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<HTML>
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<div class="navpath"><a class="el" href="namespacestk.html">stk</a>::<a class="el" href="classstk_1_1Fir.html">Fir</a>
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<h1>stk::Fir Class Reference</h1><!-- doxytag: class="stk::Fir" --><!-- doxytag: inherits="stk::Filter" -->
<p>STK general finite impulse response filter class.
<a href="#_details">More...</a></p>
<p><code>#include <<a class="el" href="Fir_8h_source.html">Fir.h</a>></code></p>
<div class="dynheader">
Inheritance diagram for stk::Fir:</div>
<div class="dynsection">
<div class="center">
<img src="classstk_1_1Fir.png" usemap="#stk::Fir_map" alt=""/>
<map id="stk::Fir_map" name="stk::Fir_map">
<area href="classstk_1_1Filter.html" alt="stk::Filter" shape="rect" coords="0,56,62,80"/>
<area href="classstk_1_1Stk.html" alt="stk::Stk" shape="rect" coords="0,0,62,24"/>
</map>
</div>
</div>
<p><a href="classstk_1_1Fir-members.html">List of all members.</a></p>
<table border="0" cellpadding="0" cellspacing="0">
<tr><td colspan="2"><h2>Public Member Functions</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a4ad986b7f644d3e22e75b0744b2f948a"></a><!-- doxytag: member="stk::Fir::Fir" ref="a4ad986b7f644d3e22e75b0744b2f948a" args="(void)" -->
</td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Fir.html#a4ad986b7f644d3e22e75b0744b2f948a">Fir</a> (void)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Default constructor creates a zero-order pass-through "filter". <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Fir.html#a6f47a21d9fa7641aad2872df70432265">Fir</a> (std::vector< StkFloat > &coefficients)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Overloaded constructor which takes filter coefficients. <a href="#a6f47a21d9fa7641aad2872df70432265"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a2a9db698672fcac97a77d95f3891b68f"></a><!-- doxytag: member="stk::Fir::~Fir" ref="a2a9db698672fcac97a77d95f3891b68f" args="(void)" -->
</td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Fir.html#a2a9db698672fcac97a77d95f3891b68f">~Fir</a> (void)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Class destructor. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Fir.html#aa3f72042fb8b13e9dcc31acbff4e1672">setCoefficients</a> (std::vector< StkFloat > &coefficients, bool clearState=false)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set filter coefficients. <a href="#aa3f72042fb8b13e9dcc31acbff4e1672"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a5182288d564977bf172439f6ecaf2377"></a><!-- doxytag: member="stk::Fir::lastOut" ref="a5182288d564977bf172439f6ecaf2377" args="(void) const " -->
StkFloat </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Fir.html#a5182288d564977bf172439f6ecaf2377">lastOut</a> (void) const </td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Return the last computed output value. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="afc5fd95f6bf72edaf4ee3060ca947793"></a><!-- doxytag: member="stk::Fir::tick" ref="afc5fd95f6bf72edaf4ee3060ca947793" args="(StkFloat input)" -->
StkFloat </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Fir.html#afc5fd95f6bf72edaf4ee3060ca947793">tick</a> (StkFloat input)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Input one sample to the filter and return one output. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Fir.html#a602e5ce0cd93f5103796ffd50ed8c988">tick</a> (<a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> &frames, unsigned int channel=0)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Take a channel of the <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> object as inputs to the filter and replace with corresponding outputs. <a href="#a602e5ce0cd93f5103796ffd50ed8c988"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Fir.html#a53bcdfc2e9ad757d2ec549529b7a9738">tick</a> (<a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> &iFrames, <a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> &oFrames, unsigned int iChannel=0, unsigned int oChannel=0)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Take a channel of the <code>iFrames</code> object as inputs to the filter and write outputs to the <code>oFrames</code> object. <a href="#a53bcdfc2e9ad757d2ec549529b7a9738"></a><br/></td></tr>
</table>
<hr/><a name="_details"></a><h2>Detailed Description</h2>
<p>STK general finite impulse response filter class. </p>
<p>This class provides a generic digital filter structure that can be used to implement FIR filters. For filters with feedback terms, the <a class="el" href="classstk_1_1Iir.html" title="STK general infinite impulse response filter class.">Iir</a> class should be used.</p>
