From b471fdc6926ee79c02a1c20fff6bc37fcd9f22da Mon Sep 17 00:00:00 2001
From: SaxxonPike <saxxonpike@gmail.com>
Date: Tue, 9 Jul 2019 20:53:54 -0500
Subject: [PATCH] C64: The CPU can trigger VIC badlines on its own (needed for
 VSP)

---
 .../Commodore64/MOS/Vic.Registers.cs          | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.Registers.cs b/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.Registers.cs
index 0e63f4c16f..be8b1293af 100644
--- a/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.Registers.cs
+++ b/BizHawk.Emulation.Cores/Computers/Commodore64/MOS/Vic.Registers.cs
@@ -292,6 +292,27 @@
 					_extraColorMode = (val & 0x40) != 0;
 					_rasterInterruptLine &= 0xFF;
 					_rasterInterruptLine |= (val & 0x80) << 1;
+
+					if (_rasterLine == FirstDmaLine)
+						_badlineEnable |= _displayEnable;
+
+					if (_badlineEnable)
+					{
+						if ((_rasterLine & 0x7) == _yScroll)
+						{
+							_badline = true;
+							_idle = false;
+						}
+						else
+						{
+							_badline = false;
+						}
+					}
+					else
+					{
+						_badline = false;
+					}
+
 					UpdateBorder();
 					UpdateVideoMode();
 					break;