1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
2 <html xmlns="http://www.w3.org/1999/xhtml">
4 <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
5 <title>CMSIS DSP Software Library: arm_biquad_cascade_df1_fast_q31.c Source File</title>
6 <link href="tabs.css" rel="stylesheet" type="text/css"/>
7 <link href="search/search.css" rel="stylesheet" type="text/css"/>
8 <script type="text/javaScript" src="search/search.js"></script>
9 <link href="doxygen.css" rel="stylesheet" type="text/css"/>
11 <body onload='searchBox.OnSelectItem(0);'>
12 <!-- Generated by Doxygen 1.7.2 -->
13 <script type="text/javascript"><!--
14 var searchBox = new SearchBox("searchBox", "search",false,'Search');
16 <div class="navigation" id="top">
19 <li><a href="index.html"><span>Main Page</span></a></li>
20 <li><a href="modules.html"><span>Modules</span></a></li>
21 <li><a href="annotated.html"><span>Data Structures</span></a></li>
22 <li class="current"><a href="files.html"><span>Files</span></a></li>
23 <li><a href="examples.html"><span>Examples</span></a></li>
25 <div id="MSearchBox" class="MSearchBoxInactive">
27 <img id="MSearchSelect" src="search/mag_sel.png"
28 onmouseover="return searchBox.OnSearchSelectShow()"
29 onmouseout="return searchBox.OnSearchSelectHide()"
31 <input type="text" id="MSearchField" value="Search" accesskey="S"
32 onfocus="searchBox.OnSearchFieldFocus(true)"
33 onblur="searchBox.OnSearchFieldFocus(false)"
34 onkeyup="searchBox.OnSearchFieldChange(event)"/>
35 </span><span class="right">
36 <a id="MSearchClose" href="javascript:searchBox.CloseResultsWindow()"><img id="MSearchCloseImg" border="0" src="search/close.png" alt=""/></a>
44 <li><a href="files.html"><span>File List</span></a></li>
45 <li><a href="globals.html"><span>Globals</span></a></li>
49 <div class="headertitle">
50 <h1>arm_biquad_cascade_df1_fast_q31.c</h1> </div>
52 <div class="contents">
53 <a href="arm__biquad__cascade__df1__fast__q31_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/* ---------------------------------------------------------------------- </span>
54 <a name="l00002"></a>00002 <span class="comment">* Copyright (C) 2010 ARM Limited. All rights reserved. </span>
55 <a name="l00003"></a>00003 <span class="comment">* </span>
56 <a name="l00004"></a>00004 <span class="comment">* $Date: 15. July 2011 </span>
57 <a name="l00005"></a>00005 <span class="comment">* $Revision: V1.0.10 </span>
58 <a name="l00006"></a>00006 <span class="comment">* </span>
59 <a name="l00007"></a>00007 <span class="comment">* Project: CMSIS DSP Library </span>
60 <a name="l00008"></a>00008 <span class="comment">* Title: arm_biquad_cascade_df1_fast_q31.c </span>
61 <a name="l00009"></a>00009 <span class="comment">* </span>
62 <a name="l00010"></a>00010 <span class="comment">* Description: Processing function for the </span>
63 <a name="l00011"></a>00011 <span class="comment">* Q31 Fast Biquad cascade DirectFormI(DF1) filter. </span>
64 <a name="l00012"></a>00012 <span class="comment">* </span>
65 <a name="l00013"></a>00013 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3</span>
66 <a name="l00014"></a>00014 <span class="comment">* </span>
67 <a name="l00015"></a>00015 <span class="comment">* Version 1.0.10 2011/7/15 </span>
68 <a name="l00016"></a>00016 <span class="comment">* Big Endian support added and Merged M0 and M3/M4 Source code. </span>
69 <a name="l00017"></a>00017 <span class="comment">* </span>
70 <a name="l00018"></a>00018 <span class="comment">* Version 1.0.3 2010/11/29 </span>
71 <a name="l00019"></a>00019 <span class="comment">* Re-organized the CMSIS folders and updated documentation. </span>
72 <a name="l00020"></a>00020 <span class="comment">* </span>
73 <a name="l00021"></a>00021 <span class="comment">* Version 1.0.2 2010/11/11 </span>
