fix #3726

src/BizHawk.BizInvoke/FPCtrl.cs

@@ -0,0 +1,67 @@
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace BizHawk.BizInvoke
+{
+	// .NET is weird and sets the x87 control register to double precision
+	// It does this even on Linux which normally expects it set to extended x87 precision
+	// Even stranger is that this appears to be completely unneeded on x86-64
+	// On Windows, x87 registers are prohibited to be used in kernel code, and
+	// MSVC will not use the x87 registers (and presumably this extends to userland OS code)
+	// .NET presumbly follows MSVC and would not use the x87 registers (why would it? SSE is available! long double doesn't exist!)
+	// This thus only screws over code compiled with MinGW (which use extended x87 precision for long double)
+	// Or screws over any unmanaged code on Linux, which doubly includes all waterbox cores (!!!)
+	// Of course in practice, this only applies to any code using long double, which is rarely used typically
+	// But musl (used for waterbox cores) does end up using it for float formating in the printf family
+	// This can extend to issues in games: https://github.com/TASEmulators/BizHawk/issues/3726
+	public static class FPCtrl
+	{
+		private const CallingConvention cc = CallingConvention.Cdecl;
+
+		[UnmanagedFunctionPointer(cc)]
+		private delegate void FixFPCtrlDelegate();
+
+		private static readonly MemoryBlock? _memory;
+		private static readonly FixFPCtrlDelegate? _fixFpCtrl;
+
+		static FPCtrl()
+		{
+			// not usable outside of x64
+			if (RuntimeInformation.ProcessArchitecture != Architecture.X64)
+			{
+				return;
+			}
+
+			// generate assembly for fixing the x87 control register
+			_memory = new(4096);
+			_memory.Protect(_memory.Start, _memory.Size, MemoryBlock.Protection.RW);
+			var ss = _memory.GetStream(_memory.Start, 64, true);
+			var bw = new BinaryWriter(ss);
+
+			// FYI: The push/pop is only needed on Windows, but doesn't do any harm on Linux
+
+			bw.Write((byte)0x50); // push rax
+			bw.Write(0x06247CD9); // fnstcw word[rsp + 6]
+			bw.Write(0x07244C80); // or byte[rsp + 7], 3
+			bw.Write((byte)0x03);
+			bw.Write(0x06246CD9); // fldcw word[rsp + 6]
+			bw.Write((byte)0x58); // pop rax
+			bw.Write((byte)0xC3); // ret
+
+			_memory.Protect(_memory.Start, _memory.Size, MemoryBlock.Protection.RX);
+			_fixFpCtrl = Marshal.GetDelegateForFunctionPointer<FixFPCtrlDelegate>((IntPtr)_memory.Start);
+		}
+
+		public static void FixFPCtrl()
+		{
+			// not usable outside of x64
+			if (RuntimeInformation.ProcessArchitecture != Architecture.X64)
+			{
+				return;
+			}
+
+			_fixFpCtrl!();
+		}
+	}
+}

src/BizHawk.Client.EmuHawk/Program.cs

@@ -6,6 +6,7 @@ using System.Reflection;
 using System.Runtime.InteropServices;
 using System.Windows.Forms;
 
+using BizHawk.BizInvoke;
 using BizHawk.Bizware.BizwareGL;
 using BizHawk.Bizware.Graphics;
 using BizHawk.Common;
@@ -285,6 +286,8 @@ namespace BizHawk.Client.EmuHawk
 				}
 			}
 
+			FPCtrl.FixFPCtrl();
+
 			var exitCode = 0;
 			try
 			{

src/BizHawk.Emulation.Cores/Consoles/Nintendo/QuickNES/QuickNES.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
@@ -30,48 +29,41 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.QuickNES
 		[CoreConstructor(VSystemID.Raw.NES, Priority = CorePriority.Low)]
 		public QuickNES(byte[] file, QuickNESSettings settings, QuickNESSyncSettings syncSettings)
 		{
-			FP = OSTailoredCode.IsUnixHost
+			ServiceProvider = new BasicServiceProvider(this);
-				? (IFPCtrl) new Unix_FPCtrl()
+			Context = QN.qn_new();
-				: new Win32_FPCtrl();
+			if (Context == IntPtr.Zero)
-
-			using (FP.Save())
 			{
-				ServiceProvider = new BasicServiceProvider(this);
+				throw new InvalidOperationException($"{nameof(QN.qn_new)}() returned NULL");
-				Context = QN.qn_new();
+			}
-				if (Context == IntPtr.Zero)
-				{
-					throw new InvalidOperationException($"{nameof(QN.qn_new)}() returned NULL");
-				}
 
-				try
+			try
-				{
+			{
-					file = FixInesHeader(file);
+				file = FixInesHeader(file);
-					LibQuickNES.ThrowStringError(QN.qn_loadines(Context, file, file.Length));
+				LibQuickNES.ThrowStringError(QN.qn_loadines(Context, file, file.Length));
 
