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| <h1>arm_cfft_radix4_f32.c</h1> </div> |
| </div> |
| <div class="contents"> |
| <a href="arm__cfft__radix4__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> |
| <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_cfft_radix4_f32.c </span> |
| <a name="l00009"></a>00009 <span class="comment">* </span> |
| <a name="l00010"></a>00010 <span class="comment">* Description: Radix-4 Decimation in Frequency CFFT & CIFFT Floating point processing function </span> |
| <a name="l00011"></a>00011 <span class="comment">* </span> |
| <a name="l00012"></a>00012 <span class="comment">* </span> |
| <a name="l00013"></a>00013 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0</span> |
| <a name="l00014"></a>00014 <span class="comment">* </span> |
| <a name="l00015"></a>00015 <span class="comment">* Version 1.0.10 2011/7/15 </span> |
| <a name="l00016"></a>00016 <span class="comment">* Big Endian support added and Merged M0 and M3/M4 Source code. </span> |
| <a name="l00017"></a>00017 <span class="comment">* </span> |
| <a name="l00018"></a>00018 <span class="comment">* Version 1.0.3 2010/11/29 </span> |
| <a name="l00019"></a>00019 <span class="comment">* Re-organized the CMSIS folders and updated documentation. </span> |
| <a name="l00020"></a>00020 <span class="comment">* </span> |
| <a name="l00021"></a>00021 <span class="comment">* Version 1.0.2 2010/11/11 </span> |
| <a name="l00022"></a>00022 <span class="comment">* Documentation updated. </span> |
| <a name="l00023"></a>00023 <span class="comment">* </span> |
| <a name="l00024"></a>00024 <span class="comment">* Version 1.0.1 2010/10/05 </span> |
| <a name="l00025"></a>00025 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00026"></a>00026 <span class="comment">* </span> |
| <a name="l00027"></a>00027 <span class="comment">* Version 1.0.0 2010/09/20 </span> |
| <a name="l00028"></a>00028 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00029"></a>00029 <span class="comment">* </span> |
| <a name="l00030"></a>00030 <span class="comment">* Version 0.0.5 2010/04/26 </span> |
| <a name="l00031"></a>00031 <span class="comment">* incorporated review comments and updated with latest CMSIS layer </span> |
| <a name="l00032"></a>00032 <span class="comment">* </span> |
| <a name="l00033"></a>00033 <span class="comment">* Version 0.0.3 2010/03/10 </span> |
| <a name="l00034"></a>00034 <span class="comment">* Initial version </span> |
| <a name="l00035"></a>00035 <span class="comment">* -------------------------------------------------------------------- */</span> |
| <a name="l00036"></a>00036 |
| <a name="l00037"></a>00037 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span> |
| <a name="l00038"></a>00038 |
| <a name="l00177"></a><a class="code" href="group___c_f_f_t___c_i_f_f_t.html#ga521f670cd9c571bc61aff9bec89f4c26">00177</a> <span class="keywordtype">void</span> <a class="code" href="group___c_f_f_t___c_i_f_f_t.html#ga521f670cd9c571bc61aff9bec89f4c26" title="Processing function for the floating-point CFFT/CIFFT.">arm_cfft_radix4_f32</a>( |
| <a name="l00178"></a>00178 <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, |
| <a name="l00179"></a>00179 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc) |
| <a name="l00180"></a>00180 { |
| <a name="l00181"></a>00181 |
| <a name="l00182"></a>00182 <span class="keywordflow">if</span>(S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a25d1da64dd6487c291f04d226f9acc66">ifftFlag</a> == 1u) |
| <a name="l00183"></a>00183 { |
| <a name="l00184"></a>00184 <span class="comment">/* Complex IFFT radix-4 */</span> |
| <a name="l00185"></a>00185 <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>(pSrc, S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a7e6a6d290ce158ce9a15a45e364b021a">fftLen</a>, S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a14860c7544911702ca1fa0bf78204ef3">pTwiddle</a>, |
| <a name="l00186"></a>00186 S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#abe31ea2157dfa233e389cdfd3b9993ee">twidCoefModifier</a>, S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#ab9eed39e40b8d7c16381fbccf84467cd">onebyfftLen</a>); |
| <a name="l00187"></a>00187 } |
| <a name="l00188"></a>00188 <span class="keywordflow">else</span> |
| <a name="l00189"></a>00189 { |
| <a name="l00190"></a>00190 <span class="comment">/* Complex FFT radix-4 */</span> |
| <a name="l00191"></a>00191 <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-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a7e6a6d290ce158ce9a15a45e364b021a">fftLen</a>, S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a14860c7544911702ca1fa0bf78204ef3">pTwiddle</a>, |
| <a name="l00192"></a>00192 S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#abe31ea2157dfa233e389cdfd3b9993ee">twidCoefModifier</a>); |
| <a name="l00193"></a>00193 } |
| <a name="l00194"></a>00194 |
| <a name="l00195"></a>00195 <span class="keywordflow">if</span>(S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#ac10927a1620195a88649ce63dab66120">bitReverseFlag</a> == 1u) |
| <a name="l00196"></a>00196 { |
| <a name="l00197"></a>00197 <span class="comment">/* Bit Reversal */</span> |
| <a name="l00198"></a>00198 <a class="code" href="arm__cfft__radix4__f32_8c.html#a3d4062fdfa6aaa3f51f41cab868e508b" title="In-place bit reversal function.">arm_bitreversal_f32</a>(pSrc, S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a7e6a6d290ce158ce9a15a45e364b021a">fftLen</a>, S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#acc8cb18a8b901b8321ab9d86491e41a3">bitRevFactor</a>, S-><a class="code" href="structarm__cfft__radix4__instance__f32.html#a8da0d2ca69749fde8cbb95caeac6fe6a">pBitRevTable</a>); |
| <a name="l00199"></a>00199 } |
| <a name="l00200"></a>00200 |
| <a name="l00201"></a>00201 } |
| <a name="l00202"></a>00202 |
| <a name="l00203"></a>00203 |
| <a name="l00210"></a>00210 <span class="comment">/* ---------------------------------------------------------------------- </span> |
| <a name="l00211"></a>00211 <span class="comment">** Internal helper function used by the FFTs </span> |
| <a name="l00212"></a>00212 <span class="comment">** ------------------------------------------------------------------- */</span> |
| <a name="l00213"></a>00213 |
| <a name="l00214"></a>00214 <span class="comment">/* </span> |
| <a name="l00215"></a>00215 <span class="comment"> * @brief Core function for the floating-point CFFT butterfly process. </span> |
| <a name="l00216"></a>00216 <span class="comment"> * @param[in, out] *pSrc points to the in-place buffer of floating-point data type. </span> |
| <a name="l00217"></a>00217 <span class="comment"> * @param[in] fftLen length of the FFT. </span> |
| <a name="l00218"></a>00218 <span class="comment"> * @param[in] *pCoef points to the twiddle coefficient buffer. </span> |
| <a name="l00219"></a>00219 <span class="comment"> * @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. </span> |
| <a name="l00220"></a>00220 <span class="comment"> * @return none. </span> |
| <a name="l00221"></a>00221 <span class="comment"> */</span> |
| <a name="l00222"></a>00222 |
| <a name="l00223"></a><a class="code" href="arm__math_8h.html#ae239ddf995d1607115f9e84d5c069b9c">00223</a> <span class="keywordtype">void</span> <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>( |
| <a name="l00224"></a>00224 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc, |
| <a name="l00225"></a>00225 uint16_t fftLen, |
| <a name="l00226"></a>00226 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pCoef, |
| <a name="l00227"></a>00227 uint16_t twidCoefModifier) |
| <a name="l00228"></a>00228 { |
| <a name="l00229"></a>00229 |
| <a name="l00230"></a>00230 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> co1, co2, co3, si1, si2, si3; |
| <a name="l00231"></a>00231 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> t1, t2, r1, r2, s1, s2; |
| <a name="l00232"></a>00232 uint32_t ia1, ia2, ia3; |
| <a name="l00233"></a>00233 uint32_t i0, i1, i2, i3; |
| <a name="l00234"></a>00234 uint32_t n1, n2, j, k; |
| <a name="l00235"></a>00235 |
| <a name="l00236"></a>00236 <span class="preprocessor">#ifndef ARM_MATH_CM0</span> |
| <a name="l00237"></a>00237 <span class="preprocessor"></span> |