74 <a name="l00022"></a>00022 <span class="comment">* Documentation updated. </span>
75 <a name="l00023"></a>00023 <span class="comment">* </span>
76 <a name="l00024"></a>00024 <span class="comment">* Version 1.0.1 2010/10/05 </span>
77 <a name="l00025"></a>00025 <span class="comment">* Production release and review comments incorporated. </span>
78 <a name="l00026"></a>00026 <span class="comment">* </span>
79 <a name="l00027"></a>00027 <span class="comment">* Version 1.0.0 2010/09/20 </span>
80 <a name="l00028"></a>00028 <span class="comment">* Production release and review comments incorporated. </span>
81 <a name="l00029"></a>00029 <span class="comment">* </span>
82 <a name="l00030"></a>00030 <span class="comment">* Version 0.0.9 2010/08/27 </span>
83 <a name="l00031"></a>00031 <span class="comment">* Initial version </span>
84 <a name="l00032"></a>00032 <span class="comment">* </span>
85 <a name="l00033"></a>00033 <span class="comment">* -------------------------------------------------------------------- */</span>
86 <a name="l00034"></a>00034
87 <a name="l00035"></a>00035 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span>
88 <a name="l00036"></a>00036
89 <a name="l00070"></a><a class="code" href="group___biquad_cascade_d_f1.html#ga456390f5e448afad3a38bed7d6e380e3">00070</a> <span class="keywordtype">void</span> <a class="code" href="group___biquad_cascade_d_f1.html#ga456390f5e448afad3a38bed7d6e380e3" title="Fast but less precise processing function for the Q31 Biquad cascade filter for Cortex-M3 and Cortex-...">arm_biquad_cascade_df1_fast_q31</a>(
90 <a name="l00071"></a>00071 <span class="keyword">const</span> <a class="code" href="structarm__biquad__casd__df1__inst__q31.html" title="Instance structure for the Q31 Biquad cascade filter.">arm_biquad_casd_df1_inst_q31</a> * S,
91 <a name="l00072"></a>00072 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pSrc,
92 <a name="l00073"></a>00073 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pDst,
93 <a name="l00074"></a>00074 uint32_t <a class="code" href="arm__fir__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)
94 <a name="l00075"></a>00075 {
95 <a name="l00076"></a>00076 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pIn = pSrc; <span class="comment">/* input pointer initialization */</span>
96 <a name="l00077"></a>00077 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pOut = pDst; <span class="comment">/* output pointer initialization */</span>
97 <a name="l00078"></a>00078 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pState = S-><a class="code" href="structarm__biquad__casd__df1__inst__q31.html#a5dcf4727f58eb4e8e8b392508d8657bb">pState</a>; <span class="comment">/* pState pointer initialization */</span>
98 <a name="l00079"></a>00079 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pCoeffs = S-><a class="code" href="structarm__biquad__casd__df1__inst__q31.html#aa62366c632f3b5305086f841f079dbd2">pCoeffs</a>; <span class="comment">/* coeff pointer initialization */</span>
99 <a name="l00080"></a>00080 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> acc; <span class="comment">/* accumulator */</span>
100 <a name="l00081"></a>00081 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> Xn1, Xn2, Yn1, Yn2; <span class="comment">/* Filter state variables */</span>
101 <a name="l00082"></a>00082 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> b0, b1, b2, a1, a2; <span class="comment">/* Filter coefficients */</span>
102 <a name="l00083"></a>00083 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> Xn; <span class="comment">/* temporary input */</span>
103 <a name="l00084"></a>00084 int32_t shift = (int32_t) S-><a class="code" href="structarm__biquad__casd__df1__inst__q31.html#a636c7fbe09ec4bef0bc0a4b4e2151cbe">postShift</a> + 1; <span class="comment">/* Shift to be applied to the output */</span>
