From f8a5adecb5b7f7dc045a84767341d1dda2d8eb6a Mon Sep 17 00:00:00 2001
From: CasualPokePlayer <50538166+CasualPokePlayer@users.noreply.github.com>
Date: Wed, 25 Jan 2023 22:28:26 -0800
Subject: [PATCH] fix possible deadlocks with RAIntegration due to dumb
 threading bs, cleanup some of this code also make sure to reboot core when
 starting up RetroAchievements with RAIntegration active (RAIntegration
 doesn't do this itself it seems)

---
 .../RetroAchievements/RAIntegration.Update.cs | 84 +++++++---------
 .../RetroAchievements/RAIntegration.cs        | 79 ++++++++-------
 .../RCheevos.Achievements.cs                  |  2 +-
 .../RetroAchievements/RCheevos.GameInfo.cs    | 33 ++-----
 .../RetroAchievements/RCheevos.Ping.cs        |  9 +-
 .../RetroAchievements/RCheevos.Sound.cs       |  1 +
 .../RetroAchievements/RCheevos.cs             | 34 +++----
 .../RetroAchievements.GameVerification.cs     | 56 +++++------
 .../RetroAchievements.Hardcore.cs             | 93 +++++++++---------
 .../RetroAchievements.Memory.cs               | 95 ++++++++++---------
 10 files changed, 220 insertions(+), 266 deletions(-)

diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RAIntegration.Update.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RAIntegration.Update.cs
index 8e804bfb97..f7c1c347e9 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RAIntegration.Update.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RAIntegration.Update.cs
@@ -19,7 +19,7 @@ namespace BizHawk.Client.EmuHawk
 		{
 			_resolver = new("RA_Integration-x64.dll", hasLimitedLifetime: true);
 			RA = BizInvoker.GetInvoker<RAInterface>(_resolver, CallingConventionAdapters.Native);
-			_version = new(Marshal.PtrToStringAnsi(RA.IntegrationVersion()));
+			_version = new(Marshal.PtrToStringAnsi(RA.IntegrationVersion())!);
 			Console.WriteLine($"Loaded RetroAchievements v{_version}");
 		}
 
@@ -58,58 +58,42 @@ namespace BizHawk.Client.EmuHawk
 
 					if (_version < minVer)
 					{
-						if (mainForm.ShowMessageBox2(
-							owner: null,
-							text: "An update is required to use RetroAchievements. Do you want to download the update now?",
-							caption: "Update",
-							icon: EMsgBoxIcon.Question,
-							useOKCancel: false))
-						{
-							DetachDll();
-							var ret = DownloadDll((string)info["LatestVersionUrlX64"]);
-							AttachDll();
-							return ret;
-						}
-						else
-						{
-							return false;
-						}
+						if (!mainForm.ShowMessageBox2(
+								owner: null,
+								text:
+								"An update is required to use RetroAchievements. Do you want to download the update now?",
+								caption: "Update",
+								icon: EMsgBoxIcon.Question,
+								useOKCancel: false)) return false;
+						DetachDll();
+						var ret = DownloadDll((string)info["LatestVersionUrlX64"]);
+						AttachDll();
+						return ret;
 					}
-					else if (_version < lastestVer)
-					{
-						if (mainForm.ShowMessageBox2(
-							owner: null,
-							text: "An optional update is available for RetroAchievements. Do you want to download the update now?",
-							caption: "Update",
-							icon: EMsgBoxIcon.Question,
-							useOKCancel: false))
-						{
-							DetachDll();
-							DownloadDll((string)info["LatestVersionUrlX64"]);
-							AttachDll();
-							return true; // even if this fails, should be OK to use the old dll
-						}
-						else
-						{
-							// don't have to update in this case
-							return true;
-						}
-					}
-					else
-					{
-						return true;
-					}
-				}
-				else
-				{
-					mainForm.ShowMessageBox(
-						owner: null,
-						text: "Failed to fetch update information, cannot start RetroAchievements.",
-						caption: "Error",
-						icon: EMsgBoxIcon.Error);
 
