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| <h1>arm_biquad_cascade_df1_fast_q31.c</h1> </div> |
| </div> |
| <div class="contents"> |
| <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> |
| <a name="l00002"></a>00002 <span class="comment">* Copyright (C) 2010 ARM Limited. All rights reserved. </span> |
| <a name="l00003"></a>00003 <span class="comment">* </span> |
| <a name="l00004"></a>00004 <span class="comment">* $Date: 15. July 2011 </span> |
| <a name="l00005"></a>00005 <span class="comment">* $Revision: V1.0.10 </span> |
| <a name="l00006"></a>00006 <span class="comment">* </span> |
| <a name="l00007"></a>00007 <span class="comment">* Project: CMSIS DSP Library </span> |
| <a name="l00008"></a>00008 <span class="comment">* Title: arm_biquad_cascade_df1_fast_q31.c </span> |
| <a name="l00009"></a>00009 <span class="comment">* </span> |
| <a name="l00010"></a>00010 <span class="comment">* Description: Processing function for the </span> |
| <a name="l00011"></a>00011 <span class="comment">* Q31 Fast Biquad cascade DirectFormI(DF1) filter. </span> |
| <a name="l00012"></a>00012 <span class="comment">* </span> |
| <a name="l00013"></a>00013 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3</span> |
| <a name="l00014"></a>00014 <span class="comment">* </span> |
| <a name="l00015"></a>00015 <span class="comment">* Version 1.0.10 2011/7/15 </span> |
| <a name="l00016"></a>00016 <span class="comment">* Big Endian support added and Merged M0 and M3/M4 Source code. </span> |
| <a name="l00017"></a>00017 <span class="comment">* </span> |
| <a name="l00018"></a>00018 <span class="comment">* Version 1.0.3 2010/11/29 </span> |
| <a name="l00019"></a>00019 <span class="comment">* Re-organized the CMSIS folders and updated documentation. </span> |
| <a name="l00020"></a>00020 <span class="comment">* </span> |
| <a name="l00021"></a>00021 <span class="comment">* Version 1.0.2 2010/11/11 </span> |
| <a name="l00022"></a>00022 <span class="comment">* Documentation updated. </span> |
| <a name="l00023"></a>00023 <span class="comment">* </span> |
| <a name="l00024"></a>00024 <span class="comment">* Version 1.0.1 2010/10/05 </span> |
| <a name="l00025"></a>00025 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00026"></a>00026 <span class="comment">* </span> |
| <a name="l00027"></a>00027 <span class="comment">* Version 1.0.0 2010/09/20 </span> |
| <a name="l00028"></a>00028 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00029"></a>00029 <span class="comment">* </span> |
| <a name="l00030"></a>00030 <span class="comment">* Version 0.0.9 2010/08/27 </span> |
| <a name="l00031"></a>00031 <span class="comment">* Initial version </span> |
| <a name="l00032"></a>00032 <span class="comment">* </span> |
| <a name="l00033"></a>00033 <span class="comment">* -------------------------------------------------------------------- */</span> |
| <a name="l00034"></a>00034 |
| <a name="l00035"></a>00035 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span> |
| <a name="l00036"></a>00036 |
| <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>( |
| <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, |
| <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, |
| <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, |
| <a name="l00074"></a>00074 uint32_t <a class="code" href="arm__fir__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>) |
| <a name="l00075"></a>00075 { |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| <a name="l00086"></a>00086 |
| <a name="l00087"></a>00087 |
| <a name="l00088"></a>00088 <span class="keywordflow">do</span> |
| <a name="l00089"></a>00089 { |
| <a name="l00090"></a>00090 <span class="comment">/* Reading the coefficients */</span> |
| <a name="l00091"></a>00091 b0 = *pCoeffs++; |
| <a name="l00092"></a>00092 b1 = *pCoeffs++; |