| <a name="l00238"></a>00238 <span class="comment">/* Run the below code for Cortex-M4 and Cortex-M3 */</span> |
| <a name="l00239"></a>00239 |
| <a name="l00240"></a>00240 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00241"></a>00241 n2 = fftLen; |
| <a name="l00242"></a>00242 n1 = n2; |
| <a name="l00243"></a>00243 |
| <a name="l00244"></a>00244 <span class="comment">/* n2 = fftLen/4 */</span> |
| <a name="l00245"></a>00245 n2 >>= 2u; |
| <a name="l00246"></a>00246 i0 = 0u; |
| <a name="l00247"></a>00247 ia1 = 0u; |
| <a name="l00248"></a>00248 |
| <a name="l00249"></a>00249 j = n2; |
| <a name="l00250"></a>00250 |
| <a name="l00251"></a>00251 <span class="comment">/* Calculation of first stage */</span> |
| <a name="l00252"></a>00252 <span class="keywordflow">do</span> |
| <a name="l00253"></a>00253 { |
| <a name="l00254"></a>00254 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00255"></a>00255 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00256"></a>00256 i1 = i0 + n2; |
| <a name="l00257"></a>00257 i2 = i1 + n2; |
| <a name="l00258"></a>00258 i3 = i2 + n2; |
| <a name="l00259"></a>00259 |
| <a name="l00260"></a>00260 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00261"></a>00261 |
| <a name="l00262"></a>00262 <span class="comment">/* xa + xc */</span> |
| <a name="l00263"></a>00263 r1 = pSrc[(2u * i0)] + pSrc[(2u * i2)]; |
| <a name="l00264"></a>00264 |
| <a name="l00265"></a>00265 <span class="comment">/* xa - xc */</span> |
| <a name="l00266"></a>00266 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l00267"></a>00267 |
| <a name="l00268"></a>00268 <span class="comment">/* ya + yc */</span> |
| <a name="l00269"></a>00269 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00270"></a>00270 |
| <a name="l00271"></a>00271 <span class="comment">/* ya - yc */</span> |
| <a name="l00272"></a>00272 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00273"></a>00273 |
| <a name="l00274"></a>00274 <span class="comment">/* xb + xd */</span> |
| <a name="l00275"></a>00275 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00276"></a>00276 |
| <a name="l00277"></a>00277 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00278"></a>00278 pSrc[2u * i0] = r1 + t1; |
| <a name="l00279"></a>00279 |
| <a name="l00280"></a>00280 <span class="comment">/* (xa + xc) - (xb + xd) */</span> |
| <a name="l00281"></a>00281 r1 = r1 - t1; |
| <a name="l00282"></a>00282 |
| <a name="l00283"></a>00283 <span class="comment">/* yb + yd */</span> |
| <a name="l00284"></a>00284 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00285"></a>00285 |
| <a name="l00286"></a>00286 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00287"></a>00287 pSrc[(2u * i0) + 1u] = s1 + t2; |
| <a name="l00288"></a>00288 |
| <a name="l00289"></a>00289 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00290"></a>00290 s1 = s1 - t2; |
| <a name="l00291"></a>00291 |
| <a name="l00292"></a>00292 <span class="comment">/* yb - yd */</span> |
| <a name="l00293"></a>00293 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00294"></a>00294 |
| <a name="l00295"></a>00295 <span class="comment">/* xb - xd */</span> |
| <a name="l00296"></a>00296 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00297"></a>00297 |
| <a name="l00298"></a>00298 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00299"></a>00299 ia2 = ia1 + ia1; |
| <a name="l00300"></a>00300 co2 = pCoef[ia2 * 2u]; |
| <a name="l00301"></a>00301 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00302"></a>00302 |
| <a name="l00303"></a>00303 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00304"></a>00304 pSrc[2u * i1] = (r1 * co2) + (s1 * si2); |
| <a name="l00305"></a>00305 |
| <a name="l00306"></a>00306 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00307"></a>00307 pSrc[(2u * i1) + 1u] = (s1 * co2) - (r1 * si2); |
| <a name="l00308"></a>00308 |
| <a name="l00309"></a>00309 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00310"></a>00310 r1 = r2 + t1; |
| <a name="l00311"></a>00311 |
| <a name="l00312"></a>00312 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00313"></a>00313 r2 = r2 - t1; |
| <a name="l00314"></a>00314 |
| <a name="l00315"></a>00315 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00316"></a>00316 s1 = s2 - t2; |
| <a name="l00317"></a>00317 |
| <a name="l00318"></a>00318 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00319"></a>00319 s2 = s2 + t2; |
| <a name="l00320"></a>00320 |
| <a name="l00321"></a>00321 co1 = pCoef[ia1 * 2u]; |
| <a name="l00322"></a>00322 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00323"></a>00323 |
| <a name="l00324"></a>00324 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00325"></a>00325 pSrc[2u * i2] = (r1 * co1) + (s1 * si1); |
| <a name="l00326"></a>00326 |
| <a name="l00327"></a>00327 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00328"></a>00328 pSrc[(2u * i2) + 1u] = (s1 * co1) - (r1 * si1); |
| <a name="l00329"></a>00329 |
| <a name="l00330"></a>00330 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00331"></a>00331 ia3 = ia2 + ia1; |
| <a name="l00332"></a>00332 co3 = pCoef[ia3 * 2u]; |
| <a name="l00333"></a>00333 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00334"></a>00334 |
| <a name="l00335"></a>00335 |
| <a name="l00336"></a>00336 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00337"></a>00337 pSrc[2u * i3] = (r2 * co3) + (s2 * si3); |
| <a name="l00338"></a>00338 |
| <a name="l00339"></a>00339 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00340"></a>00340 pSrc[(2u * i3) + 1u] = (s2 * co3) - (r2 * si3); |
| <a name="l00341"></a>00341 |
| <a name="l00342"></a>00342 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00343"></a>00343 ia1 = ia1 + twidCoefModifier; |
| <a name="l00344"></a>00344 |
| <a name="l00345"></a>00345 <span class="comment">/* Updating input index */</span> |
| <a name="l00346"></a>00346 i0 = i0 + 1u; |
| <a name="l00347"></a>00347 |
| <a name="l00348"></a>00348 } |
| <a name="l00349"></a>00349 <span class="keywordflow">while</span>(--j); |
| <a name="l00350"></a>00350 |
| <a name="l00351"></a>00351 twidCoefModifier <<= 2u; |
| <a name="l00352"></a>00352 |
| <a name="l00353"></a>00353 <span class="comment">/* Calculation of second stage to excluding last stage */</span> |
| <a name="l00354"></a>00354 <span class="keywordflow">for</span> (k = fftLen / 4; k > 4u; k >>= 2u) |
| <a name="l00355"></a>00355 { |
| <a name="l00356"></a>00356 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00357"></a>00357 n1 = n2; |
| <a name="l00358"></a>00358 n2 >>= 2u; |
| <a name="l00359"></a>00359 ia1 = 0u; |
| <a name="l00360"></a>00360 |
| <a name="l00361"></a>00361 <span class="comment">/* Calculation of first stage */</span> |
| <a name="l00362"></a>00362 <span class="keywordflow">for</span> (j = 0u; j <= (n2 - 1u); j++) |
| <a name="l00363"></a>00363 { |
| <a name="l00364"></a>00364 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00365"></a>00365 ia2 = ia1 + ia1; |
| <a name="l00366"></a>00366 ia3 = ia2 + ia1; |
| <a name="l00367"></a>00367 co1 = pCoef[ia1 * 2u]; |
| <a name="l00368"></a>00368 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00369"></a>00369 co2 = pCoef[ia2 * 2u]; |
| <a name="l00370"></a>00370 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00371"></a>00371 co3 = pCoef[ia3 * 2u]; |
| <a name="l00372"></a>00372 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00373"></a>00373 |
| <a name="l00374"></a>00374 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00375"></a>00375 ia1 = ia1 + twidCoefModifier; |
| <a name="l00376"></a>00376 |
| <a name="l00377"></a>00377 <span class="keywordflow">for</span> (i0 = j; i0 < fftLen; i0 += n1) |
| <a name="l00378"></a>00378 { |
| <a name="l00379"></a>00379 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00380"></a>00380 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00381"></a>00381 i1 = i0 + n2; |
| <a name="l00382"></a>00382 i2 = i1 + n2; |
| <a name="l00383"></a>00383 i3 = i2 + n2; |
| <a name="l00384"></a>00384 |
| <a name="l00385"></a>00385 <span class="comment">/* xa + xc */</span> |
| <a name="l00386"></a>00386 r1 = pSrc[(2u * i0)] + pSrc[(2u * i2)]; |
