PageRenderTime 53ms CodeModel.GetById 13ms RepoModel.GetById 0ms app.codeStats 1ms

/lib/lpc/Core/CMSIS/Documentation/DSP_Lib/html/arm__cfft__radix4__q15_8c_source.html

https://bitbucket.org/shadewind/nixiefirmware
HTML | 1976 lines | 1970 code | 2 blank | 4 comment | 0 complexity | f3db2dddd02a7e9d32709582d1fcf409 MD5 | raw file

Large files files are truncated, but you can click here to view the full file

    

  1. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    2. 

  2. <html xmlns="http://www.w3.org/1999/xhtml">
    3. 

  3. <head>
    4. 

  4. <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
    5. 

  5. <title>CMSIS DSP Software Library: arm_cfft_radix4_q15.c Source File</title>
    6. 

  6. <link href="tabs.css" rel="stylesheet" type="text/css"/>
    7. 

  7. <link href="search/search.css" rel="stylesheet" type="text/css"/>
    8. 

  8. <script type="text/javaScript" src="search/search.js"></script>
    9. 

  9. <link href="doxygen.css" rel="stylesheet" type="text/css"/>
    10. 

  10. </head>
    11. 

  11. <body onload='searchBox.OnSelectItem(0);'>
    12. 

  12. <!-- Generated by Doxygen 1.7.2 -->
    13. 

  13. <script type="text/javascript"><!--
    14. 

  14. var searchBox = new SearchBox("searchBox", "search",false,'Search');
    15. 

  15. --></script>
    16. 

  16. <div class="navigation" id="top">
    17. 

  17.   <div class="tabs">
    18. 

  18.     <ul class="tablist">
    19. 

  19.       <li><a href="index.html"><span>Main&#160;Page</span></a></li>
    20. 

  20.       <li><a href="modules.html"><span>Modules</span></a></li>
    21. 

  21.       <li><a href="annotated.html"><span>Data&#160;Structures</span></a></li>
    22. 

  22.       <li class="current"><a href="files.html"><span>Files</span></a></li>
    23. 

  23.       <li><a href="examples.html"><span>Examples</span></a></li>
    24. 

  24.       <li id="searchli">
    25. 

  25.         <div id="MSearchBox" class="MSearchBoxInactive">
    26. 

  26.         <span class="left">
    27. 

  27.           <img id="MSearchSelect" src="search/mag_sel.png"
    28. 

  28.                onmouseover="return searchBox.OnSearchSelectShow()"
    29. 

  29.                onmouseout="return searchBox.OnSearchSelectHide()"
    30. 

  30.                alt=""/>
    31. 

  31.           <input type="text" id="MSearchField" value="Search" accesskey="S"
    32. 

  32.                onfocus="searchBox.OnSearchFieldFocus(true)" 
    33. 

  33.                onblur="searchBox.OnSearchFieldFocus(false)" 
    34. 

  34.                onkeyup="searchBox.OnSearchFieldChange(event)"/>
    35. 

  35.           </span><span class="right">
    36. 

  36.             <a id="MSearchClose" href="javascript:searchBox.CloseResultsWindow()"><img id="MSearchCloseImg" border="0" src="search/close.png" alt=""/></a>
    37. 

  37.           </span>
    38. 

  38.         </div>
    39. 

  39.       </li>
    40. 

  40.     </ul>
    41. 

  41.   </div>
    42. 

  42.   <div class="tabs2">
    43. 

  43.     <ul class="tablist">
    44. 

  44.       <li><a href="files.html"><span>File&#160;List</span></a></li>
    45. 

  45.       <li><a href="globals.html"><span>Globals</span></a></li>
    46. 

  46.     </ul>
    47. 

  47.   </div>
    48. 

  48. <div class="header">
    49. 

  49.   <div class="headertitle">
    50. 

  50. <h1>arm_cfft_radix4_q15.c</h1>  </div>
    51. 

  51. </div>
    52. 

  52. <div class="contents">
    53. 

  53. <a href="arm__cfft__radix4__q15_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. 

  54. <a name="l00002"></a>00002 <span class="comment">* Copyright (C) 2010 ARM Limited. All rights reserved.   </span>
    55. 

  55. <a name="l00003"></a>00003 <span class="comment">*   </span>
    56. 

  56. <a name="l00004"></a>00004 <span class="comment">* $Date:        15. July 2011  </span>
    57. 

  57. <a name="l00005"></a>00005 <span class="comment">* $Revision:    V1.0.10  </span>
    58. 

  58. <a name="l00006"></a>00006 <span class="comment">*   </span>
    59. 

  59. <a name="l00007"></a>00007 <span class="comment">* Project:      CMSIS DSP Library   </span>
    60. 

  60. <a name="l00008"></a>00008 <span class="comment">* Title:        arm_cfft_radix4_q15.c   </span>
    61. 

  61. <a name="l00009"></a>00009 <span class="comment">*   </span>
    62. 

  62. <a name="l00010"></a>00010 <span class="comment">* Description:  This file has function definition of Radix-4 FFT &amp; IFFT function and   </span>
    63. 

  63. <a name="l00011"></a>00011 <span class="comment">*               In-place bit reversal using bit reversal table   </span>
    64. 

  64. <a name="l00012"></a>00012 <span class="comment">*   </span>
    65. 

  65. <a name="l00013"></a>00013 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0</span>
    66. 

  66. <a name="l00014"></a>00014 <span class="comment">*  </span>
    67. 

  67. <a name="l00015"></a>00015 <span class="comment">* Version 1.0.10 2011/7/15 </span>
    68. 

  68. <a name="l00016"></a>00016 <span class="comment">*    Big Endian support added and Merged M0 and M3/M4 Source code.  </span>
    69. 

  69. <a name="l00017"></a>00017 <span class="comment">*   </span>
    70. 

  70. <a name="l00018"></a>00018 <span class="comment">* Version 1.0.3 2010/11/29  </span>
    71. 

  71. <a name="l00019"></a>00019 <span class="comment">*    Re-organized the CMSIS folders and updated documentation.   </span>
    72. 

  72. <a name="l00020"></a>00020 <span class="comment">*    </span>
    73. 

  73. <a name="l00021"></a>00021 <span class="comment">* Version 1.0.2 2010/11/11   </span>
    74. 

  74. <a name="l00022"></a>00022 <span class="comment">*    Documentation updated.    </span>
    75. 

  75. <a name="l00023"></a>00023 <span class="comment">*   </span>
    76. 

  76. <a name="l00024"></a>00024 <span class="comment">* Version 1.0.1 2010/10/05    </span>
    77. 

  77. <a name="l00025"></a>00025 <span class="comment">*    Production release and review comments incorporated.   </span>
    78. 

  78. <a name="l00026"></a>00026 <span class="comment">*   </span>
    79. 

  79. <a name="l00027"></a>00027 <span class="comment">* Version 1.0.0 2010/09/20    </span>
    80. 

  80. <a name="l00028"></a>00028 <span class="comment">*    Production release and review comments incorporated.   </span>
    81. 

  81. <a name="l00029"></a>00029 <span class="comment">*   </span>
    82. 

  82. <a name="l00030"></a>00030 <span class="comment">* Version 0.0.5  2010/04/26    </span>
    83. 

  83. <a name="l00031"></a>00031 <span class="comment">*    incorporated review comments and updated with latest CMSIS layer   </span>
    84. 

  84. <a name="l00032"></a>00032 <span class="comment">*   </span>
    85. 

  85. <a name="l00033"></a>00033 <span class="comment">* Version 0.0.3  2010/03/10    </span>
    86. 

  86. <a name="l00034"></a>00034 <span class="comment">*    Initial version   </span>
    87. 

  87. <a name="l00035"></a>00035 <span class="comment">* -------------------------------------------------------------------- */</span>
    88. 

  88. <a name="l00036"></a>00036 
    89. 

  89. <a name="l00037"></a>00037 <span class="preprocessor">#include &quot;<a class="code" href="arm__math_8h.html">arm_math.h</a>&quot;</span>
    90. 

  90. <a name="l00038"></a>00038 
    91. 

  91. <a name="l00066"></a><a class="code" href="group___c_f_f_t___c_i_f_f_t.html#ga8d66cdac41b8bf6cefdb895456eee84a">00066</a> <span class="keywordtype">void</span> <a class="code" href="group___c_f_f_t___c_i_f_f_t.html#ga8d66cdac41b8bf6cefdb895456eee84a" title="Processing function for the Q15 CFFT/CIFFT.">arm_cfft_radix4_q15</a>(
    92. 

  92. <a name="l00067"></a>00067   <span class="keyword">const</span> <a class="code" href="structarm__cfft__radix4__instance__q15.html" title="Instance structure for the Q15 CFFT/CIFFT function.">arm_cfft_radix4_instance_q15</a> * S,
    93. 

