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

        private void CheckPinSingleBuffer(bool pinUsersBuffer)
        {
            if (pinUsersBuffer)
            {
                // Using app supplied buffer.
                if (_buffer == null)
                {
                    // No user buffer is set so unpin any existing single buffer pinning.
                    if (_pinState == PinState.SingleBuffer)
                    {
                        FreeOverlapped(false);
                    }
                }
                else
                {
                    if (_pinState == PinState.SingleBuffer && _pinnedSingleBuffer == _buffer)
                    {
                        // This buffer is already pinned - update if offset or count has changed.
                        if (_offset != _pinnedSingleBufferOffset)
                        {
                            _pinnedSingleBufferOffset = _offset;
                            _ptrSingleBuffer = Marshal.UnsafeAddrOfPinnedArrayElement(_buffer, _offset);
                            _wsaBuffer.Pointer = _ptrSingleBuffer;
                        }
                        if (_count != _pinnedSingleBufferCount)
                        {
                            _pinnedSingleBufferCount = _count;
                            _wsaBuffer.Length = _count;
                        }
                    }
                    else
                    {
                        FreeOverlapped(false);
                        SetupOverlappedSingle(true);
                    }
                }
            }
            else
            {
                // Using internal accept buffer.
                if (!(_pinState == PinState.SingleAcceptBuffer) || !(_pinnedSingleBuffer == _acceptBuffer))
                {
                    // Not already pinned - so pin it.
                    FreeOverlapped(false);
                    SetupOverlappedSingle(false);
                }
            }
        }