1 files changed, 230 insertions, 0 deletions
diff --git a/src/Ryujinx.Audio.Backends.SDL2/SDL2HardwareDeviceSession.cs b/src/Ryujinx.Audio.Backends.SDL2/SDL2HardwareDeviceSession.cs
new file mode 100644
index 00000000..14310b93
--- /dev/null
+++ b/src/Ryujinx.Audio.Backends.SDL2/SDL2HardwareDeviceSession.cs
@@ -0,0 +1,230 @@
+using Ryujinx.Audio.Backends.Common;
+using Ryujinx.Audio.Common;
+using Ryujinx.Common.Logging;
+using Ryujinx.Memory;
+using System;
+using System.Collections.Concurrent;
+using System.Threading;
+
+using static SDL2.SDL;
+
+namespace Ryujinx.Audio.Backends.SDL2
+{
+    class SDL2HardwareDeviceSession : HardwareDeviceSessionOutputBase
+    {
+        private SDL2HardwareDeviceDriver _driver;
+        private ConcurrentQueue<SDL2AudioBuffer> _queuedBuffers;
+        private DynamicRingBuffer _ringBuffer;
+        private ulong _playedSampleCount;
+        private ManualResetEvent _updateRequiredEvent;
+        private uint _outputStream;
+        private bool _hasSetupError;
+        private SDL_AudioCallback _callbackDelegate;
+        private int _bytesPerFrame;
+        private uint _sampleCount;
+        private bool _started;
+        private float _volume;
+        private ushort _nativeSampleFormat;
+
+        public SDL2HardwareDeviceSession(SDL2HardwareDeviceDriver driver, IVirtualMemoryManager memoryManager, SampleFormat requestedSampleFormat, uint requestedSampleRate, uint requestedChannelCount, float requestedVolume) : base(memoryManager, requestedSampleFormat, requestedSampleRate, requestedChannelCount)
+        {
+            _driver = driver;
+            _updateRequiredEvent = _driver.GetUpdateRequiredEvent();
+            _queuedBuffers = new ConcurrentQueue<SDL2AudioBuffer>();
+            _ringBuffer = new DynamicRingBuffer();
+            _callbackDelegate = Update;
+            _bytesPerFrame = BackendHelper.GetSampleSize(RequestedSampleFormat) * (int)RequestedChannelCount;
+            _nativeSampleFormat = SDL2HardwareDeviceDriver.GetSDL2Format(RequestedSampleFormat);
+            _sampleCount = uint.MaxValue;
+            _started = false;
+            _volume = requestedVolume;
+        }
+
+        private void EnsureAudioStreamSetup(AudioBuffer buffer)
+        {
+            uint bufferSampleCount = (uint)GetSampleCount(buffer);
+            bool needAudioSetup = (_outputStream == 0 && !_hasSetupError) ||
+                (bufferSampleCount >= Constants.TargetSampleCount && bufferSampleCount < _sampleCount);
+
+            if (needAudioSetup)
+            {
+                _sampleCount = Math.Max(Constants.TargetSampleCount, bufferSampleCount);
+
+                uint newOutputStream = SDL2HardwareDeviceDriver.OpenStream(RequestedSampleFormat, RequestedSampleRate, RequestedChannelCount, _sampleCount, _callbackDelegate);
+
+                _hasSetupError = newOutputStream == 0;
+
+                if (!_hasSetupError)
+                {
+                    if (_outputStream != 0)
+                    {
+                        SDL_CloseAudioDevice(_outputStream);
+                    }
+
+                    _outputStream = newOutputStream;
+
+                    SDL_PauseAudioDevice(_outputStream, _started ? 0 : 1);
+
+                    Logger.Info?.Print(LogClass.Audio, $"New audio stream setup with a target sample count of {_sampleCount}");
+                }
+            }
+        }
+
+        private unsafe void Update(IntPtr userdata, IntPtr stream, int streamLength)
+        {
+            Span<byte> streamSpan = new Span<byte>((void*)stream, streamLength);
+
+            int maxFrameCount = (int)GetSampleCount(streamLength);
+            int bufferedFrames = _ringBuffer.Length / _bytesPerFrame;
+
+            int frameCount = Math.Min(bufferedFrames, maxFrameCount);
+
+            if (frameCount == 0)
+            {
+                // SDL2 left the responsibility to the user to clear the buffer.