<p>In particular, this class implements the standard difference equation:</p>
<p>y[n] = b[0]*x[n] + ... + b[nb]*x[n-nb]</p>
<p>The <em>gain</em> parameter is applied at the filter input and does not affect the coefficient values. The default gain value is 1.0. This structure results in one extra multiply per computed sample, but allows easy control of the overall filter gain.</p>
<p>by Perry R. Cook and Gary P. Scavone, 1995-2012. </p>
<hr/><h2>Constructor & Destructor Documentation</h2>
<a class="anchor" id="a6f47a21d9fa7641aad2872df70432265"></a><!-- doxytag: member="stk::Fir::Fir" ref="a6f47a21d9fa7641aad2872df70432265" args="(std::vector< StkFloat > &coefficients)" -->
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<td class="memname">stk::Fir::Fir </td>
<td>(</td>
<td class="paramtype">std::vector< StkFloat > & </td>
<td class="paramname"> <em>coefficients</em></td>
<td> ) </td>
<td></td>
</tr>
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<p>Overloaded constructor which takes filter coefficients. </p>
<p>An <a class="el" href="classstk_1_1StkError.html" title="STK error handling class.">StkError</a> can be thrown if the coefficient vector size is zero. </p>
</div>
</div>
<hr/><h2>Member Function Documentation</h2>
<a class="anchor" id="aa3f72042fb8b13e9dcc31acbff4e1672"></a><!-- doxytag: member="stk::Fir::setCoefficients" ref="aa3f72042fb8b13e9dcc31acbff4e1672" args="(std::vector< StkFloat > &coefficients, bool clearState=false)" -->
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<td class="memname">void stk::Fir::setCoefficients </td>
<td>(</td>
<td class="paramtype">std::vector< StkFloat > & </td>
<td class="paramname"> <em>coefficients</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">bool </td>
<td class="paramname"> <em>clearState</em> = <code>false</code></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td></td>
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<p>Set filter coefficients. </p>
<p>An <a class="el" href="classstk_1_1StkError.html" title="STK error handling class.">StkError</a> can be thrown if the coefficient vector size is zero. The internal state of the filter is not cleared unless the <em>clearState</em> flag is <code>true</code>. </p>
</div>
</div>
<a class="anchor" id="a602e5ce0cd93f5103796ffd50ed8c988"></a><!-- doxytag: member="stk::Fir::tick" ref="a602e5ce0cd93f5103796ffd50ed8c988" args="(StkFrames &frames, unsigned int channel=0)" -->
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<div class="memproto">
<table class="memname">
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<td class="memname"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & stk::Fir::tick </td>
<td>(</td>
<td class="paramtype"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td>
<td class="paramname"> <em>frames</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">unsigned int </td>
<td class="paramname"> <em>channel</em> = <code>0</code></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td><code> [inline, virtual]</code></td>
</tr>
</table>
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<div class="memdoc">
<p>Take a channel of the <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> object as inputs to the filter and replace with corresponding outputs. </p>
<p>The <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> argument reference is returned. The <code>channel</code> argument must be less than the number of channels in the <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an <a class="el" href="classstk_1_1StkError.html" title="STK error handling class.">StkError</a> exception. </p>
<p>Implements <a class="el" href="classstk_1_1Filter.html#a3260a238824c4a748ac057b84b7d3f21">stk::Filter</a>.</p>
<p><div class="fragment"><pre class="fragment"><a name="l00101"></a>00101 {
<a name="l00102"></a>00102 <span class="preprocessor">#if defined(_STK_DEBUG_)</span>
<a name="l00103"></a>00103 <span class="preprocessor"></span> <span class="keywordflow">if</span> ( channel >= frames.channels() ) {
<a name="l00104"></a>00104 oStream_ << <span class="stringliteral">"Fir::tick(): channel and StkFrames arguments are incompatible!"</span>;
<a name="l00105"></a>00105 <a class="code" href="classstk_1_1Stk.html#a48ac73a0d8ca28445ba1a054e1f061ff" title="Static function for error reporting and handling using c-strings.">handleError</a>( StkError::FUNCTION_ARGUMENT );
<a name="l00106"></a>00106 }
<a name="l00107"></a>00107 <span class="preprocessor">#endif</span>
<a name="l00108"></a>00108 <span class="preprocessor"></span>
<a name="l00109"></a>00109 StkFloat *samples = &frames[channel];
<a name="l00110"></a>00110 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i, hop = frames.channels();
