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mbed-os/features/unsupported/dsp/cmsis_dsp/TransformFunctions/arm_rfft_f32.c@0:6bf0743ece18, 2020-03-28 (annotated)

Committer:
demayer
Date:
Sat Mar 28 15:28:19 2020 +0000
Revision:
0:6bf0743ece18
IMU Thread with an event-queue running parallel to handle tasks like a 5 times blinking LED. Button with interrupt detected.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
demayer 0:6bf0743ece18 1 /* ----------------------------------------------------------------------
demayer 0:6bf0743ece18 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
demayer 0:6bf0743ece18 3 *
demayer 0:6bf0743ece18 4 * $Date: 19. March 2015
demayer 0:6bf0743ece18 5 * $Revision: V.1.4.5
demayer 0:6bf0743ece18 6 *
demayer 0:6bf0743ece18 7 * Project: CMSIS DSP Library
demayer 0:6bf0743ece18 8 * Title: arm_rfft_f32.c
demayer 0:6bf0743ece18 9 *
demayer 0:6bf0743ece18 10 * Description: RFFT & RIFFT Floating point process function
demayer 0:6bf0743ece18 11 *
demayer 0:6bf0743ece18 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
demayer 0:6bf0743ece18 13 *
demayer 0:6bf0743ece18 14 * Redistribution and use in source and binary forms, with or without
demayer 0:6bf0743ece18 15 * modification, are permitted provided that the following conditions
demayer 0:6bf0743ece18 16 * are met:
demayer 0:6bf0743ece18 17 * - Redistributions of source code must retain the above copyright
demayer 0:6bf0743ece18 18 * notice, this list of conditions and the following disclaimer.
demayer 0:6bf0743ece18 19 * - Redistributions in binary form must reproduce the above copyright
demayer 0:6bf0743ece18 20 * notice, this list of conditions and the following disclaimer in
demayer 0:6bf0743ece18 21 * the documentation and/or other materials provided with the
demayer 0:6bf0743ece18 22 * distribution.
demayer 0:6bf0743ece18 23 * - Neither the name of ARM LIMITED nor the names of its contributors
demayer 0:6bf0743ece18 24 * may be used to endorse or promote products derived from this
demayer 0:6bf0743ece18 25 * software without specific prior written permission.
demayer 0:6bf0743ece18 26 *
demayer 0:6bf0743ece18 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
demayer 0:6bf0743ece18 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
demayer 0:6bf0743ece18 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
demayer 0:6bf0743ece18 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
demayer 0:6bf0743ece18 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
demayer 0:6bf0743ece18 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
demayer 0:6bf0743ece18 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
demayer 0:6bf0743ece18 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
demayer 0:6bf0743ece18 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
demayer 0:6bf0743ece18 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
demayer 0:6bf0743ece18 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
demayer 0:6bf0743ece18 38 * POSSIBILITY OF SUCH DAMAGE.
