Refactoring HOS folder structure (#771)

* Refactoring HOS folder structure

Refactoring HOS folder structure:

- Added some subfolders when needed (Following structure decided in private).
- Added some `Types` folders when needed.
- Little cleanup here and there.
- Add services placeholders for every HOS services (close #766 and #753).

* Remove Types namespaces

Ryujinx.HLE/HOS/Services/Audio/HardwareOpusDecoderManager/IHardwareOpusDecoder.cs

@@ -0,0 +1,81 @@
+using Concentus.Structs;
+
+namespace Ryujinx.HLE.HOS.Services.Audio.HardwareOpusDecoderManager
+{
+    class IHardwareOpusDecoder : IpcService
+    {
+        private const int FixedSampleRate = 48000;
+
+        private int _sampleRate;
+        private int _channelsCount;
+
+        private OpusDecoder _decoder;
+
+        public IHardwareOpusDecoder(int sampleRate, int channelsCount)
+        {
+            _sampleRate    = sampleRate;
+            _channelsCount = channelsCount;
+
+            _decoder = new OpusDecoder(FixedSampleRate, channelsCount);
+        }
+
+        [Command(0)]
+        // DecodeInterleaved(buffer<unknown, 5>) -> (u32, u32, buffer<unknown, 6>)
+        public ResultCode DecodeInterleaved(ServiceCtx context)
+        {
+            long inPosition = context.Request.SendBuff[0].Position;
+            long inSize     = context.Request.SendBuff[0].Size;
+
+            if (inSize < 8)
+            {
+                return ResultCode.OpusInvalidInput;
+            }
+
+            long outPosition = context.Request.ReceiveBuff[0].Position;
+            long outSize     = context.Request.ReceiveBuff[0].Size;
+
+            byte[] opusData = context.Memory.ReadBytes(inPosition, inSize);
+
+            int processed = ((opusData[0] << 24) |
+                             (opusData[1] << 16) |
+                             (opusData[2] << 8)  |
+                             (opusData[3] << 0)) + 8;
+
+            if ((uint)processed > (ulong)inSize)
+            {
+                return ResultCode.OpusInvalidInput;
+            }
+
+            short[] pcm = new short[outSize / 2];
+
+            int frameSize = pcm.Length / (_channelsCount * 2);
+
+            int samples = _decoder.Decode(opusData, 0, opusData.Length, pcm, 0, frameSize);
+
+            foreach (short sample in pcm)
+            {
+                context.Memory.WriteInt16(outPosition, sample);
+
+                outPosition += 2;
+            }
+
+            context.ResponseData.Write(processed);
+            context.ResponseData.Write(samples);
+
+            return ResultCode.Success;
+        }
+
+        [Command(4)]
+        // DecodeInterleavedWithPerf(buffer<unknown, 5>) -> (u32, u32, u64, buffer<unknown, 0x46>)
+        public ResultCode DecodeInterleavedWithPerf(ServiceCtx context)
+        {
+            ResultCode result = DecodeInterleaved(context);
+
+            // TODO: Figure out what this value is.
+            // According to switchbrew, it is now used.
+            context.ResponseData.Write(0L);
+
+            return result;
+        }
+    }
+}