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mtdm.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 <ardour/mtdm.h>

MTDM::MTDM (void) 
      : _cnt (0)
      , _inv (0)
{
      int   i;
      Freq  *F;
      
      _freq [0].f = 4096;
      _freq [1].f =  512;
      _freq [2].f = 1088;
      _freq [3].f = 1544;
      _freq [4].f = 2049;
      
      _freq [0].a = 0.2f;
      _freq [1].a = 0.1f;
      _freq [2].a = 0.1f;
      _freq [3].a = 0.1f;
      _freq [4].a = 0.1f;
      
      for (i = 0, F = _freq; i < 5; i++, F++) {
            F->p = 128;
            F->xa = F->ya = 0.0f;
            F->xf = F->yf = 0.0f;
      }
}

int 
MTDM::process (size_t len, float *ip, float *op)
{
      int    i;
      float  vip, vop, a, c, s;
      Freq   *F;
      
      while (len--)
      {
            vop = 0.0f;
            vip = *ip++;
            for (i = 0, F = _freq; i < 5; i++, F++)
            {
                  a = 2 * (float) M_PI * (F->p & 65535) / 65536.0; 
                  F->p += F->f;
                  c =  cosf (a); 
                  s = -sinf (a); 
                  vop += F->a * s;
                  F->xa += s * vip;
                  F->ya += c * vip;
            } 
            *op++ = vop;
            if (++_cnt == 16)
            {
                  for (i = 0, F = _freq; i < 5; i++, F++)
                  {
                        F->xf += 1e-3f * (F->xa - F->xf + 1e-20);
                        F->yf += 1e-3f * (F->ya - F->yf + 1e-20);
                        F->xa = F->ya = 0.0f;
                  }
                  _cnt = 0;
            }
      }

      return 0;
}

int 
MTDM::resolve ()
{
      int     i, k, m;
      double  d, e, f0, p;
      Freq    *F = _freq;
      
      if (hypot (F->xf, F->yf) < 0.01) {
            return -1;
      }

      d = atan2 (F->yf, F->xf) / (2 * M_PI);

      if (_inv) {
            d += 0.5f;
      }

      if (d > 0.5f) {
            d -= 1.0f;
      }

      f0 = _freq [0].f;
      m = 1;
      _err = 0.0;

      for (i = 0; i < 4; i++) {
            F++;
            p = atan2 (F->yf, F->xf) / (2 * M_PI) - d * F->f / f0;
            if (_inv) {
                  p += 0.5f;
            }
            p -= floor (p);
            p *= 8;
            k = (int)(floor (p + 0.5));
            e = fabs (p - k);
            if (e > _err) {
                  _err = e;
            }
            if (e > 0.4) {
                  return 1; 
            }
            d += m * (k & 7);
            m *= 8;
      }  

      _del = 16 * d;
      
      return 0;
}

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