sinetablesource.h

Go to the documentation of this file.

#ifndef _SineSource_h
#define _SineSource_h

#include "synthfunctions.h"

// -----------------------------
//  --- SynthLab SDK File --- // 
//  ----------------------------
// -----------------------------------------------------------------------------
namespace SynthLab
{

    class SineTableSource : public IWavetableSource
    {
    public:
        SineTableSource() 
        {
            sineWavetable.dTable = &sinetable[0];
            sineWavetable.tableLength = sineTableLength;
            sineWavetable.wrapMask = sineTableLength - 1;
            sineWavetable.waveformName = "sinewave";
        }

        ~SineTableSource() { } 

        virtual const char* getWaveformName() override
        {
            return sineWavetable.waveformName;
        }

        inline virtual void selectTable(uint32_t midiNoteNumber) override { }

        inline virtual double readWaveTable(double normalizedPhaseInc) override
        {
            // --- two samples from table
            double wtData[2] = { 0.0, 0.0 };

            // --- location = N(fo/fs)
            double wtReadLocation = sineWavetable.tableLength * normalizedPhaseInc;

            // --- split the fractional index into int.frac parts
            double dIntPart = 0.0;
            double fracPart = modf(wtReadLocation, &dIntPart);
            uint32_t readIndex = (uint32_t)dIntPart;
            uint32_t nextReadIndex = (readIndex + 1) & sineWavetable.wrapMask;

            // --- two table reads
            wtData[0] = sineWavetable.dTable[readIndex];
            wtData[1] = sineWavetable.dTable[nextReadIndex];

            // --- interpolate the output
            double output = doLinearInterpolation(wtData[0], wtData[1], fracPart);

            // --- scale as needed
            return sineWavetable.outputComp * output;
        }

        virtual uint32_t getWaveTableLength()  override { return sineWavetable.tableLength; }

    protected:
        // --- prefab table valid for all MIDI notes
        StaticWavetable sineWavetable;
    };

}
#endif // definer