| <a name="l00387"></a>00387 |
| <a name="l00388"></a>00388 <span class="comment">/* xa - xc */</span> |
| <a name="l00389"></a>00389 r2 = pSrc[(2u * i0)] - pSrc[(2u * i2)]; |
| <a name="l00390"></a>00390 |
| <a name="l00391"></a>00391 <span class="comment">/* ya + yc */</span> |
| <a name="l00392"></a>00392 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00393"></a>00393 |
| <a name="l00394"></a>00394 <span class="comment">/* ya - yc */</span> |
| <a name="l00395"></a>00395 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00396"></a>00396 |
| <a name="l00397"></a>00397 <span class="comment">/* xb + xd */</span> |
| <a name="l00398"></a>00398 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00399"></a>00399 |
| <a name="l00400"></a>00400 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00401"></a>00401 pSrc[2u * i0] = r1 + t1; |
| <a name="l00402"></a>00402 |
| <a name="l00403"></a>00403 <span class="comment">/* xa + xc -(xb + xd) */</span> |
| <a name="l00404"></a>00404 r1 = r1 - t1; |
| <a name="l00405"></a>00405 |
| <a name="l00406"></a>00406 <span class="comment">/* yb + yd */</span> |
| <a name="l00407"></a>00407 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00408"></a>00408 |
| <a name="l00409"></a>00409 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00410"></a>00410 pSrc[(2u * i0) + 1u] = s1 + t2; |
| <a name="l00411"></a>00411 |
| <a name="l00412"></a>00412 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00413"></a>00413 s1 = s1 - t2; |
| <a name="l00414"></a>00414 |
| <a name="l00415"></a>00415 <span class="comment">/* (yb - yd) */</span> |
| <a name="l00416"></a>00416 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00417"></a>00417 |
| <a name="l00418"></a>00418 <span class="comment">/* (xb - xd) */</span> |
| <a name="l00419"></a>00419 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00420"></a>00420 |
| <a name="l00421"></a>00421 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00422"></a>00422 pSrc[2u * i1] = (r1 * co2) + (s1 * si2); |
| <a name="l00423"></a>00423 |
| <a name="l00424"></a>00424 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00425"></a>00425 pSrc[(2u * i1) + 1u] = (s1 * co2) - (r1 * si2); |
| <a name="l00426"></a>00426 |
| <a name="l00427"></a>00427 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00428"></a>00428 r1 = r2 + t1; |
| <a name="l00429"></a>00429 |
| <a name="l00430"></a>00430 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00431"></a>00431 r2 = r2 - t1; |
| <a name="l00432"></a>00432 |
| <a name="l00433"></a>00433 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00434"></a>00434 s1 = s2 - t2; |
| <a name="l00435"></a>00435 |
| <a name="l00436"></a>00436 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00437"></a>00437 s2 = s2 + t2; |
| <a name="l00438"></a>00438 |
| <a name="l00439"></a>00439 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00440"></a>00440 pSrc[2u * i2] = (r1 * co1) + (s1 * si1); |
| <a name="l00441"></a>00441 |
| <a name="l00442"></a>00442 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00443"></a>00443 pSrc[(2u * i2) + 1u] = (s1 * co1) - (r1 * si1); |
| <a name="l00444"></a>00444 |
| <a name="l00445"></a>00445 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00446"></a>00446 pSrc[2u * i3] = (r2 * co3) + (s2 * si3); |
| <a name="l00447"></a>00447 |
| <a name="l00448"></a>00448 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00449"></a>00449 pSrc[(2u * i3) + 1u] = (s2 * co3) - (r2 * si3); |
| <a name="l00450"></a>00450 } |
| <a name="l00451"></a>00451 } |
| <a name="l00452"></a>00452 twidCoefModifier <<= 2u; |
| <a name="l00453"></a>00453 } |
| <a name="l00454"></a>00454 |
| <a name="l00455"></a>00455 <span class="comment">/* Initializations of last stage */</span> |
| <a name="l00456"></a>00456 n1 = n2; |
| <a name="l00457"></a>00457 n2 >>= 2u; |
| <a name="l00458"></a>00458 |
| <a name="l00459"></a>00459 <span class="comment">/* Calculations of last stage */</span> |
| <a name="l00460"></a>00460 <span class="keywordflow">for</span> (i0 = 0u; i0 <= (fftLen - n1); i0 += n1) |
| <a name="l00461"></a>00461 { |
| <a name="l00462"></a>00462 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00463"></a>00463 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00464"></a>00464 i1 = i0 + n2; |
| <a name="l00465"></a>00465 i2 = i1 + n2; |
| <a name="l00466"></a>00466 i3 = i2 + n2; |
| <a name="l00467"></a>00467 |
| <a name="l00468"></a>00468 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00469"></a>00469 |
| <a name="l00470"></a>00470 <span class="comment">/* xa + xb */</span> |
| <a name="l00471"></a>00471 r1 = pSrc[2u * i0] + pSrc[2u * i2]; |
| <a name="l00472"></a>00472 |
| <a name="l00473"></a>00473 <span class="comment">/* xa - xb */</span> |
| <a name="l00474"></a>00474 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l00475"></a>00475 |
| <a name="l00476"></a>00476 <span class="comment">/* ya + yc */</span> |
| <a name="l00477"></a>00477 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00478"></a>00478 |
| <a name="l00479"></a>00479 <span class="comment">/* ya - yc */</span> |
| <a name="l00480"></a>00480 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00481"></a>00481 |
| <a name="l00482"></a>00482 <span class="comment">/* xc + xd */</span> |
| <a name="l00483"></a>00483 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00484"></a>00484 |
| <a name="l00485"></a>00485 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00486"></a>00486 pSrc[2u * i0] = r1 + t1; |
| <a name="l00487"></a>00487 |
| <a name="l00488"></a>00488 <span class="comment">/* (xa + xb) - (xc + xd) */</span> |
| <a name="l00489"></a>00489 r1 = r1 - t1; |
| <a name="l00490"></a>00490 |
| <a name="l00491"></a>00491 <span class="comment">/* yb + yd */</span> |
| <a name="l00492"></a>00492 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00493"></a>00493 |
| <a name="l00494"></a>00494 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00495"></a>00495 pSrc[(2u * i0) + 1u] = s1 + t2; |
| <a name="l00496"></a>00496 |
| <a name="l00497"></a>00497 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00498"></a>00498 s1 = s1 - t2; |
| <a name="l00499"></a>00499 |
| <a name="l00500"></a>00500 <span class="comment">/* (yb-yd) */</span> |
| <a name="l00501"></a>00501 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00502"></a>00502 |
| <a name="l00503"></a>00503 <span class="comment">/* (xb-xd) */</span> |
| <a name="l00504"></a>00504 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00505"></a>00505 |
| <a name="l00506"></a>00506 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00507"></a>00507 pSrc[2u * i1] = r1; |
| <a name="l00508"></a>00508 |
| <a name="l00509"></a>00509 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00510"></a>00510 pSrc[(2u * i1) + 1u] = s1; |
| <a name="l00511"></a>00511 |
| <a name="l00512"></a>00512 <span class="comment">/* (xa+yb-xc-yd) */</span> |
| <a name="l00513"></a>00513 r1 = r2 + t1; |
| <a name="l00514"></a>00514 |
| <a name="l00515"></a>00515 <span class="comment">/* (xa-yb-xc+yd) */</span> |
| <a name="l00516"></a>00516 r2 = r2 - t1; |
| <a name="l00517"></a>00517 |
| <a name="l00518"></a>00518 <span class="comment">/* (ya-xb-yc+xd) */</span> |
| <a name="l00519"></a>00519 s1 = s2 - t2; |
| <a name="l00520"></a>00520 |
| <a name="l00521"></a>00521 <span class="comment">/* (ya+xb-yc-xd) */</span> |
| <a name="l00522"></a>00522 s2 = s2 + t2; |
| <a name="l00523"></a>00523 |
| <a name="l00524"></a>00524 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00525"></a>00525 pSrc[2u * i2] = r1; |
| <a name="l00526"></a>00526 |
| <a name="l00527"></a>00527 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00528"></a>00528 pSrc[(2u * i2) + 1u] = s1; |
| <a name="l00529"></a>00529 |
| <a name="l00530"></a>00530 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00531"></a>00531 pSrc[2u * i3] = r2; |
| <a name="l00532"></a>00532 |
| <a name="l00533"></a>00533 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00534"></a>00534 pSrc[(2u * i3) + 1u] = s2; |
| <a name="l00535"></a>00535 } |
| <a name="l00536"></a>00536 |
| <a name="l00537"></a>00537 |
| <a name="l00538"></a>00538 <span class="preprocessor">#else</span> |
