160 lines
4.4 KiB
C++
160 lines
4.4 KiB
C++
// ---------------------------------------------------------------------------
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// This file is part of reSID, a MOS6581_2 SID2 emulator engine.
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// Copyright (C) 2004 Dag Lem <resid@nimrod.no>
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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// ---------------------------------------------------------------------------
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#define __WAVE_CC__
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#include "wave.h"
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// ----------------------------------------------------------------------------
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// Constructor.
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// ----------------------------------------------------------------------------
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WaveformGenerator2::WaveformGenerator2()
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{
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sync_source = this;
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set_chip_model(MOS6581_2);
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reset();
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}
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// ----------------------------------------------------------------------------
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// Set sync source.
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// ----------------------------------------------------------------------------
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void WaveformGenerator2::set_sync_source(WaveformGenerator2* source)
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{
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sync_source = source;
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source->sync_dest = this;
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}
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// ----------------------------------------------------------------------------
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// Set chip model.
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// ----------------------------------------------------------------------------
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void WaveformGenerator2::set_chip_model(chip_model2 model)
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{
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wave__ST = wave8580__ST;
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wave_P_T = wave8580_P_T;
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wave_PS_ = wave8580_PS_;
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wave_PST = wave8580_PST;
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}
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// ----------------------------------------------------------------------------
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// Register functions.
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// ----------------------------------------------------------------------------
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void WaveformGenerator2::writeFREQ_LO(reg8 freq_lo)
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{
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freq = (freq & 0x1ff00) | (freq_lo & 0x00ff);
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}
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void WaveformGenerator2::writeFREQ_HI(reg8 freq_hi)
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{
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freq = ((freq_hi << 8) & 0xff00) | (freq & 0x100ff);
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}
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void WaveformGenerator2::writeFREQ_HIGHEST(reg8 freq_highest)
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{
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freq = ((freq_highest << 16) & 0x10000) | (freq & 0xffff);
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}
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void WaveformGenerator2::writePW_LO(reg8 pw_lo)
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{
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pw = (pw & 0xf00) | (pw_lo & 0x0ff);
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}
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void WaveformGenerator2::writePW_HI(reg8 pw_hi)
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{
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pw = ((pw_hi << 8) & 0xf00) | (pw & 0x0ff);
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}
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void WaveformGenerator2::writeCONTROL_REG(reg8 control)
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{
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waveform = (control >> 4) & 0x0f;
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ring_mod = control & 0x04;
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sync = control & 0x02;
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reg8 test_next = control & 0x08;
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// Test bit set.
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// The accumulator and the shift register are both cleared.
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// NB! The shift register is not really cleared immediately. It seems like
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// the individual bits in the shift register start to fade down towards
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// zero when test is set. All bits reach zero within approximately
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// $2000 - $4000 cycles.
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// This is not modeled. There should fortunately be little audible output
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// from this peculiar behavior.
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if (test_next) {
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accumulator = 0;
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shift_register = 0;
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}
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// Test bit cleared.
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// The accumulator starts counting, and the shift register is reset to
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// the value 0x7ffff8.
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// NB! The shift register will not actually be set to this exact value if the
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// shift register bits have not had time to fade to zero.
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// This is not modeled.
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else if (test) {
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shift_register = 0x7ffff8;
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}
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test = test_next;
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// The gate bit is handled by the EnvelopeGenerator2.
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}
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void WaveformGenerator2::writeNOISE_MODE(reg8 value)
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{
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if(noise_mode != value)
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{
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shift_register = 0x7ffff8;
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}
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noise_mode = value;
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}
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void WaveformGenerator2::writeMIX_MODE(reg8 value)
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{
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mix_mode = value;
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}
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reg8 WaveformGenerator2::readOSC()
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{
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return output() >> 4;
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}
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// ----------------------------------------------------------------------------
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// SID2 reset.
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// ----------------------------------------------------------------------------
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void WaveformGenerator2::reset()
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{
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accumulator = 0;
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shift_register = 0x7ffff8;
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freq = 0;
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pw = 0;
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test = 0;
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ring_mod = 0;
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sync = 0;
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msb_rising = false;
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mix_mode = 0;
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noise_mode = 3;
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}
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