From 57c6149274c876ba622ddc6a892e7e4b0109f93b Mon Sep 17 00:00:00 2001
From: alyosha-tas <alexei.f.k@gmail.com>
Date: Sat, 7 Jul 2018 09:02:56 -0400
Subject: [PATCH] NESHawk: Fix VRC IRQ timing

---
 .../Consoles/Nintendo/NES/Boards/VRC2_4.cs               | 9 +++++++--
 .../Consoles/Nintendo/NES/Boards/VRC7.cs                 | 9 +++++++--
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/VRC2_4.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/VRC2_4.cs
index a90509f4c0..51e4bc3af9 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/VRC2_4.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/VRC2_4.cs
@@ -435,7 +435,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 						//enabled
 						irq_enabled = true;
 						irq_counter = irq_reload;
-						irq_prescaler = 341;
+						irq_prescaler = 341 + 3;
 					}
 					else
 					{
@@ -466,7 +466,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			{
 				irq_pending = true;
 				irq_counter = irq_reload;
-				SyncIRQ();
+				//SyncIRQ();
 			}
 			else
 				irq_counter++;
@@ -474,6 +474,11 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 
 		public override void ClockCPU()
 		{
+			if (irq_pending)
+			{
+				SyncIRQ();
+			}
+
 			if (type == 2) return;
 			if (!irq_enabled) return;
 
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/VRC7.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/VRC7.cs
index 0012ee430c..3804ca06d1 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/VRC7.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/VRC7.cs
@@ -247,7 +247,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 						//enabled
 						irq_enabled = true;
 						irq_counter = irq_reload;
-						irq_prescaler = 341;
+						irq_prescaler = 341 + 3;
 					}
 					else
 					{
@@ -294,7 +294,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			{
 				irq_pending = true;
 				irq_counter = irq_reload;
-				SyncIRQ();
+				//SyncIRQ();
 			}
 			else
 				irq_counter++;
@@ -302,6 +302,11 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 
 		public override void ClockCPU()
 		{
+			if (irq_pending)
+			{
+				SyncIRQ();
+			}
+
 			if (!irq_enabled) return;
 
 			if (irq_mode)