Haydn: Part 1 (#2007)

* Haydn: Part 1

Based on my reverse of audio 11.0.0.

As always, core implementation under LGPLv3 for the same reasons as for Amadeus.

This place the bases of a more flexible audio system while making audout & audin accurate.

This have the following improvements:
- Complete reimplementation of audout and audin.
- Audin currently only have a dummy backend.
- Dramatically reduce CPU usage by up to 50% in common cases (SoundIO and OpenAL).
- Audio Renderer now can output to 5.1 devices when supported.
- Audio Renderer init its backend on demand instead of keeping two up all the time.
- All backends implementation are now in their own project.
- Ryujinx.Audio.Renderer was renamed Ryujinx.Audio and was refactored because of this.

As a note, games having issues with OpenAL haven't improved and will not
because of OpenAL design (stopping when buffers finish playing causing
possible audio "pops" when buffers are very small).

* Update for latest hexkyz's edits on Switchbrew

* audren: Rollback channel configuration changes

* Address gdkchan's comments

* Fix typo in OpenAL backend driver

* Address last comments

* Fix a nit

* Address gdkchan's comments

Ryujinx.Audio/AudioManager.cs

@@ -0,0 +1,137 @@
+//
+// Copyright (c) 2019-2021 Ryujinx
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//
+
+using System;
+using System.Threading;
+
+namespace Ryujinx.Audio
+{
+    /// <summary>
+    /// Manage audio input and output system.
+    /// </summary>
+    public class AudioManager : IDisposable
+    {
+        /// <summary>
+        /// Lock used to control the waiters registration.
+        /// </summary>
+        private object _lock = new object();
+
+        /// <summary>
+        /// Events signaled when the driver played audio buffers.
+        /// </summary>
+        private ManualResetEvent[] _updateRequiredEvents;
+
+        /// <summary>
+        /// Action to execute when the driver played audio buffers.
+        /// </summary>
+        private Action[] _actions;
+
+        /// <summary>
+        /// The worker thread in charge of handling sessions update.
+        /// </summary>
+        private Thread _workerThread;
+
+        /// <summary>
+        /// Create a new <see cref="AudioManager"/>.
+        /// </summary>
+        public AudioManager()
+        {
+            _updateRequiredEvents = new ManualResetEvent[2];
+            _actions = new Action[2];
+
+            // Termination event.
+            _updateRequiredEvents[1] = new ManualResetEvent(false);
+
+            _workerThread = new Thread(Update)
+            {
+                Name = "AudioManager.Worker"
+            };
+        }
+
+        /// <summary>
+        /// Start the <see cref="AudioManager"/>.
+        /// </summary>
+        public void Start()
+        {
+            if (_workerThread.IsAlive)
+            {
+                throw new InvalidOperationException();
+            }
+
+            _workerThread.Start();
+        }
+
+        /// <summary>
+        /// Initialize update handlers.
+        /// </summary>
+        /// <param name="updatedRequiredEvent ">The driver event that will get signaled by the device driver when an audio buffer finished playing/being captured</param>
+        /// <param name="outputCallback">The callback to call when an audio buffer finished playing</param>
+        /// <param name="inputCallback">The callback to call when an audio buffer was captured</param>
+        public void Initialize(ManualResetEvent updatedRequiredEvent, Action outputCallback, Action inputCallback)
+        {
+            lock (_lock)
+            {
+                _updateRequiredEvents[0] = updatedRequiredEvent;
+                _actions[0] = outputCallback;
+                _actions[1] = inputCallback;
+            }
+        }
+
+        /// <summary>
+        /// Entrypoint of the <see cref="_workerThread"/> in charge of updating the <see cref="AudioManager"/>.
+        /// </summary>
+        private void Update()
+        {
+            while (true)
+            {
+                int index = WaitHandle.WaitAny(_updateRequiredEvents);
+
+                // Last index is here to indicate thread termination.
+                if (index + 1 == _updateRequiredEvents.Length)
+                {
+                    break;
+                }
+
+                lock (_lock)
+                {
+                    foreach (Action action in _actions)
+                    {
+                        action?.Invoke();
+                    }
+
+                    _updateRequiredEvents[0].Reset();
+                }
+            }
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _updateRequiredEvents[1].Set();
+                _workerThread.Join();
+
+                _updateRequiredEvents[1].Dispose();
+            }
+        }
+    }
+}