Look at the code, man!
Code:
            szLine = g_szBuffer;
            while (szLine)
            {
                // Find the end of the current line
                szLineEnd = strstr(szLine, "\r\n");
                if (szLineEnd)
                {
                    szLineEnd += 2;
                    // Add line end - line start to the counter
                    g_ulMsgRead += (szLineEnd - szLine);
                }
...
                szLine = szLineEnd;
           }