| <a name="l00093"></a>00093 b2 = *pCoeffs++; |
| <a name="l00094"></a>00094 a1 = *pCoeffs++; |
| <a name="l00095"></a>00095 a2 = *pCoeffs++; |
| <a name="l00096"></a>00096 |
| <a name="l00097"></a>00097 <span class="comment">/* Reading the state values */</span> |
| <a name="l00098"></a>00098 Xn1 = pState[0]; |
| <a name="l00099"></a>00099 Xn2 = pState[1]; |
| <a name="l00100"></a>00100 Yn1 = pState[2]; |
| <a name="l00101"></a>00101 Yn2 = pState[3]; |
| <a name="l00102"></a>00102 |
| <a name="l00103"></a>00103 <span class="comment">/* Apply loop unrolling and compute 4 output values simultaneously. */</span> |
| <a name="l00104"></a>00104 <span class="comment">/* The variables acc ... acc3 hold output values that are being computed: </span> |
| <a name="l00105"></a>00105 <span class="comment"> * </span> |
| <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> |
| <a name="l00107"></a>00107 <span class="comment"> */</span> |
| <a name="l00108"></a>00108 |
| <a name="l00109"></a>00109 sample = blockSize >> 2u; |
| <a name="l00110"></a>00110 |
| <a name="l00111"></a>00111 <span class="comment">/* First part of the processing with loop unrolling. Compute 4 outputs at a time. </span> |
| <a name="l00112"></a>00112 <span class="comment"> ** a second loop below computes the remaining 1 to 3 samples. */</span> |
| <a name="l00113"></a>00113 <span class="keywordflow">while</span>(sample > 0u) |
| <a name="l00114"></a>00114 { |
| <a name="l00115"></a>00115 <span class="comment">/* Read the input */</span> |
| <a name="l00116"></a>00116 Xn = *pIn++; |
| <a name="l00117"></a>00117 |
| <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> |
| <a name="l00119"></a>00119 <span class="comment">/* acc = b0 * x[n] */</span> |
| <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); |
| <a name="l00121"></a>00121 <span class="comment">/* acc += b1 * x[n-1] */</span> |
| <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); |
| <a name="l00123"></a>00123 <span class="comment">/* acc += b[2] * x[n-2] */</span> |
| <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); |
| <a name="l00125"></a>00125 <span class="comment">/* acc += a1 * y[n-1] */</span> |
| <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); |
| <a name="l00127"></a>00127 <span class="comment">/* acc += a2 * y[n-2] */</span> |
| <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); |
| <a name="l00129"></a>00129 |
| <a name="l00130"></a>00130 <span class="comment">/* The result is converted to 1.31 , Yn2 variable is reused */</span> |
| <a name="l00131"></a>00131 Yn2 = acc << shift; |
| <a name="l00132"></a>00132 |
| <a name="l00133"></a>00133 <span class="comment">/* Store the output in the destination buffer. */</span> |
| <a name="l00134"></a>00134 *pOut++ = Yn2; |
| <a name="l00135"></a>00135 |
| <a name="l00136"></a>00136 <span class="comment">/* Read the second input */</span> |
| <a name="l00137"></a>00137 Xn2 = *pIn++; |
| <a name="l00138"></a>00138 |
| <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> |
| <a name="l00140"></a>00140 <span class="comment">/* acc = b0 * x[n] */</span> |
| <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); |
| <a name="l00142"></a>00142 <span class="comment">/* acc += b1 * x[n-1] */</span> |
| <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); |
| <a name="l00144"></a>00144 <span class="comment">/* acc += b[2] * x[n-2] */</span> |
| <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); |
| <a name="l00146"></a>00146 <span class="comment">/* acc += a1 * y[n-1] */</span> |
| <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); |
| <a name="l00148"></a>00148 <span class="comment">/* acc += a2 * y[n-2] */</span> |
| <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); |
| <a name="l00150"></a>00150 |
