src/mt32/freeverb/allpass.h

// Allpass filter declaration
//
// Written by Jezar at Dreampoint, June 2000
// http://www.dreampoint.co.uk
// This code is public domain

#ifndef _allpass_
#define _allpass_
#include "denormals.h"
#include "../FileStream.h"

class allpass
{
public:
                        allpass();
                void    setbuffer(float *buf, int size);
                void    deletebuffer();
        inline  float   process(float input);
                void    mute();
                void    setfeedback(float val);
                float   getfeedback();

                                        void            saveState( std::ostream &stream );
                                        void            loadState( std::istream &stream );

// private:
        float   feedback;
        float   *buffer;
        int     bufsize;
        int     bufidx;
};


// Big to inline - but crucial for speed

inline float allpass::process(float input)
{
        float output;
        float bufout;

        bufout = undenormalise(buffer[bufidx]);

        output = -input + bufout;
        buffer[bufidx] = input + (bufout*feedback);

        if (++bufidx>=bufsize) bufidx = 0;

        return output;
}

#endif//_allpass