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49 <div class="headertitle">
50 <h1>arm_rfft_f32.c</h1> </div>
52 <div class="contents">
53 <a href="arm__rfft__f32_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/* ---------------------------------------------------------------------- </span>
54 <a name="l00002"></a>00002 <span class="comment">* Copyright (C) 2010 ARM Limited. All rights reserved. </span>
55 <a name="l00003"></a>00003 <span class="comment">* </span>
56 <a name="l00004"></a>00004 <span class="comment">* $Date: 15. July 2011 </span>
57 <a name="l00005"></a>00005 <span class="comment">* $Revision: V1.0.10 </span>
58 <a name="l00006"></a>00006 <span class="comment">* </span>
59 <a name="l00007"></a>00007 <span class="comment">* Project: CMSIS DSP Library </span>
60 <a name="l00008"></a>00008 <span class="comment">* Title: arm_rfft_f32.c </span>
61 <a name="l00009"></a>00009 <span class="comment">* </span>
62 <a name="l00010"></a>00010 <span class="comment">* Description: RFFT & RIFFT Floating point process function </span>
63 <a name="l00011"></a>00011 <span class="comment">* </span>
64 <a name="l00012"></a>00012 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0</span>
65 <a name="l00013"></a>00013 <span class="comment">* </span>
66 <a name="l00014"></a>00014 <span class="comment">* Version 1.0.10 2011/7/15 </span>
67 <a name="l00015"></a>00015 <span class="comment">* Big Endian support added and Merged M0 and M3/M4 Source code. </span>
68 <a name="l00016"></a>00016 <span class="comment">* </span>
69 <a name="l00017"></a>00017 <span class="comment">* Version 1.0.3 2010/11/29 </span>
70 <a name="l00018"></a>00018 <span class="comment">* Re-organized the CMSIS folders and updated documentation. </span>
71 <a name="l00019"></a>00019 <span class="comment">* </span>
72 <a name="l00020"></a>00020 <span class="comment">* Version 1.0.2 2010/11/11 </span>
73 <a name="l00021"></a>00021 <span class="comment">* Documentation updated. </span>
74 <a name="l00022"></a>00022 <span class="comment">* </span>
75 <a name="l00023"></a>00023 <span class="comment">* Version 1.0.1 2010/10/05 </span>
76 <a name="l00024"></a>00024 <span class="comment">* Production release and review comments incorporated. </span>
77 <a name="l00025"></a>00025 <span class="comment">* </span>
78 <a name="l00026"></a>00026 <span class="comment">* Version 1.0.0 2010/09/20 </span>
79 <a name="l00027"></a>00027 <span class="comment">* Production release and review comments incorporated. </span>
80 <a name="l00028"></a>00028 <span class="comment">* </span>
81 <a name="l00029"></a>00029 <span class="comment">* Version 0.0.7 2010/06/10 </span>
82 <a name="l00030"></a>00030 <span class="comment">* Misra-C changes done </span>
83 <a name="l00031"></a>00031 <span class="comment">* -------------------------------------------------------------------- */</span>
84 <a name="l00032"></a>00032
85 <a name="l00033"></a>00033 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span>
86 <a name="l00034"></a>00034
87 <a name="l00118"></a>00118 <span class="comment">/*-------------------------------------------------------------------- </span>
88 <a name="l00119"></a>00119 <span class="comment"> * Internal functions prototypes </span>
89 <a name="l00120"></a>00120 <span class="comment"> *--------------------------------------------------------------------*/</span>
90 <a name="l00121"></a>00121
91 <a name="l00122"></a>00122 <span class="keywordtype">void</span> <a class="code" href="arm__rfft__f32_8c.html#a6cfdb6bdc66b13732ef2351caf98fdbb" title="Core Real FFT process.">arm_split_rfft_f32</a>(
92 <a name="l00123"></a>00123 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc,
93 <a name="l00124"></a>00124 uint32_t fftLen,
94 <a name="l00125"></a>00125 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pATable,
