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// ---------------------------------------------------------------------------
// This file is part of reSID, a MOS6581 SID emulator engine.
// Copyright (C) 2002 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
// ---------------------------------------------------------------------------
#define __WAVE_CC__
#include "wave.h"
RESID_NAMESPACE_START
// ----------------------------------------------------------------------------
// Constructor.
// ----------------------------------------------------------------------------
WaveformGenerator::WaveformGenerator()
{
sync_source = this;
set_chip_model(MOS6581);
reset();
}
// ----------------------------------------------------------------------------
// Set sync source.
// ----------------------------------------------------------------------------
void WaveformGenerator::set_sync_source(WaveformGenerator* source)
{
sync_source = source;
source->sync_dest = this;
}
// ----------------------------------------------------------------------------
// Set chip model.
// ----------------------------------------------------------------------------
void WaveformGenerator::set_chip_model(chip_model model)
{
if (model == MOS6581) {
wave__ST = wave6581__ST;
wave_P_T = wave6581_P_T;
wave_PS_ = wave6581_PS_;
wave_PST = wave6581_PST;
}
else {
wave__ST = wave8580__ST;
wave_P_T = wave8580_P_T;
wave_PS_ = wave8580_PS_;
wave_PST = wave8580_PST;
}
}
// ----------------------------------------------------------------------------
// Register functions.
// ----------------------------------------------------------------------------
void WaveformGenerator::writeFREQ_LO(reg8 freq_lo)
{
freq = freq & 0xff00 | freq_lo & 0x00ff;
}
void WaveformGenerator::writeFREQ_HI(reg8 freq_hi)
{
freq = (freq_hi << 8) & 0xff00 | freq & 0x00ff;
}
void WaveformGenerator::writePW_LO(reg8 pw_lo)
{
pw = pw & 0xf00 | pw_lo & 0x0ff;
}
void WaveformGenerator::writePW_HI(reg8 pw_hi)
{
pw = (pw_hi << 8) & 0xf00 | pw & 0x0ff;
}
void WaveformGenerator::writeCONTROL_REG(reg8 control)
{
waveform = (control >> 4) & 0x0f;
ring_mod = control & 0x04;
sync = control & 0x02;
reg8 test_next = control & 0x08;
// Test bit set.
// The accumulator and the shift register are both cleared.
// NB! The shift register is not really cleared immediately. It seems like
// the individual bits in the shift register start to fade down towards
// zero when test is set. All bits reach zero within approximately
// $2000 - $4000 cycles.
// This is not modeled. There should fortunately be little audible output
// from this peculiar behavior.
if (test_next) {
accumulator = 0;
shift_register = 0;
}
// Test bit cleared.
// The accumulator starts counting, and the shift register is reset to
// the value 0x7ffff8.
// NB! The shift register will not actually be set to this exact value if the
// shift register bits have not had time to fade to zero.
// This is not modeled.
else if (test) {
shift_register = 0x7ffff8;
}
test = test_next;
// The gate bit is handled by the EnvelopeGenerator.
}
reg8 WaveformGenerator::readOSC()
{
return output() >> 4;
}
// ----------------------------------------------------------------------------
// SID reset.
// ----------------------------------------------------------------------------
void WaveformGenerator::reset()
{
accumulator = 0;
shift_register = 0x7ffff8;
freq = 0;
pw = 0;
test = 0;
ring_mod = 0;
sync = 0;
msb_rising = false;
}
RESID_NAMESPACE_STOP
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