demayer 0:6bf0743ece18 39 * -------------------------------------------------------------------- */
demayer 0:6bf0743ece18 40
demayer 0:6bf0743ece18 41 #include "arm_math.h"
demayer 0:6bf0743ece18 42
demayer 0:6bf0743ece18 43 extern void arm_radix4_butterfly_f32(
demayer 0:6bf0743ece18 44 float32_t * pSrc,
demayer 0:6bf0743ece18 45 uint16_t fftLen,
demayer 0:6bf0743ece18 46 float32_t * pCoef,
demayer 0:6bf0743ece18 47 uint16_t twidCoefModifier);
demayer 0:6bf0743ece18 48
demayer 0:6bf0743ece18 49 extern void arm_radix4_butterfly_inverse_f32(
demayer 0:6bf0743ece18 50 float32_t * pSrc,
demayer 0:6bf0743ece18 51 uint16_t fftLen,
demayer 0:6bf0743ece18 52 float32_t * pCoef,
demayer 0:6bf0743ece18 53 uint16_t twidCoefModifier,
demayer 0:6bf0743ece18 54 float32_t onebyfftLen);
demayer 0:6bf0743ece18 55
demayer 0:6bf0743ece18 56 extern void arm_bitreversal_f32(
demayer 0:6bf0743ece18 57 float32_t * pSrc,
demayer 0:6bf0743ece18 58 uint16_t fftSize,
demayer 0:6bf0743ece18 59 uint16_t bitRevFactor,
demayer 0:6bf0743ece18 60 uint16_t * pBitRevTab);
demayer 0:6bf0743ece18 61
demayer 0:6bf0743ece18 62 /**
demayer 0:6bf0743ece18 63 * @ingroup groupTransforms
demayer 0:6bf0743ece18 64 */
demayer 0:6bf0743ece18 65
demayer 0:6bf0743ece18 66 /*--------------------------------------------------------------------
demayer 0:6bf0743ece18 67 * Internal functions prototypes
demayer 0:6bf0743ece18 68 *--------------------------------------------------------------------*/
demayer 0:6bf0743ece18 69
demayer 0:6bf0743ece18 70 void arm_split_rfft_f32(
demayer 0:6bf0743ece18 71 float32_t * pSrc,
demayer 0:6bf0743ece18 72 uint32_t fftLen,
demayer 0:6bf0743ece18 73 float32_t * pATable,
demayer 0:6bf0743ece18 74 float32_t * pBTable,
demayer 0:6bf0743ece18 75 float32_t * pDst,
demayer 0:6bf0743ece18 76 uint32_t modifier);
demayer 0:6bf0743ece18 77 void arm_split_rifft_f32(
demayer 0:6bf0743ece18 78 float32_t * pSrc,
demayer 0:6bf0743ece18 79 uint32_t fftLen,
demayer 0:6bf0743ece18 80 float32_t * pATable,
demayer 0:6bf0743ece18 81 float32_t * pBTable,
demayer 0:6bf0743ece18 82 float32_t * pDst,
demayer 0:6bf0743ece18 83 uint32_t modifier);
demayer 0:6bf0743ece18 84
demayer 0:6bf0743ece18 85 /**
demayer 0:6bf0743ece18 86 * @addtogroup RealFFT
demayer 0:6bf0743ece18 87 * @{
demayer 0:6bf0743ece18 88 */
demayer 0:6bf0743ece18 89
demayer 0:6bf0743ece18 90 /**
demayer 0:6bf0743ece18 91 * @brief Processing function for the floating-point RFFT/RIFFT.
demayer 0:6bf0743ece18 92 * @deprecated Do not use this function. It has been superceded by \ref arm_rfft_fast_f32 and will be removed
demayer 0:6bf0743ece18 93 * in the future.
demayer 0:6bf0743ece18 94 * @param[in] *S points to an instance of the floating-point RFFT/RIFFT structure.
demayer 0:6bf0743ece18 95 * @param[in] *pSrc points to the input buffer.
demayer 0:6bf0743ece18 96 * @param[out] *pDst points to the output buffer.
demayer 0:6bf0743ece18 97 * @return none.