95 <a name="l00126"></a>00126 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pBTable,
96 <a name="l00127"></a>00127 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pDst,
97 <a name="l00128"></a>00128 uint32_t modifier);
98 <a name="l00129"></a>00129 <span class="keywordtype">void</span> <a class="code" href="arm__rfft__f32_8c.html#a585bef78c103d150a116241a4feb6442" title="Core Real IFFT process.">arm_split_rifft_f32</a>(
99 <a name="l00130"></a>00130 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc,
100 <a name="l00131"></a>00131 uint32_t fftLen,
101 <a name="l00132"></a>00132 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pATable,
102 <a name="l00133"></a>00133 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pBTable,
103 <a name="l00134"></a>00134 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pDst,
104 <a name="l00135"></a>00135 uint32_t modifier);
105 <a name="l00136"></a>00136
106 <a name="l00150"></a><a class="code" href="group___r_f_f_t___r_i_f_f_t.html#ga3df1766d230532bc068fc4ed69d0fcdc">00150</a> <span class="keywordtype">void</span> <a class="code" href="group___r_f_f_t___r_i_f_f_t.html#ga3df1766d230532bc068fc4ed69d0fcdc" title="Processing function for the floating-point RFFT/RIFFT.">arm_rfft_f32</a>(
107 <a name="l00151"></a>00151 <span class="keyword">const</span> <a class="code" href="structarm__rfft__instance__f32.html" title="Instance structure for the floating-point RFFT/RIFFT function.">arm_rfft_instance_f32</a> * S,
108 <a name="l00152"></a>00152 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc,
109 <a name="l00153"></a>00153 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pDst)
110 <a name="l00154"></a>00154 {
111 <a name="l00155"></a>00155 <span class="keyword">const</span> <a class="code" href="structarm__cfft__radix4__instance__f32.html" title="Instance structure for the floating-point CFFT/CIFFT function.">arm_cfft_radix4_instance_f32</a> *S_CFFT = S-><a class="code" href="structarm__rfft__instance__f32.html#a9f47ba9f50c81e4445ae3827b981bc05">pCfft</a>;
112 <a name="l00156"></a>00156
113 <a name="l00157"></a>00157
114 <a name="l00158"></a>00158 <span class="comment">/* Calculation of Real IFFT of input */</span>
115 <a name="l00159"></a>00159 <span class="keywordflow">if</span>(S-><a class="code" href="structarm__rfft__instance__f32.html#a5ee6d10a934ab4b666e0bb286c3d633f">ifftFlagR</a> == 1u)
116 <a name="l00160"></a>00160 {
117 <a name="l00161"></a>00161 <span class="comment">/* Real IFFT core process */</span>
118 <a name="l00162"></a>00162 <a class="code" href="arm__rfft__f32_8c.html#a585bef78c103d150a116241a4feb6442" title="Core Real IFFT process.">arm_split_rifft_f32</a>(pSrc, S-><a class="code" href="structarm__rfft__instance__f32.html#a075076e07ebb8521d8e3b49a31db6c57">fftLenBy2</a>, S-><a class="code" href="structarm__rfft__instance__f32.html#a534cc7e6e9b3e3dd022fad611c762142">pTwiddleAReal</a>,
119 <a name="l00163"></a>00163 S-><a class="code" href="structarm__rfft__instance__f32.html#a23543ecfd027fea2477fe1eea23c3c4d">pTwiddleBReal</a>, pDst, S-><a class="code" href="structarm__rfft__instance__f32.html#aede85350fb5ae6baa1b3e8bfa15b18d6">twidCoefRModifier</a>);
120 <a name="l00164"></a>00164
121 <a name="l00165"></a>00165
122 <a name="l00166"></a>00166 <span class="comment">/* Complex radix-4 IFFT process */</span>
123 <a name="l00167"></a>00167 <a class="code" href="arm__cfft__radix4__f32_8c.html#a2a78df6e4bbf080624f2b6349224ec93" title="Core function for the floating-point CIFFT butterfly process.">arm_radix4_butterfly_inverse_f32</a>(pDst, S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a7e6a6d290ce158ce9a15a45e364b021a">fftLen</a>,
124 <a name="l00168"></a>00168 S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a14860c7544911702ca1fa0bf78204ef3">pTwiddle</a>,
