furnace/src/engine/platform/sound/c64_fp/SID.cpp
2022-08-28 15:10:44 -05:00

505 lines
13 KiB
C++

/*
* This file is part of libsidplayfp, a SID player engine.
*
* Copyright 2011-2016 Leandro Nini <drfiemost@users.sourceforge.net>
* Copyright 2007-2010 Antti Lankila
* Copyright 2004 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#define SID_CPP
#include "SID.h"
#include <limits>
#include "array.h"
#include "Dac.h"
#include "Filter6581.h"
#include "Filter8580.h"
#include "Potentiometer.h"
#include "WaveformCalculator.h"
#include "resample/TwoPassSincResampler.h"
#include "resample/ZeroOrderResampler.h"
namespace reSIDfp
{
const unsigned int ENV_DAC_BITS = 8;
const unsigned int OSC_DAC_BITS = 12;
/**
* The waveform D/A converter introduces a DC offset in the signal
* to the envelope multiplying D/A converter. The "zero" level of
* the waveform D/A converter can be found as follows:
*
* Measure the "zero" voltage of voice 3 on the SID audio output
* pin, routing only voice 3 to the mixer ($d417 = $0b, $d418 =
* $0f, all other registers zeroed).
*
* Then set the sustain level for voice 3 to maximum and search for
* the waveform output value yielding the same voltage as found
* above. This is done by trying out different waveform output
* values until the correct value is found, e.g. with the following
* program:
*
* lda #$08
* sta $d412
* lda #$0b
* sta $d417
* lda #$0f
* sta $d418
* lda #$f0
* sta $d414
* lda #$21
* sta $d412
* lda #$01
* sta $d40e
*
* ldx #$00
* lda #$38 ; Tweak this to find the "zero" level
*l cmp $d41b
* bne l
* stx $d40e ; Stop frequency counter - freeze waveform output
* brk
*
* The waveform output range is 0x000 to 0xfff, so the "zero"
* level should ideally have been 0x800. In the measured chip, the
* waveform output "zero" level was found to be 0x380 (i.e. $d41b
* = 0x38) at an audio output voltage of 5.94V.
*
* With knowledge of the mixer op-amp characteristics, further estimates
* of waveform voltages can be obtained by sampling the EXT IN pin.
* From EXT IN samples, the corresponding waveform output can be found by
* using the model for the mixer.
*
* Such measurements have been done on a chip marked MOS 6581R4AR
* 0687 14, and the following results have been obtained:
* * The full range of one voice is approximately 1.5V.
* * The "zero" level rides at approximately 5.0V.
*
*
* zero-x did the measuring on the 8580 (https://sourceforge.net/p/vice-emu/bugs/1036/#c5b3):
* When it sits on basic from powerup it's at 4.72
* Run 1.prg and check the output pin level.
* Then run 2.prg andadjust it until the output level is the same...
* 0x94-0xA8 gives me the same 4.72 1.prg shows.
* On another 8580 it's 0x90-0x9C
* Third chip 0x94-0xA8
* Fourth chip 0x90-0xA4
* On the 8580 that plays digis the output is 4.66 and 0x93 is the only value to reach that.
* To me that seems as regular 8580s have somewhat wide 0-level range,
* whereas that digi-compatible 8580 has it very narrow.
* On my 6581R4AR has 0x3A as the only value giving the same output level as 1.prg
*/
//@{
unsigned int constexpr OFFSET_6581 = 0x380;
unsigned int constexpr OFFSET_8580 = 0x9c0;
//@}
/**
* Bus value stays alive for some time after each operation.
* Values differs between chip models, the timings used here
* are taken from VICE [1].
* See also the discussion "How do I reliably detect 6581/8580 sid?" on CSDb [2].
*
* Results from real C64 (testprogs/SID/bitfade/delayfrq0.prg):
*
* (new SID) (250469/8580R5) (250469/8580R5)
* delayfrq0 ~7a000 ~108000
*
* (old SID) (250407/6581)
* delayfrq0 ~01d00
*
* [1]: http://sourceforge.net/p/vice-emu/patches/99/
* [2]: http://noname.c64.org/csdb/forums/?roomid=11&topicid=29025&showallposts=1
*/
//@{
int constexpr BUS_TTL_6581 = 0x01d00;
int constexpr BUS_TTL_8580 = 0xa2000;
//@}
SID::SID() :
filter6581(new Filter6581()),
filter8580(new Filter8580()),
externalFilter(new ExternalFilter()),
resampler(nullptr),
potX(new Potentiometer()),
potY(new Potentiometer())
{
voice[0].reset(new Voice());
voice[1].reset(new Voice());
voice[2].reset(new Voice());
muted[0] = muted[1] = muted[2] = false;
reset();
setChipModel(MOS8580);
}
SID::~SID()
{
// Needed to delete auto_ptr with complete type
}
void SID::setFilter6581Curve(double filterCurve)
{
filter6581->setFilterCurve(filterCurve);
}
void SID::setFilter8580Curve(double filterCurve)
{
filter8580->setFilterCurve(filterCurve);
}
void SID::enableFilter(bool enable)
{
filter6581->enable(enable);
filter8580->enable(enable);
}
void SID::voiceSync(bool sync)
{
if (sync)
{
// Synchronize the 3 waveform generators.
