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/*
* Copyright 2011 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.unitgen;
import com.jsyn.engine.SynthesisEngine;
import com.jsyn.ports.UnitInputPort;
/**
* Two stage Attack/Decay envelope that is triggered by an input level greater than THRESHOLD. This
* does not sustain.
*
* @author Phil Burk (C) 2011 Mobileer Inc
*/
public class EnvelopeAttackDecay extends UnitGate {
public static final double THRESHOLD = 0.01;
private static final double MIN_DURATION = (1.0 / 100000.0);
/**
* Time in seconds for the rising stage of the envelope to go from 0.0 to 1.0. The attack is a
* linear ramp.
*/
public UnitInputPort attack;
/**
* Time in seconds for the falling stage to go from 0 dB to -90 dB.
*/
public UnitInputPort decay;
public UnitInputPort amplitude;
private enum State {
IDLE, ATTACKING, DECAYING
}
private State state = State.IDLE;
private double scaler = 1.0;
private double level;
private double increment;
public EnvelopeAttackDecay() {
super();
addPort(attack = new UnitInputPort("Attack"));
attack.setup(0.001, 0.05, 8.0);
addPort(decay = new UnitInputPort("Decay"));
decay.setup(0.001, 0.2, 8.0);
addPort(amplitude = new UnitInputPort("Amplitude", 1.0));
startIdle();
}
public void export(Circuit circuit, String prefix) {
circuit.addPort(attack, prefix + attack.getName());
circuit.addPort(decay, prefix + decay.getName());
}
@Override
public void generate(int start, int limit) {
double[] amplitudes = amplitude.getValues();
double[] outputs = output.getValues();
for (int i = start; i < limit;) {
boolean triggered = input.checkGate(i);
switch (state) {
case IDLE:
for (; i < limit; i++) {
outputs[i] = level;
if (triggered) {
startAttack(i);
break;
}
}
break;
case ATTACKING:
for (; i < limit; i++) {
// Increment first so we can render fast attacks.
level += increment;
if (level >= 1.0) {
level = 1.0;
outputs[i] = level * amplitudes[i];
startDecay(i);
break;
}
outputs[i] = level * amplitudes[i];
}
break;
case DECAYING:
for (; i < limit; i++) {
outputs[i] = level * amplitudes[i];
level *= scaler;
if (triggered) {
startAttack(i);
break;
} else if (level < SynthesisEngine.DB90) {
input.checkAutoDisable();
startIdle();
break;
}
}
break;
}
}
}
private void startIdle() {
state = State.IDLE;
level = 0.0;
}
private void startAttack(int i) {
double[] attacks = attack.getValues();
double duration = attacks[i];
if (duration < MIN_DURATION) {
level = 1.0;
startDecay(i);
} else {
// assume going from 0.0 to 1.0 even if retriggering
increment = getFramePeriod() / duration;
state = State.ATTACKING;
}
}
private void startDecay(int i) {
double[] decays = decay.getValues();
double duration = decays[i];
if (duration < MIN_DURATION) {
startIdle();
} else {
scaler = getSynthesisEngine().convertTimeToExponentialScaler(duration);
state = State.DECAYING;
}
}
}
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