125 <a name="l00169"></a>00169 S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#abe31ea2157dfa233e389cdfd3b9993ee">twidCoefModifier</a>,
126 <a name="l00170"></a>00170 S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#ab9eed39e40b8d7c16381fbccf84467cd">onebyfftLen</a>);
127 <a name="l00171"></a>00171
128 <a name="l00172"></a>00172 <span class="comment">/* Bit reversal process */</span>
129 <a name="l00173"></a>00173 <span class="keywordflow">if</span>(S-><a class="code" href="structarm__rfft__instance__f32.html#ac342f3248157cbbd2f04a3c8ec9fc9eb">bitReverseFlagR</a> == 1u)
130 <a name="l00174"></a>00174 {
131 <a name="l00175"></a>00175 <a class="code" href="arm__cfft__radix4__f32_8c.html#a3d4062fdfa6aaa3f51f41cab868e508b" title="In-place bit reversal function.">arm_bitreversal_f32</a>(pDst, S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a7e6a6d290ce158ce9a15a45e364b021a">fftLen</a>,
132 <a name="l00176"></a>00176 S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#acc8cb18a8b901b8321ab9d86491e41a3">bitRevFactor</a>, S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a8da0d2ca69749fde8cbb95caeac6fe6a">pBitRevTable</a>);
133 <a name="l00177"></a>00177 }
134 <a name="l00178"></a>00178 }
135 <a name="l00179"></a>00179 <span class="keywordflow">else</span>
136 <a name="l00180"></a>00180 {
137 <a name="l00181"></a>00181
138 <a name="l00182"></a>00182 <span class="comment">/* Calculation of RFFT of input */</span>
139 <a name="l00183"></a>00183
140 <a name="l00184"></a>00184 <span class="comment">/* Complex radix-4 FFT process */</span>
141 <a name="l00185"></a>00185 <a class="code" href="arm__cfft__radix4__f32_8c.html#ae239ddf995d1607115f9e84d5c069b9c" title="Core function for the floating-point CFFT butterfly process.">arm_radix4_butterfly_f32</a>(pSrc, S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a7e6a6d290ce158ce9a15a45e364b021a">fftLen</a>,
142 <a name="l00186"></a>00186 S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a14860c7544911702ca1fa0bf78204ef3">pTwiddle</a>, S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#abe31ea2157dfa233e389cdfd3b9993ee">twidCoefModifier</a>);
143 <a name="l00187"></a>00187
144 <a name="l00188"></a>00188 <span class="comment">/* Bit reversal process */</span>
145 <a name="l00189"></a>00189 <span class="keywordflow">if</span>(S-><a class="code" href="structarm__rfft__instance__f32.html#ac342f3248157cbbd2f04a3c8ec9fc9eb">bitReverseFlagR</a> == 1u)
146 <a name="l00190"></a>00190 {
147 <a name="l00191"></a>00191 <a class="code" href="arm__cfft__radix4__f32_8c.html#a3d4062fdfa6aaa3f51f41cab868e508b" title="In-place bit reversal function.">arm_bitreversal_f32</a>(pSrc, S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a7e6a6d290ce158ce9a15a45e364b021a">fftLen</a>,
148 <a name="l00192"></a>00192 S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#acc8cb18a8b901b8321ab9d86491e41a3">bitRevFactor</a>, S_CFFT-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a8da0d2ca69749fde8cbb95caeac6fe6a">pBitRevTable</a>);
149 <a name="l00193"></a>00193 }
150 <a name="l00194"></a>00194
151 <a name="l00195"></a>00195
152 <a name="l00196"></a>00196 <span class="comment">/* Real FFT core process */</span>
153 <a name="l00197"></a>00197 <a class="code" href="arm__rfft__f32_8c.html#a6cfdb6bdc66b13732ef2351caf98fdbb" title="Core Real FFT process.">arm_split_rfft_f32</a>(pSrc, S-><a class="code" href="structarm__rfft__instance__f32.html#a075076e07ebb8521d8e3b49a31db6c57">fftLenBy2</a>, S-><a class="code" href="structarm__rfft__instance__f32.html#a534cc7e6e9b3e3dd022fad611c762142">pTwiddleAReal</a>,
154 <a name="l00198"></a>00198 S-><a class="code" href="structarm__rfft__instance__f32.html#a23543ecfd027fea2477fe1eea23c3c4d">pTwiddleBReal</a>, pDst, S-><a class="code" href="structarm__rfft__instance__f32.html#aede85350fb5ae6baa1b3e8bfa15b18d6">twidCoefRModifier</a>);
