruptSource;
+import com.jogamp.common.util.InterruptedRuntimeException;
+import com.jogamp.common.util.SourcedInterruptedException;
+import com.jogamp.openal.sound3d.Context;
+import com.jogamp.openal.sound3d.Device;
+import com.jogamp.openal.sound3d.Source;
+
+/**
+ * A continuous simple off-thread mutable sine wave synthesizer.
+ * <p>
+ * Implementation utilizes an off-thread worker thread streaming the generated wave to OpenAL,
+ * allowing to change frequency and amplitude without disturbance.
+ * </p>
+ */
+public final class SimpleSineSynth {
+    private static final boolean DEBUG = false;
+
+    /** The value PI, i.e. 180 degrees in radians. */
+    private static final float PI = 3.14159265358979323846f;
+
+    /** The value 2PI, i.e. 360 degrees in radians. */
+    private static final float TWO_PI = 2f * PI;
+
+    private static final float EPSILON = 1.1920929E-7f; // Float.MIN_VALUE == 1.4e-45f ; double EPSILON 2.220446049250313E-16d
+
+    private static final float SHORT_MAX = 32767.0f; // == Short.MAX_VALUE
+
+    public static final float MIDDLE_C = 261.625f;
+
+    private final ALAudioSink audioSink;
+    private final Object stateLock = new Object();
+    private volatile float audioAmplitude = 1.0f;
+    private volatile float audioFreq = MIDDLE_C;
+    private volatile int lastAudioPTS = 0;
+    private SynthWorker streamWorker;
+
+    public SimpleSineSynth() {
+        this(null);
+    }
+    public SimpleSineSynth(final Device device) {
+        audioSink = new ALAudioSink(device);
+        streamWorker = new SynthWorker();
+    }
+
+    public ALAudioSink getSink() { return audioSink; }
+    /** Return this instance's OpenAL {@link Device}. */
+    public final Device getDevice() { return audioSink.getDevice(); }
+    /** Return this instance's OpenAL {@link Context}. */
+    public final Context getContext() { return audioSink.getContext(); }
+    /** Return this instance's OpenAL {@link Source}. */
+    public final Source getSource() { return audioSink.getSource(); }
+
+    public void setFreq(final float f) {
+        audioFreq = f;
+    }
+    public float getFreq() { return audioFreq; }
+
+    public void setAmplitude(final float a) {
+        audioAmplitude = Math.min(1.0f, Math.max(0.0f, a)); // clip [0..1]
+    }
+    public float getAmplitude() { return audioAmplitude; }
+
+    /** Returns latency or frame-duration in milliseconds */
+    public int getLatency() { return null != streamWorker ? streamWorker.frameDuration : 2*AudioSink.DefaultFrameDuration; }
+
+    public void play() {
+        synchronized( stateLock ) {
+            if( null == streamWorker ) {
+                streamWorker = new SynthWorker();
+            }
+            streamWorker.doResume();
+        }
+    }
+
+    public void pause() {
+        synchronized( stateLock ) {
+            if( null != streamWorker ) {
+                streamWorker.doPause(true);
+            }
+        }
+    }
+
+    public void stop() {
+        synchronized( stateLock ) {
+            if( null != streamWorker ) {
+                streamWorker.doStop();
+                streamWorker = null;
+            }
+        }
+    }
+
+    public boolean isPlaying() {
+        synchronized( stateLock ) {
+            if( null != streamWorker ) {
+                return streamWorker.isPlaying();
+            }
+        }
+        return false;
+    }
+
+    public boolean isRunning() {
+        synchronized( stateLock ) {
+            if( null != streamWorker ) {
+                return streamWorker.isRunning();
+            }
+        }
+        return false;
+    }
+
+    public int getGenPTS() { return lastAudioPTS; }
+
+    public int getPTS() { return audioSink.getPTS(); }
+
+    @Override
+    public final String toString() {
+        synchronized( stateLock ) {
+            final int pts = getPTS();
+            final int lag = getGenPTS() - pts;
+            return getClass().getSimpleName()+"[f "+audioFreq+", a "+audioAmplitude+", latency "+getLatency()+
+                    ", state[running "+isRunning()+", playing "+isPlaying()+"], pts[gen "+getGenPTS()+", play "+pts+", lag "+lag+"], "+audioSink.toString()+"]";
+        }
+    }
+
+    private static ByteBuffer allocate(final int size) {
+        // return ByteBuffer.allocate(size);
+        return Buffers.newDirectByteBuffer(size);
+    }
+
+    class SynthWorker extends InterruptSource.Thread {
+        private volatile boolean isRunning = false;
+        private volatile boolean isPlaying = false;
+        private volatile boolean isBlocked = false;
+
+        private volatile boolean shallPause = true;
+        private volatile boolean shallStop = false;
+
+        private final boolean useFloat32SampleType;
+        private final int bytesPerSample;
+        private final AudioFormat audioFormat;
+        private ByteBuffer sampleBuffer;
+        private int frameDuration;
+        private int audioQueueLimit;
+
+        private float lastFreq;
+        private float nextSin;
+        private boolean upSin;
+        private int nextStep;
+
+        /**
+         * Starts this daemon thread,
+         * <p>
+         * This thread pauses after it's started!