104 <a name="l00085"></a>00085 uint32_t sample, stage = S-><a class="code" href="structarm__biquad__casd__df1__inst__q31.html#a2c2b579f1df1d8273a5d9d945c27e1b2">numStages</a>; <span class="comment">/* loop counters */</span>
105 <a name="l00086"></a>00086
106 <a name="l00087"></a>00087
107 <a name="l00088"></a>00088 <span class="keywordflow">do</span>
108 <a name="l00089"></a>00089 {
109 <a name="l00090"></a>00090 <span class="comment">/* Reading the coefficients */</span>
110 <a name="l00091"></a>00091 b0 = *pCoeffs++;
111 <a name="l00092"></a>00092 b1 = *pCoeffs++;
112 <a name="l00093"></a>00093 b2 = *pCoeffs++;
113 <a name="l00094"></a>00094 a1 = *pCoeffs++;
114 <a name="l00095"></a>00095 a2 = *pCoeffs++;
115 <a name="l00096"></a>00096
116 <a name="l00097"></a>00097 <span class="comment">/* Reading the state values */</span>
117 <a name="l00098"></a>00098 Xn1 = pState[0];
118 <a name="l00099"></a>00099 Xn2 = pState[1];
119 <a name="l00100"></a>00100 Yn1 = pState[2];
120 <a name="l00101"></a>00101 Yn2 = pState[3];
121 <a name="l00102"></a>00102
122 <a name="l00103"></a>00103 <span class="comment">/* Apply loop unrolling and compute 4 output values simultaneously. */</span>
123 <a name="l00104"></a>00104 <span class="comment">/* The variables acc ... acc3 hold output values that are being computed: </span>
124 <a name="l00105"></a>00105 <span class="comment"> * </span>
125 <a name="l00106"></a>00106 <span class="comment"> * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] </span>
126 <a name="l00107"></a>00107 <span class="comment"> */</span>
127 <a name="l00108"></a>00108
128 <a name="l00109"></a>00109 sample = blockSize >> 2u;
129 <a name="l00110"></a>00110
130 <a name="l00111"></a>00111 <span class="comment">/* First part of the processing with loop unrolling. Compute 4 outputs at a time. </span>
131 <a name="l00112"></a>00112 <span class="comment"> ** a second loop below computes the remaining 1 to 3 samples. */</span>
132 <a name="l00113"></a>00113 <span class="keywordflow">while</span>(sample > 0u)
133 <a name="l00114"></a>00114 {
134 <a name="l00115"></a>00115 <span class="comment">/* Read the input */</span>
135 <a name="l00116"></a>00116 Xn = *pIn++;
136 <a name="l00117"></a>00117
137 <a name="l00118"></a>00118 <span class="comment">/* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */</span>
138 <a name="l00119"></a>00119 <span class="comment">/* acc = b0 * x[n] */</span>
139 <a name="l00120"></a>00120 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) b0 * Xn) >> 32);
140 <a name="l00121"></a>00121 <span class="comment">/* acc += b1 * x[n-1] */</span>
141 <a name="l00122"></a>00122 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);
142 <a name="l00123"></a>00123 <span class="comment">/* acc += b[2] * x[n-2] */</span>
143 <a name="l00124"></a>00124 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) b2 * (Xn2))) >> 32);
144 <a name="l00125"></a>00125 <span class="comment">/* acc += a1 * y[n-1] */</span>
145 <a name="l00126"></a>00126 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);
146 <a name="l00127"></a>00127 <span class="comment">/* acc += a2 * y[n-2] */</span>
147 <a name="l00128"></a>00128 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);
148 <a name="l00129"></a>00129
149 <a name="l00130"></a>00130 <span class="comment">/* The result is converted to 1.31 , Yn2 variable is reused */</span>
150 <a name="l00131"></a>00131 Yn2 = acc << shift;
151 <a name="l00132"></a>00132
152 <a name="l00133"></a>00133 <span class="comment">/* Store the output in the destination buffer. */</span>
153 <a name="l00134"></a>00134 *pOut++ = Yn2;