155 <a name="l00199"></a>00199 }
156 <a name="l00200"></a>00200
157 <a name="l00201"></a>00201 }
158 <a name="l00202"></a>00202
159 <a name="l00218"></a><a class="code" href="arm__rfft__f32_8c.html#a6cfdb6bdc66b13732ef2351caf98fdbb">00218</a> <span class="keywordtype">void</span> <a class="code" href="arm__rfft__f32_8c.html#a6cfdb6bdc66b13732ef2351caf98fdbb" title="Core Real FFT process.">arm_split_rfft_f32</a>(
160 <a name="l00219"></a>00219 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc,
161 <a name="l00220"></a>00220 uint32_t fftLen,
162 <a name="l00221"></a>00221 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pATable,
163 <a name="l00222"></a>00222 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pBTable,
164 <a name="l00223"></a>00223 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pDst,
165 <a name="l00224"></a>00224 uint32_t modifier)
166 <a name="l00225"></a>00225 {
167 <a name="l00226"></a>00226 uint32_t i; <span class="comment">/* Loop Counter */</span>
168 <a name="l00227"></a>00227 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> outR, outI; <span class="comment">/* Temporary variables for output */</span>
169 <a name="l00228"></a>00228 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> *pCoefA, *pCoefB; <span class="comment">/* Temporary pointers for twiddle factors */</span>
170 <a name="l00229"></a>00229 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> CoefA1, CoefA2, CoefB1; <span class="comment">/* Temporary variables for twiddle coefficients */</span>
171 <a name="l00230"></a>00230 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> *pDst1 = &pDst[2], *pDst2 = &pDst[(4u * fftLen) - 1u]; <span class="comment">/* temp pointers for output buffer */</span>
172 <a name="l00231"></a>00231 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> *pSrc1 = &pSrc[2], *pSrc2 = &pSrc[(2u * fftLen) - 1u]; <span class="comment">/* temp pointers for input buffer */</span>
173 <a name="l00232"></a>00232
174 <a name="l00233"></a>00233
175 <a name="l00234"></a>00234 pSrc[2u * fftLen] = pSrc[0];
176 <a name="l00235"></a>00235 pSrc[(2u * fftLen) + 1u] = pSrc[1];
177 <a name="l00236"></a>00236
178 <a name="l00237"></a>00237 <span class="comment">/* Init coefficient pointers */</span>
179 <a name="l00238"></a>00238 pCoefA = &pATable[modifier * 2u];
180 <a name="l00239"></a>00239 pCoefB = &pBTable[modifier * 2u];
181 <a name="l00240"></a>00240
182 <a name="l00241"></a>00241 i = fftLen - 1u;
183 <a name="l00242"></a>00242
184 <a name="l00243"></a>00243 <span class="keywordflow">while</span>(i > 0u)
185 <a name="l00244"></a>00244 {
186 <a name="l00245"></a>00245 <span class="comment">/* </span>
187 <a name="l00246"></a>00246 <span class="comment"> outR = (pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1] </span>
188 <a name="l00247"></a>00247 <span class="comment"> + pSrc[2 * n - 2 * i] * pBTable[2 * i] + </span>
189 <a name="l00248"></a>00248 <span class="comment"> pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]); </span>
190 <a name="l00249"></a>00249 <span class="comment"> */</span>
191 <a name="l00250"></a>00250
192 <a name="l00251"></a>00251 <span class="comment">/* outI = (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] + </span>
193 <a name="l00252"></a>00252 <span class="comment"> pIn[2 * n - 2 * i] * pBTable[2 * i + 1] - </span>
194 <a name="l00253"></a>00253 <span class="comment"> pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); */</span>
195 <a name="l00254"></a>00254
196 <a name="l00255"></a>00255 <span class="comment">/* read pATable[2 * i] */</span>
197 <a name="l00256"></a>00256 CoefA1 = *pCoefA++;
198 <a name="l00257"></a>00257 <span class="comment">/* pATable[2 * i + 1] */</span>
