voice.h
// ---------------------------------------------------------------------------
// 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
// ---------------------------------------------------------------------------
#ifndef RESID_VOICE_H
#define RESID_VOICE_H
#include "resid-config.h"
#include "wave.h"
#include "envelope.h"
namespace reSID
{
class Voice
{
public:
Voice();
void set_chip_model(chip_model model);
void set_sync_source(Voice*);
void reset();
void writeCONTROL_REG(reg8);
// Amplitude modulated waveform output.
// Range [-2048*255, 2047*255].
int output();
WaveformGenerator wave;
EnvelopeGenerator envelope;
protected:
// Waveform D/A zero level.
short wave_zero;
friend class SID;
};
// ----------------------------------------------------------------------------
// Inline functions.
// The following function is defined inline because it is called every
// time a sample is calculated.
// ----------------------------------------------------------------------------
#if RESID_INLINING || defined(RESID_VOICE_CC)
// ----------------------------------------------------------------------------
// Amplitude modulated waveform output (20 bits).
// Ideal range [-2048*255, 2047*255].
// ----------------------------------------------------------------------------
// The output for a voice is produced by a multiplying DAC, where the
// waveform output modulates the envelope output.
//
// As noted by Bob Yannes: "The 8-bit output of the Envelope Generator was then
// sent to the Multiplying D/A converter to modulate the amplitude of the
// selected Oscillator Waveform (to be technically accurate, actually the
// waveform was modulating the output of the Envelope Generator, but the result
// is the same)".
//
// 7 6 5 4 3 2 1 0 VGND
// | | | | | | | | | Missing
// 2R 2R 2R 2R 2R 2R 2R 2R 2R termination
// | | | | | | | | |
// --R---R---R---R---R---R---R-- ---
// | _____
// __|__ __|__ |
// ----- ===== |
// | | | | |
// 12V --- ----- ------- GND
// |
// vout
//
// Bit on: wout (see figure in wave.h)
// Bit off: 5V (VGND)
//
// As is the case with all MOS 6581 DACs, the termination to (virtual) ground
// at bit 0 is missing. The MOS 8580 has correct termination.
//
RESID_INLINE
int Voice::output()
{
// Multiply oscillator output with envelope output.
return (wave.output() - wave_zero)*envelope.output();
}
#endif // RESID_INLINING || defined(RESID_VOICE_CC)
} // namespace reSID
#endif // not RESID_VOICE_H
reSID
Definition: dac.cc:45
reSID::WaveformGenerator
Definition: wave.h:36
reSID::SID
Definition: sid.h:34
reSID::Voice
Definition: voice.h:30
reSID::EnvelopeGenerator
Definition: envelope.h:37