From d7c59e8bd4ff2573af4487847ead467b32a9ba37 Mon Sep 17 00:00:00 2001
From: alyosha-tas <alexei.f.k@gmail.com>
Date: Thu, 22 Oct 2020 20:24:54 -0400
Subject: [PATCH] GBHawk: Fix behaviour of button pressed during STOP

---
 src/BizHawk.Emulation.Cores/CPUs/LR35902/Execute.cs   |  2 +-
 src/BizHawk.Emulation.Cores/CPUs/LR35902/LR35902.cs   | 11 ++++++-----
 .../Consoles/Nintendo/GBHawk/GBHawk.IEmulator.cs      |  7 ++++++-
 .../Consoles/Nintendo/GBHawk/GBHawk.cs                |  1 +
 .../Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC1.cs   |  2 +-
 5 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/BizHawk.Emulation.Cores/CPUs/LR35902/Execute.cs b/src/BizHawk.Emulation.Cores/CPUs/LR35902/Execute.cs
index 3638714352..d92a81b290 100644
--- a/src/BizHawk.Emulation.Cores/CPUs/LR35902/Execute.cs
+++ b/src/BizHawk.Emulation.Cores/CPUs/LR35902/Execute.cs
@@ -19,7 +19,7 @@ namespace BizHawk.Emulation.Cores.Components.LR35902
 
 		// unsaved variables
 		public bool checker;
-		byte interrupt_src_reg, interrupt_enable_reg;
+		byte interrupt_src_reg, interrupt_enable_reg, buttons_pressed;
 
 		public void BuildInstructionTable()
 		{
diff --git a/src/BizHawk.Emulation.Cores/CPUs/LR35902/LR35902.cs b/src/BizHawk.Emulation.Cores/CPUs/LR35902/LR35902.cs
index e5884b3c8d..d3f019539f 100644
--- a/src/BizHawk.Emulation.Cores/CPUs/LR35902/LR35902.cs
+++ b/src/BizHawk.Emulation.Cores/CPUs/LR35902/LR35902.cs
@@ -92,7 +92,8 @@ namespace BizHawk.Emulation.Cores.Components.LR35902
 		public Func<ushort, byte> PeekMemory;
 		public Func<ushort, byte> DummyReadMemory;
 
-		// Get external interrupt registers
+		// Get external interrupt registers and button presses
+		public Func<ushort, byte> GetButtons;
 		public Func<ushort, byte> GetIntRegs;
 		public Action<byte> SetIntRegs;
 
@@ -477,11 +478,11 @@ namespace BizHawk.Emulation.Cores.Components.LR35902
 						stop_check = true;
 					}
 
-					interrupt_src_reg = GetIntRegs(0);
+					buttons_pressed = GetButtons(0);
 
 					if (stop_time > 0)
 					{
-						// Timer interrupts can prematurely terminate a speedchange, nt sure about other sources
+						// Timer interrupts can prematurely terminate a speedchange, not sure about other sources
 						// NOTE: some testing around the edge case of where the speed actually changes is needed						
 						if (I_use && interrupts_enabled)
 						{
@@ -536,7 +537,7 @@ namespace BizHawk.Emulation.Cores.Components.LR35902
 						}
 
 						// If a button is pressed during speed change, the processor will jam
-						if (interrupt_src_reg.Bit(4))
+						if ((buttons_pressed & 0xF) != 0xF)
 						{
 							stop_time++;
 							break;
@@ -544,7 +545,7 @@ namespace BizHawk.Emulation.Cores.Components.LR35902
 					}
 					
 					// Button press will exit stop loop even if speed change in progress, even without interrupts enabled
-					if (interrupt_src_reg.Bit(4))
+					if ((buttons_pressed & 0xF) != 0xF)
 					{
 						// TODO: On a gameboy, you can only un-STOP once, needs further testing
 						TraceCallback?.Invoke(new TraceInfo
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBHawk.IEmulator.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBHawk.IEmulator.cs
index 6e792d20b4..b14ca47467 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBHawk.IEmulator.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBHawk.IEmulator.cs
@@ -119,7 +119,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 
 					if (ppu.DMA_start && !cpu.halted && !cpu.stopped) { ppu.DMA_tick(); }
 					serialport.serial_transfer_tick();
-					timer.tick();
+					timer.tick();	
 					cpu.ExecuteOne();
 					timer.divider_reg++;
 
@@ -344,6 +344,11 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 			Acc_Y_state = _controllerDeck.ReadAccY1(controller);
 		}
 
+		public byte GetButtons(ushort r)
+		{
+			return input_register;
+		}
+
 		public byte GetIntRegs(ushort r)
 		{
 			if (r==0)
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBHawk.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBHawk.cs
index ad7922e0ed..6b589baf03 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBHawk.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/GBHawk.cs
@@ -109,6 +109,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 				DummyReadMemory = ReadMemory,
 				OnExecFetch = ExecFetch,
 				SpeedFunc = SpeedFunc,
+				GetButtons = GetButtons,
 				GetIntRegs = GetIntRegs,
 				SetIntRegs = SetIntRegs
 			};
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC1.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC1.cs
index f7812baaf6..9b226e80c4 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC1.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC1.cs
@@ -1,5 +1,6 @@
 using BizHawk.Common;
 using BizHawk.Emulation.Cores.Components.LR35902;
+using System;
 
 namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 {
@@ -60,7 +61,6 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
 				{
 					return 0xFF;
 				}
-
 			}
 			else
 			{