+         * </p>
+         **/
+        SynthWorker() {
+            setDaemon(true);
+            synchronized(this) {
+                lastAudioPTS = 0;
+
+                // Note: float32 is OpenAL-Soft's internally used format to mix samples etc.
+                final AudioFormat f32 = new AudioFormat(audioSink.getPreferredFormat().sampleRate, 4<<3, 1, true /* signed */,
+                                                        false /* fixed point */, false /* planar */, true /* littleEndian */);
+                if( audioSink.isSupported(f32) ) {
+                    useFloat32SampleType = true;
+                    bytesPerSample = 4;
+                    audioFormat = f32;
+                } else {
+                    useFloat32SampleType = false;
+                    bytesPerSample = 2;
+                    audioFormat = new AudioFormat(audioSink.getPreferredFormat().sampleRate, bytesPerSample<<3, 1, true /* signed */,
+                                                  true /* fixed point */, false /* planar */, true /* littleEndian */);
+                }
+                System.err.println("OpenAL float32 supported: "+useFloat32SampleType);
+
+                sampleBuffer = allocate( audioFormat.getDurationsByteSize(30/1000f) ); // pre-allocate buffer for 30ms
+
+                // clip [16 .. 2*AudioSink.DefaultFrameDuration]
+                frameDuration = 10; // let's try for the best ..
+                audioQueueLimit = Math.max( 16, Math.min(3*AudioSink.DefaultFrameDuration, 3*Math.round( 1000f*audioSink.getDefaultLatency() ) ) ); // ms
+
+                audioSink.init(audioFormat, frameDuration, audioQueueLimit, 0, audioQueueLimit);
+                frameDuration = Math.round( 1000f*audioSink.getLatency() ); // actual number
+                lastFreq = 0;
+                nextSin = 0;
+                upSin = true;
+                nextStep = 0;
+                start();
+                try {
+                    this.notifyAll();  // wake-up startup-block
+                    while( !isRunning && !shallStop ) {
+                        this.wait();  // wait until started
+                    }
+                } catch (final InterruptedException e) {
+                    throw new InterruptedRuntimeException(e);
+                }
+            }
+        }
+
+        private final int findNextStep(final boolean upSin, final float nextSin, final float freq, final int sampleRate, final int sampleCount) {
+            final float sample_step = ( TWO_PI * freq ) / sampleRate;
+
+            float s_diff = Float.MAX_VALUE;
+            float s_best = 0;
+            int i_best = -1;
+            float s0 = 0;
+            for(int i=0; i < sampleCount && s_diff >= EPSILON ; ++i) {
+                final float s1 = (float) Math.sin( sample_step * i );
+                final float s_d = Math.abs(nextSin - s1);
+                if( s_d < s_diff && ( ( upSin && s1 >= s0 ) || ( !upSin && s1 < s0 ) ) ) {
+                    s_best = s1;
+                    s_diff = s_d;
+                    i_best = i;
+                }
+                s0 = s1;
+            }
+            if( DEBUG ) {
+                System.err.printf("%nBest: %d/[%d..%d]: s %f / %f (up %b), s_diff %f%n", i_best, 0, sampleCount, s_best, nextSin, upSin, s_diff);
+            }
+            return i_best;
+        }
+
+        private final void enqueueWave() {
+            // use local cache of volatiles, stable values
+            final float freq = audioFreq;
+            final float amp = audioAmplitude;
+
+            final float period = 1.0f / freq; // [s]
+            final float sample_step = ( TWO_PI * freq ) / audioFormat.sampleRate;
+
+            final float duration = frameDuration / 1000.0f; // [s]
+            final int sample_count = (int)( duration * audioFormat.sampleRate ); // [n]
+
+            final boolean overflow;
+            final boolean changedFreq;
+            if( Math.abs( freq - lastFreq ) >= EPSILON ) {
+                changedFreq = true;
+                overflow = false;
+                lastFreq = freq;
+                nextStep = findNextStep(upSin, nextSin, freq, audioFormat.sampleRate, sample_count);
+            } else {
+                changedFreq = false;
+                if( nextStep + sample_count >= Integer.MAX_VALUE/1000 ) {
+                    nextStep = findNextStep(upSin, nextSin, freq, audioFormat.sampleRate, sample_count);
+                    overflow = true;
+                } else {
+                    overflow = false;
+                }
+            }
+
+            if( DEBUG ) {
+                if( changedFreq || overflow ) {
+                    final float wave_count = duration / period;
+                    System.err.printf("%nFreq %f Hz, period %f [ms], waves %.2f, duration %f [ms], sample[count %d, rate %d, step %f, next[up %b, sin %f, step %d]]%n", freq,
+                            1000.0*period, wave_count, 1000.0*duration, sample_count, audioFormat.sampleRate, sample_step, upSin, nextSin, nextStep);
+                    // System.err.println(Synth02AL.this.toString());
+                }
+            }
+
+            if( sampleBuffer.capacity() < bytesPerSample*sample_count ) {
+                if( DEBUG ) {
+                    System.err.printf("SampleBuffer grow: %d -> %d%n", sampleBuffer.capacity(), bytesPerSample*sample_count);
+                }
+                sampleBuffer = allocate(bytesPerSample*sample_count);
