f@0: #pragma once 
f@0: 
f@0: namespace collidoscope {
f@0: 
f@2: 
f@2: /* 
f@2:  * An ASR envelope with linear shape. It is modeled after the STK envelope classes.
f@2:  * The tick() method advances the computation of the envelope one sample and returns the computed sample
f@2:  * The class is templated for the type of the samples that each tick of the envelope produces. 
f@2:  *
f@2:  * Client classes can set/get the current state of the envelope with the
f@2:  * respective getter/setter methods
f@2:  *
f@2:  */
f@0: template <typename T>
f@0: class EnvASR
f@0: {
f@0: public:
f@0: 
f@0:     enum class State {
f@0:         eAttack,
f@0:         eSustain,
f@0:         eRelease,
f@0:         eIdle // before attack after release  
f@0:     };
f@0: 
f@0:     EnvASR( T sustainLevel, T attackTime, T releaseTime, std::size_t sampleRate ) :
f@0:         mSustainLevel( sustainLevel ),
f@0:         mState( State::eIdle ),
f@0:         mValue( 0 )
f@0:         
f@0:     {
f@0:         if ( attackTime <= 0 )
f@0:             attackTime = T( 0.001 );
f@0: 
f@0:         if ( releaseTime <= 0 )
f@0:             releaseTime = T( 0.001 );
f@0:         
f@0:         mAttackRate =  T( 1.0 ) / (attackTime * sampleRate);
f@0:         mReleaseRate = T( 1.0 ) / (releaseTime * sampleRate);
f@0:     }
f@0: 
f@0:     T tick()
f@0:     {
f@0: 
f@0:         switch ( mState )
f@0:         {
f@0: 
f@0:         case State::eIdle: {
f@0:             mValue = 0;
f@0:         };
f@0:             break;
f@0: 
f@0:         case State::eAttack: {
f@0:             mValue += mAttackRate;
f@0:             if ( mValue >= mSustainLevel ){
f@0:                 mValue = mSustainLevel;
f@0:                 mState = State::eSustain;
f@0:             }
f@0:         };
f@0:             break;
f@0: 
f@0:         case State::eRelease:
f@0:             mValue -= mReleaseRate;
f@0:             if ( mValue <= 0 ){
f@0:                 mValue = 0;
f@0:                 mState = State::eIdle;
f@0:             }
f@0:             break;
f@0:         default:
f@0:             break;
f@0:         }
f@0: 
f@0:         return mValue;
f@0: 
f@0:     }
f@0: 
f@0:     State getState() const
f@0:     {
f@0:         return mState;
f@0:     }
f@0: 
f@0:     void setState( State state )
f@0:     {
f@0:         mState = state;
f@0:     }
f@0: 
f@0: private:
f@0:     T mSustainLevel;
f@0:     T mAttackRate;
f@0:     T mReleaseRate;
f@0: 
f@0:     // output
f@0:     T mValue;
f@0: 
f@0:     State mState;
f@0: 
f@0: };
f@0: 
f@0: 
f@2: }