199 <a name="l00258"></a>00258 CoefA2 = *pCoefA;
200 <a name="l00259"></a>00259
201 <a name="l00260"></a>00260 <span class="comment">/* pSrc[2 * i] * pATable[2 * i] */</span>
202 <a name="l00261"></a>00261 outR = *pSrc1 * CoefA1;
203 <a name="l00262"></a>00262 <span class="comment">/* pSrc[2 * i] * CoefA2 */</span>
204 <a name="l00263"></a>00263 outI = *pSrc1++ * CoefA2;
205 <a name="l00264"></a>00264
206 <a name="l00265"></a>00265 <span class="comment">/* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */</span>
207 <a name="l00266"></a>00266 outR -= (*pSrc1 + *pSrc2) * CoefA2;
208 <a name="l00267"></a>00267 <span class="comment">/* pSrc[2 * i + 1] * CoefA1 */</span>
209 <a name="l00268"></a>00268 outI += *pSrc1++ * CoefA1;
210 <a name="l00269"></a>00269
211 <a name="l00270"></a>00270 CoefB1 = *pCoefB;
212 <a name="l00271"></a>00271
213 <a name="l00272"></a>00272 <span class="comment">/* pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */</span>
214 <a name="l00273"></a>00273 outI -= *pSrc2-- * CoefB1;
215 <a name="l00274"></a>00274 <span class="comment">/* pSrc[2 * fftLen - 2 * i] * CoefA2 */</span>
216 <a name="l00275"></a>00275 outI -= *pSrc2 * CoefA2;
217 <a name="l00276"></a>00276
218 <a name="l00277"></a>00277 <span class="comment">/* pSrc[2 * fftLen - 2 * i] * CoefB1 */</span>
219 <a name="l00278"></a>00278 outR += *pSrc2-- * CoefB1;
220 <a name="l00279"></a>00279
221 <a name="l00280"></a>00280 <span class="comment">/* write output */</span>
222 <a name="l00281"></a>00281 *pDst1++ = outR;
223 <a name="l00282"></a>00282 *pDst1++ = outI;
224 <a name="l00283"></a>00283
225 <a name="l00284"></a>00284 <span class="comment">/* write complex conjugate output */</span>
226 <a name="l00285"></a>00285 *pDst2-- = -outI;
227 <a name="l00286"></a>00286 *pDst2-- = outR;
228 <a name="l00287"></a>00287
229 <a name="l00288"></a>00288 <span class="comment">/* update coefficient pointer */</span>
230 <a name="l00289"></a>00289 pCoefB = pCoefB + (modifier * 2u);
231 <a name="l00290"></a>00290 pCoefA = pCoefA + ((modifier * 2u) - 1u);
232 <a name="l00291"></a>00291
233 <a name="l00292"></a>00292 i--;
234 <a name="l00293"></a>00293
235 <a name="l00294"></a>00294 }
236 <a name="l00295"></a>00295
237 <a name="l00296"></a>00296 pDst[2u * fftLen] = pSrc[0] - pSrc[1];
238 <a name="l00297"></a>00297 pDst[(2u * fftLen) + 1u] = 0.0f;
239 <a name="l00298"></a>00298
240 <a name="l00299"></a>00299 pDst[0] = pSrc[0] + pSrc[1];
241 <a name="l00300"></a>00300 pDst[1] = 0.0f;
242 <a name="l00301"></a>00301
243 <a name="l00302"></a>00302 }
244 <a name="l00303"></a>00303
245 <a name="l00304"></a>00304
246 <a name="l00316"></a><a class="code" href="arm__rfft__f32_8c.html#a585bef78c103d150a116241a4feb6442">00316</a> <span class="keywordtype">void</span> <a class="code" href="arm__rfft__f32_8c.html#a585bef78c103d150a116241a4feb6442" title="Core Real IFFT process.">arm_split_rifft_f32</a>(
247 <a name="l00317"></a>00317 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc,
248 <a name="l00318"></a>00318 uint32_t fftLen,
249 <a name="l00319"></a>00319 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pATable,
250 <a name="l00320"></a>00320 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pBTable,
251 <a name="l00321"></a>00321 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pDst,
252 <a name="l00322"></a>00322 uint32_t modifier)
253 <a name="l00323"></a>00323 {
254 <a name="l00324"></a>00324 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> outR, outI; <span class="comment">/* Temporary variables for output */</span>
255 <a name="l00325"></a>00325 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> *pCoefA, *pCoefB; <span class="comment">/* Temporary pointers for twiddle factors */</span>