| <a name="l00151"></a>00151 <span class="comment">/* The result is converted to 1.31, Yn1 variable is reused */</span> |
| <a name="l00152"></a>00152 Yn1 = acc << shift; |
| <a name="l00153"></a>00153 |
| <a name="l00154"></a>00154 <span class="comment">/* Store the output in the destination buffer. */</span> |
| <a name="l00155"></a>00155 *pOut++ = Yn1; |
| <a name="l00156"></a>00156 |
| <a name="l00157"></a>00157 <span class="comment">/* Read the third input */</span> |
| <a name="l00158"></a>00158 Xn1 = *pIn++; |
| <a name="l00159"></a>00159 |
| <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> |
| <a name="l00161"></a>00161 <span class="comment">/* acc = b0 * x[n] */</span> |
| <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); |
| <a name="l00163"></a>00163 <span class="comment">/* acc += b1 * x[n-1] */</span> |
| <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); |
| <a name="l00165"></a>00165 <span class="comment">/* acc += b[2] * x[n-2] */</span> |
| <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); |
| <a name="l00167"></a>00167 <span class="comment">/* acc += a1 * y[n-1] */</span> |
| <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); |
| <a name="l00169"></a>00169 <span class="comment">/* acc += a2 * y[n-2] */</span> |
| <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); |
| <a name="l00171"></a>00171 |
| <a name="l00172"></a>00172 <span class="comment">/* The result is converted to 1.31, Yn2 variable is reused */</span> |
| <a name="l00173"></a>00173 Yn2 = acc << shift; |
| <a name="l00174"></a>00174 |
| <a name="l00175"></a>00175 <span class="comment">/* Store the output in the destination buffer. */</span> |
| <a name="l00176"></a>00176 *pOut++ = Yn2; |
| <a name="l00177"></a>00177 |
| <a name="l00178"></a>00178 <span class="comment">/* Read the forth input */</span> |
| <a name="l00179"></a>00179 Xn = *pIn++; |
| <a name="l00180"></a>00180 |
| <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> |
| <a name="l00182"></a>00182 <span class="comment">/* acc = b0 * x[n] */</span> |
| <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); |
| <a name="l00184"></a>00184 <span class="comment">/* acc += b1 * x[n-1] */</span> |
| <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); |
| <a name="l00186"></a>00186 <span class="comment">/* acc += b[2] * x[n-2] */</span> |
| <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); |
| <a name="l00188"></a>00188 <span class="comment">/* acc += a1 * y[n-1] */</span> |
| <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); |
| <a name="l00190"></a>00190 <span class="comment">/* acc += a2 * y[n-2] */</span> |
| <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); |
| <a name="l00192"></a>00192 |
| <a name="l00193"></a>00193 <span class="comment">/* The result is converted to 1.31, Yn1 variable is reused */</span> |
| <a name="l00194"></a>00194 Yn1 = acc << shift; |
| <a name="l00195"></a>00195 |
| <a name="l00196"></a>00196 <span class="comment">/* Every time after the output is computed state should be updated. */</span> |
| <a name="l00197"></a>00197 <span class="comment">/* The states should be updated as: */</span> |
| <a name="l00198"></a>00198 <span class="comment">/* Xn2 = Xn1 */</span> |
| <a name="l00199"></a>00199 <span class="comment">/* Xn1 = Xn */</span> |
| <a name="l00200"></a>00200 <span class="comment">/* Yn2 = Yn1 */</span> |
| <a name="l00201"></a>00201 <span class="comment">/* Yn1 = acc */</span> |
| <a name="l00202"></a>00202 Xn2 = Xn1; |
| <a name="l00203"></a>00203 Xn1 = Xn; |
| <a name="l00204"></a>00204 |
| <a name="l00205"></a>00205 <span class="comment">/* Store the output in the destination buffer. */</span> |
| <a name="l00206"></a>00206 *pOut++ = Yn1; |
| <a name="l00207"></a>00207 |
| <a name="l00208"></a>00208 <span class="comment">/* decrement the loop counter */</span> |