-					return false;
+					if (_version >= lastestVer) return true;
+
+					if (!mainForm.ShowMessageBox2(
+							owner: null,
+							text:
+							"An optional update is available for RetroAchievements. Do you want to download the update now?",
+							caption: "Update",
+							icon: EMsgBoxIcon.Question,
+							useOKCancel: false)) return true;
+
+					DetachDll();
+					DownloadDll((string)info["LatestVersionUrlX64"]);
+					AttachDll();
+					return true; // even if this fails, should be OK to use the old dll
 				}
+
+				mainForm.ShowMessageBox(
+					owner: null,
+					text: "Failed to fetch update information, cannot start RetroAchievements.",
+					caption: "Error",
+					icon: EMsgBoxIcon.Error);
+
+				return false;
 			}
 			catch (Exception ex)
 			{
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RAIntegration.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RAIntegration.cs
index c57bae5f0f..3a8ff6e3be 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RAIntegration.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RAIntegration.cs
@@ -43,12 +43,11 @@ namespace BizHawk.Client.EmuHawk
 
 		private readonly RAInterface.MenuItem[] _menuItems = new RAInterface.MenuItem[40];
 
-		// Memory may be accessed by another thread (for rich presence)
+		// Memory may be accessed by another thread (mainly rich presence, some other things too)
 		// and peeks for us are not thread safe, so we need to guard it
-		private readonly AutoResetEvent _memAccessReady = new(false);
-		private readonly AutoResetEvent _memAccessGo = new(false);
-		private readonly AutoResetEvent _memAccessDone = new(false);
-		private readonly RAMemGuard _memGuard;
+		private readonly RAMemGuard _memGuard = new();
+
+		private bool _firstRestart = true;
 
 		private void RebuildMenu()
 		{
@@ -111,8 +110,6 @@ namespace BizHawk.Client.EmuHawk
 			Func<Config> getConfig, ToolStripItemCollection raDropDownItems, Action shutdownRACallback)
 			: base(mainForm, inputManager, tools, getConfig, raDropDownItems, shutdownRACallback)
 		{
-			_memGuard = new(_memAccessReady, _memAccessGo, _memAccessDone);
-
 			RA.InitClient(_mainForm.Handle, "BizHawk", VersionInfo.GetEmuVersion());
 
 			_isActive = () => !Emu.IsNull();
@@ -125,7 +122,7 @@ namespace BizHawk.Client.EmuHawk
 				Marshal.Copy(name, 0, buffer, Math.Min(name.Length, 256));
 			};
 			_resetEmulator = () => _mainForm.RebootCore();
-			_loadROM = path => _ = _mainForm.LoadRom(path, new LoadRomArgs { OpenAdvanced = OpenAdvancedSerializer.ParseWithLegacy(path) });
+			_loadROM = path => _ = _mainForm.LoadRom(path, new() { OpenAdvanced = OpenAdvancedSerializer.ParseWithLegacy(path) });
 
 			RA.InstallSharedFunctionsExt(_isActive, _unpause, _pause, _rebuildMenu, _estimateTitle, _resetEmulator, _loadROM);
 
@@ -159,6 +156,25 @@ namespace BizHawk.Client.EmuHawk
 
 		public override void Restart()
 		{
+			if (_firstRestart)
+			{
+				_firstRestart = false;
+				if (RA.HardcoreModeIsActive())
+				{
+					if (!_mainForm.RebootCore())
+					{
+						// unset hardcore mode if we fail to reboot core somehow
+						HandleHardcoreModeDisable("Failed to reboot core.");
+					}
+					if (RA.HardcoreModeIsActive() && _mainForm.CurrentlyOpenRomArgs is not null)
+					{
+						// if we aren't hardcore anymore, we failed to reboot the core (and didn't call Restart probably)
+						// if CurrentlyOpenRomArgs is null, then Restart won't be called (as RebootCore returns true immediately), so
+						return;
+					}
+				}
+			}
+
 			var consoleId = SystemIdToConsoleId();
 			RA.SetConsoleID(consoleId);
 
@@ -168,7 +184,7 @@ namespace BizHawk.Client.EmuHawk
 			{
 				_memFunctions = CreateMemoryBanks(consoleId, Domains, Emu.CanDebug() ? Emu.AsDebuggable() : null);
 
-				for (int i = 0; i < _memFunctions.Count; i++)
+				for (var i = 0; i < _memFunctions.Count; i++)
 				{
 					_memFunctions[i].MemGuard = _memGuard;
 					RA.InstallMemoryBank(i, _memFunctions[i].ReadFunc, _memFunctions[i].WriteFunc, _memFunctions[i].BankSize);
@@ -209,6 +225,8 @@ namespace BizHawk.Client.EmuHawk
 
 		public override void Update()
 		{
+			using var access = _memGuard.GetAccess();
+
 			if (RA.HardcoreModeIsActive())
 			{
 				CheckHardcoreModeConditions();
@@ -219,41 +237,32 @@ namespace BizHawk.Client.EmuHawk
 				RA.SetPaused(true);
 			}
 
