Convert LARGE_INTEGER to base 64 string
<p>I am using <code>QueryPerformanceCounter();</code> to get a number for use as a unique timestamp to be included in a filename.</p>

<pre><code>LARGE_INTEGER performanceCount;
QueryPerformanceCounter(&amp;performanceCount);
</code></pre>

<p>I need to encode <code>performanceCount.HighPart</code> which is of type <code>LONG</code> and <code>performanceCount.LowPart</code> which is of type <code>DWORD</code> as base64 strings. Then concatenate them and store them in a <code>wstring</code> variable.</p>

<p>How can I achieve this?</p>
