AudioDelay.h

/*
 * AudioDelay.h
 *
 * This file is part of Mozzi.
 *
 * Copyright 2012-2024 Tim Barrass and the Mozzi Team
 *
 * Mozzi is licensed under the GNU Lesser General Public Licence (LGPL) Version 2.1 or later.
 *
 */
 
#ifndef AUDIODELAY_H_
#define AUDIODELAY_H_
 
 
template <unsigned int NUM_BUFFER_SAMPLES, class T = int8_t>
class AudioDelay
{
 
private:
 
    T delay_array[NUM_BUFFER_SAMPLES];
    unsigned int _write_pos;
    unsigned int _delaytime_cells;
    
public:
 
    AudioDelay(): _write_pos(0)
    {}
    
    
    AudioDelay(unsigned int delaytime_cells): _write_pos(0), _delaytime_cells(delaytime_cells)
    {}
 
    
 
    inline
    T next(T in_value, unsigned int delaytime_cells)
    {
        ++_write_pos &= (NUM_BUFFER_SAMPLES - 1);
        unsigned int read_pos = (_write_pos - delaytime_cells) & (NUM_BUFFER_SAMPLES - 1);
 
        // why does delay jump if I read it before writing?
        delay_array[_write_pos] = in_value;         // write to buffer
        T delay_sig = delay_array[read_pos] ;   // read the delay buffer
 
        return (T)delay_sig;
    }
    
    
    
    inline
    T next(T in_value)
    {
        ++_write_pos &= (NUM_BUFFER_SAMPLES - 1);
        unsigned int read_pos = (_write_pos - _delaytime_cells) & (NUM_BUFFER_SAMPLES - 1);
 
        // why does delay jump if I read it before writing?
        delay_array[_write_pos] = in_value;         // write to buffer
        T delay_sig = delay_array[read_pos] ;   // read the delay buffer
 
        return delay_sig;
    }
 
    
    inline
    void set(unsigned int delaytime_cells){
        _delaytime_cells = delaytime_cells;
    }
 
    
    inline
    T read(unsigned int delaytime_cells)
    {
        unsigned int read_pos = (_write_pos - delaytime_cells) & (NUM_BUFFER_SAMPLES - 1);
        return delay_array[read_pos];
    }
    
    
    // /** Input a value to the delay but don't advance the write position, change the delay time or retrieve the output signal.
    // This can be useful for manually adding feedback to the delay line, "behind" the advancing write head.
    // @param input the signal input.
    // */
    // inline
    // void writeFeedback(T input)
    // {
        // delay_array[_write_pos] = input;
    // }
 
};
 
#endif        //  #ifndef AUDIODELAY_H_