-			if (RA.IsOverlayFullyVisible())
+			if (!RA.IsOverlayFullyVisible()) return;
+
+			var ci = new RAInterface.ControllerInput
 			{
-				var ci = new RAInterface.ControllerInput
-				{
-					UpPressed = _inputManager.ClientControls["RA Up"],
-					DownPressed = _inputManager.ClientControls["RA Down"],
-					LeftPressed = _inputManager.ClientControls["RA Left"],
-					RightPressed = _inputManager.ClientControls["RA Right"],
-					ConfirmPressed = _inputManager.ClientControls["RA Confirm"],
-					CancelPressed = _inputManager.ClientControls["RA Cancel"],
-					QuitPressed = _inputManager.ClientControls["RA Quit"],
-				};
+				UpPressed = _inputManager.ClientControls["RA Up"],
+				DownPressed = _inputManager.ClientControls["RA Down"],
+				LeftPressed = _inputManager.ClientControls["RA Left"],
+				RightPressed = _inputManager.ClientControls["RA Right"],
+				ConfirmPressed = _inputManager.ClientControls["RA Confirm"],
+				CancelPressed = _inputManager.ClientControls["RA Cancel"],
+				QuitPressed = _inputManager.ClientControls["RA Quit"],
+			};
 
-				RA.NavigateOverlay(ref ci);
+			RA.NavigateOverlay(ref ci);
 
-				// todo: suppress user inputs with overlay active?
-			}
-
-			if (_memAccessReady.WaitOne(0))
-			{
-				_memAccessGo.Set();
-				_memAccessDone.WaitOne();
-			}
+			// todo: suppress user inputs with overlay active?
 		}
 
 		public override void OnFrameAdvance()
 		{
+			using var access = _memGuard.GetAccess();
+
 			var input = _inputManager.ControllerOutput;
-			foreach (var resetButton in input.Definition.BoolButtons.Where(b => b.Contains("Power") || b.Contains("Reset")))
+			if (input.Definition.BoolButtons.Any(b => (b.Contains("Power") || b.Contains("Reset")) && input.IsPressed(b)))
 			{
-				if (input.IsPressed(resetButton))
-				{
-					RA.OnReset();
-					break;
-				}
+				RA.OnReset();
 			}
 
 			if (Emu.HasMemoryDomains())
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Achievements.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Achievements.cs
index 233c94a4ec..2086b8eed7 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Achievements.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Achievements.cs
@@ -102,7 +102,7 @@ namespace BizHawk.Client.EmuHawk
 
 		private readonly byte[] _cheevoFormatBuffer = new byte[1024];
 
-		public string GetCheevoProgress(int id)
+		private string GetCheevoProgress(int id)
 		{
 			var len = _lib.rc_runtime_format_achievement_measured(ref _runtime, id, _cheevoFormatBuffer, _cheevoFormatBuffer.Length);
 			return Encoding.ASCII.GetString(_cheevoFormatBuffer, 0, len);
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.GameInfo.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.GameInfo.cs
index 352bd30b8a..531833f2bb 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.GameInfo.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.GameInfo.cs
@@ -53,9 +53,9 @@ namespace BizHawk.Client.EmuHawk
 						unsafe
 						{
 							var unlocks = (int*)resp.achievement_ids;
-							for (int i = 0; i < resp.num_achievement_ids; i++)
+							for (var i = 0; i < resp.num_achievement_ids; i++)
 							{
-								if (_cheevos.TryGetValue(unlocks[i], out var cheevo))
+								if (_cheevos.TryGetValue(unlocks![i], out var cheevo))
 								{
 									cheevo.SetUnlocked(hardcore, true);
 								}
@@ -104,18 +104,18 @@ namespace BizHawk.Client.EmuHawk
 
 				var cheevos = new Dictionary<int, Cheevo>();
 				var cptr = (LibRCheevos.rc_api_achievement_definition_t*)resp.achievements;
-				for (int i = 0; i < resp.num_achievements; i++)
+				for (var i = 0; i < resp.num_achievements; i++)
 				{
-					cheevos.Add(cptr[i].id, new(in cptr[i], allowUnofficialCheevos));
+					cheevos.Add(cptr![i].id, new(in cptr[i], allowUnofficialCheevos));
 				}
 
 				_cheevos = cheevos;
 
 				var lboards = new Dictionary<int, LBoard>();
 				var lptr = (LibRCheevos.rc_api_leaderboard_definition_t*)resp.leaderboards;
-				for (int i = 0; i < resp.num_leaderboards; i++)
+				for (var i = 0; i < resp.num_leaderboards; i++)
 				{
-					lboards.Add(lptr[i].id, new(in lptr[i]));
+					lboards.Add(lptr![i].id, new(in lptr[i]));
 				}
 