| <a name="l00539"></a>00539 <span class="preprocessor"></span> |
| <a name="l00540"></a>00540 <span class="comment">/* Run the below code for Cortex-M0 */</span> |
| <a name="l00541"></a>00541 |
| <a name="l00542"></a>00542 <span class="comment">/* Initializations for the fft calculation */</span> |
| <a name="l00543"></a>00543 n2 = fftLen; |
| <a name="l00544"></a>00544 n1 = n2; |
| <a name="l00545"></a>00545 <span class="keywordflow">for</span> (k = fftLen; k > 1u; k >>= 2u) |
| <a name="l00546"></a>00546 { |
| <a name="l00547"></a>00547 <span class="comment">/* Initializations for the fft calculation */</span> |
| <a name="l00548"></a>00548 n1 = n2; |
| <a name="l00549"></a>00549 n2 >>= 2u; |
| <a name="l00550"></a>00550 ia1 = 0u; |
| <a name="l00551"></a>00551 |
| <a name="l00552"></a>00552 <span class="comment">/* FFT Calculation */</span> |
| <a name="l00553"></a>00553 <span class="keywordflow">for</span> (j = 0u; j <= (n2 - 1u); j++) |
| <a name="l00554"></a>00554 { |
| <a name="l00555"></a>00555 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00556"></a>00556 ia2 = ia1 + ia1; |
| <a name="l00557"></a>00557 ia3 = ia2 + ia1; |
| <a name="l00558"></a>00558 co1 = pCoef[ia1 * 2u]; |
| <a name="l00559"></a>00559 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00560"></a>00560 co2 = pCoef[ia2 * 2u]; |
| <a name="l00561"></a>00561 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00562"></a>00562 co3 = pCoef[ia3 * 2u]; |
| <a name="l00563"></a>00563 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00564"></a>00564 |
| <a name="l00565"></a>00565 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00566"></a>00566 ia1 = ia1 + twidCoefModifier; |
| <a name="l00567"></a>00567 |
| <a name="l00568"></a>00568 <span class="keywordflow">for</span> (i0 = j; i0 < fftLen; i0 += n1) |
| <a name="l00569"></a>00569 { |
| <a name="l00570"></a>00570 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00571"></a>00571 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00572"></a>00572 i1 = i0 + n2; |
| <a name="l00573"></a>00573 i2 = i1 + n2; |
| <a name="l00574"></a>00574 i3 = i2 + n2; |
| <a name="l00575"></a>00575 |
| <a name="l00576"></a>00576 <span class="comment">/* xa + xc */</span> |
| <a name="l00577"></a>00577 r1 = pSrc[(2u * i0)] + pSrc[(2u * i2)]; |
| <a name="l00578"></a>00578 |
| <a name="l00579"></a>00579 <span class="comment">/* xa - xc */</span> |
| <a name="l00580"></a>00580 r2 = pSrc[(2u * i0)] - pSrc[(2u * i2)]; |
| <a name="l00581"></a>00581 |
| <a name="l00582"></a>00582 <span class="comment">/* ya + yc */</span> |
| <a name="l00583"></a>00583 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00584"></a>00584 |
| <a name="l00585"></a>00585 <span class="comment">/* ya - yc */</span> |
| <a name="l00586"></a>00586 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00587"></a>00587 |
| <a name="l00588"></a>00588 <span class="comment">/* xb + xd */</span> |
| <a name="l00589"></a>00589 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00590"></a>00590 |
| <a name="l00591"></a>00591 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00592"></a>00592 pSrc[2u * i0] = r1 + t1; |
| <a name="l00593"></a>00593 |
| <a name="l00594"></a>00594 <span class="comment">/* xa + xc -(xb + xd) */</span> |
| <a name="l00595"></a>00595 r1 = r1 - t1; |
| <a name="l00596"></a>00596 |
| <a name="l00597"></a>00597 <span class="comment">/* yb + yd */</span> |
| <a name="l00598"></a>00598 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00599"></a>00599 |
| <a name="l00600"></a>00600 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00601"></a>00601 pSrc[(2u * i0) + 1u] = s1 + t2; |
| <a name="l00602"></a>00602 |
| <a name="l00603"></a>00603 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00604"></a>00604 s1 = s1 - t2; |
| <a name="l00605"></a>00605 |
| <a name="l00606"></a>00606 <span class="comment">/* (yb - yd) */</span> |
| <a name="l00607"></a>00607 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00608"></a>00608 |
| <a name="l00609"></a>00609 <span class="comment">/* (xb - xd) */</span> |
| <a name="l00610"></a>00610 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00611"></a>00611 |
| <a name="l00612"></a>00612 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00613"></a>00613 pSrc[2u * i1] = (r1 * co2) + (s1 * si2); |
| <a name="l00614"></a>00614 |
| <a name="l00615"></a>00615 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00616"></a>00616 pSrc[(2u * i1) + 1u] = (s1 * co2) - (r1 * si2); |
| <a name="l00617"></a>00617 |
| <a name="l00618"></a>00618 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00619"></a>00619 r1 = r2 + t1; |
| <a name="l00620"></a>00620 |
| <a name="l00621"></a>00621 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00622"></a>00622 r2 = r2 - t1; |
| <a name="l00623"></a>00623 |
| <a name="l00624"></a>00624 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00625"></a>00625 s1 = s2 - t2; |
| <a name="l00626"></a>00626 |
| <a name="l00627"></a>00627 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00628"></a>00628 s2 = s2 + t2; |
| <a name="l00629"></a>00629 |
| <a name="l00630"></a>00630 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00631"></a>00631 pSrc[2u * i2] = (r1 * co1) + (s1 * si1); |
| <a name="l00632"></a>00632 |
| <a name="l00633"></a>00633 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00634"></a>00634 pSrc[(2u * i2) + 1u] = (s1 * co1) - (r1 * si1); |
| <a name="l00635"></a>00635 |
| <a name="l00636"></a>00636 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00637"></a>00637 pSrc[2u * i3] = (r2 * co3) + (s2 * si3); |
| <a name="l00638"></a>00638 |
| <a name="l00639"></a>00639 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00640"></a>00640 pSrc[(2u * i3) + 1u] = (s2 * co3) - (r2 * si3); |
| <a name="l00641"></a>00641 } |
| <a name="l00642"></a>00642 } |
| <a name="l00643"></a>00643 twidCoefModifier <<= 2u; |
| <a name="l00644"></a>00644 } |
| <a name="l00645"></a>00645 |
| <a name="l00646"></a>00646 <span class="preprocessor">#endif </span><span class="comment">/* #ifndef ARM_MATH_CM0 */</span> |
| <a name="l00647"></a>00647 |
| <a name="l00648"></a>00648 } |
| <a name="l00649"></a>00649 |
| <a name="l00650"></a>00650 <span class="comment">/* </span> |
| <a name="l00651"></a>00651 <span class="comment"> * @brief Core function for the floating-point CIFFT butterfly process. </span> |
| <a name="l00652"></a>00652 <span class="comment"> * @param[in, out] *pSrc points to the in-place buffer of floating-point data type. </span> |
| <a name="l00653"></a>00653 <span class="comment"> * @param[in] fftLen length of the FFT. </span> |
| <a name="l00654"></a>00654 <span class="comment"> * @param[in] *pCoef points to twiddle coefficient buffer. </span> |
| <a name="l00655"></a>00655 <span class="comment"> * @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. </span> |
| <a name="l00656"></a>00656 <span class="comment"> * @param[in] onebyfftLen value of 1/fftLen. </span> |
| <a name="l00657"></a>00657 <span class="comment"> * @return none. </span> |
| <a name="l00658"></a>00658 <span class="comment"> */</span> |
| <a name="l00659"></a>00659 |
| <a name="l00660"></a><a class="code" href="arm__math_8h.html#a2a78df6e4bbf080624f2b6349224ec93">00660</a> <span class="keywordtype">void</span> <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>( |
| <a name="l00661"></a>00661 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc, |
| <a name="l00662"></a>00662 uint16_t fftLen, |
| <a name="l00663"></a>00663 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pCoef, |
| <a name="l00664"></a>00664 uint16_t twidCoefModifier, |
| <a name="l00665"></a>00665 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> onebyfftLen) |
| <a name="l00666"></a>00666 { |
| <a name="l00667"></a>00667 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> co1, co2, co3, si1, si2, si3; |
| <a name="l00668"></a>00668 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> t1, t2, r1, r2, s1, s2; |
| <a name="l00669"></a>00669 uint32_t ia1, ia2, ia3; |
| <a name="l00670"></a>00670 uint32_t i0, i1, i2, i3; |
| <a name="l00671"></a>00671 uint32_t n1, n2, j, k; |
| <a name="l00672"></a>00672 |