| <a name="l00209"></a>00209 sample--; |
| <a name="l00210"></a>00210 } |
| <a name="l00211"></a>00211 |
| <a name="l00212"></a>00212 <span class="comment">/* If the blockSize is not a multiple of 4, compute any remaining output samples here. </span> |
| <a name="l00213"></a>00213 <span class="comment"> ** No loop unrolling is used. */</span> |
| <a name="l00214"></a>00214 sample = (blockSize & 0x3u); |
| <a name="l00215"></a>00215 |
| <a name="l00216"></a>00216 <span class="keywordflow">while</span>(sample > 0u) |
| <a name="l00217"></a>00217 { |
| <a name="l00218"></a>00218 <span class="comment">/* Read the input */</span> |
| <a name="l00219"></a>00219 Xn = *pIn++; |
| <a name="l00220"></a>00220 |
| <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> |
| <a name="l00222"></a>00222 <span class="comment">/* acc = b0 * x[n] */</span> |
| <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); |
| <a name="l00224"></a>00224 <span class="comment">/* acc += b1 * x[n-1] */</span> |
| <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); |
| <a name="l00226"></a>00226 <span class="comment">/* acc += b[2] * x[n-2] */</span> |
| <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); |
| <a name="l00228"></a>00228 <span class="comment">/* acc += a1 * y[n-1] */</span> |
| <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); |
| <a name="l00230"></a>00230 <span class="comment">/* acc += a2 * y[n-2] */</span> |
| <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); |
| <a name="l00232"></a>00232 <span class="comment">/* The result is converted to 1.31 */</span> |
| <a name="l00233"></a>00233 acc = acc << shift; |
| <a name="l00234"></a>00234 |
| <a name="l00235"></a>00235 <span class="comment">/* Every time after the output is computed state should be updated. */</span> |
| <a name="l00236"></a>00236 <span class="comment">/* The states should be updated as: */</span> |
| <a name="l00237"></a>00237 <span class="comment">/* Xn2 = Xn1 */</span> |
| <a name="l00238"></a>00238 <span class="comment">/* Xn1 = Xn */</span> |
| <a name="l00239"></a>00239 <span class="comment">/* Yn2 = Yn1 */</span> |
| <a name="l00240"></a>00240 <span class="comment">/* Yn1 = acc */</span> |
| <a name="l00241"></a>00241 Xn2 = Xn1; |
| <a name="l00242"></a>00242 Xn1 = Xn; |
| <a name="l00243"></a>00243 Yn2 = Yn1; |
| <a name="l00244"></a>00244 Yn1 = acc; |
| <a name="l00245"></a>00245 |
| <a name="l00246"></a>00246 <span class="comment">/* Store the output in the destination buffer. */</span> |
| <a name="l00247"></a>00247 *pOut++ = acc; |
| <a name="l00248"></a>00248 |
| <a name="l00249"></a>00249 <span class="comment">/* decrement the loop counter */</span> |
| <a name="l00250"></a>00250 sample--; |
| <a name="l00251"></a>00251 } |
| <a name="l00252"></a>00252 |
| <a name="l00253"></a>00253 <span class="comment">/* The first stage goes from the input buffer to the output buffer. */</span> |
| <a name="l00254"></a>00254 <span class="comment">/* Subsequent stages occur in-place in the output buffer */</span> |
| <a name="l00255"></a>00255 pIn = pDst; |
| <a name="l00256"></a>00256 |
| <a name="l00257"></a>00257 <span class="comment">/* Reset to destination pointer */</span> |
| <a name="l00258"></a>00258 pOut = pDst; |
| <a name="l00259"></a>00259 |
| <a name="l00260"></a>00260 <span class="comment">/* Store the updated state variables back into the pState array */</span> |
| <a name="l00261"></a>00261 *pState++ = Xn1; |
| <a name="l00262"></a>00262 *pState++ = Xn2; |
| <a name="l00263"></a>00263 *pState++ = Yn1; |
| <a name="l00264"></a>00264 *pState++ = Yn2; |
| <a name="l00265"></a>00265 |
| <a name="l00266"></a>00266 } <span class="keywordflow">while</span>(--stage); |
| <a name="l00267"></a>00267 } |
| <a name="l00268"></a>00268 |
| </pre></div></div> |
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