 				_lboards = lboards;
@@ -133,21 +133,8 @@ namespace BizHawk.Client.EmuHawk
 				GameBadge = null;
 				RichPresenseScript = gameData.RichPresenseScript;
 
-				var cheevos = new Dictionary<int, Cheevo>();
-				foreach (var cheevo in gameData.CheevoEnumerable)
-				{
-					cheevos.Add(cheevo.ID, new(in cheevo, allowUnofficialCheevos));
-				}
-
-				_cheevos = cheevos;
-
-				var lboards = new Dictionary<int, LBoard>();
-				foreach (var lboard in gameData.LBoardEnumerable)
-				{
-					lboards.Add(lboard.ID, new(in lboard));
-				}
-
-				_lboards = lboards;
+				_cheevos = gameData.CheevoEnumerable.ToDictionary<Cheevo, int, Cheevo>(cheevo => cheevo.ID, cheevo => new(in cheevo, allowUnofficialCheevos));
+				_lboards = gameData.LBoardEnumerable.ToDictionary<LBoard, int, LBoard>(lboard => lboard.ID, lboard => new(in lboard));
 
 				SoftcoreInitUnlocksReady = new(false);
 				HardcoreInitUnlocksReady = new(false);
@@ -159,7 +146,7 @@ namespace BizHawk.Client.EmuHawk
 			}
 		}
 
-		private async Task<int> SendHashAsync(string hash)
+		private static async Task<int> SendHashAsync(string hash)
 		{
 			var api_params = new LibRCheevos.rc_api_resolve_hash_request_t(null, null, hash);
 			var ret = 0;
@@ -244,7 +231,7 @@ namespace BizHawk.Client.EmuHawk
 				try
 				{
 					var serv_resp = await SendAPIRequest(in api_req).ConfigureAwait(false);
-					ret = new Bitmap(new MemoryStream(serv_resp));
+					ret = new(new MemoryStream(serv_resp));
 				}
 				catch
 				{
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Ping.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Ping.cs
index a12053eadf..5758e63dd6 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Ping.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Ping.cs
@@ -7,7 +7,6 @@ namespace BizHawk.Client.EmuHawk
 	public partial class RCheevos
 	{
 		private bool RichPresenceActive { get; set; }
-
 		private string CurrentRichPresence { get; set; }
 
 		private static async Task<bool> StartGameSessionAsync(string username, string api_token, int id)
@@ -63,11 +62,9 @@ namespace BizHawk.Client.EmuHawk
 			}
 
 			var now = DateTime.Now;
-			if ((now - _lastPingTime) >= _pingCooldown)
-			{
-				SendPing(Username, ApiToken, _gameData.GameID, CurrentRichPresence);
-				_lastPingTime = now;
-			}
+			if (now - _lastPingTime < _pingCooldown) return;
+			SendPing(Username, ApiToken, _gameData.GameID, CurrentRichPresence);
+			_lastPingTime = now;
 		}
 	}
 }
\ No newline at end of file
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Sound.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Sound.cs
index b6fd226035..6c1a577d6f 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Sound.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.Sound.cs
@@ -29,6 +29,7 @@ namespace BizHawk.Client.EmuHawk
 			}
 			catch
 			{
+				// ignored
 			}
 		}
 	}
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.cs
index 70687a5f60..f179b303a4 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RCheevos.cs
@@ -246,12 +246,11 @@ namespace BizHawk.Client.EmuHawk
 
 			_lib.rc_runtime_reset(ref _runtime);
 
-			if (File.Exists(path + ".rap"))
-			{
-				using var file = File.OpenRead(path + ".rap");
-				var buffer = file.ReadAllBytes();
-				_lib.rc_runtime_deserialize_progress(ref _runtime, buffer, IntPtr.Zero);
-			}
+			if (!File.Exists(path + ".rap")) return;
+
+			using var file = File.OpenRead(path + ".rap");
+			var buffer = file.ReadAllBytes();
+			_lib.rc_runtime_deserialize_progress(ref _runtime, buffer, IntPtr.Zero);
 		}
 
 		// not sure if we really need to do anything here...
@@ -333,14 +332,9 @@ namespace BizHawk.Client.EmuHawk
 
 				if (gameId != 0)
 				{
-					if (_cachedGameDatas.TryGetValue(gameId, out var cachedGameData))
-					{
-						_gameData = new GameData(cachedGameData, () => AllowUnofficialCheevos);
-					}
-					else
-					{
-						_gameData = GetGameData(Username, ApiToken, gameId, () => AllowUnofficialCheevos);
-					}
+					_gameData = _cachedGameDatas.TryGetValue(gameId, out var cachedGameData)
+						? new(cachedGameData, () => AllowUnofficialCheevos)
+						: GetGameData(Username, ApiToken, gameId, () => AllowUnofficialCheevos);
 
