robert@464: //
robert@464: //  ADRS.h
robert@464: //
robert@464: //  Created by Nigel Redmon on 12/18/12.
robert@464: //  EarLevel Engineering: earlevel.com
robert@464: //  Copyright 2012 Nigel Redmon
robert@464: //
robert@464: //  For a complete explanation of the ADSR envelope generator and code,
robert@464: //  read the series of articles by the author, starting here:
robert@464: //  http://www.earlevel.com/main/2013/06/01/envelope-generators/
robert@464: //
robert@464: //  License:
robert@464: //
robert@464: //  This source code is provided as is, without warranty.
robert@464: //  You may copy and distribute verbatim copies of this document.
robert@464: //  You may modify and use this source code to create binary code for your own purposes, free or commercial.
robert@464: //
robert@464: 
robert@464: #ifndef ADRS_h
robert@464: #define ADRS_h
robert@464: 
robert@464: #include <stdio.h>
robert@464: #include <string>
robert@464: 
robert@464: using namespace std;
robert@464: 
robert@464: enum envState {
robert@464: 	env_idle = 0,
robert@464: 	env_attack,
robert@464: 	env_decay,
robert@464: 	env_sustain,
robert@464: 	env_release
robert@464: };
robert@464: 
robert@464: class ADSR {
robert@464: public:
robert@464: 	ADSR(void);
robert@464: 	~ADSR(void);
robert@464: 	float process(void);
robert@464: 	float process(int sampleCount);
robert@464:     float getOutput(void);
robert@464:     int getState(void);
robert@464: 	void gate(int on);
robert@464:     void setAttackRate(float rate);
robert@464:     void setDecayRate(float rate);
robert@464:     void setReleaseRate(float rate);
robert@464: 	void setSustainLevel(float level);
robert@464:     void setTargetRatioA(float targetRatio);
robert@464:     void setTargetRatioDR(float targetRatio);
robert@464:     void reset(void);
robert@464: 
robert@464: protected:
robert@464: 	int state;
robert@464: 	float output;
robert@464: 	float attackRate;
robert@464: 	float decayRate;
robert@464: 	float releaseRate;
robert@464: 	float attackCoef;
robert@464: 	float decayCoef;
robert@464: 	float releaseCoef;
robert@464: 	float sustainLevel;
robert@464:     float targetRatioA;
robert@464:     float targetRatioDR;
robert@464:     float attackBase;
robert@464:     float decayBase;
robert@464:     float releaseBase;
robert@464: 	string name;
robert@464:     float calcCoef(float rate, float targetRatio);
robert@464: };
robert@464: 
robert@464: inline float ADSR::process() {
robert@464: 	switch (state) {
robert@464:         case env_idle:
robert@464:             break;
robert@464:         case env_attack:
robert@464:             output = attackBase + output * attackCoef;
robert@464:             if (output >= 1.0) {
robert@464:                 output = 1.0;
robert@464:                 state = env_decay;
robert@464:             }
robert@464:             break;
robert@464:         case env_decay:
robert@464:             output = decayBase + output * decayCoef;
robert@464:             if (output <= sustainLevel) {
robert@464:                 output = sustainLevel;
robert@464:                 state = env_sustain;
robert@464:             }
robert@464:             break;
robert@464:         case env_sustain:
robert@464:             break;
robert@464:         case env_release:
robert@464:             output = releaseBase + output * releaseCoef;
robert@464:             if (output <= 0.0) {
robert@464:                 output = 0.0;
robert@464:                 state = env_idle;
robert@464:             }
robert@464:             break;
robert@464: 	}
robert@464: 	return output;
robert@464: }
robert@464: 
robert@464: inline float ADSR::process(int sampleCount)
robert@464: {
robert@464: 	float retVal = 0;
robert@464: 
robert@464: 	if(state != env_idle)
robert@464: 	{
robert@464: 		for(int i=0; i<sampleCount; i++)
robert@464: 			retVal = process();
robert@464: 	}
robert@464: 
robert@464: 	return retVal;
robert@464: }
robert@464: 
robert@464: inline void ADSR::gate(int gate) {
robert@464: 
robert@464: 	if (gate)
robert@464: 		state = env_attack;
robert@464: 	else if (state != env_idle)
robert@464:         state = env_release;
robert@464: }
robert@464: 
robert@464: inline int ADSR::getState() {
robert@464:     return state;
robert@464: }
robert@464: 
robert@464: inline void ADSR::reset() {
robert@464:     state = env_idle;
robert@464:     output = 0.0;
robert@464: }
robert@464: 
robert@464: inline float ADSR::getOutput() {
robert@464: 	return output;
robert@464: }
robert@464: 
robert@464: 
robert@464: #endif