+                streamSpan.Fill(0);
+
+                return;
+            }
+
+            byte[] samples = new byte[frameCount * _bytesPerFrame];
+
+            _ringBuffer.Read(samples, 0, samples.Length);
+
+            fixed (byte* p = samples)
+            {
+                IntPtr pStreamSrc = (IntPtr)p;
+
+                // Zero the dest buffer
+                streamSpan.Fill(0);
+
+                // Apply volume to written data
+                SDL_MixAudioFormat(stream, pStreamSrc, _nativeSampleFormat, (uint)samples.Length, (int)(_volume * SDL_MIX_MAXVOLUME));
+            }
+
+            ulong sampleCount = GetSampleCount(samples.Length);
+
+            ulong availaibleSampleCount = sampleCount;
+
+            bool needUpdate = false;
+
+            while (availaibleSampleCount > 0 && _queuedBuffers.TryPeek(out SDL2AudioBuffer driverBuffer))
+            {
+                ulong sampleStillNeeded = driverBuffer.SampleCount - Interlocked.Read(ref driverBuffer.SamplePlayed);
+                ulong playedAudioBufferSampleCount = Math.Min(sampleStillNeeded, availaibleSampleCount);
+
+                ulong currentSamplePlayed = Interlocked.Add(ref driverBuffer.SamplePlayed, playedAudioBufferSampleCount);
+                availaibleSampleCount -= playedAudioBufferSampleCount;
+
+                if (currentSamplePlayed == driverBuffer.SampleCount)
+                {
+                    _queuedBuffers.TryDequeue(out _);
+
+                    needUpdate = true;
+                }
+
+                Interlocked.Add(ref _playedSampleCount, playedAudioBufferSampleCount);
+            }
+
+            // Notify the output if needed.
+            if (needUpdate)
+            {
+                _updateRequiredEvent.Set();
+            }
+        }
+
+        public override ulong GetPlayedSampleCount()
+        {
+            return Interlocked.Read(ref _playedSampleCount);
+        }
+
+        public override float GetVolume()
+        {
+            return _volume;
+        }
+
+        public override void PrepareToClose() { }
+
+        public override void QueueBuffer(AudioBuffer buffer)
+        {
+            EnsureAudioStreamSetup(buffer);
+
+            if (_outputStream != 0)
+            {
+                SDL2AudioBuffer driverBuffer = new SDL2AudioBuffer(buffer.DataPointer, GetSampleCount(buffer));
+
+                _ringBuffer.Write(buffer.Data, 0, buffer.Data.Length);
+
+                _queuedBuffers.Enqueue(driverBuffer);
+            }
+            else
+            {
+                Interlocked.Add(ref _playedSampleCount, GetSampleCount(buffer));
+
+                _updateRequiredEvent.Set();
+            }
+        }
+
+        public override void SetVolume(float volume)
+        {
+            _volume = volume;
+        }
+
+        public override void Start()
+        {
+            if (!_started)
+            {
+                if (_outputStream != 0)
+                {
+                    SDL_PauseAudioDevice(_outputStream, 0);
+                }
+
+                _started = true;
+            }
+        }
+
+        public override void Stop()
+        {
+            if (_started)
+            {
+                if (_outputStream != 0)
+                {
+                    SDL_PauseAudioDevice(_outputStream, 1);
+                }
+
+                _started = false;
+            }
+        }
+
+        public override void UnregisterBuffer(AudioBuffer buffer) { }
+
+        public override bool WasBufferFullyConsumed(AudioBuffer buffer)
+        {
+            if (!_queuedBuffers.TryPeek(out SDL2AudioBuffer driverBuffer))
+            {
+                return true;
+            }
+
+            return driverBuffer.DriverIdentifier != buffer.DataPointer;
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing && _driver.Unregister(this))
+            {
+                PrepareToClose();
+                Stop();
+
+                if (_outputStream != 0)
+                {
+                    SDL_CloseAudioDevice(_outputStream);
+                }
+            }
+        }
+
+        public override void Dispose()
+        {
+            Dispose(true);
+        }
+    }
+}