From 547fbab29fa1869bee1b9d1b8a2ffbdd24b0b934 Mon Sep 17 00:00:00 2001
From: Souryo <mesenemu@gmail.com>
Date: Mon, 17 Jul 2017 19:35:16 -0400
Subject: [PATCH] Overclocking: Improved compatibility with games that write to
 $4011 + fixed PAL issues with OC

---
 Core/DeltaModulationChannel.cpp | 9 +++++++--
 Core/DeltaModulationChannel.h   | 2 ++
 Core/EmulationSettings.cpp      | 1 -
 Core/EmulationSettings.h        | 7 -------
 Core/PPU.cpp                    | 4 +---
 Core/PPU.h                      | 6 +++---
 6 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/Core/DeltaModulationChannel.cpp b/Core/DeltaModulationChannel.cpp
index 4cb6c718..e256b14a 100644
--- a/Core/DeltaModulationChannel.cpp
+++ b/Core/DeltaModulationChannel.cpp
@@ -33,6 +33,8 @@ void DeltaModulationChannel::Reset(bool softReset)
 	_silenceFlag = true;
 	_needToRun = false;
 
+	_lastValue4011 = 0;
+
 	//Not sure if this is accurate, but it seems to make things better rather than worse (for dpcmletterbox)
 	//"On the real thing, I think the power-on value is 428 (or the equivalent at least - it uses a linear feedback shift register), though only the even/oddness should matter for this test."
 	_period = (GetNesModel() == NesModel::NTSC ? _dmcPeriodLookupTableNtsc : _dmcPeriodLookupTablePal)[0] - 1;
@@ -153,8 +155,9 @@ void DeltaModulationChannel::WriteRAM(uint16_t addr, uint8_t value)
 			break;
 
 		case 1: {		//4011
+			uint8_t newValue = value & 0x7F;
 			uint8_t previousLevel = _outputLevel;
-			_outputLevel = value & 0x7F;
+			_outputLevel = newValue;
 			
 			if(EmulationSettings::CheckFlag(EmulationFlags::ReduceDmcPopping) && abs(_outputLevel - previousLevel) > 50) {
 				//Reduce popping sounds for 4011 writes
@@ -164,9 +167,11 @@ void DeltaModulationChannel::WriteRAM(uint16_t addr, uint8_t value)
 			//4011 applies new output right away, not on the timer's reload.  This fixes bad DMC sound when playing through 4011.
 			AddOutput(_outputLevel);
 			
-			if((value & 0x7F) > 0 && EmulationSettings::GetOverclockAdjustApu()) {
+			if(_lastValue4011 != value && newValue > 0) {
 				Console::SetNextFrameOverclockStatus(true);
 			}
+
+			_lastValue4011 = newValue;
 			break;
 		}
 
diff --git a/Core/DeltaModulationChannel.h b/Core/DeltaModulationChannel.h
index a3e9edc8..a19f65ee 100644
--- a/Core/DeltaModulationChannel.h
+++ b/Core/DeltaModulationChannel.h
@@ -30,6 +30,8 @@ private:
 	bool _silenceFlag = true;
 	bool _needToRun = false;
 
+	uint8_t _lastValue4011 = 0;
+
 	void InitSample();
 	void FillReadBuffer();
 	
diff --git a/Core/EmulationSettings.cpp b/Core/EmulationSettings.cpp
index c291acfd..6d071bcf 100644
--- a/Core/EmulationSettings.cpp
+++ b/Core/EmulationSettings.cpp
@@ -42,7 +42,6 @@ bool EmulationSettings::_hasOverclock = false;
 uint32_t EmulationSettings::_overclockRate = 100;
 uint32_t EmulationSettings::_extraScanlinesBeforeNmi = 0;
 uint32_t EmulationSettings::_extraScanlinesAfterNmi = 0;
-uint32_t EmulationSettings::_ppuScanlineCount = 262;
 double EmulationSettings::_effectiveOverclockRate = 100;
 bool EmulationSettings::_overclockAdjustApu = true;
 bool EmulationSettings::_disableOverclocking = false;
diff --git a/Core/EmulationSettings.h b/Core/EmulationSettings.h
index e00ebe5f..d6af830a 100644
--- a/Core/EmulationSettings.h
+++ b/Core/EmulationSettings.h
@@ -397,7 +397,6 @@ private:
 	static bool _disableOverclocking;
 	static uint32_t _extraScanlinesBeforeNmi;
 	static uint32_t _extraScanlinesAfterNmi;
-	static uint32_t _ppuScanlineCount;
 	static double _effectiveOverclockRate;
 	static double _effectiveOverclockRateSound;
 
@@ -727,12 +726,6 @@ public:
 		_audioSettingsChanged = true;
 	}
 
-	static void SetPpuScanlineCount(uint32_t scanlineCount)
-	{
-		_ppuScanlineCount = scanlineCount;		
-		UpdateEffectiveOverclockRate();
-	}
-
 	static void DisableOverclocking(bool disabled)
 	{
 		_disableOverclocking = disabled;
diff --git a/Core/PPU.cpp b/Core/PPU.cpp
index aa58b4a7..9f443a4e 100644
--- a/Core/PPU.cpp
+++ b/Core/PPU.cpp
@@ -112,25 +112,23 @@ void PPU::SetNesModel(NesModel model)
 			_vblankEnd = 260;
 			_standardNmiScanline = 241;
 			_standardVblankEnd = 260;
-			EmulationSettings::SetPpuScanlineCount(262);
 			break;
 		case NesModel::PAL:
 			_nmiScanline = 241;
 			_vblankEnd = 310;
 			_standardNmiScanline = 241;
 			_standardVblankEnd = 310;
-			EmulationSettings::SetPpuScanlineCount(312);
 			break;
 		case NesModel::Dendy:
 			_nmiScanline = 291;
 			_vblankEnd = 310;
 			_standardNmiScanline = 291;
 			_standardVblankEnd = 310;
-			EmulationSettings::SetPpuScanlineCount(312);
 			break;
 	}
 
 	_nmiScanline += EmulationSettings::GetPpuExtraScanlinesBeforeNmi();
+	_palSpriteEvalScanline = _nmiScanline + 24;
 	_standardVblankEnd += EmulationSettings::GetPpuExtraScanlinesBeforeNmi();
 	_vblankEnd += EmulationSettings::GetPpuExtraScanlinesAfterNmi() + EmulationSettings::GetPpuExtraScanlinesBeforeNmi();
 }
diff --git a/Core/PPU.h b/Core/PPU.h
index 5dd58185..4cb4ef16 100644
--- a/Core/PPU.h
+++ b/Core/PPU.h
@@ -28,8 +28,7 @@ class PPU : public IMemoryHandler, public Snapshotable
 {
 	protected:
 		static PPU* Instance;
-		static constexpr uint16_t _palSpriteEvalScanline = 265;
-	
+
 		BaseMapper *_mapper;
 
 		PPUState _state;
@@ -52,7 +51,8 @@ class PPU : public IMemoryHandler, public Snapshotable
 		uint16_t _standardNmiScanline;
 		uint16_t _vblankEnd;
 		uint16_t _nmiScanline;
-
+		uint16_t _palSpriteEvalScanline;
+		
 		PPUControlFlags _flags;
 		PPUStatusFlags _statusFlags;