+            }
+
+            {
+                int i;
+                float s = 0;
+                if( useFloat32SampleType ) {
+                    final FloatBuffer f32sb = sampleBuffer.asFloatBuffer();
+                    final int l = nextStep;
+                    for(i=l; i<l+sample_count; ++i) {
+                        s = (float) Math.sin( sample_step * i );
+                        f32sb.put(s * amp);
+                    }
+                } else {
+                    final int l = nextStep;
+                    for(i=l; i<l+sample_count; ++i) {
+                        s = (float) Math.sin( sample_step * i );
+                        final short s16 = (short)( SHORT_MAX * s * amp );
+                        sampleBuffer.put( (byte) ( s16 & 0xff ) );
+                        sampleBuffer.put( (byte) ( ( s16 >>> 8 ) & 0xff ) );
+                    }
+                }
+                nextStep = i;
+                nextSin = (float) Math.sin( sample_step * nextStep );
+                upSin = nextSin >= s;
+            }
+            sampleBuffer.rewind();
+            audioSink.enqueueData(lastAudioPTS, sampleBuffer, sample_count*bytesPerSample);
+            sampleBuffer.clear();
+            lastAudioPTS += frameDuration;
+        }
+
+        public final synchronized void doPause(final boolean waitUntilDone) {
+            if( isPlaying ) {
+                shallPause = true;
+                if( java.lang.Thread.currentThread() != this ) {
+                    if( isBlocked && isPlaying ) {
+                        this.interrupt();
+                    }
+                    if( waitUntilDone ) {
+                        try {
+                            while( isPlaying && isRunning ) {
+                                this.wait(); // wait until paused
+                            }
+                        } catch (final InterruptedException e) {
+                            throw new InterruptedRuntimeException(e);
+                        }
+                    }
+                }
+            }
+        }
+        public final synchronized void doResume() {
+            if( isRunning && !isPlaying ) {
+                shallPause = false;
+                if( java.lang.Thread.currentThread() != this ) {
+                    try {
+                        this.notifyAll();  // wake-up pause-block
+                        while( !isPlaying && !shallPause && isRunning ) {
+                            this.wait(); // wait until resumed
+                        }
+                    } catch (final InterruptedException e) {
+                        final InterruptedException e2 = SourcedInterruptedException.wrap(e);
+                        doPause(false);
+                        throw new InterruptedRuntimeException(e2);
+                    }
+                }
+            }
+        }
+        public final synchronized void doStop() {
+            if( isRunning ) {
+                shallStop = true;
+                if( java.lang.Thread.currentThread() != this ) {
+                    if( isBlocked && isRunning ) {
+                        this.interrupt();
+                    }
+                    try {
+                        this.notifyAll();  // wake-up pause-block (opt)
+                        while( isRunning ) {
+                            this.wait();  // wait until stopped
+                        }
+                    } catch (final InterruptedException e) {
+                        throw new InterruptedRuntimeException(e);
+                    }
+                }
+            }
+            audioSink.destroy();
+        }
+        public final boolean isRunning() { return isRunning; }
+        public final boolean isPlaying() { return isPlaying; }
+
+        @Override
+        public final void run() {
+            setName(getName()+"-SynthWorker_"+SynthWorkerInstanceId);
+            SynthWorkerInstanceId++;
+
+            synchronized ( this ) {
+                isRunning = true;
+                this.notifyAll(); // wake-up ctor()
+            }
+
+            while( !shallStop ) {
+                if( shallPause ) {
+                    synchronized ( this ) {
+                        while( shallPause && !shallStop ) {
+                            audioSink.pause();
+                            isPlaying = false;
+                            this.notifyAll(); // wake-up doPause()
+                            try {
+                                this.wait();  // wait until resumed
+                            } catch (final InterruptedException e) {
+                                if( !shallPause ) {
+                                    e.printStackTrace();
+                                }
+                            }
+                        }
+                        audioSink.play();
+                        isPlaying = true;
+                        this.notifyAll(); // wake-up doResume()
+                    }
+                }
+                if( !shallStop ) {
+                    isBlocked = true;
+                    enqueueWave();
+                    isBlocked = false;
+                }
+            }
+
+            synchronized ( this ) {
+                isRunning = false;
+                isPlaying = false;
+                this.notifyAll(); // wake-up doStop()
+            }
+        }
+    }
+    static int SynthWorkerInstanceId = 0;
+}