 					StartGameSession(Username, ApiToken, gameId);
 
@@ -373,12 +367,12 @@ namespace BizHawk.Client.EmuHawk
 				}
 				else
 				{
-					_gameData = new GameData();
+					_gameData = new();
 				}
 			}
 			else
 			{
-				_gameData = new GameData();
+				_gameData = new();
 			}
 
 			// validate addresses now that we have cheevos init
@@ -593,13 +587,9 @@ namespace BizHawk.Client.EmuHawk
 			}
 
 			var input = _inputManager.ControllerOutput;
-			foreach (var resetButton in input.Definition.BoolButtons.Where(b => b.Contains("Power") || b.Contains("Reset")))
+			if (input.Definition.BoolButtons.Any(b => (b.Contains("Power") || b.Contains("Reset")) && input.IsPressed(b)))
 			{
-				if (input.IsPressed(resetButton))
-				{
-					_lib.rc_runtime_reset(ref _runtime);
-					break;
-				}
+				_lib.rc_runtime_reset(ref _runtime);
 			}
 
 			if (Emu.HasMemoryDomains())
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.GameVerification.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.GameVerification.cs
index ae6098a4ed..d722f679b9 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.GameVerification.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.GameVerification.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Text;
 
 using BizHawk.Common;
@@ -48,7 +49,7 @@ namespace BizHawk.Client.EmuHawk
 						buffer.AddRange(new ArraySegment<byte>(buf2048, 0, 128));
 						var bootSector = (buf2048[35] << 24) | (buf2048[34] << 16) | (buf2048[33] << 8) | buf2048[32];
 						var numSectors = (buf2048[39] << 24) | (buf2048[38] << 16) | (buf2048[37] << 8) | buf2048[36];
-						for (int i = 0; i < numSectors; i++)
+						for (var i = 0; i < numSectors; i++)
 						{
 							dsr.ReadLBA_2048(bootSector + i, buf2048, 0);
 							buffer.AddRange(buf2048);
@@ -82,7 +83,7 @@ namespace BizHawk.Client.EmuHawk
 							return -1;
 						}
 
-						string exePath = "PSX.EXE";
+						var exePath = "PSX.EXE";
 
 						// find SYSTEM.CNF sector
 						var sector = GetFileSector("SYSTEM.CNF", out _);
@@ -154,36 +155,30 @@ namespace BizHawk.Client.EmuHawk
 						var numLbas = disc.Session1.FirstInformationTrack.NextTrack.LBA - disc.Session1.FirstInformationTrack.LBA;
 						int bootLen = 0, bootLba = 0, bootOff = 0;
 						bool byteswapped = false, foundHeader = false;
-						for (int i = 0; i < numLbas; i++)
+						for (var i = 0; i < numLbas; i++)
 						{
 							dsr.ReadLBA_2352(startLba + i, buf2352, 0);
 
-							for (int j = 0; j < (2352 - 32 - 4 - 4); j++)
+							for (var  j = 0; j < 2352 - 32 - 4 - 4; j++)
 							{
 								if (buf2352[j] == _jaguarHeader[0])
 								{
-									if (_jaguarHeader == Encoding.ASCII.GetString(buf2352, j, 32))
-									{
-										bootLen = (buf2352[j + 36] << 24) | (buf2352[j + 37] << 16) | (buf2352[j + 38] << 8) | buf2352[j + 39];
-										bootLba = startLba + i;
-										bootOff = j + 32 + 4 + 4;
-										byteswapped = false;
-										foundHeader = true;
-										break;
-									}
-								}
-								else if (buf2352[j] == _jaguarBSHeader[0])
-								{
-									if (_jaguarBSHeader == Encoding.ASCII.GetString(buf2352, j, 32))
-									{
-										bootLen = (buf2352[j + 37] << 24) | (buf2352[j + 36] << 16) | (buf2352[j + 39] << 8) | buf2352[j + 38];
-										bootLba = startLba + i;
-										bootOff = j + 32 + 4 + 4;
-										byteswapped = true;
-										foundHeader = true;
-										break;
-									}
+									if (_jaguarHeader != Encoding.ASCII.GetString(buf2352, j, 32)) continue;
+									bootLen = (buf2352[j + 36] << 24) | (buf2352[j + 37] << 16) | (buf2352[j + 38] << 8) | buf2352[j + 39];
+									bootLba = startLba + i;
+									bootOff = j + 32 + 4 + 4;
+									byteswapped = false;
+									foundHeader = true;
+									break;
 								}
+
+								if (buf2352[j] != _jaguarBSHeader[0] || _jaguarBSHeader != Encoding.ASCII.GetString(buf2352, j, 32)) continue;
+								bootLen = (buf2352[j + 37] << 24) | (buf2352[j + 36] << 16) | (buf2352[j + 39] << 8) | buf2352[j + 38];
+								bootLba = startLba + i;
+								bootOff = j + 32 + 4 + 4;
+								byteswapped = true;
+								foundHeader = true;
+								break;
 							}
 
