From 154eefd2ad293de126f4c9ecc8b2fa522066d15d Mon Sep 17 00:00:00 2001
From: SaxxonPike <saxxonpike@gmail.com>
Date: Sat, 13 Jul 2019 16:51:30 -0500
Subject: [PATCH] C64: Give BA/IRQ counting another go, seems to resolve many
 issues

---
 .../Computers/Commodore64/MOS/Chip6510.cs                    | 5 ++++-
 .../Computers/Commodore64/MOS/Vic.Parse.cs                   | 2 +-
 BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.cs     | 4 ++--
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Chip6510.cs b/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Chip6510.cs
index a4343f44fc..87825957b9 100644
--- a/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Chip6510.cs
+++ b/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Chip6510.cs
@@ -137,7 +137,10 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.MOS
 				case 0x0001:
 					return PortData;
 				default:
-					return ReadAec() ? ReadMemory(addr) : ReadBus();
+					if (ReadAec())
+						return ReadMemory(addr);
+					else
+						return ReadBus();
 			}
 		}
 
diff --git a/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.Parse.cs b/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.Parse.cs
index 9d8ba3ce4f..c593082dad 100644
--- a/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.Parse.cs
+++ b/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.Parse.cs
@@ -72,7 +72,7 @@
 						if (_badline)
 						{
 							_parseAddr = _pointerVm | _vc;
-							_dataC = ReadMemory(_parseAddr);
+							_dataC = _baCount >= 0 ? 0xFF : ReadMemory(_parseAddr);
 							_dataC |= (ReadColorRam(_parseAddr) & 0xF) << 8;
 							_bufferC[_vmli] = _dataC;
 						}
diff --git a/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.cs b/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.cs
index fe987dd613..4ba40d3fc1 100644
--- a/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.cs
+++ b/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.cs
@@ -320,7 +320,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.MOS
 		{
 			if (_ba)
 				_baCount = BaResetCounter;
-			else if (_baCount > 0)
+			else if (_baCount >= 0)
 				_baCount--;
 		}
 
@@ -343,7 +343,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64.MOS
 			// IRQ buffer is treated as a delay line
 			_irqBuffer >>= 1;
 			_irqBuffer |= irqTemp ? 0x8 : 0;
-			_pinAec = _ba || _baCount > 0;
+			_pinAec = _ba || _baCount >= 0;
 			_pinBa = _ba;
 		}