| <a name="l00673"></a>00673 <span class="preprocessor">#ifndef ARM_MATH_CM0</span> |
| <a name="l00674"></a>00674 <span class="preprocessor"></span> |
| <a name="l00675"></a>00675 <span class="comment">/* Run the below code for Cortex-M4 and Cortex-M3 */</span> |
| <a name="l00676"></a>00676 |
| <a name="l00677"></a>00677 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00678"></a>00678 n2 = fftLen; |
| <a name="l00679"></a>00679 n1 = n2; |
| <a name="l00680"></a>00680 |
| <a name="l00681"></a>00681 <span class="comment">/* n2 = fftLen/4 */</span> |
| <a name="l00682"></a>00682 n2 >>= 2u; |
| <a name="l00683"></a>00683 i0 = 0u; |
| <a name="l00684"></a>00684 ia1 = 0u; |
| <a name="l00685"></a>00685 |
| <a name="l00686"></a>00686 j = n2; |
| <a name="l00687"></a>00687 |
| <a name="l00688"></a>00688 <span class="comment">/* Calculation of first stage */</span> |
| <a name="l00689"></a>00689 <span class="keywordflow">do</span> |
| <a name="l00690"></a>00690 { |
| <a name="l00691"></a>00691 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00692"></a>00692 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00693"></a>00693 i1 = i0 + n2; |
| <a name="l00694"></a>00694 i2 = i1 + n2; |
| <a name="l00695"></a>00695 i3 = i2 + n2; |
| <a name="l00696"></a>00696 |
| <a name="l00697"></a>00697 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00698"></a>00698 <span class="comment">/* xa + xc */</span> |
| <a name="l00699"></a>00699 r1 = pSrc[(2u * i0)] + pSrc[(2u * i2)]; |
| <a name="l00700"></a>00700 |
| <a name="l00701"></a>00701 <span class="comment">/* xa - xc */</span> |
| <a name="l00702"></a>00702 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l00703"></a>00703 |
| <a name="l00704"></a>00704 <span class="comment">/* ya + yc */</span> |
| <a name="l00705"></a>00705 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00706"></a>00706 |
| <a name="l00707"></a>00707 <span class="comment">/* ya - yc */</span> |
| <a name="l00708"></a>00708 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00709"></a>00709 |
| <a name="l00710"></a>00710 <span class="comment">/* xb + xd */</span> |
| <a name="l00711"></a>00711 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00712"></a>00712 |
| <a name="l00713"></a>00713 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00714"></a>00714 pSrc[2u * i0] = r1 + t1; |
| <a name="l00715"></a>00715 |
| <a name="l00716"></a>00716 <span class="comment">/* (xa + xc) - (xb + xd) */</span> |
| <a name="l00717"></a>00717 r1 = r1 - t1; |
| <a name="l00718"></a>00718 |
| <a name="l00719"></a>00719 <span class="comment">/* yb + yd */</span> |
| <a name="l00720"></a>00720 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00721"></a>00721 |
| <a name="l00722"></a>00722 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00723"></a>00723 pSrc[(2u * i0) + 1u] = s1 + t2; |
| <a name="l00724"></a>00724 |
| <a name="l00725"></a>00725 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00726"></a>00726 s1 = s1 - t2; |
| <a name="l00727"></a>00727 |
| <a name="l00728"></a>00728 <span class="comment">/* yb - yd */</span> |
| <a name="l00729"></a>00729 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00730"></a>00730 |
| <a name="l00731"></a>00731 <span class="comment">/* xb - xd */</span> |
| <a name="l00732"></a>00732 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00733"></a>00733 |
| <a name="l00734"></a>00734 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00735"></a>00735 ia2 = ia1 + ia1; |
| <a name="l00736"></a>00736 co2 = pCoef[ia2 * 2u]; |
| <a name="l00737"></a>00737 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00738"></a>00738 |
| <a name="l00739"></a>00739 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00740"></a>00740 pSrc[2u * i1] = (r1 * co2) - (s1 * si2); |
| <a name="l00741"></a>00741 |
| <a name="l00742"></a>00742 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00743"></a>00743 pSrc[(2u * i1) + 1u] = (s1 * co2) + (r1 * si2); |
| <a name="l00744"></a>00744 |
| <a name="l00745"></a>00745 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00746"></a>00746 r1 = r2 - t1; |
| <a name="l00747"></a>00747 |
| <a name="l00748"></a>00748 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00749"></a>00749 r2 = r2 + t1; |
| <a name="l00750"></a>00750 |
| <a name="l00751"></a>00751 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00752"></a>00752 s1 = s2 + t2; |
| <a name="l00753"></a>00753 |
| <a name="l00754"></a>00754 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00755"></a>00755 s2 = s2 - t2; |
| <a name="l00756"></a>00756 |
| <a name="l00757"></a>00757 co1 = pCoef[ia1 * 2u]; |
| <a name="l00758"></a>00758 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00759"></a>00759 |
| <a name="l00760"></a>00760 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00761"></a>00761 pSrc[2u * i2] = (r1 * co1) - (s1 * si1); |
| <a name="l00762"></a>00762 |
| <a name="l00763"></a>00763 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00764"></a>00764 pSrc[(2u * i2) + 1u] = (s1 * co1) + (r1 * si1); |
| <a name="l00765"></a>00765 |
| <a name="l00766"></a>00766 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00767"></a>00767 ia3 = ia2 + ia1; |
| <a name="l00768"></a>00768 co3 = pCoef[ia3 * 2u]; |
| <a name="l00769"></a>00769 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00770"></a>00770 |
| <a name="l00771"></a>00771 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00772"></a>00772 pSrc[2u * i3] = (r2 * co3) - (s2 * si3); |
| <a name="l00773"></a>00773 |
| <a name="l00774"></a>00774 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00775"></a>00775 pSrc[(2u * i3) + 1u] = (s2 * co3) + (r2 * si3); |
| <a name="l00776"></a>00776 |
| <a name="l00777"></a>00777 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00778"></a>00778 ia1 = ia1 + twidCoefModifier; |
| <a name="l00779"></a>00779 |
| <a name="l00780"></a>00780 <span class="comment">/* Updating input index */</span> |
| <a name="l00781"></a>00781 i0 = i0 + 1u; |
| <a name="l00782"></a>00782 |
| <a name="l00783"></a>00783 } |
| <a name="l00784"></a>00784 <span class="keywordflow">while</span>(--j); |
| <a name="l00785"></a>00785 |
| <a name="l00786"></a>00786 twidCoefModifier <<= 2u; |
| <a name="l00787"></a>00787 |
| <a name="l00788"></a>00788 <span class="comment">/* Calculation of second stage to excluding last stage */</span> |
| <a name="l00789"></a>00789 <span class="keywordflow">for</span> (k = fftLen / 4; k > 4u; k >>= 2u) |
| <a name="l00790"></a>00790 { |
| <a name="l00791"></a>00791 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00792"></a>00792 n1 = n2; |
| <a name="l00793"></a>00793 n2 >>= 2u; |
| <a name="l00794"></a>00794 ia1 = 0u; |
| <a name="l00795"></a>00795 |
| <a name="l00796"></a>00796 <span class="comment">/* Calculation of first stage */</span> |
| <a name="l00797"></a>00797 <span class="keywordflow">for</span> (j = 0u; j <= (n2 - 1u); j++) |
| <a name="l00798"></a>00798 { |
| <a name="l00799"></a>00799 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00800"></a>00800 ia2 = ia1 + ia1; |
| <a name="l00801"></a>00801 ia3 = ia2 + ia1; |
| <a name="l00802"></a>00802 co1 = pCoef[ia1 * 2u]; |
| <a name="l00803"></a>00803 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00804"></a>00804 co2 = pCoef[ia2 * 2u]; |
| <a name="l00805"></a>00805 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00806"></a>00806 co3 = pCoef[ia3 * 2u]; |
| <a name="l00807"></a>00807 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00808"></a>00808 |
| <a name="l00809"></a>00809 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00810"></a>00810 ia1 = ia1 + twidCoefModifier; |
| <a name="l00811"></a>00811 |
| <a name="l00812"></a>00812 <span class="keywordflow">for</span> (i0 = j; i0 < fftLen; i0 += n1) |
| <a name="l00813"></a>00813 { |
| <a name="l00814"></a>00814 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00815"></a>00815 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00816"></a>00816 i1 = i0 + n2; |
| <a name="l00817"></a>00817 i2 = i1 + n2; |
| <a name="l00818"></a>00818 i3 = i2 + n2; |
| <a name="l00819"></a>00819 |
| <a name="l00820"></a>00820 <span class="comment">/* xa + xc */</span> |