  93. <a name="l00068"></a>00068   <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> * pSrc)
    94. 

  94. <a name="l00069"></a>00069 {
    95. 

  95. <a name="l00070"></a>00070   <span class="keywordflow">if</span>(S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a2ecff6ea735cb4d22e922d0fd5736655">ifftFlag</a> == 1u)
    96. 

  96. <a name="l00071"></a>00071   {
    97. 

  97. <a name="l00072"></a>00072     <span class="comment">/*  Complex IFFT radix-4  */</span>
    98. 

  98. <a name="l00073"></a>00073     <a class="code" href="arm__cfft__radix4__q15_8c.html#aad04e8439d17dab5617bf1be268bb391" title="Core function for the Q15 CIFFT butterfly process.">arm_radix4_butterfly_inverse_q15</a>(pSrc, S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a5fc543e7d84ca8cb7cf6648970f21ca6">fftLen</a>, S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a29dd693537e45421a36891f8439e1fba">pTwiddle</a>,
    99. 

  99. <a name="l00074"></a>00074                                      S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#af32fdc78bcc27ca385f9b76a0a1f71c3">twidCoefModifier</a>);
    100. 

  100. <a name="l00075"></a>00075   }
    101. 

  101. <a name="l00076"></a>00076   <span class="keywordflow">else</span>
    102. 

  102. <a name="l00077"></a>00077   {
    103. 

  103. <a name="l00078"></a>00078     <span class="comment">/*  Complex FFT radix-4  */</span>
    104. 

  104. <a name="l00079"></a>00079     <a class="code" href="arm__cfft__radix4__q15_8c.html#a2d01d2045f280c32036da97d33c52440" title="Core function for the Q15 CFFT butterfly process.">arm_radix4_butterfly_q15</a>(pSrc, S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a5fc543e7d84ca8cb7cf6648970f21ca6">fftLen</a>, S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a29dd693537e45421a36891f8439e1fba">pTwiddle</a>,
    105. 

  105. <a name="l00080"></a>00080                              S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#af32fdc78bcc27ca385f9b76a0a1f71c3">twidCoefModifier</a>);
    106. 

  106. <a name="l00081"></a>00081   }
    107. 

  107. <a name="l00082"></a>00082 
    108. 

  108. <a name="l00083"></a>00083   <span class="keywordflow">if</span>(S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a101e3f7b0bd6b5b14cd5214f23df4133">bitReverseFlag</a> == 1u)
    109. 

  109. <a name="l00084"></a>00084   {
    110. 

  110. <a name="l00085"></a>00085     <span class="comment">/*  Bit Reversal */</span>
    111. 

  111. <a name="l00086"></a>00086     <a class="code" href="arm__cfft__radix4__q15_8c.html#a12a07b49948c354172ae07358309a4a5" title="In-place bit reversal function.">arm_bitreversal_q15</a>(pSrc, S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a5fc543e7d84ca8cb7cf6648970f21ca6">fftLen</a>, S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a6b010e5f02d1130c621e3d2e26b95df1">bitRevFactor</a>, S-&gt;<a class="code" href="structarm__cfft__radix4__instance__q15.html#a4acf704ae0cf30b53bf0fbfae8e34a59">pBitRevTable</a>);
    112. 

  112. <a name="l00087"></a>00087   }
    113. 

  113. <a name="l00088"></a>00088 
    114. 

  114. <a name="l00089"></a>00089 }
    115. 

  115. <a name="l00090"></a>00090 
    116. 

  116. <a name="l00095"></a>00095 <span class="comment">/*   </span>
    117. 

  117. <a name="l00096"></a>00096 <span class="comment">* Radix-4 FFT algorithm used is :   </span>
    118. 

  118. <a name="l00097"></a>00097 <span class="comment">*   </span>
    119. 

  119. <a name="l00098"></a>00098 <span class="comment">* Input real and imaginary data:   </span>
    120. 

  120. <a name="l00099"></a>00099 <span class="comment">* x(n) = xa + j * ya   </span>
    121. 

  121. <a name="l00100"></a>00100 <span class="comment">* x(n+N/4 ) = xb + j * yb   </span>
    122. 

  122. <a name="l00101"></a>00101 <span class="comment">* x(n+N/2 ) = xc + j * yc   </span>
    123. 

  123. <a name="l00102"></a>00102 <span class="comment">* x(n+3N 4) = xd + j * yd   </span>
    124. 

  124. <a name="l00103"></a>00103 <span class="comment">*   </span>
    125. 

  125. <a name="l00104"></a>00104 <span class="comment">*   </span>
    126. 

  126. <a name="l00105"></a>00105 <span class="comment">* Output real and imaginary data:   </span>
    127. 

  127. <a name="l00106"></a>00106 <span class="comment">* x(4r) = xa&#39;+ j * ya&#39;   </span>
    128. 

  128. <a name="l00107"></a>00107 <span class="comment">* x(4r+1) = xb&#39;+ j * yb&#39;   </span>
    129. 

  129. <a name="l00108"></a>00108 <span class="comment">* x(4r+2) = xc&#39;+ j * yc&#39;   </span>
    130. 

  130. <a name="l00109"></a>00109 <span class="comment">* x(4r+3) = xd&#39;+ j * yd&#39;   </span>
    131. 

  131. <a name="l00110"></a>00110 <span class="comment">*   </span>
    132. 

  132. <a name="l00111"></a>00111 <span class="comment">*   </span>
    133. 

  133. <a name="l00112"></a>00112 <span class="comment">* Twiddle factors for radix-4 FFT:   </span>
    134. 

  134. <a name="l00113"></a>00113 <span class="comment">* Wn = co1 + j * (- si1)   </span>
    135. 

  135. <a name="l00114"></a>00114 <span class="comment">* W2n = co2 + j * (- si2)   </span>
    136. 

  136. <a name="l00115"></a>00115 <span class="comment">* W3n = co3 + j * (- si3)   </span>
    137. 

  137. <a name="l00116"></a>00116 <span class="comment">   </span>
    138. 

  138. <a name="l00117"></a>00117 <span class="comment">* The real and imaginary output values for the radix-4 butterfly are   </span>
    139. 

  139. <a name="l00118"></a>00118 <span class="comment">* xa&#39; = xa + xb + xc + xd   </span>
    140. 

  140. <a name="l00119"></a>00119 <span class="comment">* ya&#39; = ya + yb + yc + yd   </span>
    141. 

  141. <a name="l00120"></a>00120 <span class="comment">* xb&#39; = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1)   </span>
    142. 

  142. <a name="l00121"></a>00121 <span class="comment">* yb&#39; = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1)   </span>
    143. 

  143. <a name="l00122"></a>00122 <span class="comment">* xc&#39; = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2)   </span>
    144. 

  144. <a name="l00123"></a>00123 <span class="comment">* yc&#39; = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2)   </span>
    145. 

  145. <a name="l00124"></a>00124 <span class="comment">* xd&#39; = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3)   </span>
    146. 

  146. <a name="l00125"></a>00125 <span class="comment">* yd&#39; = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3)   </span>
    147. 

  147. <a name="l00126"></a>00126 <span class="comment">*   </span>
    148. 

  148. <a name="l00127"></a>00127 <span class="comment">*/</span>
    149. 

  149. <a name="l00128"></a>00128 
    150. 

  150. <a name="l00138"></a><a class="code" href="arm__math_8h.html#a2d01d2045f280c32036da97d33c52440">00138</a> <span class="keywordtype">void</span> <a class="code" href="arm__cfft__radix4__q15_8c.html#a2d01d2045f280c32036da97d33c52440" title="Core function for the Q15 CFFT butterfly process.">arm_radix4_butterfly_q15</a>(
    151. 

  151. <a name="l00139"></a>00139   <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> * pSrc16,
    152. 

  152. <a name="l00140"></a>00140   uint32_t fftLen,
    153. 

  153. <a name="l00141"></a>00141   <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> * pCoef16,
    154. 

  154. <a name="l00142"></a>00142   uint32_t twidCoefModifier)
    155. 

  155. <a name="l00143"></a>00143 {
    156. 

  156. <a name="l00144"></a>00144 
    157. 

  157. <a name="l00145"></a>00145 <span class="preprocessor">#ifndef ARM_MATH_CM0</span>
    158. 

  158. <a name="l00146"></a>00146 <span class="preprocessor"></span>
    159. 

  159. <a name="l00147"></a>00147   <span class="comment">/* Run the below code for Cortex-M4 and Cortex-M3 */</span>
    160. 

  160. <a name="l00148"></a>00148 
    161. 

