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76 lines
1.5 KiB
76 lines
1.5 KiB
#ifndef __ADSR_H__
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#define __ADSR_H__
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#include <cmath>
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#include "util.h"
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class ADSR {
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public:
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struct Envelope {
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float attackStep;
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float decayStep;
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float sustain;
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float releaseStep;
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};
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ADSR();
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void setEnvelope(const Envelope* envelope);
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void noteOn();
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void noteOff();
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float tick() {
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float out = curve(gain);
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switch(state) {
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case IDLE:
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break;
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case ATTACK:
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if(gain < 1) {
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gain += envelope->attackStep;
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} else {
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state = DECAY;
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gain = 1;
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}
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break;
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case DECAY:
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if(gain > envelope->sustain) {
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gain -= envelope->decayStep;
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} else {
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state = SUSTAIN;
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gain = envelope->sustain;
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}
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break;
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case SUSTAIN:
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break;
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case RELEASE:
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if(gain > 0) {
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gain -= envelope->releaseStep;
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} else {
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state = IDLE;
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gain = 0;
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}
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break;
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}
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return out;
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}
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private:
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enum { IDLE, ATTACK, DECAY, SUSTAIN, RELEASE } state;
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static const Envelope DEFAULT_ENVELOPE;
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const Envelope* envelope;
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float gain;
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float curve(float gain) {
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return 0.5 - 0.5 * cos(clamp(gain * M_PI, 0, M_PI));
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}
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};
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#endif |