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| <h1>arm_sqrt_q31.c</h1> </div> |
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| <div class="contents"> |
| <a href="arm__sqrt__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_sqrt_q31.c </span> |
| <a name="l00009"></a>00009 <span class="comment">* </span> |
| <a name="l00010"></a>00010 <span class="comment">* Description: Q31 square root function. </span> |
| <a name="l00011"></a>00011 <span class="comment">* </span> |
| <a name="l00012"></a>00012 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0</span> |
| <a name="l00013"></a>00013 <span class="comment">* </span> |
| <a name="l00014"></a>00014 <span class="comment">* Version 1.0.10 2011/7/15 </span> |
| <a name="l00015"></a>00015 <span class="comment">* Big Endian support added and Merged M0 and M3/M4 Source code. </span> |
| <a name="l00016"></a>00016 <span class="comment">* </span> |
| <a name="l00017"></a>00017 <span class="comment">* Version 1.0.2 2010/11/11 </span> |
| <a name="l00018"></a>00018 <span class="comment">* Documentation updated. </span> |
| <a name="l00019"></a>00019 <span class="comment">* </span> |
| <a name="l00020"></a>00020 <span class="comment">* Version 1.0.1 2010/10/05 </span> |
| <a name="l00021"></a>00021 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00022"></a>00022 <span class="comment">* </span> |
| <a name="l00023"></a>00023 <span class="comment">* Version 1.0.0 2010/09/20 </span> |
| <a name="l00024"></a>00024 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00025"></a>00025 <span class="comment">* -------------------------------------------------------------------- */</span> |
| <a name="l00026"></a>00026 |
| <a name="l00027"></a>00027 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span> |
| <a name="l00028"></a>00028 <span class="preprocessor">#include "arm_common_tables.h"</span> |
| <a name="l00029"></a>00029 |
| <a name="l00047"></a><a class="code" href="group___s_q_r_t.html#ga119e25831e141d734d7ef10636670058">00047</a> <a class="code" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6" title="Error status returned by some functions in the library.">arm_status</a> <a class="code" href="group___s_q_r_t.html#ga119e25831e141d734d7ef10636670058" title="Q31 square root function.">arm_sqrt_q31</a>( |
| <a name="l00048"></a>00048 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> in, |
| <a name="l00049"></a>00049 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pOut) |
| <a name="l00050"></a>00050 { |
| <a name="l00051"></a>00051 <a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a> prevOut; |
| <a name="l00052"></a>00052 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> oneByOut; |
| <a name="l00053"></a>00053 uint32_t signBits; |
| <a name="l00054"></a>00054 |
| <a name="l00055"></a>00055 <span class="preprocessor">#ifndef ARM_MATH_CM0</span> |
| <a name="l00056"></a>00056 <span class="preprocessor"></span> |
| <a name="l00057"></a>00057 <span class="comment">/* Run the below code for Cortex-M4 and Cortex-M3 */</span> |
| <a name="l00058"></a>00058 |
| <a name="l00059"></a>00059 <a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a> out; |
| <a name="l00060"></a>00060 |
| <a name="l00061"></a>00061 <span class="keywordflow">if</span>(in > 0) |
| <a name="l00062"></a>00062 { |
| <a name="l00063"></a>00063 |
| <a name="l00064"></a>00064 <span class="comment">/* run for ten iterations */</span> |
| <a name="l00065"></a>00065 |
| <a name="l00066"></a>00066 <span class="comment">/* Take initial guess as half of the input and first iteration */</span> |
| <a name="l00067"></a>00067 out = (in >> 1) + 0x3FFFFFFF; |
| <a name="l00068"></a>00068 |
| <a name="l00069"></a>00069 <span class="comment">/* Calculation of reciprocal of out */</span> |
| <a name="l00070"></a>00070 <span class="comment">/* oneByOut contains reciprocal of out which is in 2.30 format </span> |
| <a name="l00071"></a>00071 <span class="comment"> and oneByOut should be upscaled by signBits */</span> |
| <a name="l00072"></a>00072 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00073"></a>00073 |
| <a name="l00074"></a>00074 <span class="comment">/* 0.5 * (out) */</span> |
| <a name="l00075"></a>00075 out = out >> 1u; |
| <a name="l00076"></a>00076 |