  161. <a name="l00149"></a>00149   <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> R, S, T, U;
    162. 

  162. <a name="l00150"></a>00150   <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> C1, C2, C3, out1, out2;
    163. 

  163. <a name="l00151"></a>00151   <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pSrc, *pCoeff;
    164. 

  164. <a name="l00152"></a>00152   uint32_t n1, n2, ic, i0, i1, i2, i3, j, k;
    165. 

  165. <a name="l00153"></a>00153   <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> in;
    166. 

  166. <a name="l00154"></a>00154 
    167. 

  167. <a name="l00155"></a>00155   <span class="comment">/* Total process is divided into three stages */</span>
    168. 

  168. <a name="l00156"></a>00156 
    169. 

  169. <a name="l00157"></a>00157   <span class="comment">/* process first stage, middle stages, &amp; last stage */</span>
    170. 

  170. <a name="l00158"></a>00158 
    171. 

  171. <a name="l00159"></a>00159   <span class="comment">/*  pointer initializations for SIMD calculations */</span>
    172. 

  172. <a name="l00160"></a>00160   pSrc = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) pSrc16;
    173. 

  173. <a name="l00161"></a>00161   pCoeff = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) pCoef16;
    174. 

  174. <a name="l00162"></a>00162 
    175. 

  175. <a name="l00163"></a>00163   <span class="comment">/*  Initializations for the first stage */</span>
    176. 

  176. <a name="l00164"></a>00164   n2 = fftLen;
    177. 

  177. <a name="l00165"></a>00165   n1 = n2;
    178. 

  178. <a name="l00166"></a>00166 
    179. 

  179. <a name="l00167"></a>00167   <span class="comment">/* n2 = fftLen/4 */</span>
    180. 

  180. <a name="l00168"></a>00168   n2 &gt;&gt;= 2u;
    181. 

  181. <a name="l00169"></a>00169 
    182. 

  182. <a name="l00170"></a>00170   <span class="comment">/* Index for twiddle coefficient */</span>
    183. 

  183. <a name="l00171"></a>00171   ic = 0u;
    184. 

  184. <a name="l00172"></a>00172 
    185. 

  185. <a name="l00173"></a>00173   <span class="comment">/* Index for input read and output write */</span>
    186. 

  186. <a name="l00174"></a>00174   i0 = 0u;
    187. 

  187. <a name="l00175"></a>00175   j = n2;
    188. 

  188. <a name="l00176"></a>00176 
    189. 

  189. <a name="l00177"></a>00177   <span class="comment">/* Input is in 1.15(q15) format */</span>
    190. 

  190. <a name="l00178"></a>00178 
    191. 

  191. <a name="l00179"></a>00179   <span class="comment">/*  start of first stage process */</span>
    192. 

  192. <a name="l00180"></a>00180   <span class="keywordflow">do</span>
    193. 

  193. <a name="l00181"></a>00181   {
    194. 

  194. <a name="l00182"></a>00182     <span class="comment">/*  Butterfly implementation */</span>
    195. 

  195. <a name="l00183"></a>00183 
    196. 

  196. <a name="l00184"></a>00184     <span class="comment">/*  index calculation for the input as, */</span>
    197. 

  197. <a name="l00185"></a>00185     <span class="comment">/*  pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span>
    198. 

  198. <a name="l00186"></a>00186     i1 = i0 + n2;
    199. 

  199. <a name="l00187"></a>00187     i2 = i1 + n2;
    200. 

  200. <a name="l00188"></a>00188     i3 = i2 + n2;
    201. 

  201. <a name="l00189"></a>00189 
    202. 

  202. <a name="l00190"></a>00190     <span class="comment">/*  Reading i0, i0+fftLen/2 inputs */</span>
    203. 

  203. <a name="l00191"></a>00191     <span class="comment">/* Read ya (real), xa(imag) input */</span>
    204. 

  204. <a name="l00192"></a>00192     T = pSrc[i0];
    205. 

  205. <a name="l00193"></a>00193     in = ((int16_t) (T &amp; 0xFFFF)) &gt;&gt; 2;
    206. 

  206. <a name="l00194"></a>00194     T = ((T &gt;&gt; 2) &amp; 0xFFFF0000) | (in &amp; 0xFFFF);
    207. 

  207. <a name="l00195"></a>00195     <span class="comment">/* Read yc (real), xc(imag) input */</span>
    208. 

  208. <a name="l00196"></a>00196     S = pSrc[i2];
    209. 

  209. <a name="l00197"></a>00197     in = ((int16_t) (S &amp; 0xFFFF)) &gt;&gt; 2;
    210. 

  210. <a name="l00198"></a>00198     S = ((S &gt;&gt; 2) &amp; 0xFFFF0000) | (in &amp; 0xFFFF);
    211. 

  211. <a name="l00199"></a>00199     <span class="comment">/* R = packed((ya + yc), (xa + xc) ) */</span>
    212. 

  212. <a name="l00200"></a>00200     R = __QADD16(T, S);
    213. 

  213. <a name="l00201"></a>00201     <span class="comment">/* S = packed((ya - yc), (xa - xc) ) */</span>
    214. 

  214. <a name="l00202"></a>00202     S = __QSUB16(T, S);
    215. 

  215. <a name="l00203"></a>00203 
    216. 

  216. <a name="l00204"></a>00204     <span class="comment">/*  Reading i0+fftLen/4 , i0+3fftLen/4 inputs */</span>
    217. 

  217. <a name="l00205"></a>00205     <span class="comment">/* Read yb (real), xb(imag) input */</span>
    218. 

  218. <a name="l00206"></a>00206     T = pSrc[i1];
    219. 

  219. <a name="l00207"></a>00207     in = ((int16_t) (T &amp; 0xFFFF)) &gt;&gt; 2;
    220. 

  220. <a name="l00208"></a>00208     T = ((T &gt;&gt; 2) &amp; 0xFFFF0000) | (in &amp; 0xFFFF);
    221. 

  221. <a name="l00209"></a>00209     <span class="comment">/* Read yd (real), xd(imag) input */</span>
    222. 

  222. <a name="l00210"></a>00210     U = pSrc[i3];
    223. 

  223. <a name="l00211"></a>00211     in = ((int16_t) (U &amp; 0xFFFF)) &gt;&gt; 2;
    224. 

  224. <a name="l00212"></a>00212     U = ((U &gt;&gt; 2) &amp; 0xFFFF0000) | (in &amp; 0xFFFF);
    225. 

  225. <a name="l00213"></a>00213     <span class="comment">/* T = packed((yb + yd), (xb + xd) ) */</span>
    226. 

  226. <a name="l00214"></a>00214     T = __QADD16(T, U);
    227. 

  227. <a name="l00215"></a>00215 
    228. 

  228. <a name="l00216"></a>00216     <span class="comment">/*  writing the butterfly processed i0 sample */</span>
    229. 

  229. <a name="l00217"></a>00217     <span class="comment">/* xa&#39; = xa + xb + xc + xd */</span>
    230. 

  230. <a name="l00218"></a>00218     <span class="comment">/* ya&#39; = ya + yb + yc + yd */</span>
    231. 

  231. <a name="l00219"></a>00219     pSrc[i0] = __SHADD16(R, T);
    232. 

  232. <a name="l00220"></a>00220 
    233. 

  233. <a name="l00221"></a>00221     <span class="comment">/* R = packed((ya + yc) - (yb + yd), (xa + xc)- (xb + xd)) */</span>
    234. 

  234. <a name="l00222"></a>00222     R = __QSUB16(R, T);
    235. 

  235. <a name="l00223"></a>00223 
    236. 

  236. <a name="l00224"></a>00224     <span class="comment">/* co2 &amp; si2 are read from SIMD Coefficient pointer */</span>
    237. 

  237. <a name="l00225"></a>00225     C2 = pCoeff[2u * ic];
    238. 

  238. <a name="l00226"></a>00226 
    239. 

  239. <a name="l00227"></a>00227 
    240. 

  240. <a name="l00228"></a>00228 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
    241. 

  241. <a name="l00229"></a>00229 <span class="preprocessor"></span>
    242. 

  242. <a name="l00230"></a>00230     <span class="comment">/* xc&#39; = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) */</span>
    243. 

  243. <a name="l00231"></a>00231     out1 = __SMUAD(C2, R) &gt;&gt; 16u;
    244. 

  244. <a name="l00232"></a>00232     <span class="comment">/* yc&#39; = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */</span>
    245. 

  245. <a name="l00233"></a>00233     out2 = __SMUSDX(C2, R);
    246. 

  246. <a name="l00234"></a>00234 
    247. 

  247. <a name="l00235"></a>00235 <span class="preprocessor">#else</span>
    248. 

