IDebuggableProcess: Create and expose interface to enable implementation of debugging tools

# Conflicts:
#	src/ARMeilleure/State/DebugState.cs
#	src/ARMeilleure/State/ExecutionContext.cs
TODO: Fix comments. I also tried implementing AppleHV primitives here (it's actually broken).

src/ARMeilleure/State/DebugState.cs

@@ -0,0 +1,9 @@
+namespace ARMeilleure.State
+{
+    enum DebugState
+    {
+        Running,
+        Stopping,
+        Stopped,
+    }
+}

src/ARMeilleure/State/ExecutionContext.cs

@@ -1,5 +1,8 @@
 using ARMeilleure.Memory;
 using System;
+using System.Collections.Concurrent;
+using System.Diagnostics;
+using System.Threading;
 
 namespace ARMeilleure.State
 {
@@ -96,6 +99,14 @@ namespace ARMeilleure.State
         private readonly ExceptionCallback _supervisorCallback;
         private readonly ExceptionCallback _undefinedCallback;
 
+        internal int _debugState = (int)DebugState.Running;
+        internal int _shouldStep = 0;
+        internal ManualResetEvent _debugHalt = new ManualResetEvent(true);
+        internal Barrier _stepBarrier = new Barrier(2);
+
+        // This is only valid while debugging is enabled.
+        public ulong DebugPc;
+
         public ExecutionContext(
             IJitMemoryAllocator allocator,
             ICounter counter,
@@ -145,6 +156,33 @@ namespace ARMeilleure.State
             _interrupted = true;
         }
 
+        public void DebugStop()
+        {
+            _debugHalt.Reset();
+            Interlocked.CompareExchange(ref _debugState, (int)DebugState.Stopping, (int)DebugState.Running);
+        }
+
+        public bool DebugStep()
+        {
+            if (_debugState != (int)DebugState.Stopped)
+            {
+                return false;
+            }
+
+            _shouldStep = 1;
+            _debugHalt.Set();
+            _stepBarrier.SignalAndWait();
+            _debugHalt.Reset();
+            _stepBarrier.SignalAndWait();
+
+            return true;
+        }
+
+        public void DebugContinue()
+        {
+            _debugHalt.Set();
+        }
+
         internal void OnBreak(ulong address, int imm)
         {
             _breakCallback?.Invoke(this, address, imm);

src/Ryujinx.Cpu/AppleHv/DebugState.cs

@@ -0,0 +1,9 @@
+namespace Ryujinx.Cpu.AppleHv
+{
+    enum DebugState
+    {
+        Running,
+        Stopping,
+        Stopped,
+    }
+}

src/Ryujinx.Cpu/AppleHv/HvExecutionContext.cs

@@ -127,6 +127,15 @@ namespace Ryujinx.Cpu.AppleHv
             return Interlocked.Exchange(ref _interruptRequested, 0) != 0;
         }
 
+        /// <inheritdoc/>
+        public void DebugStop() => _impl.DebugStop();
+
+        /// <inheritdoc/>
+        public bool DebugStep() => _impl.DebugStep();
+
+        /// <inheritdoc/>
+        public void DebugContinue() => _impl.DebugContinue();
+
         /// <inheritdoc/>
         public void StopRunning()
         {

src/Ryujinx.Cpu/AppleHv/HvExecutionContextShadow.cs

@@ -46,5 +46,27 @@ namespace Ryujinx.Cpu.AppleHv
         {
             _v[index] = value;
         }
+
+        public void RequestInterrupt()
+        {
+        }
+
+        public void DebugStop()
+        {
+        }
+
+        public bool DebugStep()
+        {
+            return false;
+        }
+
+        public void DebugContinue()
+        {
+        }
+
+        public bool GetAndClearInterruptRequested()
+        {
+            return false;
+        }
     }
 }

src/Ryujinx.Cpu/AppleHv/HvExecutionContextVcpu.cs

@@ -2,11 +2,10 @@ using ARMeilleure.State;
 using Ryujinx.Memory;
 using System;
 using System.Runtime.InteropServices;
-using System.Runtime.Versioning;
+using System.Threading;
 
 namespace Ryujinx.Cpu.AppleHv
 {
-    [SupportedOSPlatform("macos")]
     class HvExecutionContextVcpu : IHvExecutionContext
     {
         private static readonly MemoryBlock _setSimdFpRegFuncMem;
@@ -14,6 +13,14 @@ namespace Ryujinx.Cpu.AppleHv
         private static readonly SetSimdFpReg _setSimdFpReg;
         private static readonly IntPtr _setSimdFpRegNativePtr;
 