256 <a name="l00326"></a>00326 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> CoefA1, CoefA2, CoefB1; <span class="comment">/* Temporary variables for twiddle coefficients */</span>
257 <a name="l00327"></a>00327 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> *pSrc1 = &pSrc[0], *pSrc2 = &pSrc[(2u * fftLen) + 1u];
258 <a name="l00328"></a>00328
259 <a name="l00329"></a>00329 pCoefA = &pATable[0];
260 <a name="l00330"></a>00330 pCoefB = &pBTable[0];
261 <a name="l00331"></a>00331
262 <a name="l00332"></a>00332 <span class="keywordflow">while</span>(fftLen > 0u)
263 <a name="l00333"></a>00333 {
264 <a name="l00334"></a>00334 <span class="comment">/* </span>
265 <a name="l00335"></a>00335 <span class="comment"> outR = (pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] + </span>
266 <a name="l00336"></a>00336 <span class="comment"> pIn[2 * n - 2 * i] * pBTable[2 * i] - </span>
267 <a name="l00337"></a>00337 <span class="comment"> pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]); </span>
268 <a name="l00338"></a>00338 <span class="comment"></span>
269 <a name="l00339"></a>00339 <span class="comment"> outI = (pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] - </span>
270 <a name="l00340"></a>00340 <span class="comment"> pIn[2 * n - 2 * i] * pBTable[2 * i + 1] - </span>
271 <a name="l00341"></a>00341 <span class="comment"> pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); </span>
272 <a name="l00342"></a>00342 <span class="comment"></span>
273 <a name="l00343"></a>00343 <span class="comment"> */</span>
274 <a name="l00344"></a>00344
275 <a name="l00345"></a>00345 CoefA1 = *pCoefA++;
276 <a name="l00346"></a>00346 CoefA2 = *pCoefA;
277 <a name="l00347"></a>00347
278 <a name="l00348"></a>00348 <span class="comment">/* outR = (pSrc[2 * i] * CoefA1 */</span>
279 <a name="l00349"></a>00349 outR = *pSrc1 * CoefA1;
280 <a name="l00350"></a>00350
281 <a name="l00351"></a>00351 <span class="comment">/* - pSrc[2 * i] * CoefA2 */</span>
282 <a name="l00352"></a>00352 outI = -(*pSrc1++) * CoefA2;
283 <a name="l00353"></a>00353
284 <a name="l00354"></a>00354 <span class="comment">/* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */</span>
285 <a name="l00355"></a>00355 outR += (*pSrc1 + *pSrc2) * CoefA2;
286 <a name="l00356"></a>00356
287 <a name="l00357"></a>00357 <span class="comment">/* pSrc[2 * i + 1] * CoefA1 */</span>
288 <a name="l00358"></a>00358 outI += (*pSrc1++) * CoefA1;
289 <a name="l00359"></a>00359
290 <a name="l00360"></a>00360 CoefB1 = *pCoefB;
291 <a name="l00361"></a>00361
292 <a name="l00362"></a>00362 <span class="comment">/* - pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */</span>
293 <a name="l00363"></a>00363 outI -= *pSrc2-- * CoefB1;
294 <a name="l00364"></a>00364
295 <a name="l00365"></a>00365 <span class="comment">/* pSrc[2 * fftLen - 2 * i] * CoefB1 */</span>
296 <a name="l00366"></a>00366 outR += *pSrc2 * CoefB1;
297 <a name="l00367"></a>00367
298 <a name="l00368"></a>00368 <span class="comment">/* pSrc[2 * fftLen - 2 * i] * CoefA2 */</span>
299 <a name="l00369"></a>00369 outI += *pSrc2-- * CoefA2;
300 <a name="l00370"></a>00370
301 <a name="l00371"></a>00371 <span class="comment">/* write output */</span>
302 <a name="l00372"></a>00372 *pDst++ = outR;
303 <a name="l00373"></a>00373 *pDst++ = outI;
304 <a name="l00374"></a>00374
305 <a name="l00375"></a>00375 <span class="comment">/* update coefficient pointer */</span>
306 <a name="l00376"></a>00376 pCoefB = pCoefB + (modifier * 2u);
307 <a name="l00377"></a>00377 pCoefA = pCoefA + ((modifier * 2u) - 1u);
308 <a name="l00378"></a>00378
309 <a name="l00379"></a>00379 <span class="comment">/* Decrement loop count */</span>
310 <a name="l00380"></a>00380 fftLen--;
311 <a name="l00381"></a>00381 }
312 <a name="l00382"></a>00382
313 <a name="l00383"></a>00383 }
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