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reverb.cc

/*
    Copyright (C) 2003-2008 Fons Adriaensen <fons@kokkinizita.net>
    
    This program 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 2 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, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/


#include <stdio.h>
#include <string.h>
#include <math.h>
#include "reverb.h"


void Delelm::init (int size, float fb)
{
    _size = size;
    _line = new float [size];
    memset (_line, 0, size * sizeof (float));
    _i = 0;
    _fb = fb;
    _slo = 0;
    _shi = 0;
}


void Delelm::fini (void)
{
    delete[] _line;
}


void Delelm::set_t60mf (float tmf)
{
    _gmf = powf (0.001f, _size / tmf);
} 

 
void Delelm::set_t60lo (float tlo, float wlo)
{
    _glo = powf (0.001f, _size / tlo) / _gmf - 1.0f;
    _wlo = wlo;    
}

 
void Delelm::set_t60hi (float thi, float chi)
{
    float g, t;

    g = powf (0.001f, _size / thi) / _gmf;
    t = (1 - g * g) / (2 * g * g * chi);
    _whi = (sqrt (1 + 4 * t) - 1) / (2 * t); 
} 

 
float Delelm::process (float x)
{
    float t;

    t = _line [_i] * _gmf;
    _slo += _wlo * (t - _slo);
    t += _glo * _slo;
    _shi += _whi * (t - _shi);
    t = x - _fb * _shi + 1e-10;
    _line [_i] = t;
    if (++_i == _size) _i = 0;
    return _shi + _fb * t;
}


void Delelm::print (void)
{
    printf ("%5d %6.3lf   %5.3lf %5.3lf   %6.4lf %6.4lf\n",
            _size, _fb, _glo, _gmf, _wlo, _whi); 
}


int Reverb::_sizes [16] = 
{ 
     839,  6732 -  839,
    1181,  7339 - 1181,
    1229,  8009 - 1229,
    2477,  8731 - 2477,
    2731,  9521 - 2731,
    1361, 10381 - 1361,
    3203, 11321 - 3203,
    1949, 12347 - 1949
};


float Reverb::_feedb [16] = 
{  
   -0.6f,  0.1f,
    0.6f,  0.1f,
    0.6f,  0.1f,
   -0.6f,  0.1f,
    0.6f,  0.1f,
   -0.6f,  0.1f,
   -0.6f,  0.1f,
    0.6f,  0.1f
};


void Reverb::init (float rate)
{
    int m;

    _rate = rate;
    _size = (int)(0.15f * rate);
    _line = new float [_size];
    memset (_line, 0, _size * sizeof (float));
    _i = 0;
    m = (rate < 64e3) ? 1 : 2;    
    for (int i = 0; i < 16; i++) _delm [i].init (m * _sizes [i], _feedb [i]);
    _x0 = _x1 = _x2 = _x3 = _x4 = _x5 = _x6 = _x7 = _z = 0;
    set_delay (0.05);
    set_t60mf (4.0f);
    set_t60lo (5.0f, 250.0f);
    set_t60hi (2.0f, 4e3f);
}


void Reverb::fini (void)
{
    delete[] _line;
    for (int i = 0; i < 16; i++) _delm [i].fini ();
}


void Reverb::set_delay (float del)
{
    if (del < 0.01f) del = 0.01f;
    _idel = (int)(_rate * del);
    if (_idel > _size) _idel = _size;
}


void Reverb::set_t60mf (float tmf)
{
    float t;

    _tmf = tmf;
    t = tmf * _rate;
    for (int i = 0; i < 16; i++) _delm [i].set_t60mf (t);
    _gain = 1.0f / sqrtf (tmf);
}


void Reverb::set_t60lo (float tlo, float flo)
{
    float t, w;

    _tlo = tlo;
    _flo = flo;
    t = tlo * _rate;
    w = 2 * M_PI * flo / _rate;
    for (int i = 0; i < 16; i++) _delm [i].set_t60lo (t, w);
}


void Reverb::set_t60hi (float thi, float fhi)
{
    float t, c;

    _thi = thi;
    _fhi = fhi;
    t = thi * _rate;
    c = 1 - cosf (2 * M_PI * fhi / _rate);
    for (int i = 0; i < 16; i++) _delm [i].set_t60hi (t, c);
}


void Reverb::print (void)
{
    for (int i = 0; i < 16; i++) _delm [i].print ();
}


void Reverb::process (int n, float gain, float *R, float *W, float *X, float *Y, float *Z)
{     
    int   i, j;
    float t, g, x;

    g = sqrtf (0.125f);
    gain *= _gain;

    i = _i;
    while (n--)   
    {
        j = i - _idel;
        if (j < 0) j += _size;
        x = _line [j];
        _z += 0.6f * (*R++ - _z) + 1e-10f;
        _line [i] = _z;
        if (++i == _size) i = 0;

        _x0 = _delm  [0].process (g * _x0 + x); 
        _x1 = _delm  [2].process (g * _x1 + x); 
        _x2 = _delm  [4].process (g * _x2 + x); 
        _x3 = _delm  [6].process (g * _x3 + x); 
        _x4 = _delm  [8].process (g * _x4 + x); 
        _x5 = _delm [10].process (g * _x5 + x); 
        _x6 = _delm [12].process (g * _x6 + x); 
        _x7 = _delm [14].process (g * _x7 + x); 

        t = _x0 - _x1; _x0 += _x1;  _x1 = t;
        t = _x2 - _x3; _x2 += _x3;  _x3 = t;
        t = _x4 - _x5; _x4 += _x5;  _x5 = t;
        t = _x6 - _x7; _x6 += _x7;  _x7 = t;

        t = _x0 - _x2; _x0 += _x2;  _x2 = t;
        t = _x1 - _x3; _x1 += _x3;  _x3 = t;
        t = _x4 - _x6; _x4 += _x6;  _x6 = t;
        t = _x5 - _x7; _x5 += _x7;  _x7 = t;

        t = _x0 - _x4; _x0 += _x4;  _x4 = t;
        t = _x1 - _x5; _x1 += _x5;  _x5 = t;
        t = _x2 - _x6; _x2 += _x6;  _x6 = t;
        t = _x3 - _x7; _x3 += _x7;  _x7 = t;

        *W++ += 1.25f * gain * _x0; 
        *X++ += gain * (_x1 - 0.05f * _x2);
        *Y++ += gain * _x2;
        *Z++ += gain * _x4;

        _x0 = _delm  [1].process (_x0);
        _x1 = _delm  [3].process (_x1); 
        _x2 = _delm  [5].process (_x2); 
        _x3 = _delm  [7].process (_x3); 
        _x4 = _delm  [9].process (_x4); 
        _x5 = _delm [11].process (_x5); 
        _x6 = _delm [13].process (_x6); 
        _x7 = _delm [15].process (_x7); 
    }
    _i = i;
}


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