  248. <a name="l00236"></a>00236 <span class="preprocessor"></span>
    249. 

  249. <a name="l00237"></a>00237     <span class="comment">/* xc&#39; = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */</span>
    250. 

  250. <a name="l00238"></a>00238     out1 = __SMUSDX(R, C2) &gt;&gt; 16u;
    251. 

  251. <a name="l00239"></a>00239     <span class="comment">/* yc&#39; = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) */</span>
    252. 

  252. <a name="l00240"></a>00240     out2 = __SMUAD(C2, R);
    253. 

  253. <a name="l00241"></a>00241 
    254. 

  254. <a name="l00242"></a>00242 <span class="preprocessor">#endif </span><span class="comment">/*      #ifndef ARM_MATH_BIG_ENDIAN     */</span>
    255. 

  255. <a name="l00243"></a>00243 
    256. 

  256. <a name="l00244"></a>00244     <span class="comment">/*  Reading i0+fftLen/4 */</span>
    257. 

  257. <a name="l00245"></a>00245     <span class="comment">/* T = packed(yb, xb) */</span>
    258. 

  258. <a name="l00246"></a>00246     T = pSrc[i1];
    259. 

  259. <a name="l00247"></a>00247     in = ((int16_t) (T &amp; 0xFFFF)) &gt;&gt; 2;
    260. 

  260. <a name="l00248"></a>00248     T = ((T &gt;&gt; 2) &amp; 0xFFFF0000) | (in &amp; 0xFFFF);
    261. 

  261. <a name="l00249"></a>00249 
    262. 

  262. <a name="l00250"></a>00250     <span class="comment">/* writing the butterfly processed i0 + fftLen/4 sample */</span>
    263. 

  263. <a name="l00251"></a>00251     <span class="comment">/* writing output(xc&#39;, yc&#39;) in little endian format */</span>
    264. 

  264. <a name="l00252"></a>00252     pSrc[i1] = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((out2) &amp; 0xFFFF0000) | (out1 &amp; 0x0000FFFF);
    265. 

  265. <a name="l00253"></a>00253 
    266. 

  266. <a name="l00254"></a>00254     <span class="comment">/*  Butterfly calculations */</span>
    267. 

  267. <a name="l00255"></a>00255     <span class="comment">/* U = packed(yd, xd) */</span>
    268. 

  268. <a name="l00256"></a>00256     U = pSrc[i3];
    269. 

  269. <a name="l00257"></a>00257     in = ((int16_t) (U &amp; 0xFFFF)) &gt;&gt; 2;
    270. 

  270. <a name="l00258"></a>00258     U = ((U &gt;&gt; 2) &amp; 0xFFFF0000) | (in &amp; 0xFFFF);
    271. 

  271. <a name="l00259"></a>00259     <span class="comment">/* T = packed(yb-yd, xb-xd) */</span>
    272. 

  272. <a name="l00260"></a>00260     T = __QSUB16(T, U);
    273. 

  273. <a name="l00261"></a>00261 
    274. 

  274. <a name="l00262"></a>00262 
    275. 

  275. <a name="l00263"></a>00263 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
    276. 

  276. <a name="l00264"></a>00264 <span class="preprocessor"></span>
    277. 

  277. <a name="l00265"></a>00265     <span class="comment">/* R = packed((ya-yc) + (xb- xd) , (xa-xc) - (yb-yd)) */</span>
    278. 

  278. <a name="l00266"></a>00266     R = __QASX(S, T);
    279. 

  279. <a name="l00267"></a>00267     <span class="comment">/* S = packed((ya-yc) - (xb- xd),  (xa-xc) + (yb-yd)) */</span>
    280. 

  280. <a name="l00268"></a>00268     S = __QSAX(S, T);
    281. 

  281. <a name="l00269"></a>00269 
    282. 

  282. <a name="l00270"></a>00270 <span class="preprocessor">#else</span>
    283. 

  283. <a name="l00271"></a>00271 <span class="preprocessor"></span>
    284. 

  284. <a name="l00272"></a>00272     <span class="comment">/* R = packed((ya-yc) + (xb- xd) , (xa-xc) - (yb-yd)) */</span>
    285. 

  285. <a name="l00273"></a>00273     R = __QSAX(S, T);
    286. 

  286. <a name="l00274"></a>00274     <span class="comment">/* S = packed((ya-yc) - (xb- xd),  (xa-xc) + (yb-yd)) */</span>
    287. 

  287. <a name="l00275"></a>00275     S = __QASX(S, T);
    288. 

  288. <a name="l00276"></a>00276 
    289. 

  289. <a name="l00277"></a>00277 <span class="preprocessor">#endif </span><span class="comment">/*      #ifndef ARM_MATH_BIG_ENDIAN     */</span>
    290. 

  290. <a name="l00278"></a>00278 
    291. 

  291. <a name="l00279"></a>00279     <span class="comment">/* co1 &amp; si1 are read from SIMD Coefficient pointer */</span>
    292. 

  292. <a name="l00280"></a>00280     C1 = pCoeff[ic];
    293. 

  293. <a name="l00281"></a>00281     <span class="comment">/*  Butterfly process for the i0+fftLen/2 sample */</span>
    294. 

  294. <a name="l00282"></a>00282 
    295. 

  295. <a name="l00283"></a>00283 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
    296. 

  296. <a name="l00284"></a>00284 <span class="preprocessor"></span>
    297. 

  297. <a name="l00285"></a>00285     <span class="comment">/* xb&#39; = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) */</span>
    298. 

  298. <a name="l00286"></a>00286     out1 = __SMUAD(C1, S) &gt;&gt; 16u;
    299. 

  299. <a name="l00287"></a>00287     <span class="comment">/* yb&#39; = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) */</span>
    300. 

  300. <a name="l00288"></a>00288     out2 = __SMUSDX(C1, S);
    301. 

  301. <a name="l00289"></a>00289 
    302. 

  302. <a name="l00290"></a>00290 <span class="preprocessor">#else</span>
    303. 

  303. <a name="l00291"></a>00291 <span class="preprocessor"></span>
    304. 

  304. <a name="l00292"></a>00292     <span class="comment">/* xb&#39; = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) */</span>
    305. 

  305. <a name="l00293"></a>00293     out1 = __SMUSDX(S, C1) &gt;&gt; 16u;
    306. 

  306. <a name="l00294"></a>00294     <span class="comment">/* yb&#39; = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) */</span>
    307. 

  307. <a name="l00295"></a>00295     out2 = __SMUAD(C1, S);
    308. 

  308. <a name="l00296"></a>00296 
    309. 

  309. <a name="l00297"></a>00297 <span class="preprocessor">#endif </span><span class="comment">/*      #ifndef ARM_MATH_BIG_ENDIAN     */</span>
    310. 

  310. <a name="l00298"></a>00298 
    311. 

  311. <a name="l00299"></a>00299     <span class="comment">/* writing output(xb&#39;, yb&#39;) in little endian format */</span>
    312. 

  312. <a name="l00300"></a>00300     pSrc[i2] = ((out2) &amp; 0xFFFF0000) | ((out1) &amp; 0x0000FFFF);
    313. 

  313. <a name="l00301"></a>00301 
    314. 

  314. <a name="l00302"></a>00302 
    315. 

  315. <a name="l00303"></a>00303     <span class="comment">/* co3 &amp; si3 are read from SIMD Coefficient pointer */</span>
    316. 

  316. <a name="l00304"></a>00304     C3 = pCoeff[3u * ic];
    317. 

  317. <a name="l00305"></a>00305     <span class="comment">/*  Butterfly process for the i0+3fftLen/4 sample */</span>
    318. 

  318. <a name="l00306"></a>00306 
    319. 

  319. <a name="l00307"></a>00307 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
    320. 

  320. <a name="l00308"></a>00308 <span class="preprocessor"></span>
    321. 

  321. <a name="l00309"></a>00309     <span class="comment">/* xd&#39; = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3) */</span>
    322. 

  322. <a name="l00310"></a>00310     out1 = __SMUAD(C3, R) &gt;&gt; 16u;
    323. 

  323. <a name="l00311"></a>00311     <span class="comment">/* yd&#39; = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3) */</span>
    324. 

  324. <a name="l00312"></a>00312     out2 = __SMUSDX(C3, R);
    325. 

  325. <a name="l00313"></a>00313 
    326. 

  326. <a name="l00314"></a>00314 <span class="preprocessor">#else</span>
    327. 

  327. <a name="l00315"></a>00315 <span class="preprocessor"></span>
    328. 

  328. <a name="l00316"></a>00316     <span class="comment">/* xd&#39; = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3) */</span>
    329. 

