System.IO.MemoryStream.InternalGetPosition C# (CSharp) Method

        internal int InternalGetPosition()
        {
            if (!_isOpen)
            {
                throw new ObjectDisposedException(null, SR.ObjectDisposed_StreamClosed);
            }
            return _position;
        }

        private unsafe int InternalReadChars(char[] buffer, int index, int count)
        {
            int num       = 0;
            int charCount = count;

            if (this.m_charBytes == null)
            {
                this.m_charBytes = new byte[0x80];
            }
            while (charCount > 0)
            {
                int num3 = 0;
                num = charCount;
                UTF8Encoding.UTF8Decoder decoder = this.m_decoder as UTF8Encoding.UTF8Decoder;
                if (((decoder != null) && decoder.HasState) && (num > 1))
                {
                    num--;
                }
                if (this.m_2BytesPerChar)
                {
                    num = num << 1;
                }
                if (num > 0x80)
                {
                    num = 0x80;
                }
                int    position  = 0;
                byte[] charBytes = null;
                if (this.m_isMemoryStream)
                {
                    MemoryStream stream = this.m_stream as MemoryStream;
                    position  = stream.InternalGetPosition();
                    num       = stream.InternalEmulateRead(num);
                    charBytes = stream.InternalGetBuffer();
                }
                else
                {
                    num       = this.m_stream.Read(this.m_charBytes, 0, num);
                    charBytes = this.m_charBytes;
                }
                if (num == 0)
                {
                    return(count - charCount);
                }

                fixed(byte *numRef = charBytes)
                {
                    fixed(char *chRef = buffer)
                    {
                        num3 = this.m_decoder.GetChars(numRef + position, num, chRef + index, charCount, false);
                    }
                }

                charCount -= num3;
                index     += num3;
            }
            return(count - charCount);
        }