| <a name="l00077"></a>00077 <span class="comment">/* prevOut = 0.5 * out + (in * (oneByOut << signBits))) */</span> |
| <a name="l00078"></a>00078 prevOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00079"></a>00079 |
| <a name="l00080"></a>00080 <span class="comment">/* Third iteration */</span> |
| <a name="l00081"></a>00081 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) prevOut, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00082"></a>00082 prevOut = prevOut >> 1u; |
| <a name="l00083"></a>00083 out = prevOut + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00084"></a>00084 |
| <a name="l00085"></a>00085 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00086"></a>00086 out = out >> 1u; |
| <a name="l00087"></a>00087 prevOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00088"></a>00088 |
| <a name="l00089"></a>00089 <span class="comment">/* Fifth iteration */</span> |
| <a name="l00090"></a>00090 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) prevOut, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00091"></a>00091 prevOut = prevOut >> 1u; |
| <a name="l00092"></a>00092 out = prevOut + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00093"></a>00093 |
| <a name="l00094"></a>00094 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00095"></a>00095 out = out >> 1u; |
| <a name="l00096"></a>00096 prevOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00097"></a>00097 |
| <a name="l00098"></a>00098 <span class="comment">/* Seventh iteration */</span> |
| <a name="l00099"></a>00099 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) prevOut, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00100"></a>00100 prevOut = prevOut >> 1u; |
| <a name="l00101"></a>00101 out = prevOut + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00102"></a>00102 |
| <a name="l00103"></a>00103 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00104"></a>00104 out = out >> 1u; |
| <a name="l00105"></a>00105 prevOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00106"></a>00106 |
| <a name="l00107"></a>00107 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) prevOut, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00108"></a>00108 prevOut = prevOut >> 1u; |
| <a name="l00109"></a>00109 out = prevOut + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00110"></a>00110 |
| <a name="l00111"></a>00111 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00112"></a>00112 out = out >> 1u; |
| <a name="l00113"></a>00113 prevOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00114"></a>00114 |
| <a name="l00115"></a>00115 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) prevOut, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00116"></a>00116 prevOut = prevOut >> 1u; |
| <a name="l00117"></a>00117 out = prevOut + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00118"></a>00118 |
| <a name="l00119"></a>00119 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00120"></a>00120 out = out >> 1u; |
| <a name="l00121"></a>00121 prevOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00122"></a>00122 |
| <a name="l00123"></a>00123 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) prevOut, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00124"></a>00124 prevOut = prevOut >> 1u; |
| <a name="l00125"></a>00125 out = prevOut + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00126"></a>00126 |
| <a name="l00127"></a>00127 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00128"></a>00128 out = out >> 1u; |
| <a name="l00129"></a>00129 prevOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00130"></a>00130 |
| <a name="l00131"></a>00131 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) prevOut, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00132"></a>00132 prevOut = prevOut >> 1u; |
| <a name="l00133"></a>00133 out = prevOut + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00134"></a>00134 |
| <a name="l00135"></a>00135 <span class="comment">/* tenth iteration */</span> |
| <a name="l00136"></a>00136 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00137"></a>00137 out = out >> 1u; |
| <a name="l00138"></a>00138 *pOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00139"></a>00139 |