154 <a name="l00135"></a>00135
155 <a name="l00136"></a>00136 <span class="comment">/* Read the second input */</span>
156 <a name="l00137"></a>00137 Xn2 = *pIn++;
157 <a name="l00138"></a>00138
158 <a name="l00139"></a>00139 <span class="comment">/* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */</span>
159 <a name="l00140"></a>00140 <span class="comment">/* acc = b0 * x[n] */</span>
160 <a name="l00141"></a>00141 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) b0 * (Xn2)) >> 32);
161 <a name="l00142"></a>00142 <span class="comment">/* acc += b1 * x[n-1] */</span>
162 <a name="l00143"></a>00143 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b1 * (Xn))) >> 32);
163 <a name="l00144"></a>00144 <span class="comment">/* acc += b[2] * x[n-2] */</span>
164 <a name="l00145"></a>00145 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b2 * (Xn1))) >> 32);
165 <a name="l00146"></a>00146 <span class="comment">/* acc += a1 * y[n-1] */</span>
166 <a name="l00147"></a>00147 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) a1 * (Yn2))) >> 32);
167 <a name="l00148"></a>00148 <span class="comment">/* acc += a2 * y[n-2] */</span>
168 <a name="l00149"></a>00149 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) a2 * (Yn1))) >> 32);
169 <a name="l00150"></a>00150
170 <a name="l00151"></a>00151 <span class="comment">/* The result is converted to 1.31, Yn1 variable is reused */</span>
171 <a name="l00152"></a>00152 Yn1 = acc << shift;
172 <a name="l00153"></a>00153
173 <a name="l00154"></a>00154 <span class="comment">/* Store the output in the destination buffer. */</span>
174 <a name="l00155"></a>00155 *pOut++ = Yn1;
175 <a name="l00156"></a>00156
176 <a name="l00157"></a>00157 <span class="comment">/* Read the third input */</span>
177 <a name="l00158"></a>00158 Xn1 = *pIn++;
178 <a name="l00159"></a>00159
179 <a name="l00160"></a>00160 <span class="comment">/* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */</span>
180 <a name="l00161"></a>00161 <span class="comment">/* acc = b0 * x[n] */</span>
181 <a name="l00162"></a>00162 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) b0 * (Xn1)) >> 32);
182 <a name="l00163"></a>00163 <span class="comment">/* acc += b1 * x[n-1] */</span>
183 <a name="l00164"></a>00164 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b1 * (Xn2))) >> 32);
184 <a name="l00165"></a>00165 <span class="comment">/* acc += b[2] * x[n-2] */</span>
185 <a name="l00166"></a>00166 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b2 * (Xn))) >> 32);
186 <a name="l00167"></a>00167 <span class="comment">/* acc += a1 * y[n-1] */</span>
187 <a name="l00168"></a>00168 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);
188 <a name="l00169"></a>00169 <span class="comment">/* acc += a2 * y[n-2] */</span>
189 <a name="l00170"></a>00170 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);
190 <a name="l00171"></a>00171
191 <a name="l00172"></a>00172 <span class="comment">/* The result is converted to 1.31, Yn2 variable is reused */</span>
192 <a name="l00173"></a>00173 Yn2 = acc << shift;
193 <a name="l00174"></a>00174
194 <a name="l00175"></a>00175 <span class="comment">/* Store the output in the destination buffer. */</span>
195 <a name="l00176"></a>00176 *pOut++ = Yn2;
196 <a name="l00177"></a>00177
197 <a name="l00178"></a>00178 <span class="comment">/* Read the forth input */</span>
198 <a name="l00179"></a>00179 Xn = *pIn++;
199 <a name="l00180"></a>00180
200 <a name="l00181"></a>00181 <span class="comment">/* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */</span>
201 <a name="l00182"></a>00182 <span class="comment">/* acc = b0 * x[n] */</span>
202 <a name="l00183"></a>00183 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) b0 * (Xn)) >> 32);