  329. <a name="l00317"></a>00317     out1 = __SMUSDX(R, C3) &gt;&gt; 16u;
    330. 

  330. <a name="l00318"></a>00318     <span class="comment">/* yd&#39; = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3) */</span>
    331. 

  331. <a name="l00319"></a>00319     out2 = __SMUAD(C3, R);
    332. 

  332. <a name="l00320"></a>00320 
    333. 

  333. <a name="l00321"></a>00321 <span class="preprocessor">#endif </span><span class="comment">/*      #ifndef ARM_MATH_BIG_ENDIAN     */</span>
    334. 

  334. <a name="l00322"></a>00322 
    335. 

  335. <a name="l00323"></a>00323     <span class="comment">/* writing output(xd&#39;, yd&#39;) in little endian format */</span>
    336. 

  336. <a name="l00324"></a>00324     pSrc[i3] = ((out2) &amp; 0xFFFF0000) | (out1 &amp; 0x0000FFFF);
    337. 

  337. <a name="l00325"></a>00325 
    338. 

  338. <a name="l00326"></a>00326     <span class="comment">/*  Twiddle coefficients index modifier */</span>
    339. 

  339. <a name="l00327"></a>00327     ic = ic + twidCoefModifier;
    340. 

  340. <a name="l00328"></a>00328 
    341. 

  341. <a name="l00329"></a>00329     <span class="comment">/*  Updating input index */</span>
    342. 

  342. <a name="l00330"></a>00330     i0 = i0 + 1u;
    343. 

  343. <a name="l00331"></a>00331 
    344. 

  344. <a name="l00332"></a>00332   } <span class="keywordflow">while</span>(--j);
    345. 

  345. <a name="l00333"></a>00333   <span class="comment">/* data is in 4.11(q11) format */</span>
    346. 

  346. <a name="l00334"></a>00334 
    347. 

  347. <a name="l00335"></a>00335   <span class="comment">/* end of first stage process */</span>
    348. 

  348. <a name="l00336"></a>00336 
    349. 

  349. <a name="l00337"></a>00337 
    350. 

  350. <a name="l00338"></a>00338   <span class="comment">/* start of middle stage process */</span>
    351. 

  351. <a name="l00339"></a>00339 
    352. 

  352. <a name="l00340"></a>00340   <span class="comment">/*  Twiddle coefficients index modifier */</span>
    353. 

  353. <a name="l00341"></a>00341   twidCoefModifier &lt;&lt;= 2u;
    354. 

  354. <a name="l00342"></a>00342 
    355. 

  355. <a name="l00343"></a>00343   <span class="comment">/*  Calculation of Middle stage */</span>
    356. 

  356. <a name="l00344"></a>00344   <span class="keywordflow">for</span> (k = fftLen / 4u; k &gt; 4u; k &gt;&gt;= 2u)
    357. 

  357. <a name="l00345"></a>00345   {
    358. 

  358. <a name="l00346"></a>00346     <span class="comment">/*  Initializations for the middle stage */</span>
    359. 

  359. <a name="l00347"></a>00347     n1 = n2;
    360. 

  360. <a name="l00348"></a>00348     n2 &gt;&gt;= 2u;
    361. 

  361. <a name="l00349"></a>00349     ic = 0u;
    362. 

  362. <a name="l00350"></a>00350 
    363. 

  363. <a name="l00351"></a>00351     <span class="keywordflow">for</span> (j = 0u; j &lt;= (n2 - 1u); j++)
    364. 

  364. <a name="l00352"></a>00352     {
    365. 

  365. <a name="l00353"></a>00353       <span class="comment">/*  index calculation for the coefficients */</span>
    366. 

  366. <a name="l00354"></a>00354       C1 = pCoeff[ic];
    367. 

  367. <a name="l00355"></a>00355       C2 = pCoeff[2u * ic];
    368. 

  368. <a name="l00356"></a>00356       C3 = pCoeff[3u * ic];
    369. 

  369. <a name="l00357"></a>00357 
    370. 

  370. <a name="l00358"></a>00358       <span class="comment">/*  Twiddle coefficients index modifier */</span>
    371. 

  371. <a name="l00359"></a>00359       ic = ic + twidCoefModifier;
    372. 

  372. <a name="l00360"></a>00360 
    373. 

  373. <a name="l00361"></a>00361       <span class="comment">/*  Butterfly implementation */</span>
    374. 

  374. <a name="l00362"></a>00362       <span class="keywordflow">for</span> (i0 = j; i0 &lt; fftLen; i0 += n1)
    375. 

  375. <a name="l00363"></a>00363       {
    376. 

  376. <a name="l00364"></a>00364         <span class="comment">/*  index calculation for the input as, */</span>
    377. 

  377. <a name="l00365"></a>00365         <span class="comment">/*  pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span>
    378. 

  378. <a name="l00366"></a>00366         i1 = i0 + n2;
    379. 

  379. <a name="l00367"></a>00367         i2 = i1 + n2;
    380. 

  380. <a name="l00368"></a>00368         i3 = i2 + n2;
    381. 

  381. <a name="l00369"></a>00369 
    382. 

  382. <a name="l00370"></a>00370         <span class="comment">/*  Reading i0, i0+fftLen/2 inputs */</span>
    383. 

  383. <a name="l00371"></a>00371         <span class="comment">/* Read ya (real), xa(imag) input */</span>
    384. 

  384. <a name="l00372"></a>00372         T = pSrc[i0];
    385. 

  385. <a name="l00373"></a>00373 
    386. 

  386. <a name="l00374"></a>00374         <span class="comment">/* Read yc (real), xc(imag) input */</span>
    387. 

  387. <a name="l00375"></a>00375         S = pSrc[i2];
    388. 

  388. <a name="l00376"></a>00376 
    389. 

  389. <a name="l00377"></a>00377         <span class="comment">/* R = packed( (ya + yc), (xa + xc)) */</span>
    390. 

  390. <a name="l00378"></a>00378         R = __QADD16(T, S);
    391. 

  391. <a name="l00379"></a>00379 
    392. 

  392. <a name="l00380"></a>00380         <span class="comment">/* S = packed((ya - yc), (xa - xc)) */</span>
    393. 

  393. <a name="l00381"></a>00381         S = __QSUB16(T, S);
    394. 

  394. <a name="l00382"></a>00382 
    395. 

  395. <a name="l00383"></a>00383         <span class="comment">/*  Reading i0+fftLen/4 , i0+3fftLen/4 inputs */</span>
    396. 

  396. <a name="l00384"></a>00384         <span class="comment">/* Read yb (real), xb(imag) input */</span>
    397. 

  397. <a name="l00385"></a>00385         T = pSrc[i1];
    398. 

  398. <a name="l00386"></a>00386 
    399. 

  399. <a name="l00387"></a>00387         <span class="comment">/* Read yd (real), xd(imag) input */</span>
    400. 

  400. <a name="l00388"></a>00388         U = pSrc[i3];
    401. 

  401. <a name="l00389"></a>00389 
    402. 

  402. <a name="l00390"></a>00390 
    403. 

  403. <a name="l00391"></a>00391         <span class="comment">/* T = packed( (yb + yd), (xb + xd)) */</span>
    404. 

  404. <a name="l00392"></a>00392         T = __QADD16(T, U);
    405. 

  405. <a name="l00393"></a>00393 
    406. 

  406. <a name="l00394"></a>00394 
    407. 

  407. <a name="l00395"></a>00395         <span class="comment">/*  writing the butterfly processed i0 sample */</span>
    408. 

  408. <a name="l00396"></a>00396 
    409. 

  409. <a name="l00397"></a>00397         <span class="comment">/* xa&#39; = xa + xb + xc + xd */</span>
    410. 

  410. <a name="l00398"></a>00398         <span class="comment">/* ya&#39; = ya + yb + yc + yd */</span>
    411. 

  411. <a name="l00399"></a>00399         out1 = __SHADD16(R, T);
    412. 

  412. <a name="l00400"></a>00400         in = ((int16_t) (out1 &amp; 0xFFFF)) &gt;&gt; 1;
    413. 

  413. <a name="l00401"></a>00401         out1 = ((out1 &gt;&gt; 1) &amp; 0xFFFF0000) | (in &amp; 0xFFFF);
    414. 

  414. <a name="l00402"></a>00402         pSrc[i0] = out1;
    415. 

  415. <a name="l00403"></a>00403 
    416. 

  416. <a name="l00404"></a>00404         <span class="comment">/* R = packed( (ya + yc) - (yb + yd), (xa + xc) - (xb + xd)) */</span>
    417. 

  417. <a name="l00405"></a>00405         R = __SHSUB16(R, T);
    418. 

  418. <a name="l00406"></a>00406 
    419. 