 							if (foundHeader)
@@ -256,14 +251,9 @@ namespace BizHawk.Client.EmuHawk
 							using var sr = new StreamReader(file.GetStream());
 							var m3u = M3U_File.Read(sr);
 							m3u.Rebase(Path.GetDirectoryName(ioa.SimplePath));
-							foreach (var entry in m3u.Entries)
-							{
-								var id = HashDisc(entry.Path, consoleID, ++discCount);
-								if (id.HasValue)
-								{
-									ret.Add(id.Value);
-								}
-							}
+							ret.AddRange(m3u.Entries.Select(entry => HashDisc(entry.Path, consoleID, ++discCount))
+								.Where(id => id.HasValue)
+								.Select(id => id.Value));
 						}
 						else if (ext == ".xml")
 						{
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Hardcore.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Hardcore.cs
index 71ed7d79f5..f743b1b19e 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Hardcore.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Hardcore.cs
@@ -29,7 +29,7 @@ namespace BizHawk.Client.EmuHawk
 		// To keep changes outside this file minimal, we'll simply check if any problematic condition arises and disable hardcore mode
 		// (with the exception of frame advance and rewind, which we can just suppress)
 
-		private static readonly Type[] HardcoreProhibitedTools = new[]
+		private static readonly Type[] HardcoreProhibitedTools =
 		{
 			typeof(LuaConsole), typeof(RamWatch), typeof(RamSearch),
 			typeof(GameShark), typeof(SNESGraphicsDebugger), typeof(PceBgViewer),
@@ -93,11 +93,9 @@ namespace BizHawk.Client.EmuHawk
 
 			foreach (var t in HardcoreProhibitedTools)
 			{
-				if (_tools.IsLoaded(t))
-				{
-					HandleHardcoreModeDisable($"Using {t.Name} in hardcore mode is not allowed.");
-					return;
-				}
+				if (!_tools.IsLoaded(t)) continue;
+				HandleHardcoreModeDisable($"Using {t.Name} in hardcore mode is not allowed.");
+				return;
 			}
 
 			// can't know what external tools are doing, so just don't allow them here
@@ -107,58 +105,53 @@ namespace BizHawk.Client.EmuHawk
 				return;
 			}
 
