Split online.cs and offline.csFile (#941)

Co-authored-by: 东风破 <birdfishs@163.com>

scripts/dotnet/OnlineStream.cs

@@ -0,0 +1,65 @@
+/// Copyright (c)  2023  Xiaomi Corporation (authors: Fangjun Kuang)
+/// Copyright (c)  2023 by manyeyes
+/// Copyright (c)  2024.5 by 东风破
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+using System;
+
+namespace SherpaOnnx
+{
+
+    public class OnlineStream : IDisposable
+    {
+        public OnlineStream(IntPtr p)
+        {
+            _handle = new HandleRef(this, p);
+        }
+
+        public void AcceptWaveform(int sampleRate, float[] samples)
+        {
+            AcceptWaveform(Handle, sampleRate, samples, samples.Length);
+        }
+
+        public void InputFinished()
+        {
+            InputFinished(Handle);
+        }
+
+        ~OnlineStream()
+        {
+            Cleanup();
+        }
+
+        public void Dispose()
+        {
+            Cleanup();
+            // Prevent the object from being placed on the
+            // finalization queue
+            System.GC.SuppressFinalize(this);
+        }
+
+        private void Cleanup()
+        {
+            DestroyOnlineStream(Handle);
+
+            // Don't permit the handle to be used again.
+            _handle = new HandleRef(this, IntPtr.Zero);
+        }
+
+        private HandleRef _handle;
+        public IntPtr Handle => _handle.Handle;
+
+        [DllImport(Dll.Filename)]
+        private static extern void DestroyOnlineStream(IntPtr handle);
+
+        [DllImport(Dll.Filename)]
+        private static extern void AcceptWaveform(IntPtr handle, int sampleRate, float[] samples, int n);
+
+        [DllImport(Dll.Filename)]
+        private static extern void InputFinished(IntPtr handle);
+    }
+
+}