  419. <a name="l00407"></a>00407 
    420. 

  420. <a name="l00408"></a>00408 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
    421. 

  421. <a name="l00409"></a>00409 <span class="preprocessor"></span>
    422. 

  422. <a name="l00410"></a>00410         <span class="comment">/* (ya-yb+yc-yd)* (si2) + (xa-xb+xc-xd)* co2 */</span>
    423. 

  423. <a name="l00411"></a>00411         out1 = __SMUAD(C2, R) &gt;&gt; 16u;
    424. 

  424. <a name="l00412"></a>00412 
    425. 

  425. <a name="l00413"></a>00413         <span class="comment">/* (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */</span>
    426. 

  426. <a name="l00414"></a>00414         out2 = __SMUSDX(C2, R);
    427. 

  427. <a name="l00415"></a>00415 
    428. 

  428. <a name="l00416"></a>00416 <span class="preprocessor">#else</span>
    429. 

  429. <a name="l00417"></a>00417 <span class="preprocessor"></span>
    430. 

  430. <a name="l00418"></a>00418         <span class="comment">/* (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */</span>
    431. 

  431. <a name="l00419"></a>00419         out1 = __SMUSDX(R, C2) &gt;&gt; 16u;
    432. 

  432. <a name="l00420"></a>00420 
    433. 

  433. <a name="l00421"></a>00421         <span class="comment">/* (ya-yb+yc-yd)* (si2) + (xa-xb+xc-xd)* co2 */</span>
    434. 

  434. <a name="l00422"></a>00422         out2 = __SMUAD(C2, R);
    435. 

  435. <a name="l00423"></a>00423 
    436. 

  436. <a name="l00424"></a>00424 <span class="preprocessor">#endif </span><span class="comment">/*      #ifndef ARM_MATH_BIG_ENDIAN     */</span>
    437. 

  437. <a name="l00425"></a>00425 
    438. 

  438. <a name="l00426"></a>00426         <span class="comment">/*  Reading i0+3fftLen/4 */</span>
    439. 

  439. <a name="l00427"></a>00427         <span class="comment">/* Read yb (real), xb(imag) input */</span>
    440. 

  440. <a name="l00428"></a>00428         T = pSrc[i1];
    441. 

  441. <a name="l00429"></a>00429 
    442. 

  442. <a name="l00430"></a>00430         <span class="comment">/*  writing the butterfly processed i0 + fftLen/4 sample */</span>
    443. 

  443. <a name="l00431"></a>00431         <span class="comment">/* xc&#39; = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) */</span>
    444. 

  444. <a name="l00432"></a>00432         <span class="comment">/* yc&#39; = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */</span>
    445. 

  445. <a name="l00433"></a>00433         pSrc[i1] = ((out2) &amp; 0xFFFF0000) | (out1 &amp; 0x0000FFFF);
    446. 

  446. <a name="l00434"></a>00434 
    447. 

  447. <a name="l00435"></a>00435         <span class="comment">/*  Butterfly calculations */</span>
    448. 

  448. <a name="l00436"></a>00436 
    449. 

  449. <a name="l00437"></a>00437         <span class="comment">/* Read yd (real), xd(imag) input */</span>
    450. 

  450. <a name="l00438"></a>00438         U = pSrc[i3];
    451. 

  451. <a name="l00439"></a>00439 
    452. 

  452. <a name="l00440"></a>00440         <span class="comment">/* T = packed(yb-yd, xb-xd) */</span>
    453. 

  453. <a name="l00441"></a>00441         T = __QSUB16(T, U);
    454. 

  454. <a name="l00442"></a>00442 
    455. 

  455. <a name="l00443"></a>00443 
    456. 

  456. <a name="l00444"></a>00444 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
    457. 

  457. <a name="l00445"></a>00445 <span class="preprocessor"></span>
    458. 

  458. <a name="l00446"></a>00446         <span class="comment">/* R = packed((ya-yc) + (xb- xd) , (xa-xc) - (yb-yd)) */</span>
    459. 

  459. <a name="l00447"></a>00447         R = __SHASX(S, T);
    460. 

  460. <a name="l00448"></a>00448 
    461. 

  461. <a name="l00449"></a>00449         <span class="comment">/* S = packed((ya-yc) - (xb- xd),  (xa-xc) + (yb-yd)) */</span>
    462. 

  462. <a name="l00450"></a>00450         S = __SHSAX(S, T);
    463. 

  463. <a name="l00451"></a>00451 
    464. 

  464. <a name="l00452"></a>00452 
    465. 

  465. <a name="l00453"></a>00453         <span class="comment">/*  Butterfly process for the i0+fftLen/2 sample */</span>
    466. 

  466. <a name="l00454"></a>00454         out1 = __SMUAD(C1, S) &gt;&gt; 16u;
    467. 

  467. <a name="l00455"></a>00455         out2 = __SMUSDX(C1, S);
    468. 

  468. <a name="l00456"></a>00456 
    469. 

  469. <a name="l00457"></a>00457 <span class="preprocessor">#else</span>
    470. 

  470. <a name="l00458"></a>00458 <span class="preprocessor"></span>
    471. 

  471. <a name="l00459"></a>00459         <span class="comment">/* R = packed((ya-yc) + (xb- xd) , (xa-xc) - (yb-yd)) */</span>
    472. 

  472. <a name="l00460"></a>00460         R = __SHSAX(S, T);
    473. 

  473. <a name="l00461"></a>00461 
    474. 

  474. <a name="l00462"></a>00462         <span class="comment">/* S = packed((ya-yc) - (xb- xd),  (xa-xc) + (yb-yd)) */</span>
    475. 

  475. <a name="l00463"></a>00463         S = __SHASX(S, T);
    476. 

  476. <a name="l00464"></a>00464 
    477. 

  477. <a name="l00465"></a>00465 
    478. 

  478. <a name="l00466"></a>00466         <span class="comment">/*  Butterfly process for the i0+fftLen/2 sample */</span>
    479. 

  479. <a name="l00467"></a>00467         out1 = __SMUSDX(S, C1) &gt;&gt; 16u;
    480. 

  480. <a name="l00468"></a>00468         out2 = __SMUAD(C1, S);
    481. 

  481. <a name="l00469"></a>00469 
    482. 

  482. <a name="l00470"></a>00470 <span class="preprocessor">#endif </span><span class="comment">/*      #ifndef ARM_MATH_BIG_ENDIAN     */</span>
    483. 

  483. <a name="l00471"></a>00471 
    484. 

  484. <a name="l00472"></a>00472         <span class="comment">/* xb&#39; = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) */</span>
    485. 

  485. <a name="l00473"></a>00473         <span class="comment">/* yb&#39; = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) */</span>
    486. 

  486. <a name="l00474"></a>00474         pSrc[i2] = ((out2) &amp; 0xFFFF0000) | (out1 &amp; 0x0000FFFF);
    487. 

  487. <a name="l00475"></a>00475 
    488. 

  488. <a name="l00476"></a>00476         <span class="comment">/*  Butterfly process for the i0+3fftLen/4 sample */</span>
    489. 

  489. <a name="l00477"></a>00477 
    490. 

  490. <a name="l00478"></a>00478 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
    491. 

  491. <a name="l00479"></a>00479 <span class="preprocessor"></span>
    492. 

  492. <a name="l00480"></a>00480         out1 = __SMUAD(C3, R) &gt;&gt; 16u;
    493. 

  493. <a name="l00481"></a>00481         out2 = __SMUSDX(C3, R);
    494. 

  494. <a name="l00482"></a>00482 
    495. 

  495. <a name="l00483"></a>00483 <span class="preprocessor">#else</span>
    496. 

  496. <a name="l00484"></a>00484 <span class="preprocessor"></span>
    497. 

  497. <a name="l00485"></a>00485         out1 = __SMUSDX(R, C3) &gt;&gt; 16u;
    498. 

  498. <a name="l00486"></a>00486         out2 = __SMUAD(C3, R);
    499. 

  499. <a name="l00487"></a>00487 
    500. 

  500. <a name="l00488"></a>00488 <span class="preprocessor">#endif </span><span class="comment">/*      #ifndef ARM_MATH_BIG_ENDIAN     */</span>
    501. 

  501. <a name="l00489"></a>00489 
    502. 

  502. <a name="l00490"></a>00490         <span class="comment">/* xd&#39; = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3) */</span>
    503. 

  503. <a name="l00491"></a>00491         <span class="comment">/* yd&#39; = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3) */</span>
    504. 

  504. <a name="l00492"></a>00492         pSrc[i3] = ((out2) &amp; 0xFFFF0000) | (out1 &amp; 0x0000FFFF);
    505. 

  505. <a name="l00493"></a>00493       }
    506. 

