audio: Rewrite SoundIo bindings (#4088)

* audio: Rewrite SoundIo bindings

This rewrite SoundIo bindings to be safer and not a pedantic autogenerated mess.

* Address comments

* Switch DllImport to LibraryImport

* Address gdkchan's comment

Ryujinx.Audio.Backends.SoundIo/Native/SoundIoContext.cs

@@ -0,0 +1,107 @@
+using System;
+using System.Reflection.Metadata;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Threading;
+using static Ryujinx.Audio.Backends.SoundIo.Native.SoundIo;
+
+namespace Ryujinx.Audio.Backends.SoundIo.Native
+{
+    public class SoundIoContext : IDisposable
+    {
+        private IntPtr _context;
+        private Action<SoundIoError> _onBackendDisconnect;
+        private OnBackendDisconnectedDelegate _onBackendDisconnectNative;
+
+        public IntPtr Context => _context;
+
+        internal SoundIoContext(IntPtr context)
+        {
+            _context = context;
+            _onBackendDisconnect = null;
+            _onBackendDisconnectNative = null;
+        }
+
+        public SoundIoError Connect() => soundio_connect(_context);
+        public void Disconnect() => soundio_disconnect(_context);
+
+        public void FlushEvents() => soundio_flush_events(_context);
+
+        public int OutputDeviceCount => soundio_output_device_count(_context);
+
+        public int DefaultOutputDeviceIndex => soundio_default_output_device_index(_context);
+
+        public Action<SoundIoError> OnBackendDisconnect
+        {
+            get { return _onBackendDisconnect; }
+            set
+            {
+                _onBackendDisconnect = value;
+
+                if (_onBackendDisconnect == null)
+                {
+                    _onBackendDisconnectNative = null;
+                }
+                else
+                {
+                    _onBackendDisconnectNative = (ctx, err) => _onBackendDisconnect(err);
+                }
+
+                GetContext().OnBackendDisconnected = Marshal.GetFunctionPointerForDelegate(_onBackendDisconnectNative);
+            }
+        }
+
+        private ref SoundIoStruct GetContext()
+        {
+            unsafe
+            {
+                return ref Unsafe.AsRef<SoundIoStruct>((SoundIoStruct*)_context);
+            }
+        }
+
+        public SoundIoDeviceContext GetOutputDevice(int index)
+        {
+            IntPtr deviceContext = soundio_get_output_device(_context, index);
+
+            if (deviceContext == IntPtr.Zero)
+            {
+                return null;
+            }
+
+            return new SoundIoDeviceContext(deviceContext);
+        }
+
+        public static SoundIoContext Create()
+        {
+            IntPtr context = soundio_create();
+
+            if (context == IntPtr.Zero)
+            {
+                return null;
+            }
+
+            return new SoundIoContext(context);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            IntPtr currentContext = Interlocked.Exchange(ref _context, IntPtr.Zero);
+
+            if (currentContext != IntPtr.Zero)
+            {
+                soundio_destroy(currentContext);
+            }
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        ~SoundIoContext()
+        {
+            Dispose(false);
+        }
+    }
+}