System.IO.FileStream.ReadByteCore C# (CSharp) Method

        private int ReadByteCore()
        {
            PrepareForReading();

            byte[] buffer = GetBuffer();
            if (_readPos == _readLength)
            {
                FlushWriteBuffer();
                Debug.Assert(_bufferLength > 0, "_bufferSize > 0");

                _readLength = ReadNative(buffer, 0, _bufferLength);
                _readPos = 0;
                if (_readLength == 0)
                {
                    return -1;
                }
            }

            return buffer[_readPos++];
        }