+        internal int _debugState = (int)DebugState.Running;
+        internal int _shouldStep = 0;
+        internal ManualResetEvent _debugHalt = new ManualResetEvent(true);
+        internal Barrier _stepBarrier = new Barrier(2);
+
+        // This is only valid while debugging is enabled.
+        public ulong DebugPc;
+
         static HvExecutionContextVcpu()
         {
             // .NET does not support passing vectors by value, so we need to pass a pointer and use a native
@@ -136,6 +143,7 @@ namespace Ryujinx.Cpu.AppleHv
         }
 
         private readonly ulong _vcpu;
+        private int _interruptRequested;
 
         public HvExecutionContextVcpu(ulong vcpu)
         {
@@ -180,9 +188,47 @@ namespace Ryujinx.Cpu.AppleHv
         }
 
         public void RequestInterrupt()
+        {
+            if (Interlocked.Exchange(ref _interruptRequested, 1) == 0)
             {
                 ulong vcpu = _vcpu;
                 HvApi.hv_vcpus_exit(ref vcpu, 1);
             }
         }
+
+        public void DebugStop()
+        {
+            _debugHalt.Reset();
+            Interlocked.CompareExchange(ref _debugState, (int)DebugState.Stopping, (int)DebugState.Running);
+            ulong vcpu = _vcpu;
+            HvApi.hv_vcpus_exit(ref vcpu, 1);
+        }
+
+        public bool DebugStep()
+        {
+            if (_debugState != (int)DebugState.Stopped)
+            {
+                return false;
+            }
+
+            _shouldStep = 1;
+            _debugHalt.Set();
+            _stepBarrier.SignalAndWait();
+            _debugHalt.Reset();
+            _stepBarrier.SignalAndWait();
+
+            return true;
+        }
+
+        public void DebugContinue()
+        {
+            _debugHalt.Set();
+            HvApi.hv_vcpu_run(_vcpu);
+        }
+
+        public bool GetAndClearInterruptRequested()
+        {
+            return Interlocked.Exchange(ref _interruptRequested, 0) != 0;
+        }
+    }
 }

src/Ryujinx.Cpu/AppleHv/IHvExecutionContext.cs

@@ -39,5 +39,13 @@ namespace Ryujinx.Cpu.AppleHv
                 SetV(i, context.GetV(i));
             }
         }
+
+        void RequestInterrupt();
+        bool GetAndClearInterruptRequested();
+
+        // TODO: comments
+        void DebugStop();
+        bool DebugStep();
+        void DebugContinue();
     }
 }

src/Ryujinx.Cpu/IExecutionContext.cs

@@ -108,5 +108,10 @@ namespace Ryujinx.Cpu
         /// If you only need to pause the thread temporarily, use <see cref="RequestInterrupt"/> instead.
         /// </remarks>
         void StopRunning();
+
+        // TODO: comments
+        void DebugStop();
+        bool DebugStep();
+        void DebugContinue();
     }
 }

src/Ryujinx.Cpu/Jit/JitExecutionContext.cs

@@ -109,6 +109,15 @@ namespace Ryujinx.Cpu.Jit
             _impl.RequestInterrupt();
         }
 
+        /// <inheritdoc/>
+        public void DebugStop() => _impl.DebugStop();
+
+        /// <inheritdoc/>
+        public bool DebugStep() => _impl.DebugStep();
+
+        /// <inheritdoc/>
+        public void DebugContinue() => _impl.DebugContinue();
+
         /// <inheritdoc/>
         public void StopRunning()
         {

src/Ryujinx.HLE/Debugger/IDebuggableProcess.cs

@@ -0,0 +1,12 @@
+using Ryujinx.Memory;
+
+namespace Ryujinx.HLE.Debugger
+{
+    public interface IDebuggableProcess
+    {
+        public void DebugStopAllThreads();
+        public ulong[] DebugGetThreadUids();
+        public Ryujinx.Cpu.IExecutionContext DebugGetThreadContext(ulong threadUid);
+        public IVirtualMemoryManager CpuMemory { get; }
+    }
+}

src/Ryujinx.HLE/HOS/Horizon.cs

@@ -473,5 +473,13 @@ namespace Ryujinx.HLE.HOS
             }
             IsPaused = pause;
         }
+
+        public Debugger.IDebuggableProcess DebugGetApplicationProcess()
+        {
+            lock (KernelContext.Processes)
+            {
+                return KernelContext.Processes.Values.Where(x => x.IsApplication).First();
+            }
+        }
     }
 }

src/Ryujinx.HLE/HOS/Kernel/Process/KProcess.cs

@@ -14,7 +14,7 @@ using System.Threading;
 
 namespace Ryujinx.HLE.HOS.Kernel.Process
 {
-    class KProcess : KSynchronizationObject
+    class KProcess : KSynchronizationObject, Debugger.IDebuggableProcess
     {
         public const uint KernelVersionMajor = 10;
         public const uint KernelVersionMinor = 4;
@@ -1175,5 +1175,32 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
         {
             return Capabilities.IsSvcPermitted(svcId);
         }
+
+        public void DebugStopAllThreads()
+        {
+            lock (_threadingLock)
+            {
+                foreach (KThread thread in _threads)
+                {
+                    thread.Context.DebugStop();
+                }
+            }
+        }
+
+        public ulong[] DebugGetThreadUids()
+        {
+            lock (_threadingLock)
+            {
+                return _threads.Select(x => x.ThreadUid).ToArray();
+            }
+        }
+
+        public Ryujinx.Cpu.IExecutionContext DebugGetThreadContext(ulong threadUid)
+        {
+            lock (_threadingLock)
+            {
+                return _threads.Where(x => x.ThreadUid == threadUid).FirstOrDefault()?.Context;
+            }
+        }
     }
 }

src/Ryujinx.HLE/HOS/Kernel/Process/ProcessExecutionContext.cs

@@ -31,6 +31,19 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
         {
         }
 
+        public void DebugStop()
+        {
+        }
+
+        public bool DebugStep()
+        {
+            return false;
+        }
+
+        public void DebugContinue()
+        {
+        }
+
         public void StopRunning()
         {
             Running = false;