for (int i = 0; i < 3; i++)
{
voice[i]->wave()->synchronize(voice[(i + 1) % 3]->wave(), voice[(i + 2) % 3]->wave());
}
}
// Calculate the time to next voice sync
nextVoiceSync = std::numeric_limits<int>::max();
for (int i = 0; i < 3; i++)
{
WaveformGenerator* const wave = voice[i]->wave();
const unsigned int freq = wave->readFreq();
if (wave->readTest() || freq == 0 || !voice[(i + 1) % 3]->wave()->readSync())
{
continue;
}
const unsigned int accumulator = wave->readAccumulator();
const unsigned int thisVoiceSync = ((0x7fffff - accumulator) & 0xffffff) / freq + 1;
if (thisVoiceSync < nextVoiceSync)
{
nextVoiceSync = thisVoiceSync;
}
}
}
void SID::setChipModel(ChipModel model)
{
switch (model)
{
case MOS6581:
filter = filter6581.get();
modelTTL = BUS_TTL_6581;
break;
case MOS8580:
filter = filter8580.get();
modelTTL = BUS_TTL_8580;
break;
default:
throw SIDError("Unknown chip type");
}
this->model = model;
// calculate waveform-related tables
matrix_t* tables = WaveformCalculator::getInstance()->buildTable(model);
// calculate envelope DAC table
{
Dac dacBuilder(ENV_DAC_BITS);
dacBuilder.kinkedDac(model);
for (unsigned int i = 0; i < (1 << ENV_DAC_BITS); i++)
{
envDAC[i] = static_cast<float>(dacBuilder.getOutput(i));
}
}
// calculate oscillator DAC table
const bool is6581 = model == MOS6581;
{
Dac dacBuilder(OSC_DAC_BITS);
dacBuilder.kinkedDac(model);
const double offset = dacBuilder.getOutput(is6581 ? OFFSET_6581 : OFFSET_8580);
for (unsigned int i = 0; i < (1 << OSC_DAC_BITS); i++)
{
const double dacValue = dacBuilder.getOutput(i);
oscDAC[i] = static_cast<float>(dacValue - offset);
}
}
// set voice tables
for (int i = 0; i < 3; i++)
{
voice[i]->setEnvDAC(envDAC);
voice[i]->setWavDAC(oscDAC);
voice[i]->wave()->setModel(is6581);
voice[i]->wave()->setWaveformModels(tables);
}
}
void SID::reset()
{
for (int i = 0; i < 3; i++)
{
voice[i]->reset();
}
filter6581->reset();
filter8580->reset();
externalFilter->reset();
if (resampler.get())
{
resampler->reset();
}
busValue = 0;
busValueTtl = 0;
voiceSync(false);
}
void SID::input(int value)
{
filter6581->input(value);
filter8580->input(value);
}
unsigned char SID::read(int offset)
{
switch (offset)
{
case 0x19: // X value of paddle
busValue = potX->readPOT();
busValueTtl = modelTTL;
break;
case 0x1a: // Y value of paddle
busValue = potY->readPOT();
busValueTtl = modelTTL;
break;
case 0x1b: // Voice #3 waveform output
busValue = voice[2]->wave()->readOSC();
busValueTtl = modelTTL;
break;
case 0x1c: // Voice #3 ADSR output
busValue = voice[2]->envelope()->readENV();
busValueTtl = modelTTL;
break;
default:
// Reading from a write-only or non-existing register
// makes the bus discharge faster.