| <a name="l00821"></a>00821 r1 = pSrc[(2u * i0)] + pSrc[(2u * i2)]; |
| <a name="l00822"></a>00822 |
| <a name="l00823"></a>00823 <span class="comment">/* xa - xc */</span> |
| <a name="l00824"></a>00824 r2 = pSrc[(2u * i0)] - pSrc[(2u * i2)]; |
| <a name="l00825"></a>00825 |
| <a name="l00826"></a>00826 <span class="comment">/* ya + yc */</span> |
| <a name="l00827"></a>00827 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00828"></a>00828 |
| <a name="l00829"></a>00829 <span class="comment">/* ya - yc */</span> |
| <a name="l00830"></a>00830 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00831"></a>00831 |
| <a name="l00832"></a>00832 <span class="comment">/* xb + xd */</span> |
| <a name="l00833"></a>00833 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00834"></a>00834 |
| <a name="l00835"></a>00835 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00836"></a>00836 pSrc[2u * i0] = r1 + t1; |
| <a name="l00837"></a>00837 |
| <a name="l00838"></a>00838 <span class="comment">/* xa + xc -(xb + xd) */</span> |
| <a name="l00839"></a>00839 r1 = r1 - t1; |
| <a name="l00840"></a>00840 |
| <a name="l00841"></a>00841 <span class="comment">/* yb + yd */</span> |
| <a name="l00842"></a>00842 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00843"></a>00843 |
| <a name="l00844"></a>00844 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00845"></a>00845 pSrc[(2u * i0) + 1u] = s1 + t2; |
| <a name="l00846"></a>00846 |
| <a name="l00847"></a>00847 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00848"></a>00848 s1 = s1 - t2; |
| <a name="l00849"></a>00849 |
| <a name="l00850"></a>00850 <span class="comment">/* (yb - yd) */</span> |
| <a name="l00851"></a>00851 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00852"></a>00852 |
| <a name="l00853"></a>00853 <span class="comment">/* (xb - xd) */</span> |
| <a name="l00854"></a>00854 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00855"></a>00855 |
| <a name="l00856"></a>00856 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00857"></a>00857 pSrc[2u * i1] = (r1 * co2) - (s1 * si2); |
| <a name="l00858"></a>00858 |
| <a name="l00859"></a>00859 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00860"></a>00860 pSrc[(2u * i1) + 1u] = (s1 * co2) + (r1 * si2); |
| <a name="l00861"></a>00861 |
| <a name="l00862"></a>00862 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00863"></a>00863 r1 = r2 - t1; |
| <a name="l00864"></a>00864 |
| <a name="l00865"></a>00865 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00866"></a>00866 r2 = r2 + t1; |
| <a name="l00867"></a>00867 |
| <a name="l00868"></a>00868 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00869"></a>00869 s1 = s2 + t2; |
| <a name="l00870"></a>00870 |
| <a name="l00871"></a>00871 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00872"></a>00872 s2 = s2 - t2; |
| <a name="l00873"></a>00873 |
| <a name="l00874"></a>00874 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00875"></a>00875 pSrc[2u * i2] = (r1 * co1) - (s1 * si1); |
| <a name="l00876"></a>00876 |
| <a name="l00877"></a>00877 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00878"></a>00878 pSrc[(2u * i2) + 1u] = (s1 * co1) + (r1 * si1); |
| <a name="l00879"></a>00879 |
| <a name="l00880"></a>00880 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00881"></a>00881 pSrc[2u * i3] = (r2 * co3) - (s2 * si3); |
| <a name="l00882"></a>00882 |
| <a name="l00883"></a>00883 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00884"></a>00884 pSrc[(2u * i3) + 1u] = (s2 * co3) + (r2 * si3); |
| <a name="l00885"></a>00885 } |
| <a name="l00886"></a>00886 } |
| <a name="l00887"></a>00887 twidCoefModifier <<= 2u; |
| <a name="l00888"></a>00888 } |
| <a name="l00889"></a>00889 |
| <a name="l00890"></a>00890 <span class="comment">/* Initializations of last stage */</span> |
| <a name="l00891"></a>00891 n1 = n2; |
| <a name="l00892"></a>00892 n2 >>= 2u; |
| <a name="l00893"></a>00893 |
| <a name="l00894"></a>00894 <span class="comment">/* Calculations of last stage */</span> |
| <a name="l00895"></a>00895 <span class="keywordflow">for</span> (i0 = 0u; i0 <= (fftLen - n1); i0 += n1) |
| <a name="l00896"></a>00896 { |
| <a name="l00897"></a>00897 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00898"></a>00898 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00899"></a>00899 i1 = i0 + n2; |
| <a name="l00900"></a>00900 i2 = i1 + n2; |
| <a name="l00901"></a>00901 i3 = i2 + n2; |
| <a name="l00902"></a>00902 |
| <a name="l00903"></a>00903 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00904"></a>00904 <span class="comment">/* xa + xc */</span> |
| <a name="l00905"></a>00905 r1 = pSrc[2u * i0] + pSrc[2u * i2]; |
| <a name="l00906"></a>00906 |
| <a name="l00907"></a>00907 <span class="comment">/* xa - xc */</span> |
| <a name="l00908"></a>00908 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l00909"></a>00909 |
| <a name="l00910"></a>00910 <span class="comment">/* ya + yc */</span> |
| <a name="l00911"></a>00911 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00912"></a>00912 |
| <a name="l00913"></a>00913 <span class="comment">/* ya - yc */</span> |
| <a name="l00914"></a>00914 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00915"></a>00915 |
| <a name="l00916"></a>00916 <span class="comment">/* xc + xd */</span> |
| <a name="l00917"></a>00917 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00918"></a>00918 |
| <a name="l00919"></a>00919 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00920"></a>00920 pSrc[2u * i0] = (r1 + t1) * onebyfftLen; |
| <a name="l00921"></a>00921 |
| <a name="l00922"></a>00922 <span class="comment">/* (xa + xb) - (xc + xd) */</span> |
| <a name="l00923"></a>00923 r1 = r1 - t1; |
| <a name="l00924"></a>00924 |
| <a name="l00925"></a>00925 <span class="comment">/* yb + yd */</span> |
| <a name="l00926"></a>00926 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00927"></a>00927 |
| <a name="l00928"></a>00928 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00929"></a>00929 pSrc[(2u * i0) + 1u] = (s1 + t2) * onebyfftLen; |
| <a name="l00930"></a>00930 |
| <a name="l00931"></a>00931 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00932"></a>00932 s1 = s1 - t2; |
| <a name="l00933"></a>00933 |
| <a name="l00934"></a>00934 <span class="comment">/* (yb-yd) */</span> |
| <a name="l00935"></a>00935 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00936"></a>00936 |
| <a name="l00937"></a>00937 <span class="comment">/* (xb-xd) */</span> |
| <a name="l00938"></a>00938 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00939"></a>00939 |
| <a name="l00940"></a>00940 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00941"></a>00941 pSrc[2u * i1] = r1 * onebyfftLen; |
| <a name="l00942"></a>00942 |
| <a name="l00943"></a>00943 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00944"></a>00944 pSrc[(2u * i1) + 1u] = s1 * onebyfftLen; |
| <a name="l00945"></a>00945 |
| <a name="l00946"></a>00946 |
| <a name="l00947"></a>00947 <span class="comment">/* (xa - xc) - (yb-yd) */</span> |
| <a name="l00948"></a>00948 r1 = r2 - t1; |
| <a name="l00949"></a>00949 |
| <a name="l00950"></a>00950 <span class="comment">/* (xa - xc) + (yb-yd) */</span> |
| <a name="l00951"></a>00951 r2 = r2 + t1; |
| <a name="l00952"></a>00952 |
| <a name="l00953"></a>00953 <span class="comment">/* (ya - yc) + (xb-xd) */</span> |
| <a name="l00954"></a>00954 s1 = s2 + t2; |
| <a name="l00955"></a>00955 |
| <a name="l00956"></a>00956 <span class="comment">/* (ya - yc) - (xb-xd) */</span> |
| <a name="l00957"></a>00957 s2 = s2 - t2; |
| <a name="l00958"></a>00958 |
| <a name="l00959"></a>00959 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00960"></a>00960 pSrc[2u * i2] = r1 * onebyfftLen; |
| <a name="l00961"></a>00961 |
| <a name="l00962"></a>00962 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00963"></a>00963 pSrc[(2u * i2) + 1u] = s1 * onebyfftLen; |
| <a name="l00964"></a>00964 |
| <a name="l00965"></a>00965 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00966"></a>00966 pSrc[2u * i3] = r2 * onebyfftLen; |
| <a name="l00967"></a>00967 |
| <a name="l00968"></a>00968 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00969"></a>00969 pSrc[(2u * i3) + 1u] = s2 * onebyfftLen; |
