view CollidoscopeApp/include/EnvASR.h @ 16:4dad0b810f18

Comment tidy up + attributions

/*

 Copyright (C) 2016  Queen Mary University of London 
 Author: Fiore Martin, based on CCRMA STK ADSR.h (https://ccrma.stanford.edu/software/stk/classstk_1_1ADSR.html) 

 This file is part of Collidoscope.
 
 Collidoscope is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.

 This file incorporates work covered by the following copyright and permission notice:

    The Synthesis ToolKit in C++ (STK)

    Copyright (c) 1995--2016 Perry R. Cook and Gary P. Scavone

    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    Any person wishing to distribute modifications to the Software is
    asked to send the modifications to the original developer so that they
    can be incorporated into the canonical version.  This is, however, not
    a binding provision of this license.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
    ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

*/

#pragma once 

namespace collidoscope {


/* 
 * An ASR envelope with linear shape. It is modeled after the STK envelope classes.
 * The tick() method advances the computation of the envelope one sample and returns the computed sample
 * The class is templated for the type of the samples that each tick of the envelope produces. 
 *
 * Client classes can set/get the current state of the envelope with the
 * respective getter/setter methods
 *
 */
template <typename T>
class EnvASR
{
public:

    /** Possible states of the envelope. Idle means the envelope ouputs 0 */
    enum class State {
        eAttack,
        eSustain,
        eRelease,
        eIdle // before attack after release  
    };

    EnvASR( T sustainLevel, T attackTime, T releaseTime, std::size_t sampleRate ) :
        mSustainLevel( sustainLevel ),
        mState( State::eIdle ),
        mValue( 0 )
        
    {
        if ( attackTime <= 0 )
            attackTime = T( 0.001 );

        if ( releaseTime <= 0 )
            releaseTime = T( 0.001 );
        
        mAttackRate =  T( 1.0 ) / (attackTime * sampleRate);
        mReleaseRate = T( 1.0 ) / (releaseTime * sampleRate);
    }

    /** Produces one sample worth of envelope */
    T tick()
    {

        switch ( mState )
        {

        case State::eIdle: {
            mValue = 0;
        };
            break;

        case State::eAttack: {
            mValue += mAttackRate;
            if ( mValue >= mSustainLevel ){
                mValue = mSustainLevel;
                mState = State::eSustain;
            }
        };
            break;

        case State::eRelease:
            mValue -= mReleaseRate;
            if ( mValue <= 0 ){
                mValue = 0;
                mState = State::eIdle;
            }
            break;
        default:
            break;
        }

        return mValue;

    }

    State getState() const
    {
        return mState;
    }

    void setState( State state )
    {
        mState = state;
    }

private:
    T mSustainLevel;
    T mAttackRate;
    T mReleaseRate;

    // output
    T mValue;

    State mState;

};


}