// Emulate this by halving the residual TTL.
busValueTtl /= 2;
break;
}
return busValue;
}
void SID::write(int offset, unsigned char value)
{
busValue = value;
busValueTtl = modelTTL;
switch (offset)
{
case 0x00: // Voice #1 frequency (Low-byte)
voice[0]->wave()->writeFREQ_LO(value);
break;
case 0x01: // Voice #1 frequency (High-byte)
voice[0]->wave()->writeFREQ_HI(value);
break;
case 0x02: // Voice #1 pulse width (Low-byte)
voice[0]->wave()->writePW_LO(value);
break;
case 0x03: // Voice #1 pulse width (bits #8-#15)
voice[0]->wave()->writePW_HI(value);
break;
case 0x04: // Voice #1 control register
voice[0]->writeCONTROL_REG(muted[0] ? 0 : value);
break;
case 0x05: // Voice #1 Attack and Decay length
voice[0]->envelope()->writeATTACK_DECAY(value);
break;
case 0x06: // Voice #1 Sustain volume and Release length
voice[0]->envelope()->writeSUSTAIN_RELEASE(value);
break;
case 0x07: // Voice #2 frequency (Low-byte)
voice[1]->wave()->writeFREQ_LO(value);
break;
case 0x08: // Voice #2 frequency (High-byte)
voice[1]->wave()->writeFREQ_HI(value);
break;
case 0x09: // Voice #2 pulse width (Low-byte)
voice[1]->wave()->writePW_LO(value);
break;
case 0x0a: // Voice #2 pulse width (bits #8-#15)
voice[1]->wave()->writePW_HI(value);
break;
case 0x0b: // Voice #2 control register
voice[1]->writeCONTROL_REG(muted[1] ? 0 : value);
break;
case 0x0c: // Voice #2 Attack and Decay length
voice[1]->envelope()->writeATTACK_DECAY(value);
break;
case 0x0d: // Voice #2 Sustain volume and Release length
voice[1]->envelope()->writeSUSTAIN_RELEASE(value);
break;
case 0x0e: // Voice #3 frequency (Low-byte)
voice[2]->wave()->writeFREQ_LO(value);
break;
case 0x0f: // Voice #3 frequency (High-byte)
voice[2]->wave()->writeFREQ_HI(value);
break;
case 0x10: // Voice #3 pulse width (Low-byte)
voice[2]->wave()->writePW_LO(value);
break;
case 0x11: // Voice #3 pulse width (bits #8-#15)
voice[2]->wave()->writePW_HI(value);
break;
case 0x12: // Voice #3 control register
voice[2]->writeCONTROL_REG(muted[2] ? 0 : value);
break;
case 0x13: // Voice #3 Attack and Decay length
voice[2]->envelope()->writeATTACK_DECAY(value);
break;
case 0x14: // Voice #3 Sustain volume and Release length
voice[2]->envelope()->writeSUSTAIN_RELEASE(value);
break;
case 0x15: // Filter cut off frequency (bits #0-#2)
filter6581->writeFC_LO(value);
filter8580->writeFC_LO(value);
break;
case 0x16: // Filter cut off frequency (bits #3-#10)
filter6581->writeFC_HI(value);
filter8580->writeFC_HI(value);
break;
case 0x17: // Filter control
filter6581->writeRES_FILT(value);
filter8580->writeRES_FILT(value);
break;
case 0x18: // Volume and filter modes
filter6581->writeMODE_VOL(value);
filter8580->writeMODE_VOL(value);
break;
default:
break;
}
// Update voicesync just in case.
voiceSync(false);
}
void SID::setSamplingParameters(double clockFrequency, SamplingMethod method, double samplingFrequency, double highestAccurateFrequency)
{
externalFilter->setClockFrequency(clockFrequency);
switch (method)
{
case DECIMATE:
resampler.reset(new ZeroOrderResampler(clockFrequency, samplingFrequency));
break;
case RESAMPLE:
resampler.reset(TwoPassSincResampler::create(clockFrequency, samplingFrequency, highestAccurateFrequency));
break;
default:
throw SIDError("Unknown sampling method");
}
}
void SID::clockSilent(unsigned int cycles)
{
ageBusValue(cycles);
while (cycles != 0)
{
int delta_t = std::min(nextVoiceSync, cycles);
if (delta_t > 0)
{
for (int i = 0; i < delta_t; i++)
{
// clock waveform generators (can affect OSC3)
voice[0]->wave()->clock();
voice[1]->wave()->clock();
voice[2]->wave()->clock();
voice[0]->wave()->output(voice[2]->wave());
voice[1]->wave()->output(voice[0]->wave());
voice[2]->wave()->output(voice[1]->wave());
// clock ENV3 only
voice[2]->envelope()->clock();
}
cycles -= delta_t;
nextVoiceSync -= delta_t;
}
if (nextVoiceSync == 0)
{
voiceSync(true);
}
}
}
} // namespace reSIDfp