| <a name="l00970"></a>00970 } |
| <a name="l00971"></a>00971 |
| <a name="l00972"></a>00972 |
| <a name="l00973"></a>00973 <span class="preprocessor">#else</span> |
| <a name="l00974"></a>00974 <span class="preprocessor"></span> |
| <a name="l00975"></a>00975 <span class="comment">/* Run the below code for Cortex-M0 */</span> |
| <a name="l00976"></a>00976 |
| <a name="l00977"></a>00977 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00978"></a>00978 n2 = fftLen; |
| <a name="l00979"></a>00979 n1 = n2; |
| <a name="l00980"></a>00980 |
| <a name="l00981"></a>00981 <span class="comment">/* Calculation of first stage */</span> |
| <a name="l00982"></a>00982 <span class="keywordflow">for</span> (k = fftLen; k > 4u; k >>= 2u) |
| <a name="l00983"></a>00983 { |
| <a name="l00984"></a>00984 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00985"></a>00985 n1 = n2; |
| <a name="l00986"></a>00986 n2 >>= 2u; |
| <a name="l00987"></a>00987 ia1 = 0u; |
| <a name="l00988"></a>00988 |
| <a name="l00989"></a>00989 <span class="comment">/* Calculation of first stage */</span> |
| <a name="l00990"></a>00990 <span class="keywordflow">for</span> (j = 0u; j <= (n2 - 1u); j++) |
| <a name="l00991"></a>00991 { |
| <a name="l00992"></a>00992 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00993"></a>00993 ia2 = ia1 + ia1; |
| <a name="l00994"></a>00994 ia3 = ia2 + ia1; |
| <a name="l00995"></a>00995 co1 = pCoef[ia1 * 2u]; |
| <a name="l00996"></a>00996 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00997"></a>00997 co2 = pCoef[ia2 * 2u]; |
| <a name="l00998"></a>00998 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00999"></a>00999 co3 = pCoef[ia3 * 2u]; |
| <a name="l01000"></a>01000 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l01001"></a>01001 |
| <a name="l01002"></a>01002 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l01003"></a>01003 ia1 = ia1 + twidCoefModifier; |
| <a name="l01004"></a>01004 |
| <a name="l01005"></a>01005 <span class="keywordflow">for</span> (i0 = j; i0 < fftLen; i0 += n1) |
| <a name="l01006"></a>01006 { |
| <a name="l01007"></a>01007 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l01008"></a>01008 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l01009"></a>01009 i1 = i0 + n2; |
| <a name="l01010"></a>01010 i2 = i1 + n2; |
| <a name="l01011"></a>01011 i3 = i2 + n2; |
| <a name="l01012"></a>01012 |
| <a name="l01013"></a>01013 <span class="comment">/* xa + xc */</span> |
| <a name="l01014"></a>01014 r1 = pSrc[(2u * i0)] + pSrc[(2u * i2)]; |
| <a name="l01015"></a>01015 |
| <a name="l01016"></a>01016 <span class="comment">/* xa - xc */</span> |
| <a name="l01017"></a>01017 r2 = pSrc[(2u * i0)] - pSrc[(2u * i2)]; |
| <a name="l01018"></a>01018 |
| <a name="l01019"></a>01019 <span class="comment">/* ya + yc */</span> |
| <a name="l01020"></a>01020 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l01021"></a>01021 |
| <a name="l01022"></a>01022 <span class="comment">/* ya - yc */</span> |
| <a name="l01023"></a>01023 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l01024"></a>01024 |
| <a name="l01025"></a>01025 <span class="comment">/* xb + xd */</span> |
| <a name="l01026"></a>01026 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l01027"></a>01027 |
| <a name="l01028"></a>01028 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l01029"></a>01029 pSrc[2u * i0] = r1 + t1; |
| <a name="l01030"></a>01030 |
| <a name="l01031"></a>01031 <span class="comment">/* xa + xc -(xb + xd) */</span> |
| <a name="l01032"></a>01032 r1 = r1 - t1; |
| <a name="l01033"></a>01033 |
| <a name="l01034"></a>01034 <span class="comment">/* yb + yd */</span> |
| <a name="l01035"></a>01035 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l01036"></a>01036 |
| <a name="l01037"></a>01037 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l01038"></a>01038 pSrc[(2u * i0) + 1u] = s1 + t2; |
| <a name="l01039"></a>01039 |
| <a name="l01040"></a>01040 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l01041"></a>01041 s1 = s1 - t2; |
| <a name="l01042"></a>01042 |
| <a name="l01043"></a>01043 <span class="comment">/* (yb - yd) */</span> |
| <a name="l01044"></a>01044 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l01045"></a>01045 |
| <a name="l01046"></a>01046 <span class="comment">/* (xb - xd) */</span> |
| <a name="l01047"></a>01047 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l01048"></a>01048 |
| <a name="l01049"></a>01049 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */</span> |
| <a name="l01050"></a>01050 pSrc[2u * i1] = (r1 * co2) - (s1 * si2); |
| <a name="l01051"></a>01051 |
| <a name="l01052"></a>01052 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */</span> |
| <a name="l01053"></a>01053 pSrc[(2u * i1) + 1u] = (s1 * co2) + (r1 * si2); |
| <a name="l01054"></a>01054 |
| <a name="l01055"></a>01055 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l01056"></a>01056 r1 = r2 - t1; |
| <a name="l01057"></a>01057 |
| <a name="l01058"></a>01058 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l01059"></a>01059 r2 = r2 + t1; |
| <a name="l01060"></a>01060 |
| <a name="l01061"></a>01061 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l01062"></a>01062 s1 = s2 + t2; |
| <a name="l01063"></a>01063 |
| <a name="l01064"></a>01064 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l01065"></a>01065 s2 = s2 - t2; |
| <a name="l01066"></a>01066 |
| <a name="l01067"></a>01067 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */</span> |
| <a name="l01068"></a>01068 pSrc[2u * i2] = (r1 * co1) - (s1 * si1); |
| <a name="l01069"></a>01069 |
| <a name="l01070"></a>01070 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */</span> |
| <a name="l01071"></a>01071 pSrc[(2u * i2) + 1u] = (s1 * co1) + (r1 * si1); |
| <a name="l01072"></a>01072 |
| <a name="l01073"></a>01073 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */</span> |
| <a name="l01074"></a>01074 pSrc[2u * i3] = (r2 * co3) - (s2 * si3); |
| <a name="l01075"></a>01075 |
| <a name="l01076"></a>01076 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */</span> |
| <a name="l01077"></a>01077 pSrc[(2u * i3) + 1u] = (s2 * co3) + (r2 * si3); |
| <a name="l01078"></a>01078 } |
| <a name="l01079"></a>01079 } |
| <a name="l01080"></a>01080 twidCoefModifier <<= 2u; |
| <a name="l01081"></a>01081 } |
| <a name="l01082"></a>01082 <span class="comment">/* Initializations of last stage */</span> |
| <a name="l01083"></a>01083 n1 = n2; |
| <a name="l01084"></a>01084 n2 >>= 2u; |
| <a name="l01085"></a>01085 |
| <a name="l01086"></a>01086 <span class="comment">/* Calculations of last stage */</span> |
| <a name="l01087"></a>01087 <span class="keywordflow">for</span> (i0 = 0u; i0 <= (fftLen - n1); i0 += n1) |
| <a name="l01088"></a>01088 { |
| <a name="l01089"></a>01089 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l01090"></a>01090 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l01091"></a>01091 i1 = i0 + n2; |
| <a name="l01092"></a>01092 i2 = i1 + n2; |
| <a name="l01093"></a>01093 i3 = i2 + n2; |
| <a name="l01094"></a>01094 |
| <a name="l01095"></a>01095 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l01096"></a>01096 <span class="comment">/* xa + xc */</span> |
| <a name="l01097"></a>01097 r1 = pSrc[2u * i0] + pSrc[2u * i2]; |
| <a name="l01098"></a>01098 |
| <a name="l01099"></a>01099 <span class="comment">/* xa - xc */</span> |
| <a name="l01100"></a>01100 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l01101"></a>01101 |
| <a name="l01102"></a>01102 <span class="comment">/* ya + yc */</span> |
| <a name="l01103"></a>01103 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l01104"></a>01104 |
| <a name="l01105"></a>01105 <span class="comment">/* ya - yc */</span> |
| <a name="l01106"></a>01106 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l01107"></a>01107 |
| <a name="l01108"></a>01108 <span class="comment">/* xc + xd */</span> |
| <a name="l01109"></a>01109 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l01110"></a>01110 |
| <a name="l01111"></a>01111 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l01112"></a>01112 pSrc[2u * i0] = (r1 + t1) * onebyfftLen; |
| <a name="l01113"></a>01113 |
