From b5fe44a0379a025829cc28ef18bd5b32cbcac081 Mon Sep 17 00:00:00 2001
From: Sour <mesenemu@gmail.com>
Date: Tue, 19 Feb 2019 18:01:27 -0500
Subject: [PATCH] PPU: Implement basic sprite time/range over flags, forced
 vblank flag + Stub for IO port registers

---
 Core/InternalRegisters.cpp | 11 ++++++++++-
 Core/InternalRegisters.h   |  2 ++
 Core/Ppu.cpp               | 40 +++++++++++++++++++++++++++++++++++---
 Core/Ppu.h                 |  6 ++++++
 4 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/Core/InternalRegisters.cpp b/Core/InternalRegisters.cpp
index 7dad669..918a01a 100644
--- a/Core/InternalRegisters.cpp
+++ b/Core/InternalRegisters.cpp
@@ -73,6 +73,10 @@ uint8_t InternalRegisters::Read(uint16_t addr)
 			);
 		}
 
+		case 0x4213:
+			//TODO  RDIO - Programmable I/O port (in-port)
+			return 0;
+						 
 		case 0x4214: return (uint8_t)_divResult;
 		case 0x4215: return (uint8_t)(_divResult >> 8);
 
@@ -102,6 +106,11 @@ void InternalRegisters::Write(uint16_t addr, uint8_t value)
 			_enableAutoJoypadRead = (value & 0x01) != 0;
 			break;
 
+		case 0x4201: 
+			//TODO WRIO - Programmable I/O port (out-port)
+			_ioPortOutput = value;
+			break;
+
 		case 0x4202: _multOperand1 = value; break;
 		case 0x4203:
 			_multOperand2 = value;
@@ -129,7 +138,7 @@ void InternalRegisters::Write(uint16_t addr, uint8_t value)
 		case 0x420A: _verticalTimer = (_verticalTimer & 0xFF) | ((value & 0x01) << 8); break;
 
 		default:
-			MessageManager::DisplayMessage("Debug", "Unimplemented register write: " + HexUtilities::ToHex(addr));
+			MessageManager::DisplayMessage("Debug", "Unimplemented register write: " + HexUtilities::ToHex(addr) + " = " + HexUtilities::ToHex(value));
 			break;
 	}
 }
diff --git a/Core/InternalRegisters.h b/Core/InternalRegisters.h
index 534266d..da2ff44 100644
--- a/Core/InternalRegisters.h
+++ b/Core/InternalRegisters.h
@@ -25,6 +25,8 @@ private:
 	uint16_t _horizontalTimer = 0x1FF;
 	uint16_t _verticalTimer = 0x1FF;
 
+	uint8_t _ioPortOutput = 0;
+
 	uint16_t _controllerData[4];
 
 public:
diff --git a/Core/Ppu.cpp b/Core/Ppu.cpp
index 7eb52d8..62fbe49 100644
--- a/Core/Ppu.cpp
+++ b/Core/Ppu.cpp
@@ -63,6 +63,9 @@ void Ppu::Exec()
 	if(_cycle == 340) {
 		_cycle = -1;
 		_scanline++;
+
+		_rangeOver = false;
+		_timeOver = false;
 		if(_scanline < 224) {
 			RenderScanline();
 		} else if(_scanline == 225) {
@@ -151,6 +154,11 @@ void Ppu::RenderScanline()
 	memset(_filled, 0, sizeof(_filled));
 	memset(_subScreenFilled, 0, sizeof(_subScreenFilled));
 
+	if(_forcedVblank) {
+		RenderBgColor<true>();
+		return;
+	}
+
 	switch(_bgMode) {
 		case 0:
 			DrawSprites<3, true>();
@@ -248,6 +256,8 @@ void Ppu::RenderScanline()
 	memset(_spritePriority, 0xFF, sizeof(_spritePriority));
 	memset(_spritePixels, 0xFFFF, sizeof(_spritePixels));
 	_spriteCount = 0;
+	uint16_t totalWidth = 0;
+
 	for(int i = 0; i < 512; i += 4) {
 		uint8_t y = _oamRam[i + 1];
 
@@ -322,13 +332,20 @@ void Ppu::RenderScanline()
 			}
 		}
 
-		_spriteCount++;
+		totalWidth += width;
+		if(totalWidth >= 34 * 8) {
+			_timeOver = true;
+		}
 
+		_spriteCount++;
 		if(_spriteCount == 32) {
+			_rangeOver = true;
+		}
+
+		if(_timeOver || _rangeOver) {
 			break;
 		}
 	}
-
 }
 
 template<bool forMainScreen>
@@ -466,6 +483,14 @@ uint8_t* Ppu::GetSpriteRam()
 uint8_t Ppu::Read(uint16_t addr)
 {
 	switch(addr) {
+		case 0x213E:
+			//TODO open bus on bit 4
+			return (
+				(_timeOver ? 0x80 : 0) |
+				(_rangeOver ? 0x40 : 0) |
+				0x01 //PPU chip version
+			);
+
 		default:
 			MessageManager::DisplayMessage("Debug", "Unimplemented register read: " + HexUtilities::ToHex(addr));
 			break;
@@ -477,6 +502,15 @@ uint8_t Ppu::Read(uint16_t addr)
 void Ppu::Write(uint32_t addr, uint8_t value)
 {
 	switch(addr) {
+		case 0x2100:
+			_forcedVblank = (value & 0x80) != 0;
+
+			//TODO Apply brightness
+			_screenBrightness = value & 0x0F;
+
+			//TODO : Also, writing this register on the first line of V-Blank (225 or 240, depending on overscan) when force blank is currently active causes the OAM Address Reset to occur. 
+			break;
+
 		case 0x2101:
 			_oamMode = (value & 0xE0) >> 5;
 			_oamBaseAddress = (value & 0x07) << 13;
@@ -622,7 +656,7 @@ void Ppu::Write(uint32_t addr, uint8_t value)
 			break;
 
 		default:
-			MessageManager::DisplayMessage("Debug", "Unimplemented register write: " + HexUtilities::ToHex(addr));
+			MessageManager::DisplayMessage("Debug", "Unimplemented register write: " + HexUtilities::ToHex(addr) + " = " + HexUtilities::ToHex(value));
 			break;
 	}
 }
diff --git a/Core/Ppu.h b/Core/Ppu.h
index d105c83..68e017a 100644
--- a/Core/Ppu.h
+++ b/Core/Ppu.h
@@ -27,6 +27,9 @@ private:
 	shared_ptr<Console> _console;
 	shared_ptr<InternalRegisters> _regs;
 
+	bool _forcedVblank = false;
+	uint8_t _screenBrightness = 0;
+
 	uint16_t _cycle = 0;
 	uint16_t _scanline = 0;
 	uint32_t _frameCount = 0;
@@ -65,6 +68,9 @@ private:
 	uint16_t _internalOamAddress = 0;
 	uint8_t _oamWriteBuffer = 0;
 
+	bool _timeOver = false;
+	bool _rangeOver = false;
+
 	bool _directColorMode = false;
 
 	uint8_t _colorMathClipMode = 0;