demayer 0:6bf0743ece18 98 */
demayer 0:6bf0743ece18 99
demayer 0:6bf0743ece18 100 void arm_rfft_f32(
demayer 0:6bf0743ece18 101 const arm_rfft_instance_f32 * S,
demayer 0:6bf0743ece18 102 float32_t * pSrc,
demayer 0:6bf0743ece18 103 float32_t * pDst)
demayer 0:6bf0743ece18 104 {
demayer 0:6bf0743ece18 105 const arm_cfft_radix4_instance_f32 *S_CFFT = S->pCfft;
demayer 0:6bf0743ece18 106
demayer 0:6bf0743ece18 107
demayer 0:6bf0743ece18 108 /* Calculation of Real IFFT of input */
demayer 0:6bf0743ece18 109 if(S->ifftFlagR == 1u)
demayer 0:6bf0743ece18 110 {
demayer 0:6bf0743ece18 111 /* Real IFFT core process */
demayer 0:6bf0743ece18 112 arm_split_rifft_f32(pSrc, S->fftLenBy2, S->pTwiddleAReal,
demayer 0:6bf0743ece18 113 S->pTwiddleBReal, pDst, S->twidCoefRModifier);
demayer 0:6bf0743ece18 114
demayer 0:6bf0743ece18 115
demayer 0:6bf0743ece18 116 /* Complex radix-4 IFFT process */
demayer 0:6bf0743ece18 117 arm_radix4_butterfly_inverse_f32(pDst, S_CFFT->fftLen,
demayer 0:6bf0743ece18 118 S_CFFT->pTwiddle,
demayer 0:6bf0743ece18 119 S_CFFT->twidCoefModifier,
demayer 0:6bf0743ece18 120 S_CFFT->onebyfftLen);
demayer 0:6bf0743ece18 121
demayer 0:6bf0743ece18 122 /* Bit reversal process */
demayer 0:6bf0743ece18 123 if(S->bitReverseFlagR == 1u)
demayer 0:6bf0743ece18 124 {
demayer 0:6bf0743ece18 125 arm_bitreversal_f32(pDst, S_CFFT->fftLen,
demayer 0:6bf0743ece18 126 S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
demayer 0:6bf0743ece18 127 }
demayer 0:6bf0743ece18 128 }
demayer 0:6bf0743ece18 129 else
demayer 0:6bf0743ece18 130 {
demayer 0:6bf0743ece18 131
demayer 0:6bf0743ece18 132 /* Calculation of RFFT of input */
demayer 0:6bf0743ece18 133
demayer 0:6bf0743ece18 134 /* Complex radix-4 FFT process */
demayer 0:6bf0743ece18 135 arm_radix4_butterfly_f32(pSrc, S_CFFT->fftLen,
demayer 0:6bf0743ece18 136 S_CFFT->pTwiddle, S_CFFT->twidCoefModifier);
demayer 0:6bf0743ece18 137
demayer 0:6bf0743ece18 138 /* Bit reversal process */
demayer 0:6bf0743ece18 139 if(S->bitReverseFlagR == 1u)
demayer 0:6bf0743ece18 140 {
demayer 0:6bf0743ece18 141 arm_bitreversal_f32(pSrc, S_CFFT->fftLen,
demayer 0:6bf0743ece18 142 S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
demayer 0:6bf0743ece18 143 }
demayer 0:6bf0743ece18 144
demayer 0:6bf0743ece18 145
demayer 0:6bf0743ece18 146 /* Real FFT core process */
demayer 0:6bf0743ece18 147 arm_split_rfft_f32(pSrc, S->fftLenBy2, S->pTwiddleAReal,
demayer 0:6bf0743ece18 148 S->pTwiddleBReal, pDst, S->twidCoefRModifier);
demayer 0:6bf0743ece18 149 }
demayer 0:6bf0743ece18 150
demayer 0:6bf0743ece18 151 }
demayer 0:6bf0743ece18 152
demayer 0:6bf0743ece18 153 /**
demayer 0:6bf0743ece18 154 * @} end of RealFFT group
demayer 0:6bf0743ece18 155 */
demayer 0:6bf0743ece18 156
demayer 0:6bf0743ece18 157 /**
demayer 0:6bf0743ece18 158 * @brief Core Real FFT process
demayer 0:6bf0743ece18 159 * @param[in] *pSrc points to the input buffer.
demayer 0:6bf0743ece18 160 * @param[in] fftLen length of FFT.
demayer 0:6bf0743ece18 161 * @param[in] *pATable points to the twiddle Coef A buffer.
demayer 0:6bf0743ece18 162 * @param[in] *pBTable points to the twiddle Coef B buffer.
demayer 0:6bf0743ece18 163 * @param[out] *pDst points to the output buffer.
demayer 0:6bf0743ece18 164 * @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
demayer 0:6bf0743ece18 165 * @return none.