<a name="l00111"></a>00111 <span class="keywordflow">for</span> ( <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> j=0; j<frames.frames(); j++, samples += hop ) {
<a name="l00112"></a>00112 inputs_[0] = gain_ * *samples;
<a name="l00113"></a>00113 *samples = 0.0;
<a name="l00114"></a>00114
<a name="l00115"></a>00115 <span class="keywordflow">for</span> ( i=b_.size()-1; i>0; i-- ) {
<a name="l00116"></a>00116 *samples += b_[i] * inputs_[i];
<a name="l00117"></a>00117 inputs_[i] = inputs_[i-1];
<a name="l00118"></a>00118 }
<a name="l00119"></a>00119 *samples += b_[0] * inputs_[0];
<a name="l00120"></a>00120 }
<a name="l00121"></a>00121
<a name="l00122"></a>00122 lastFrame_[0] = *(samples-hop);
<a name="l00123"></a>00123 <span class="keywordflow">return</span> frames;
<a name="l00124"></a>00124 }
</pre></div></p>
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</div>
<a class="anchor" id="a53bcdfc2e9ad757d2ec549529b7a9738"></a><!-- doxytag: member="stk::Fir::tick" ref="a53bcdfc2e9ad757d2ec549529b7a9738" args="(StkFrames &iFrames, StkFrames &oFrames, unsigned int iChannel=0, unsigned int oChannel=0)" -->
<div class="memitem">
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<td class="memname"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & stk::Fir::tick </td>
<td>(</td>
<td class="paramtype"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td>
<td class="paramname"> <em>iFrames</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td>
<td class="paramname"> <em>oFrames</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">unsigned int </td>
<td class="paramname"> <em>iChannel</em> = <code>0</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">unsigned int </td>
<td class="paramname"> <em>oChannel</em> = <code>0</code></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td><code> [inline]</code></td>
</tr>
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<div class="memdoc">
<p>Take a channel of the <code>iFrames</code> object as inputs to the filter and write outputs to the <code>oFrames</code> object. </p>
<p>The <code>iFrames</code> object reference is returned. Each channel argument must be less than the number of channels in the corresponding <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an <a class="el" href="classstk_1_1StkError.html" title="STK error handling class.">StkError</a> exception. </p>
<p><div class="fragment"><pre class="fragment"><a name="l00127"></a>00127 {
<a name="l00128"></a>00128 <span class="preprocessor">#if defined(_STK_DEBUG_)</span>
<a name="l00129"></a>00129 <span class="preprocessor"></span> <span class="keywordflow">if</span> ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
<a name="l00130"></a>00130 oStream_ << <span class="stringliteral">"Fir::tick(): channel and StkFrames arguments are incompatible!"</span>;
<a name="l00131"></a>00131 <a class="code" href="classstk_1_1Stk.html#a48ac73a0d8ca28445ba1a054e1f061ff" title="Static function for error reporting and handling using c-strings.">handleError</a>( StkError::FUNCTION_ARGUMENT );
<a name="l00132"></a>00132 }
<a name="l00133"></a>00133 <span class="preprocessor">#endif</span>
<a name="l00134"></a>00134 <span class="preprocessor"></span>
<a name="l00135"></a>00135 StkFloat *iSamples = &iFrames[iChannel];
<a name="l00136"></a>00136 StkFloat *oSamples = &oFrames[oChannel];
<a name="l00137"></a>00137 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i, iHop = iFrames.channels(), oHop = oFrames.channels();
<a name="l00138"></a>00138 <span class="keywordflow">for</span> ( <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> j=0; j<iFrames.frames(); j++, iSamples += iHop, oSamples += oHop ) {
<a name="l00139"></a>00139 inputs_[0] = gain_ * *iSamples;
<a name="l00140"></a>00140 *oSamples = 0.0;
<a name="l00141"></a>00141
<a name="l00142"></a>00142 <span class="keywordflow">for</span> ( i=b_.size()-1; i>0; i-- ) {
<a name="l00143"></a>00143 *oSamples += b_[i] * inputs_[i];
<a name="l00144"></a>00144 inputs_[i] = inputs_[i-1];
<a name="l00145"></a>00145 }
<a name="l00146"></a>00146 *oSamples += b_[0] * inputs_[0];
<a name="l00147"></a>00147 }
<a name="l00148"></a>00148
<a name="l00149"></a>00149 lastFrame_[0] = *(oSamples-oHop);
<a name="l00150"></a>00150 <span class="keywordflow">return</span> iFrames;
<a name="l00151"></a>00151 }
</pre></div></p>
</div>
</div>
<hr/>The documentation for this class was generated from the following file:<ul>
<li><a class="el" href="Fir_8h_source.html">Fir.h</a></li>
</ul>
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<tr><td><A HREF="http://ccrma.stanford.edu/software/stk/"><I>The Synthesis ToolKit in C++ (STK)</I></A></td></tr>
<tr><td>©1995-2012 Perry R. Cook and Gary P. Scavone. All Rights Reserved.</td></tr>
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