-					InitSaveRamBuff();
+				InitSaveRamBuff();
-					InitSaveStateBuff();
+				InitSaveStateBuff();
-					InitAudio();
+				InitAudio();
-					InitMemoryDomains();
+				InitMemoryDomains();
 
-					int mapper = 0;
+				int mapper = 0;
-					string mappername = Marshal.PtrToStringAnsi(QN.qn_get_mapper(Context, ref mapper));
+				string mappername = Marshal.PtrToStringAnsi(QN.qn_get_mapper(Context, ref mapper));
-					Console.WriteLine("QuickNES: Booted with Mapper #{0} \"{1}\"", mapper, mappername);
+				Console.WriteLine("QuickNES: Booted with Mapper #{0} \"{1}\"", mapper, mappername);
-					BoardName = mappername;
+				BoardName = mappername;
-					PutSettings((QuickNESSettings)settings ?? new QuickNESSettings());
+				PutSettings((QuickNESSettings)settings ?? new QuickNESSettings());
 
-					_syncSettings = (QuickNESSyncSettings)syncSettings ?? new QuickNESSyncSettings();
+				_syncSettings = (QuickNESSyncSettings)syncSettings ?? new QuickNESSyncSettings();
-					_syncSettingsNext = _syncSettings.Clone();
+				_syncSettingsNext = _syncSettings.Clone();
 
-					SetControllerDefinition();
+				SetControllerDefinition();
-					ComputeBootGod();
+				ComputeBootGod();
 
-					ConnectTracer();
+				ConnectTracer();
-				}
+			}
-				catch
+			catch
-				{
+			{
-					Dispose();
+				Dispose();
-					throw;
+				throw;
-				}
 			}
 		}
 
@@ -83,40 +75,6 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.QuickNES
 
 		int IVideoLogicalOffsets.ScreenY => _settings.ClipTopAndBottom ? 8 : 0;
 
-		private interface IFPCtrl : IDisposable
-		{
-			IDisposable Save();
-		}
-
-		private class Win32_FPCtrl : IFPCtrl
-		{
-			[Conditional("DEBUG")]
-			public static void PrintCurrentFP() => Console.WriteLine($"Current FP word: 0x{Win32Imports._control87(0, 0):X8}");
-
-			private uint cw;
-
-			public IDisposable Save()
-			{
-				cw = Win32Imports._control87(0, 0);
-				Win32Imports._control87(0x00000, 0x30000);
-				return this;
-			}
-
-			public void Dispose()
-			{
-				Win32Imports._control87(cw, 0x30000);
-			}
-		}
-
-		private class Unix_FPCtrl : IFPCtrl
-		{
-			public IDisposable Save() => this;
-
-			public void Dispose() {}
-		}
-
-		private readonly IFPCtrl FP;
-
 		public ControllerDefinition ControllerDefinition { get; private set; }
 
 		private void SetControllerDefinition()
@@ -185,34 +143,32 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.QuickNES
 		public bool FrameAdvance(IController controller, bool render, bool rendersound = true)
 		{
 			CheckDisposed();
-			using (FP.Save())
-			{
-				if (controller.IsPressed("Power"))
-					QN.qn_reset(Context, true);
-				if (controller.IsPressed("Reset"))
-					QN.qn_reset(Context, false);
 
-				SetPads(controller, out var j1, out var j2);
+			if (controller.IsPressed("Power"))
+				QN.qn_reset(Context, true);
+			if (controller.IsPressed("Reset"))
+				QN.qn_reset(Context, false);
 
-				QN.qn_set_tracecb(Context, Tracer.IsEnabled() ? _traceCb : null);
+			SetPads(controller, out var j1, out var j2);
 
-				LibQuickNES.ThrowStringError(QN.qn_emulate_frame(Context, j1, j2));
+			QN.qn_set_tracecb(Context, Tracer.IsEnabled() ? _traceCb : null);
-				IsLagFrame = QN.qn_get_joypad_read_count(Context) == 0;
-				if (IsLagFrame)
-					LagCount++;
 
-				if (render)
+			LibQuickNES.ThrowStringError(QN.qn_emulate_frame(Context, j1, j2));
-					Blit();
+			IsLagFrame = QN.qn_get_joypad_read_count(Context) == 0;
-				if (rendersound)
+			if (IsLagFrame)
-					DrainAudio();
+				LagCount++;
 
-				_callBack1?.Invoke();
+			if (render)
-				_callBack2?.Invoke();
+				Blit();
+			if (rendersound)
+				DrainAudio();
 
-				Frame++;
+			_callBack1?.Invoke();
+			_callBack2?.Invoke();
 
-				return true;
+			Frame++;
-			}
+
+			return true;
 		}
 
 		private IntPtr Context;