Refactor SVC handler (#540)

* Refactor SVC handler

* Get rid of KernelErr

* Split kernel code files into multiple folders

Ryujinx.HLE/HOS/Kernel/Threading/KReadableEvent.cs

@@ -0,0 +1,64 @@
+using Ryujinx.HLE.HOS.Kernel.Common;
+
+namespace Ryujinx.HLE.HOS.Kernel.Threading
+{
+    class KReadableEvent : KSynchronizationObject
+    {
+        private KEvent _parent;
+
+        private bool _signaled;
+
+        public KReadableEvent(Horizon system, KEvent parent) : base(system)
+        {
+            _parent = parent;
+        }
+
+        public override void Signal()
+        {
+            System.CriticalSection.Enter();
+
+            if (!_signaled)
+            {
+                _signaled = true;
+
+                base.Signal();
+            }
+
+            System.CriticalSection.Leave();
+        }
+
+        public KernelResult Clear()
+        {
+            _signaled = false;
+
+            return KernelResult.Success;
+        }
+
+        public KernelResult ClearIfSignaled()
+        {
+            KernelResult result;
+
+            System.CriticalSection.Enter();
+
+            if (_signaled)
+            {
+                _signaled = false;
+
+                result = KernelResult.Success;
+            }
+            else
+            {
+                result = KernelResult.InvalidState;
+            }
+
+            System.CriticalSection.Leave();
+
+            return result;
+        }
+
+        public override bool IsSignaled()
+        {
+            return _signaled;
+        }
+    }
+}