203 <a name="l00184"></a>00184 <span class="comment">/* acc += b1 * x[n-1] */</span>
204 <a name="l00185"></a>00185 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);
205 <a name="l00186"></a>00186 <span class="comment">/* acc += b[2] * x[n-2] */</span>
206 <a name="l00187"></a>00187 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);
207 <a name="l00188"></a>00188 <span class="comment">/* acc += a1 * y[n-1] */</span>
208 <a name="l00189"></a>00189 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) a1 * (Yn2))) >> 32);
209 <a name="l00190"></a>00190 <span class="comment">/* acc += a2 * y[n-2] */</span>
210 <a name="l00191"></a>00191 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) a2 * (Yn1))) >> 32);
211 <a name="l00192"></a>00192
212 <a name="l00193"></a>00193 <span class="comment">/* The result is converted to 1.31, Yn1 variable is reused */</span>
213 <a name="l00194"></a>00194 Yn1 = acc << shift;
214 <a name="l00195"></a>00195
215 <a name="l00196"></a>00196 <span class="comment">/* Every time after the output is computed state should be updated. */</span>
216 <a name="l00197"></a>00197 <span class="comment">/* The states should be updated as: */</span>
217 <a name="l00198"></a>00198 <span class="comment">/* Xn2 = Xn1 */</span>
218 <a name="l00199"></a>00199 <span class="comment">/* Xn1 = Xn */</span>
219 <a name="l00200"></a>00200 <span class="comment">/* Yn2 = Yn1 */</span>
220 <a name="l00201"></a>00201 <span class="comment">/* Yn1 = acc */</span>
221 <a name="l00202"></a>00202 Xn2 = Xn1;
222 <a name="l00203"></a>00203 Xn1 = Xn;
223 <a name="l00204"></a>00204
224 <a name="l00205"></a>00205 <span class="comment">/* Store the output in the destination buffer. */</span>
225 <a name="l00206"></a>00206 *pOut++ = Yn1;
226 <a name="l00207"></a>00207
227 <a name="l00208"></a>00208 <span class="comment">/* decrement the loop counter */</span>
228 <a name="l00209"></a>00209 sample--;
229 <a name="l00210"></a>00210 }
230 <a name="l00211"></a>00211
231 <a name="l00212"></a>00212 <span class="comment">/* If the blockSize is not a multiple of 4, compute any remaining output samples here. </span>
232 <a name="l00213"></a>00213 <span class="comment"> ** No loop unrolling is used. */</span>
233 <a name="l00214"></a>00214 sample = (blockSize & 0x3u);
234 <a name="l00215"></a>00215
235 <a name="l00216"></a>00216 <span class="keywordflow">while</span>(sample > 0u)
236 <a name="l00217"></a>00217 {
237 <a name="l00218"></a>00218 <span class="comment">/* Read the input */</span>
238 <a name="l00219"></a>00219 Xn = *pIn++;
239 <a name="l00220"></a>00220
240 <a name="l00221"></a>00221 <span class="comment">/* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */</span>
241 <a name="l00222"></a>00222 <span class="comment">/* acc = b0 * x[n] */</span>
242 <a name="l00223"></a>00223 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) b0 * (Xn)) >> 32);
243 <a name="l00224"></a>00224 <span class="comment">/* acc += b1 * x[n-1] */</span>
244 <a name="l00225"></a>00225 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);
245 <a name="l00226"></a>00226 <span class="comment">/* acc += b[2] * x[n-2] */</span>
246 <a name="l00227"></a>00227 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);
247 <a name="l00228"></a>00228 <span class="comment">/* acc += a1 * y[n-1] */</span>
248 <a name="l00229"></a>00229 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);
249 <a name="l00230"></a>00230 <span class="comment">/* acc += a2 * y[n-2] */</span>
250 <a name="l00231"></a>00231 acc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);
251 <a name="l00232"></a>00232 <span class="comment">/* The result is converted to 1.31 */</span>
252 <a name="l00233"></a>00233 acc = acc << shift;
253 <a name="l00234"></a>00234