  506. <a name="l00494"></a>00494     }
    507. 

  507. <a name="l00495"></a>00495     <span class="comment">/*  Twiddle coefficients index modifier */</span>
    508. 

  508. <a name="l00496"></a>00496     twidCoefModifier &lt;&lt;= 2u;
    509. 

  509. <a name="l00497"></a>00497   }
    510. 

  510. <a name="l00498"></a>00498   <span class="comment">/* end of middle stage process */</span>
    511. 

  511. <a name="l00499"></a>00499 
    512. 

  512. <a name="l00500"></a>00500 
    513. 

  513. <a name="l00501"></a>00501   <span class="comment">/* data is in 10.6(q6) format for the 1024 point */</span>
    514. 

  514. <a name="l00502"></a>00502   <span class="comment">/* data is in 8.8(q8) format for the 256 point */</span>
    515. 

  515. <a name="l00503"></a>00503   <span class="comment">/* data is in 6.10(q10) format for the 64 point */</span>
    516. 

  516. <a name="l00504"></a>00504   <span class="comment">/* data is in 4.12(q12) format for the 16 point */</span>
    517. 

  517. <a name="l00505"></a>00505 
    518. 

  518. <a name="l00506"></a>00506   <span class="comment">/*  Initializations for the last stage */</span>
    519. 

  519. <a name="l00507"></a>00507   n1 = n2;
    520. 

  520. <a name="l00508"></a>00508   n2 &gt;&gt;= 2u;
    521. 

  521. <a name="l00509"></a>00509 
    522. 

  522. <a name="l00510"></a>00510   <span class="comment">/* start of last stage process */</span>
    523. 

  523. <a name="l00511"></a>00511 
    524. 

  524. <a name="l00512"></a>00512   <span class="comment">/*  Butterfly implementation */</span>
    525. 

  525. <a name="l00513"></a>00513   <span class="keywordflow">for</span> (i0 = 0u; i0 &lt;= (fftLen - n1); i0 += n1)
    526. 

  526. <a name="l00514"></a>00514   {
    527. 

  527. <a name="l00515"></a>00515     <span class="comment">/*  index calculation for the input as, */</span>
    528. 

  528. <a name="l00516"></a>00516     <span class="comment">/*  pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span>
    529. 

  529. <a name="l00517"></a>00517     i1 = i0 + n2;
    530. 

  530. <a name="l00518"></a>00518     i2 = i1 + n2;
    531. 

  531. <a name="l00519"></a>00519     i3 = i2 + n2;
    532. 

  532. <a name="l00520"></a>00520 
    533. 

  533. <a name="l00521"></a>00521     <span class="comment">/*  Reading i0, i0+fftLen/2 inputs */</span>
    534. 

  534. <a name="l00522"></a>00522     <span class="comment">/* Read ya (real), xa(imag) input */</span>
    535. 

  535. <a name="l00523"></a>00523     T = pSrc[i0];
    536. 

  536. <a name="l00524"></a>00524     <span class="comment">/* Read yc (real), xc(imag) input */</span>
    537. 

  537. <a name="l00525"></a>00525     S = pSrc[i2];
    538. 

  538. <a name="l00526"></a>00526 
    539. 

  539. <a name="l00527"></a>00527     <span class="comment">/* R = packed((ya + yc), (xa + xc)) */</span>
    540. 

  540. <a name="l00528"></a>00528     R = __QADD16(T, S);
    541. 

  541. <a name="l00529"></a>00529     <span class="comment">/* S = packed((ya - yc), (xa - xc)) */</span>
    542. 

  542. <a name="l00530"></a>00530     S = __QSUB16(T, S);
    543. 

  543. <a name="l00531"></a>00531 
    544. 

  544. <a name="l00532"></a>00532     <span class="comment">/*  Reading i0+fftLen/4 , i0+3fftLen/4 inputs */</span>
    545. 

  545. <a name="l00533"></a>00533     <span class="comment">/* Read yb (real), xb(imag) input */</span>
    546. 

  546. <a name="l00534"></a>00534     T = pSrc[i1];
    547. 

  547. <a name="l00535"></a>00535     <span class="comment">/* Read yd (real), xd(imag) input */</span>
    548. 

  548. <a name="l00536"></a>00536     U = pSrc[i3];
    549. 

  549. <a name="l00537"></a>00537 
    550. 

  550. <a name="l00538"></a>00538     <span class="comment">/* T = packed((yb + yd), (xb + xd)) */</span>
    551. 

  551. <a name="l00539"></a>00539     T = __QADD16(T, U);
    552. 

  552. <a name="l00540"></a>00540 
    553. 

  553. <a name="l00541"></a>00541     <span class="comment">/*  writing the butterfly processed i0 sample */</span>
    554. 

  554. <a name="l00542"></a>00542     <span class="comment">/* xa&#39; = xa + xb + xc + xd */</span>
    555. 

  555. <a name="l00543"></a>00543     <span class="comment">/* ya&#39; = ya + yb + yc + yd */</span>
    556. 

  556. <a name="l00544"></a>00544     pSrc[i0] = __SHADD16(R, T);
    557. 

  557. <a name="l00545"></a>00545 
    558. 

  558. <a name="l00546"></a>00546     <span class="comment">/* R = packed((ya + yc) - (yb + yd), (xa + xc) - (xb + xd)) */</span>
    559. 

  559. <a name="l00547"></a>00547     R = __SHSUB16(R, T);
    560. 

  560. <a name="l00548"></a>00548 
    561. 

  561. <a name="l00549"></a>00549     <span class="comment">/* Read yb (real), xb(imag) input */</span>
    562. 

  562. <a name="l00550"></a>00550     T = pSrc[i1];
    563. 

  563. <a name="l00551"></a>00551 
    564. 

  564. <a name="l00552"></a>00552     <span class="comment">/*  writing the butterfly processed i0 + fftLen/4 sample */</span>
    565. 

  565. <a name="l00553"></a>00553     <span class="comment">/* xc&#39; = (xa-xb+xc-xd) */</span>
    566. 

  566. <a name="l00554"></a>00554     <span class="comment">/* yc&#39; = (ya-yb+yc-yd) */</span>
    567. 

  567. <a name="l00555"></a>00555     pSrc[i1] = R;
    568. 

  568. <a name="l00556"></a>00556 
    569. 

  569. <a name="l00557"></a>00557     <span class="comment">/* Read yd (real), xd(imag) input */</span>
    570. 

  570. <a name="l00558"></a>00558     U = pSrc[i3];
    571. 

  571. <a name="l00559"></a>00559     <span class="comment">/* T = packed( (yb - yd), (xb - xd))  */</span>
    572. 

  572. <a name="l00560"></a>00560     T = __QSUB16(T, U);
    573. 

  573. <a name="l00561"></a>00561 
    574. 

  574. <a name="l00562"></a>00562 
    575. 

  575. <a name="l00563"></a>00563 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
    576. 

  576. <a name="l00564"></a>00564 <span class="preprocessor"></span>
    577. 

  577. <a name="l00565"></a>00565     <span class="comment">/*  writing the butterfly processed i0 + fftLen/2 sample */</span>
    578. 

  578. <a name="l00566"></a>00566     <span class="comment">/* xb&#39; = (xa+yb-xc-yd) */</span>
    579. 

  579. <a name="l00567"></a>00567     <span class="comment">/* yb&#39; = (ya-xb-yc+xd) */</span>
    580. 

  580. <a name="l00568"></a>00568     pSrc[i2] = __SHSAX(S, T);
    581. 

  581. <a name="l00569"></a>00569 
    582. 

  582. <a name="l00570"></a>00570     <span class="comment">/*  writing the butterfly processed i0 + 3fftLen/4 sample */</span>
    583. 

  583. <a name="l00571"></a>00571     <span class="comment">/* xd&#39; = (xa-yb-xc+yd) */</span>
    584. 

  584. <a name="l00572"></a>00572     <span class="comment">/* yd&#39; = (ya+xb-yc-xd) */</span>
    585. 

  585. <a name="l00573"></a>00573     pSrc[i3] = __SHASX(S, T);
    586. 

  586. <a name="l00574"></a>00574 
    587. 

  587. <a name="l00575"></a>00575 <span class="preprocessor">#else</span>
    588. 

  588. <a name="l00576"></a>00576 <span class="preprocessor"></span>
    589. 

  589. <a name="l00577"></a>00577     <span class="comment">/*  writing the butterfly processed i0 + fftLen/2 sample */</span>
    590. 

  590. <a name="l00578"></a>00578     <span class="comment">/* xb&#39; = (xa+yb-xc-yd) */</span>
    591. 

  591. <a name="l00579"></a>00579     <span class="comment">/* yb&#39; = (ya-xb-yc+xd) */</span>
    592. 

