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119 lines
3 KiB
C++
119 lines
3 KiB
C++
#pragma once
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#include "stdafx.h"
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#include "APU.h"
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#include "IMemoryHandler.h"
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#include "ApuEnvelope.h"
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#include "CPU.h"
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#include "MemoryManager.h"
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class TriangleChannel : public ApuLengthCounter
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{
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private:
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const uint8_t _sequence[32] = { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
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uint8_t _linearCounter = 0;
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uint8_t _linearCounterReload = 0;
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bool _linearReloadFlag = false;
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bool _linearControlFlag = false;
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uint8_t _sequencePosition = 0;
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protected:
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void Clock() override
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{
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//The sequencer is clocked by the timer as long as both the linear counter and the length counter are nonzero.
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if(_lengthCounter > 0 && _linearCounter > 0) {
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_sequencePosition = (_sequencePosition + 1) & 0x1F;
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if(_period >= 2 || !_console->GetSettings()->CheckFlag(EmulationFlags::SilenceTriangleHighFreq)) {
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//Disabling the triangle channel when period is < 2 removes "pops" in the audio that are caused by the ultrasonic frequencies
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//This is less "accurate" in terms of emulation, so this is an option (disabled by default)
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AddOutput(_sequence[_sequencePosition]);
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}
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}
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}
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public:
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TriangleChannel(AudioChannel channel, shared_ptr<Console> console, SoundMixer* mixer) : ApuLengthCounter(channel, console, mixer)
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{
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}
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virtual void Reset(bool softReset) override
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{
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ApuLengthCounter::Reset(softReset);
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_linearCounter = 0;
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_linearCounterReload = 0;
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_linearReloadFlag = false;
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_linearControlFlag = false;
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_sequencePosition = 0;
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}
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virtual void StreamState(bool saving) override
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{
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ApuLengthCounter::StreamState(saving);
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Stream(_linearCounter, _linearCounterReload, _linearReloadFlag, _linearControlFlag, _sequencePosition);
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}
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void GetMemoryRanges(MemoryRanges &ranges) override
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{
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ranges.AddHandler(MemoryOperation::Write, 0x4008, 0x400B);
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}
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void WriteRAM(uint16_t addr, uint8_t value) override
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{
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_console->GetApu()->Run();
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switch(addr & 0x03) {
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case 0: //4008
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_linearControlFlag = (value & 0x80) == 0x80;
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_linearCounterReload = value & 0x7F;
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InitializeLengthCounter(_linearControlFlag);
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break;
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case 2: //400A
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_period &= ~0x00FF;
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_period |= value;
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break;
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case 3: //400B
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LoadLengthCounter(value >> 3);
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_period &= ~0xFF00;
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_period |= (value & 0x07) << 8;
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//Side effects Sets the linear counter reload flag
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_linearReloadFlag = true;
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break;
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}
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}
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void TickLinearCounter()
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{
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if(_linearReloadFlag) {
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_linearCounter = _linearCounterReload;
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} else if(_linearCounter > 0) {
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_linearCounter--;
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}
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if(!_linearControlFlag) {
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_linearReloadFlag = false;
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}
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}
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ApuTriangleState GetState()
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{
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ApuTriangleState state;
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state.Enabled = _enabled;
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state.Frequency = _console->GetCpu()->GetClockRate(GetNesModel()) / 32.0 / (_period + 1);
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state.LengthCounter = ApuLengthCounter::GetState();
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state.OutputVolume = _lastOutput;
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state.Period = _period;
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state.Timer = _timer;
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state.SequencePosition = _sequencePosition;
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return state;
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}
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}; |