demayer 0:6bf0743ece18 166 */
demayer 0:6bf0743ece18 167
demayer 0:6bf0743ece18 168 void arm_split_rfft_f32(
demayer 0:6bf0743ece18 169 float32_t * pSrc,
demayer 0:6bf0743ece18 170 uint32_t fftLen,
demayer 0:6bf0743ece18 171 float32_t * pATable,
demayer 0:6bf0743ece18 172 float32_t * pBTable,
demayer 0:6bf0743ece18 173 float32_t * pDst,
demayer 0:6bf0743ece18 174 uint32_t modifier)
demayer 0:6bf0743ece18 175 {
demayer 0:6bf0743ece18 176 uint32_t i; /* Loop Counter */
demayer 0:6bf0743ece18 177 float32_t outR, outI; /* Temporary variables for output */
demayer 0:6bf0743ece18 178 float32_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */
demayer 0:6bf0743ece18 179 float32_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */
demayer 0:6bf0743ece18 180 float32_t *pDst1 = &pDst[2], *pDst2 = &pDst[(4u * fftLen) - 1u]; /* temp pointers for output buffer */
demayer 0:6bf0743ece18 181 float32_t *pSrc1 = &pSrc[2], *pSrc2 = &pSrc[(2u * fftLen) - 1u]; /* temp pointers for input buffer */
demayer 0:6bf0743ece18 182
demayer 0:6bf0743ece18 183 /* Init coefficient pointers */
demayer 0:6bf0743ece18 184 pCoefA = &pATable[modifier * 2u];
demayer 0:6bf0743ece18 185 pCoefB = &pBTable[modifier * 2u];
demayer 0:6bf0743ece18 186
demayer 0:6bf0743ece18 187 i = fftLen - 1u;
demayer 0:6bf0743ece18 188
demayer 0:6bf0743ece18 189 while(i > 0u)
demayer 0:6bf0743ece18 190 {
demayer 0:6bf0743ece18 191 /*
demayer 0:6bf0743ece18 192 outR = (pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1]
demayer 0:6bf0743ece18 193 + pSrc[2 * n - 2 * i] * pBTable[2 * i] +
demayer 0:6bf0743ece18 194 pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
demayer 0:6bf0743ece18 195 */
demayer 0:6bf0743ece18 196
demayer 0:6bf0743ece18 197 /* outI = (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] +
demayer 0:6bf0743ece18 198 pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
demayer 0:6bf0743ece18 199 pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); */
demayer 0:6bf0743ece18 200
demayer 0:6bf0743ece18 201 /* read pATable[2 * i] */
demayer 0:6bf0743ece18 202 CoefA1 = *pCoefA++;
demayer 0:6bf0743ece18 203 /* pATable[2 * i + 1] */
demayer 0:6bf0743ece18 204 CoefA2 = *pCoefA;
demayer 0:6bf0743ece18 205
demayer 0:6bf0743ece18 206 /* pSrc[2 * i] * pATable[2 * i] */
demayer 0:6bf0743ece18 207 outR = *pSrc1 * CoefA1;
demayer 0:6bf0743ece18 208 /* pSrc[2 * i] * CoefA2 */
demayer 0:6bf0743ece18 209 outI = *pSrc1++ * CoefA2;
demayer 0:6bf0743ece18 210
demayer 0:6bf0743ece18 211 /* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */
demayer 0:6bf0743ece18 212 outR -= (*pSrc1 + *pSrc2) * CoefA2;
demayer 0:6bf0743ece18 213 /* pSrc[2 * i + 1] * CoefA1 */
demayer 0:6bf0743ece18 214 outI += *pSrc1++ * CoefA1;
demayer 0:6bf0743ece18 215
demayer 0:6bf0743ece18 216 CoefB1 = *pCoefB;
demayer 0:6bf0743ece18 217
demayer 0:6bf0743ece18 218 /* pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */
demayer 0:6bf0743ece18 219 outI -= *pSrc2-- * CoefB1;
