From 64ef1bfc1704cd750d39ba7e1774a415258ee0a0 Mon Sep 17 00:00:00 2001
From: CasualPokePlayer <50538166+CasualPokePlayer@users.noreply.github.com>
Date: Mon, 24 Jun 2024 19:22:11 -0700
Subject: [PATCH] Make NDS sys bus hack work better

fixes e6f8450685c731587528596b39dd480983560e61
---
 .../Consoles/Nintendo/NDS/MelonDS.IDebuggable.cs   |  5 +++--
 .../Consoles/Nintendo/NDS/MelonDS.cs               | 14 ++++++++++++--
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.IDebuggable.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.IDebuggable.cs
index a35d857290..0ecf734c2b 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.IDebuggable.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.IDebuggable.cs
@@ -52,7 +52,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 
 		public IMemoryCallbackSystem MemoryCallbacks => _memoryCallbacks;
 
-		private readonly MemoryCallbackSystem _memoryCallbacks = new(new[] { "System Bus" });
+		// FIXME: internally the code actually just does this for either bus (probably don't want to bother adding support)
+		private readonly MemoryCallbackSystem _memoryCallbacks = new([ "ARM9 System Bus" ]);
 
 		private LibMelonDS.MemoryCallback _readCallback;
 		private LibMelonDS.MemoryCallback _writeCallback;
@@ -67,7 +68,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 				{
 					if (getHasCBOfType())
 					{
-						MemoryCallbacks.CallMemoryCallbacks(address, 0, rawFlags, "System Bus");
+						MemoryCallbacks.CallMemoryCallbacks(address, 0, rawFlags, "ARM9 System Bus");
 					}
 				};
 			}
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs
index 71b59712e0..aba1a36105 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs
@@ -576,7 +576,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 				Size = 1L << 32;
 				WordSize = 4;
 				EndianType = Endian.Little;
-				Writable = false;
+				Writable = true;
 
 				Arm9Bus = arm9;
 				Arm7Bus = arm7;
@@ -596,7 +596,17 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 
 			public override byte PeekByte(long addr) => UseArm9 ? Arm9Bus.PeekByte(addr) : Arm7Bus.PeekByte(addr);
 
-			public override void PokeByte(long addr, byte val) => throw new InvalidOperationException();
+			public override void PokeByte(long addr, byte val)
+			{
+				if (UseArm9)
+				{
+					Arm9Bus.PokeByte(addr, val);
+				}
+				else
+				{
+					Arm7Bus.PokeByte(addr, val);
+				}
+			}
 		}
 	}
 }