//  ---------------------------------------------------------------------------
//  This file is part of reSID, a MOS6581 SID emulator engine.
//  Copyright (C) 2010  Dag Lem <resid@nimrod.no>
//
//  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//  ---------------------------------------------------------------------------

#include "ep128emu.hpp"
#include "extfilt.hpp"

namespace Ep128 {

  // --------------------------------------------------------------------------
  // Constructor.
  // --------------------------------------------------------------------------
  ExternalFilter::ExternalFilter()
  {
    reset();
    enable_filter(true);

    // Low-pass:  R = 10 kOhm, C = 1000 pF; w0l = 1/RC = 1/(1e4*1e-9) = 100 000
    // High-pass: R =  1 kOhm, C =   10 uF; w0h = 1/RC = 1/(1e3*1e-5) =     100

    // Cutoff frequency accuracy (4 bits) is traded off for filter signal
    // accuracy (27 bits). This is crucial since w0lp and w0hp are so far apart.
    w0lp_1_s7 = int((100000.0 / RESID_CLOCK_FREQUENCY)*(1 << 7) + 0.5);
    w0hp_1_s17 = int((100.0 / RESID_CLOCK_FREQUENCY)*(1 << 17) + 0.5);
  }

  // --------------------------------------------------------------------------
  // Enable filter.
  // --------------------------------------------------------------------------
  void ExternalFilter::enable_filter(bool enable)
  {
    enabled = enable;
  }

  // --------------------------------------------------------------------------
  // SID reset.
  // --------------------------------------------------------------------------
  void ExternalFilter::reset()
  {
    // State of filter.
    Vlp = 0;
    Vhp = 0;
  }

}       // namespace Ep128