| <a name="l00140"></a>00140 <span class="keywordflow">return</span> (<a class="code" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a>); |
| <a name="l00141"></a>00141 } |
| <a name="l00142"></a>00142 |
| <a name="l00143"></a>00143 <span class="preprocessor">#else</span> |
| <a name="l00144"></a>00144 <span class="preprocessor"></span> |
| <a name="l00145"></a>00145 <span class="comment">/* Run the below code for Cortex-M0 */</span> |
| <a name="l00146"></a>00146 |
| <a name="l00147"></a>00147 <a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a> out, loopVar; <span class="comment">/* Temporary variable for output, loop variable */</span> |
| <a name="l00148"></a>00148 <span class="keywordflow">if</span>(in > 0) |
| <a name="l00149"></a>00149 { |
| <a name="l00150"></a>00150 |
| <a name="l00151"></a>00151 <span class="comment">/* run for ten iterations */</span> |
| <a name="l00152"></a>00152 |
| <a name="l00153"></a>00153 <span class="comment">/* Take initial guess as half of the input and first iteration */</span> |
| <a name="l00154"></a>00154 out = (in >> 1) + 0x3FFFFFFF; |
| <a name="l00155"></a>00155 |
| <a name="l00156"></a>00156 <span class="comment">/* Calculation of reciprocal of out */</span> |
| <a name="l00157"></a>00157 <span class="comment">/* oneByOut contains reciprocal of out which is in 2.30 format </span> |
| <a name="l00158"></a>00158 <span class="comment"> and oneByOut should be upscaled by sign bits */</span> |
| <a name="l00159"></a>00159 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) out, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00160"></a>00160 |
| <a name="l00161"></a>00161 <span class="comment">/* 0.5 * (out) */</span> |
| <a name="l00162"></a>00162 out = out >> 1u; |
| <a name="l00163"></a>00163 |
| <a name="l00164"></a>00164 <span class="comment">/* prevOut = 0.5 * out + (in * (oneByOut) << signbits) */</span> |
| <a name="l00165"></a>00165 prevOut = out + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00166"></a>00166 |
| <a name="l00167"></a>00167 |
| <a name="l00168"></a>00168 <span class="comment">/* loop for third iteration to tength iteration */</span> |
| <a name="l00169"></a>00169 |
| <a name="l00170"></a>00170 <span class="keywordflow">for</span> (loopVar = 1; loopVar <= 14; loopVar++) |
| <a name="l00171"></a>00171 { |
| <a name="l00172"></a>00172 |
| <a name="l00173"></a>00173 signBits = <a class="code" href="arm__math_8h.html#a43140f04ca94c2a7394e7a222e2d8fb4" title="Function to Calculates 1/in(reciprocal) value of Q31 Data type.">arm_recip_q31</a>((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) prevOut, &oneByOut, <a class="code" href="arm__common__tables_8c.html#aae6056f6c4e8f7e494445196bf864479">armRecipTableQ31</a>); |
| <a name="l00174"></a>00174 <span class="comment">/* 0.5 * (prevOut) */</span> |
| <a name="l00175"></a>00175 prevOut = prevOut >> 1u; |
| <a name="l00176"></a>00176 <span class="comment">/* out = 0.5 * prevOut + (in * oneByOut) << signbits))) */</span> |
| <a name="l00177"></a>00177 out = prevOut + (((<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>) in * oneByOut) >> 32)) << signBits); |
| <a name="l00178"></a>00178 <span class="comment">/* prevOut = out */</span> |
| <a name="l00179"></a>00179 prevOut = out; |
| <a name="l00180"></a>00180 |
| <a name="l00181"></a>00181 } |
| <a name="l00182"></a>00182 <span class="comment">/* output is moved to pOut pointer */</span> |
| <a name="l00183"></a>00183 *pOut = prevOut; |
| <a name="l00184"></a>00184 |
| <a name="l00185"></a>00185 <span class="keywordflow">return</span> (<a class="code" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a>); |
| <a name="l00186"></a>00186 } |
| <a name="l00187"></a>00187 |
| <a name="l00188"></a>00188 <span class="preprocessor">#endif </span><span class="comment">/* #ifndef ARM_MATH_CM0 */</span> |
| <a name="l00189"></a>00189 |
| <a name="l00190"></a>00190 <span class="keywordflow">else</span> |
| <a name="l00191"></a>00191 { |
| <a name="l00192"></a>00192 *pOut = 0; |
| <a name="l00193"></a>00193 <span class="keywordflow">return</span> (<a class="code" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a>); |
| <a name="l00194"></a>00194 } |
| <a name="l00195"></a>00195 } |
| <a name="l00196"></a>00196 |
| </pre></div></div> |
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