-			if (Emu is SubNESHawk or SubBsnesCore or SubGBHawk)
+			switch (Emu)
 			{
-				// this is mostly due to wonkiness with subframes which can be used as pseudo slowdown
-				HandleHardcoreModeDisable($"Using subframes in hardcore mode is not allowed.");
-				return;
-			}
-			else if (Emu is NymaCore nyma)
-			{
-				if (nyma.GetSettings().DisabledLayers.Any())
-				{
-					HandleHardcoreModeDisable($"Disabling {Emu.GetType().Name}'s graphics layers in hardcore mode is not allowed.");
-					return;
-				}
-			}
-			else if (Emu is GambatteLink gl)
-			{
-				foreach (var ss in gl.GetSyncSettings()._linkedSyncSettings)
-				{
-					if (!ss.DisplayBG || !ss.DisplayOBJ || !ss.DisplayWindow)
+				case SubNESHawk or SubBsnesCore or SubGBHawk:
+					// this is mostly due to wonkiness with subframes which can be used as pseudo slowdown
+					HandleHardcoreModeDisable($"Using subframes in hardcore mode is not allowed.");
+					break;
+				case NymaCore nyma:
+					if (nyma.GetSettings().DisabledLayers.Any())
+					{
+						HandleHardcoreModeDisable($"Disabling {Emu.GetType().Name}'s graphics layers in hardcore mode is not allowed.");
+					}
+					break;
+				case GambatteLink gl:
+					if (gl.GetSyncSettings()._linkedSyncSettings.Any(ss => !ss.DisplayBG || !ss.DisplayOBJ || !ss.DisplayWindow))
 					{
 						HandleHardcoreModeDisable($"Disabling GambatteLink's graphics layers in hardcore mode is not allowed.");
-						return;
 					}
-				}
-			}
-			else if (Emu is Gameboy gb)
-			{
-				var ss = gb.GetSyncSettings();
-				if (!ss.DisplayBG || !ss.DisplayOBJ || !ss.DisplayWindow)
+					break;
+				case Gameboy gb:
 				{
-					HandleHardcoreModeDisable($"Disabling Gambatte's graphics layers in hardcore mode is not allowed.");
-					return;
-				}
-				if (ss.FrameLength is Gameboy.GambatteSyncSettings.FrameLengthType.UserDefinedFrames)
-				{
-					HandleHardcoreModeDisable($"Using subframes in hardcore mode is not allowed.");
-					return;
-				}
-			}
-			else if (CoreGraphicsLayers.TryGetValue(Emu.GetType(), out var layers))
-			{
-				var s = _mainForm.GetSettingsAdapterForLoadedCoreUntyped().GetSettings();
-				var t = s.GetType();
-				foreach (var layer in layers)
-				{
-					// annoyingly NES has fields instead of properties for layers
-					if (!(bool)(t.GetProperty(layer)?.GetValue(s) ?? t.GetField(layer).GetValue(s)))
+					var ss = gb.GetSyncSettings();
+					if (!ss.DisplayBG || !ss.DisplayOBJ || !ss.DisplayWindow)
 					{
-						HandleHardcoreModeDisable($"Disabling {Emu.GetType().Name}'s {layer} in hardcore mode is not allowed.");
-						return;
+						HandleHardcoreModeDisable($"Disabling Gambatte's graphics layers in hardcore mode is not allowed.");
 					}
+					else if (ss.FrameLength is Gameboy.GambatteSyncSettings.FrameLengthType.UserDefinedFrames)
+					{
+						HandleHardcoreModeDisable($"Using subframes in hardcore mode is not allowed.");
+					}
+					break;
 				}
+				default:
+					if (CoreGraphicsLayers.TryGetValue(Emu.GetType(), out var layers))
+					{
+						var s = _mainForm.GetSettingsAdapterForLoadedCoreUntyped().GetSettings();
+						var t = s.GetType();
+						foreach (var layer in layers)
+						{
+							// annoyingly NES has fields instead of properties for layers
+							if ((bool)(t.GetProperty(layer)
+									?.GetValue(s) ?? t.GetField(layer)
+									.GetValue(s))) continue;
+							HandleHardcoreModeDisable($"Disabling {Emu.GetType().Name}'s {layer} in hardcore mode is not allowed.");
+							return;
+						}
+					}
+					break;
 			}
 		}
 	}
diff --git a/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Memory.cs b/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Memory.cs
index 5646345e5a..77f80b5214 100644
--- a/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Memory.cs
+++ b/src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Memory.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading;
 
@@ -10,45 +11,55 @@ namespace BizHawk.Client.EmuHawk
 {
 	public abstract partial class RetroAchievements
 	{
-		public struct RAMemGuard : IMonitor, IDisposable
+		public class RAMemGuard : IMonitor, IDisposable
 		{
-			private readonly AutoResetEvent _start, _go, _end;
-			private readonly ThreadLocal<bool> _isMainThread;
-
-			private bool IsNotMainThread => !_isMainThread.Value;
-
-			public RAMemGuard(AutoResetEvent start, AutoResetEvent go, AutoResetEvent end)
-			{
-				_start = start;
-				_go = go;
-				_end = end;
-				_isMainThread = new() { Value = true };
-			}
-
-			public void Dispose()
-			{
-				_start.Dispose();
-				_go.Dispose();
-				_end.Dispose();
-				_isMainThread.Dispose();
-			}
+			private readonly ManualResetEventSlim MemLock = new(false);
+			private readonly SemaphoreSlim MemSema = new(1);
+			private readonly object MemSync = new();
 
 			public void Enter()
 			{
-				if (IsNotMainThread)
+				lock (MemSync)
 				{
-					_start.Set();
-					_go.WaitOne();
+					MemSema.Wait();
+					MemLock.Wait();
 				}
 			}
 
 			public void Exit()
 			{
-				if (IsNotMainThread)
+				MemSema.Release();
+			}
+
+			public void Dispose()
+			{
+				MemLock.Dispose();
+				MemSema.Dispose();
+			}
+
+			public readonly ref struct AccessWrapper
+			{
+				private readonly RAMemGuard _guard;
+
+				internal AccessWrapper(RAMemGuard guard)
 				{
-					_end.Set();
+					_guard = guard;
+					_guard.MemLock.Set();
+				}
+
+				public void Dispose()
+				{
+					lock (_guard.MemSync)
+					{
+						_guard.MemLock.Reset();
+						_guard.MemSema.Wait();
+						_guard.MemSema.Release();
+					}
 				}
 			}
+
+			public AccessWrapper GetAccess()
+				=> new(this);
 		}
 
