System.Net.Sockets.SocketAsyncEventArgs.SetupOverlappedSingle C# (CSharp) Method

        unsafe private void SetupOverlappedSingle(bool pinSingleBuffer)
        {
            // Pin buffer, get native pointers, and fill in WSABuffer descriptor.
            if (pinSingleBuffer)
            {
                if (_buffer != null)
                {
                    _preAllocatedOverlapped = new PreAllocatedOverlapped(CompletionPortCallback, this, _buffer);
                    if (NetEventSource.IsEnabled) NetEventSource.Info(this, $"new PreAllocatedOverlapped pinSingleBuffer=true, non-null buffer:{_preAllocatedOverlapped}");

                    _pinnedSingleBuffer = _buffer;
                    _pinnedSingleBufferOffset = _offset;
                    _pinnedSingleBufferCount = _count;
                    _ptrSingleBuffer = Marshal.UnsafeAddrOfPinnedArrayElement(_buffer, _offset);
                    _ptrAcceptBuffer = IntPtr.Zero;
                    _wsaBuffer.Pointer = _ptrSingleBuffer;
                    _wsaBuffer.Length = _count;
                    _pinState = PinState.SingleBuffer;
                }
                else
                {
                    _preAllocatedOverlapped = new PreAllocatedOverlapped(CompletionPortCallback, this, null);
                    if (NetEventSource.IsEnabled) NetEventSource.Info(this, $"new PreAllocatedOverlapped pinSingleBuffer=true, null buffer: {_preAllocatedOverlapped}");

                    _pinnedSingleBuffer = null;
                    _pinnedSingleBufferOffset = 0;
                    _pinnedSingleBufferCount = 0;
                    _ptrSingleBuffer = IntPtr.Zero;
                    _ptrAcceptBuffer = IntPtr.Zero;
                    _wsaBuffer.Pointer = _ptrSingleBuffer;
                    _wsaBuffer.Length = _count;
                    _pinState = PinState.NoBuffer;
                }
            }
            else
            {
                _preAllocatedOverlapped = new PreAllocatedOverlapped(CompletionPortCallback, this, _acceptBuffer);
                if (NetEventSource.IsEnabled) NetEventSource.Info(this, $"new PreAllocatedOverlapped pinSingleBuffer=false:{_preAllocatedOverlapped}");

                _pinnedAcceptBuffer = _acceptBuffer;
                _ptrAcceptBuffer = Marshal.UnsafeAddrOfPinnedArrayElement(_acceptBuffer, 0);
                _ptrSingleBuffer = IntPtr.Zero;
                _pinState = PinState.SingleAcceptBuffer;
            }
        }