Improvements to audout (#58)

* Some audout refactoring and improvements

* More audio improvements

* Change ReadAsciiString to use long for the Size, avoids some casting

Ryujinx.Core/VirtualFileSystem.cs

@@ -0,0 +1,85 @@
+using System;
+using System.IO;
+
+namespace Ryujinx.Core
+{
+    class VirtualFileSystem : IDisposable
+    {
+        private const string BasePath   = "RyuFs";
+        private const string NandPath   = "nand";
+        private const string SdCardPath = "sdmc";
+
+        public Stream RomFs { get; private set; }
+
+        public void LoadRomFs(string FileName)
+        {
+            RomFs = new FileStream(FileName, FileMode.Open, FileAccess.Read);
+        }
+
+        public string GetFullPath(string BasePath, string FileName)
+        {
+            if (FileName.StartsWith("//"))
+            {
+                FileName = FileName.Substring(2);
+            }
+            else if (FileName.StartsWith('/'))
+            {
+                FileName = FileName.Substring(1);
+            }
+            else
+            {
+                return null;
+            }
+
+            string FullPath = Path.GetFullPath(Path.Combine(BasePath, FileName));
+
+            if (!FullPath.StartsWith(GetBasePath()))
+            {
+                return null;
+            }
+
+            return FullPath;
+        }
+
+        public string GetSdCardPath() => MakeDirAndGetFullPath(SdCardPath);
+
+        public string GetGameSavesPath() => MakeDirAndGetFullPath(NandPath);
+
+        private string MakeDirAndGetFullPath(string Dir)
+        {
+            string FullPath = Path.Combine(GetBasePath(), Dir);
+
+            if (!Directory.Exists(FullPath))
+            {
+                Directory.CreateDirectory(FullPath);
+            }
+
+            return FullPath;
+        }
+
+        public DriveInfo GetDrive()
+        {
+            return new DriveInfo(Path.GetPathRoot(GetBasePath()));
+        }
+
+        public string GetBasePath()
+        {
+            string AppDataPath = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
+
+            return Path.Combine(AppDataPath, BasePath);
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                RomFs?.Dispose();
+            }
+        }
+    }
+}