254 <a name="l00235"></a>00235 <span class="comment">/* Every time after the output is computed state should be updated. */</span>
255 <a name="l00236"></a>00236 <span class="comment">/* The states should be updated as: */</span>
256 <a name="l00237"></a>00237 <span class="comment">/* Xn2 = Xn1 */</span>
257 <a name="l00238"></a>00238 <span class="comment">/* Xn1 = Xn */</span>
258 <a name="l00239"></a>00239 <span class="comment">/* Yn2 = Yn1 */</span>
259 <a name="l00240"></a>00240 <span class="comment">/* Yn1 = acc */</span>
260 <a name="l00241"></a>00241 Xn2 = Xn1;
261 <a name="l00242"></a>00242 Xn1 = Xn;
262 <a name="l00243"></a>00243 Yn2 = Yn1;
263 <a name="l00244"></a>00244 Yn1 = acc;
264 <a name="l00245"></a>00245
265 <a name="l00246"></a>00246 <span class="comment">/* Store the output in the destination buffer. */</span>
266 <a name="l00247"></a>00247 *pOut++ = acc;
267 <a name="l00248"></a>00248
268 <a name="l00249"></a>00249 <span class="comment">/* decrement the loop counter */</span>
269 <a name="l00250"></a>00250 sample--;
270 <a name="l00251"></a>00251 }
271 <a name="l00252"></a>00252
272 <a name="l00253"></a>00253 <span class="comment">/* The first stage goes from the input buffer to the output buffer. */</span>
273 <a name="l00254"></a>00254 <span class="comment">/* Subsequent stages occur in-place in the output buffer */</span>
274 <a name="l00255"></a>00255 pIn = pDst;
275 <a name="l00256"></a>00256
276 <a name="l00257"></a>00257 <span class="comment">/* Reset to destination pointer */</span>
277 <a name="l00258"></a>00258 pOut = pDst;
278 <a name="l00259"></a>00259
279 <a name="l00260"></a>00260 <span class="comment">/* Store the updated state variables back into the pState array */</span>
280 <a name="l00261"></a>00261 *pState++ = Xn1;
281 <a name="l00262"></a>00262 *pState++ = Xn2;
282 <a name="l00263"></a>00263 *pState++ = Yn1;
283 <a name="l00264"></a>00264 *pState++ = Yn2;
284 <a name="l00265"></a>00265
285 <a name="l00266"></a>00266 } <span class="keywordflow">while</span>(--stage);
286 <a name="l00267"></a>00267 }
287 <a name="l00268"></a>00268
290 <!--- window showing the filter options -->
291 <div id="MSearchSelectWindow"
292 onmouseover="return searchBox.OnSearchSelectShow()"
293 onmouseout="return searchBox.OnSearchSelectHide()"
294 onkeydown="return searchBox.OnSearchSelectKey(event)">
295 <a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(0)"><span class="SelectionMark"> </span>All</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(1)"><span class="SelectionMark"> </span>Data Structures</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(2)"><span class="SelectionMark"> </span>Files</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(3)"><span class="SelectionMark"> </span>Functions</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(4)"><span class="SelectionMark"> </span>Variables</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(5)"><span class="SelectionMark"> </span>Typedefs</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(6)"><span class="SelectionMark"> </span>Enumerations</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(7)"><span class="SelectionMark"> </span>Enumerator</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(8)"><span class="SelectionMark"> </span>Defines</a></div>
297 <!-- iframe showing the search results (closed by default) -->
298 <div id="MSearchResultsWindow">
299 <iframe src="" frameborder="0"
300 name="MSearchResults" id="MSearchResults">
304 <hr class="footer"/><address class="footer"><small>Generated on Fri Jul 15 2011 13:16:15 for CMSIS DSP Software Library by 
305 <a href="http://www.doxygen.org/index.html">
306 <img class="footer" src="doxygen.png" alt="doxygen"/></a> 1.7.2 </small></address>
projects / fw / stlink / blob