| <a name="l01114"></a>01114 <span class="comment">/* (xa + xb) - (xc + xd) */</span> |
| <a name="l01115"></a>01115 r1 = r1 - t1; |
| <a name="l01116"></a>01116 |
| <a name="l01117"></a>01117 <span class="comment">/* yb + yd */</span> |
| <a name="l01118"></a>01118 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l01119"></a>01119 |
| <a name="l01120"></a>01120 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l01121"></a>01121 pSrc[(2u * i0) + 1u] = (s1 + t2) * onebyfftLen; |
| <a name="l01122"></a>01122 |
| <a name="l01123"></a>01123 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l01124"></a>01124 s1 = s1 - t2; |
| <a name="l01125"></a>01125 |
| <a name="l01126"></a>01126 <span class="comment">/* (yb-yd) */</span> |
| <a name="l01127"></a>01127 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l01128"></a>01128 |
| <a name="l01129"></a>01129 <span class="comment">/* (xb-xd) */</span> |
| <a name="l01130"></a>01130 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l01131"></a>01131 |
| <a name="l01132"></a>01132 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */</span> |
| <a name="l01133"></a>01133 pSrc[2u * i1] = r1 * onebyfftLen; |
| <a name="l01134"></a>01134 |
| <a name="l01135"></a>01135 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */</span> |
| <a name="l01136"></a>01136 pSrc[(2u * i1) + 1u] = s1 * onebyfftLen; |
| <a name="l01137"></a>01137 |
| <a name="l01138"></a>01138 |
| <a name="l01139"></a>01139 <span class="comment">/* (xa - xc) - (yb-yd) */</span> |
| <a name="l01140"></a>01140 r1 = r2 - t1; |
| <a name="l01141"></a>01141 |
| <a name="l01142"></a>01142 <span class="comment">/* (xa - xc) + (yb-yd) */</span> |
| <a name="l01143"></a>01143 r2 = r2 + t1; |
| <a name="l01144"></a>01144 |
| <a name="l01145"></a>01145 <span class="comment">/* (ya - yc) + (xb-xd) */</span> |
| <a name="l01146"></a>01146 s1 = s2 + t2; |
| <a name="l01147"></a>01147 |
| <a name="l01148"></a>01148 <span class="comment">/* (ya - yc) - (xb-xd) */</span> |
| <a name="l01149"></a>01149 s2 = s2 - t2; |
| <a name="l01150"></a>01150 |
| <a name="l01151"></a>01151 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */</span> |
| <a name="l01152"></a>01152 pSrc[2u * i2] = r1 * onebyfftLen; |
| <a name="l01153"></a>01153 |
| <a name="l01154"></a>01154 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */</span> |
| <a name="l01155"></a>01155 pSrc[(2u * i2) + 1u] = s1 * onebyfftLen; |
| <a name="l01156"></a>01156 |
| <a name="l01157"></a>01157 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */</span> |
| <a name="l01158"></a>01158 pSrc[2u * i3] = r2 * onebyfftLen; |
| <a name="l01159"></a>01159 |
| <a name="l01160"></a>01160 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */</span> |
| <a name="l01161"></a>01161 pSrc[(2u * i3) + 1u] = s2 * onebyfftLen; |
| <a name="l01162"></a>01162 } |
| <a name="l01163"></a>01163 |
| <a name="l01164"></a>01164 <span class="preprocessor">#endif </span><span class="comment">/* #ifndef ARM_MATH_CM0 */</span> |
| <a name="l01165"></a>01165 |
| <a name="l01166"></a>01166 } |
| <a name="l01167"></a>01167 |
| <a name="l01168"></a>01168 <span class="comment">/* </span> |
| <a name="l01169"></a>01169 <span class="comment"> * @brief In-place bit reversal function. </span> |
| <a name="l01170"></a>01170 <span class="comment"> * @param[in, out] *pSrc points to the in-place buffer of floating-point data type. </span> |
| <a name="l01171"></a>01171 <span class="comment"> * @param[in] fftSize length of the FFT. </span> |
| <a name="l01172"></a>01172 <span class="comment"> * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table. </span> |
| <a name="l01173"></a>01173 <span class="comment"> * @param[in] *pBitRevTab points to the bit reversal table. </span> |
| <a name="l01174"></a>01174 <span class="comment"> * @return none. </span> |
| <a name="l01175"></a>01175 <span class="comment"> */</span> |
| <a name="l01176"></a>01176 |
| <a name="l01177"></a><a class="code" href="arm__math_8h.html#a3d4062fdfa6aaa3f51f41cab868e508b">01177</a> <span class="keywordtype">void</span> <a class="code" href="arm__cfft__radix4__f32_8c.html#a3d4062fdfa6aaa3f51f41cab868e508b" title="In-place bit reversal function.">arm_bitreversal_f32</a>( |
| <a name="l01178"></a>01178 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> * pSrc, |
| <a name="l01179"></a>01179 uint16_t <a class="code" href="arm__fft__bin__example__f32_8c.html#a9b500899c581f6df3ffc0a9f3a9ef6aa">fftSize</a>, |
| <a name="l01180"></a>01180 uint16_t bitRevFactor, |
| <a name="l01181"></a>01181 uint16_t * pBitRevTab) |
| <a name="l01182"></a>01182 { |
| <a name="l01183"></a>01183 uint16_t fftLenBy2, fftLenBy2p1; |
| <a name="l01184"></a>01184 uint16_t i, j; |
| <a name="l01185"></a>01185 <a class="code" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715" title="32-bit floating-point type definition.">float32_t</a> in; |
| <a name="l01186"></a>01186 |
| <a name="l01187"></a>01187 <span class="comment">/* Initializations */</span> |
| <a name="l01188"></a>01188 j = 0u; |
| <a name="l01189"></a>01189 fftLenBy2 = fftSize >> 1u; |
| <a name="l01190"></a>01190 fftLenBy2p1 = (fftSize >> 1u) + 1u; |
| <a name="l01191"></a>01191 |
| <a name="l01192"></a>01192 <span class="comment">/* Bit Reversal Implementation */</span> |
| <a name="l01193"></a>01193 <span class="keywordflow">for</span> (i = 0u; i <= (fftLenBy2 - 2u); i += 2u) |
| <a name="l01194"></a>01194 { |
| <a name="l01195"></a>01195 <span class="keywordflow">if</span>(i < j) |
| <a name="l01196"></a>01196 { |
| <a name="l01197"></a>01197 <span class="comment">/* pSrc[i] <-> pSrc[j]; */</span> |
| <a name="l01198"></a>01198 in = pSrc[2u * i]; |
| <a name="l01199"></a>01199 pSrc[2u * i] = pSrc[2u * j]; |
| <a name="l01200"></a>01200 pSrc[2u * j] = in; |
| <a name="l01201"></a>01201 |
| <a name="l01202"></a>01202 <span class="comment">/* pSrc[i+1u] <-> pSrc[j+1u] */</span> |
| <a name="l01203"></a>01203 in = pSrc[(2u * i) + 1u]; |
| <a name="l01204"></a>01204 pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u]; |
| <a name="l01205"></a>01205 pSrc[(2u * j) + 1u] = in; |
| <a name="l01206"></a>01206 |
| <a name="l01207"></a>01207 <span class="comment">/* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */</span> |
| <a name="l01208"></a>01208 in = pSrc[2u * (i + fftLenBy2p1)]; |
| <a name="l01209"></a>01209 pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)]; |
| <a name="l01210"></a>01210 pSrc[2u * (j + fftLenBy2p1)] = in; |
| <a name="l01211"></a>01211 |
| <a name="l01212"></a>01212 <span class="comment">/* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */</span> |
| <a name="l01213"></a>01213 in = pSrc[(2u * (i + fftLenBy2p1)) + 1u]; |
| <a name="l01214"></a>01214 pSrc[(2u * (i + fftLenBy2p1)) + 1u] = |
| <a name="l01215"></a>01215 pSrc[(2u * (j + fftLenBy2p1)) + 1u]; |
| <a name="l01216"></a>01216 pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in; |
| <a name="l01217"></a>01217 |
| <a name="l01218"></a>01218 } |
| <a name="l01219"></a>01219 |
| <a name="l01220"></a>01220 <span class="comment">/* pSrc[i+1u] <-> pSrc[j+1u] */</span> |
| <a name="l01221"></a>01221 in = pSrc[2u * (i + 1u)]; |
| <a name="l01222"></a>01222 pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)]; |
| <a name="l01223"></a>01223 pSrc[2u * (j + fftLenBy2)] = in; |
| <a name="l01224"></a>01224 |
| <a name="l01225"></a>01225 <span class="comment">/* pSrc[i+2u] <-> pSrc[j+2u] */</span> |
| <a name="l01226"></a>01226 in = pSrc[(2u * (i + 1u)) + 1u]; |
| <a name="l01227"></a>01227 pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u]; |
| <a name="l01228"></a>01228 pSrc[(2u * (j + fftLenBy2)) + 1u] = in; |
| <a name="l01229"></a>01229 |
| <a name="l01230"></a>01230 <span class="comment">/* Reading the index for the bit reversal */</span> |
| <a name="l01231"></a>01231 j = *pBitRevTab; |
| <a name="l01232"></a>01232 |
| <a name="l01233"></a>01233 <span class="comment">/* Updating the bit reversal index depending on the fft length */</span> |
| <a name="l01234"></a>01234 pBitRevTab += bitRevFactor; |
| <a name="l01235"></a>01235 } |
| <a name="l01236"></a>01236 } |
| </pre></div></div> |
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