 		[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
@@ -60,7 +71,7 @@ namespace BizHawk.Client.EmuHawk
 		[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
 		public delegate int ReadMemoryBlockFunc(int address, IntPtr buffer, int bytes);
 
-		public class MemFunctions
+		protected class MemFunctions
 		{
 			protected readonly MemoryDomain _domain;
 			private readonly int _domainAddrStart; // addr of _domain where bank begins
@@ -72,7 +83,7 @@ namespace BizHawk.Client.EmuHawk
 
 			public readonly int BankSize;
 
-			public RAMemGuard? MemGuard { get; set; }
+			public RAMemGuard MemGuard { get; set; }
 
 			protected virtual int FixAddr(int addr)
 				=> _domainAddrStart + addr;
@@ -119,7 +130,7 @@ namespace BizHawk.Client.EmuHawk
 						{
 							for (var i = addr; i < end; i++)
 							{
-								((byte*)buffer)[i - addr] = _domain.PeekByte(i ^ _addressMangler);
+								((byte*)buffer)![i - addr] = _domain.PeekByte(i ^ _addressMangler);
 							}
 						}
 					}
@@ -202,11 +213,11 @@ namespace BizHawk.Client.EmuHawk
 						{
 							if ((i & 2) != 0)
 							{
-								((byte*)buffer)[i - addr] = 0;
+								((byte*)buffer)![i - addr] = 0;
 							}
 							else
 							{
-								((byte*)buffer)[i - addr] = _domain.PeekByte(FixAddr(i));
+								((byte*)buffer)![i - addr] = _domain.PeekByte(FixAddr(i));
 							}
 						}
 					}
@@ -279,7 +290,7 @@ namespace BizHawk.Client.EmuHawk
 				{
 					var regs = _debuggable.GetCpuFlagsAndRegisters();
 					var end = Math.Min(addr + bytes, BankSize);
-					for (int i = addr; i < end; i++)
+					for (var i = addr; i < end; i++)
 					{
 						byte val;
 						if (i < 0x40)
@@ -293,7 +304,7 @@ namespace BizHawk.Client.EmuHawk
 
 						unsafe
 						{
-							((byte*)buffer)[i - addr] = val;
+							((byte*)buffer)![i - addr] = val;
 						}
 					}
 
@@ -310,13 +321,13 @@ namespace BizHawk.Client.EmuHawk
 		}
 
 		// these consoles will use the entire system bus
-		private static readonly ConsoleID[] UseFullSysBus = new[]
+		private static readonly ConsoleID[] UseFullSysBus =
 		{
 			ConsoleID.NES, ConsoleID.C64, ConsoleID.AmstradCPC, ConsoleID.Atari7800,
 		};
 
 		// these consoles will use the entire main memory domain
-		private static readonly ConsoleID[] UseFullMainMem = new[]
+		private static readonly ConsoleID[] UseFullMainMem =
 		{
 			ConsoleID.PlayStation, ConsoleID.Lynx, ConsoleID.Lynx, ConsoleID.NeoGeoPocket,
 			ConsoleID.Jaguar, ConsoleID.JaguarCD, ConsoleID.DS, ConsoleID.AppleII,
@@ -370,10 +381,7 @@ namespace BizHawk.Client.EmuHawk
 			}
 			else if (UsePartialSysBus.TryGetValue(consoleId, out var pairs))
 			{
-				foreach (var pair in pairs)
-				{
-					mfs.Add(new(domains.SystemBus, pair.Start, pair.Size));
-				}
+				mfs.AddRange(pairs.Select(pair => new MemFunctions(domains.SystemBus, pair.Start, pair.Size)));
 			}
 			else
 			{
@@ -502,13 +510,8 @@ namespace BizHawk.Client.EmuHawk
 						mfs.Add(new(domains.MainMemory, 0, domains.MainMemory.Size, 3));
 						break;
 					case ConsoleID.Arcade:
-						foreach (var domain in domains)
-						{
-							if (domain.Name.Contains("ram"))
-							{
-								mfs.Add(new(domain, 0, domain.Size));
-							}
-						}
+						mfs.AddRange(domains.Where(domain => domain.Name.Contains("ram"))
+							.Select(domain => new MemFunctions(domain, 0, domain.Size)));
 						break;
 					case ConsoleID.UnknownConsoleID:
 					case ConsoleID.ZXSpectrum: // this doesn't actually have anything standardized, so...