S_LSHIFT)); <span class="comment">// this works best for now</span></div><div class="line"><a name="l00100"></a><span class="lineno">  100</span>&#160;    <span class="comment">// f = (Q15n16)(((Q16n16_2PI*centre_freq)&lt;&lt;(16-AUDIO_RATE_AS_LSHIFT))&gt;&gt;16);</span></div><div class="line"><a name="l00101"></a><span class="lineno">  101</span>&#160;    <span class="comment">// // a small shift left and a round 16 right is faster than big</span></div><div class="line"><a name="l00102"></a><span class="li