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