  592. <a name="l00580"></a>00580     pSrc[i2] = __SHASX(S, T);
    593. 

  593. <a name="l00581"></a>00581 
    594. 

  594. <a name="l00582"></a>00582     <span class="comment">/*  writing the butterfly processed i0 + 3fftLen/4 sample */</span>
    595. 

  595. <a name="l00583"></a>00583     <span class="comment">/* xd&#39; = (xa-yb-xc+yd) */</span>
    596. 

  596. <a name="l00584"></a>00584     <span class="comment">/* yd&#39; = (ya+xb-yc-xd) */</span>
    597. 

  597. <a name="l00585"></a>00585     pSrc[i3] = __SHSAX(S, T);
    598. 

  598. <a name="l00586"></a>00586 
    599. 

  599. <a name="l00587"></a>00587 <span class="preprocessor">#endif </span><span class="comment">/*      #ifndef ARM_MATH_BIG_ENDIAN     */</span>
    600. 

  600. <a name="l00588"></a>00588 
    601. 

  601. <a name="l00589"></a>00589   }
    602. 

  602. <a name="l00590"></a>00590 
    603. 

  603. <a name="l00591"></a>00591   <span class="comment">/* end of last stage process */</span>
    604. 

  604. <a name="l00592"></a>00592 
    605. 

  605. <a name="l00593"></a>00593   <span class="comment">/* output is in 11.5(q5) format for the 1024 point */</span>
    606. 

  606. <a name="l00594"></a>00594   <span class="comment">/* output is in 9.7(q7) format for the 256 point   */</span>
    607. 

  607. <a name="l00595"></a>00595   <span class="comment">/* output is in 7.9(q9) format for the 64 point  */</span>
    608. 

  608. <a name="l00596"></a>00596   <span class="comment">/* output is in 5.11(q11) format for the 16 point  */</span>
    609. 

  609. <a name="l00597"></a>00597 
    610. 

  610. <a name="l00598"></a>00598 
    611. 

  611. <a name="l00599"></a>00599 <span class="preprocessor">#else</span>
    612. 

  612. <a name="l00600"></a>00600 <span class="preprocessor"></span>
    613. 

  613. <a name="l00601"></a>00601   <span class="comment">/* Run the below code for Cortex-M0 */</span>
    614. 

  614. <a name="l00602"></a>00602 
    615. 

  615. <a name="l00603"></a>00603   <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> R0, R1, S0, S1, T0, T1, U0, U1;
    616. 

  616. <a name="l00604"></a>00604   <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> Co1, Si1, Co2, Si2, Co3, Si3, out1, out2;
    617. 

  617. <a name="l00605"></a>00605   uint32_t n1, n2, ic, i0, i1, i2, i3, j, k;
    618. 

  618. <a name="l00606"></a>00606 
    619. 

  619. <a name="l00607"></a>00607   <span class="comment">/* Total process is divided into three stages */</span>
    620. 

  620. <a name="l00608"></a>00608 
    621. 

  621. <a name="l00609"></a>00609   <span class="comment">/* process first stage, middle stages, &amp; last stage */</span>
    622. 

  622. <a name="l00610"></a>00610 
    623. 

  623. <a name="l00611"></a>00611   <span class="comment">/*  Initializations for the first stage */</span>
    624. 

  624. <a name="l00612"></a>00612   n2 = fftLen;
    625. 

  625. <a name="l00613"></a>00613   n1 = n2;
    626. 

  626. <a name="l00614"></a>00614 
    627. 

  627. <a name="l00615"></a>00615   <span class="comment">/* n2 = fftLen/4 */</span>
    628. 

  628. <a name="l00616"></a>00616   n2 &gt;&gt;= 2u;
    629. 

  629. <a name="l00617"></a>00617 
    630. 

  630. <a name="l00618"></a>00618   <span class="comment">/* Index for twiddle coefficient */</span>
    631. 

  631. <a name="l00619"></a>00619   ic = 0u;
    632. 

  632. <a name="l00620"></a>00620 
    633. 

  633. <a name="l00621"></a>00621   <span class="comment">/* Index for input read and output write */</span>
    634. 

  634. <a name="l00622"></a>00622   i0 = 0u;
    635. 

  635. <a name="l00623"></a>00623   j = n2;
    636. 

  636. <a name="l00624"></a>00624 
    637. 

  637. <a name="l00625"></a>00625   <span class="comment">/* Input is in 1.15(q15) format */</span>
    638. 

  638. <a name="l00626"></a>00626 
    639. 

  639. <a name="l00627"></a>00627   <span class="comment">/*  start of first stage process */</span>
    640. 

  640. <a name="l00628"></a>00628   <span class="keywordflow">do</span>
    641. 

  641. <a name="l00629"></a>00629   {
    642. 

  642. <a name="l00630"></a>00630     <span class="comment">/*  Butterfly implementation */</span>
    643. 

  643. <a name="l00631"></a>00631 
    644. 

  644. <a name="l00632"></a>00632     <span class="comment">/*  index calculation for the input as, */</span>
    645. 

  645. <a name="l00633"></a>00633     <span class="comment">/*  pSrc16[i0 + 0], pSrc16[i0 + fftLen/4], pSrc16[i0 + fftLen/2], pSrc16[i0 + 3fftLen/4] */</span>
    646. 

  646. <a name="l00634"></a>00634     i1 = i0 + n2;
    647. 

  647. <a name="l00635"></a>00635     i2 = i1 + n2;
    648. 

  648. <a name="l00636"></a>00636     i3 = i2 + n2;
    649. 

  649. <a name="l00637"></a>00637 
    650. 

  650. <a name="l00638"></a>00638     <span class="comment">/*  Reading i0, i0+fftLen/2 inputs */</span>
    651. 

  651. <a name="l00639"></a>00639 
    652. 

  652. <a name="l00640"></a>00640     <span class="comment">/* input is down scale by 4 to avoid overflow */</span>
    653. 

  653. <a name="l00641"></a>00641     <span class="comment">/* Read ya (real), xa(imag) input */</span>
    654. 

  654. <a name="l00642"></a>00642     T0 = pSrc16[i0 * 2u] &gt;&gt; 2u;
    655. 

  655. <a name="l00643"></a>00643     T1 = pSrc16[(i0 * 2u) + 1u] &gt;&gt; 2u;
    656. 

  656. <a name="l00644"></a>00644 
    657. 

  657. <a name="l00645"></a>00645     <span class="comment">/* input is down scale by 4 to avoid overflow */</span>
    658. 

  658. <a name="l00646"></a>00646     <span class="comment">/* Read yc (real), xc(imag) input */</span>
    659. 

  659. <a name="l00647"></a>00647     S0 = pSrc16[i2 * 2u] &gt;&gt; 2u;
    660. 

  660. <a name="l00648"></a>00648     S1 = pSrc16[(i2 * 2u) + 1u] &gt;&gt; 2u;
    661. 

  661. <a name="l00649"></a>00649 
    662. 

  662. <a name="l00650"></a>00650     <span class="comment">/* R0 = (ya + yc) */</span>
    663. 

  663. <a name="l00651"></a>00651     R0 = __SSAT(T0 + S0, 16u);
    664. 

  664. <a name="l00652"></a>00652     <span class="comment">/* R1 = (xa + xc) */</span>
    665. 

  665. <a name="l00653"></a>00653     R1 = __SSAT(T1 + S1, 16u);
    666. 

  666. <a name="l00654"></a>00654 
    667. 

  667. <a name="l00655"></a>00655     <span class="comment">/* S0 = (ya - yc) */</span>
    668. 

  668. <a name="l00656"></a>00656     S0 = __SSAT(T0 - S0, 16);
    669. 

  669. <a name="l00657"></a>00657     <span class="comment">/* S1 = (xa - xc) */</span>
    670. 

  670. <a name="l00658"></a>00658     S1 = __SSAT(T1 - S1, 16);
    671. 

  671. <a name="l00659"></a>00659 
    672. 

  672. <a name="l00660"></a>00660     <span class="comment">/*  Reading i0+fftLen/4 , i0+3fftLen/4 inputs */</span>
    673. 

  673. <a name="l00661"></a>00661     <span class="comment">/* input is down scale by 4 to avoid overflow */</span>
    674. 

  674. <a name="l00662"></a>00662     <span class="comment">/* Read yb (real), xb(imag) input */</span>
    675. 

  675. <a name="l00663"></a>00663     T0 = pSrc16[i1 * 2u] &gt;&gt; 2u;
    676. 

  676. <a name="l00664"></a>00664     T1 = pSrc16[(i1 …
    677.

Large files files are truncated, but you can click here to view the full file