demayer 0:6bf0743ece18 220 /* pSrc[2 * fftLen - 2 * i] * CoefA2 */
demayer 0:6bf0743ece18 221 outI -= *pSrc2 * CoefA2;
demayer 0:6bf0743ece18 222
demayer 0:6bf0743ece18 223 /* pSrc[2 * fftLen - 2 * i] * CoefB1 */
demayer 0:6bf0743ece18 224 outR += *pSrc2-- * CoefB1;
demayer 0:6bf0743ece18 225
demayer 0:6bf0743ece18 226 /* write output */
demayer 0:6bf0743ece18 227 *pDst1++ = outR;
demayer 0:6bf0743ece18 228 *pDst1++ = outI;
demayer 0:6bf0743ece18 229
demayer 0:6bf0743ece18 230 /* write complex conjugate output */
demayer 0:6bf0743ece18 231 *pDst2-- = -outI;
demayer 0:6bf0743ece18 232 *pDst2-- = outR;
demayer 0:6bf0743ece18 233
demayer 0:6bf0743ece18 234 /* update coefficient pointer */
demayer 0:6bf0743ece18 235 pCoefB = pCoefB + (modifier * 2u);
demayer 0:6bf0743ece18 236 pCoefA = pCoefA + ((modifier * 2u) - 1u);
demayer 0:6bf0743ece18 237
demayer 0:6bf0743ece18 238 i--;
demayer 0:6bf0743ece18 239
demayer 0:6bf0743ece18 240 }
demayer 0:6bf0743ece18 241
demayer 0:6bf0743ece18 242 pDst[2u * fftLen] = pSrc[0] - pSrc[1];
demayer 0:6bf0743ece18 243 pDst[(2u * fftLen) + 1u] = 0.0f;
demayer 0:6bf0743ece18 244
demayer 0:6bf0743ece18 245 pDst[0] = pSrc[0] + pSrc[1];
demayer 0:6bf0743ece18 246 pDst[1] = 0.0f;
demayer 0:6bf0743ece18 247
demayer 0:6bf0743ece18 248 }
demayer 0:6bf0743ece18 249
demayer 0:6bf0743ece18 250
demayer 0:6bf0743ece18 251 /**
demayer 0:6bf0743ece18 252 * @brief Core Real IFFT process
demayer 0:6bf0743ece18 253 * @param[in] *pSrc points to the input buffer.
demayer 0:6bf0743ece18 254 * @param[in] fftLen length of FFT.
demayer 0:6bf0743ece18 255 * @param[in] *pATable points to the twiddle Coef A buffer.
demayer 0:6bf0743ece18 256 * @param[in] *pBTable points to the twiddle Coef B buffer.
demayer 0:6bf0743ece18 257 * @param[out] *pDst points to the output buffer.
demayer 0:6bf0743ece18 258 * @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
demayer 0:6bf0743ece18 259 * @return none.
demayer 0:6bf0743ece18 260 */
demayer 0:6bf0743ece18 261
demayer 0:6bf0743ece18 262 void arm_split_rifft_f32(
demayer 0:6bf0743ece18 263 float32_t * pSrc,
demayer 0:6bf0743ece18 264 uint32_t fftLen,
demayer 0:6bf0743ece18 265 float32_t * pATable,
demayer 0:6bf0743ece18 266 float32_t * pBTable,
demayer 0:6bf0743ece18 267 float32_t * pDst,
demayer 0:6bf0743ece18 268 uint32_t modifier)
demayer 0:6bf0743ece18 269 {
demayer 0:6bf0743ece18 270 float32_t outR, outI; /* Temporary variables for output */
demayer 0:6bf0743ece18 271 float32_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */
demayer 0:6bf0743ece18 272 float32_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */
demayer 0:6bf0743ece18 273 float32_t *pSrc1 = &pSrc[0], *pSrc2 = &pSrc[(2u * fftLen) + 1u];
demayer 0:6bf0743ece18 274
demayer 0:6bf0743ece18 275 pCoefA = &pATable[0];
demayer 0:6bf0743ece18 276 pCoefB = &pBTable[0];
demayer 0:6bf0743ece18 277
demayer 0:6bf0743ece18 278 while(fftLen > 0u)
demayer 0:6bf0743ece18 279 {
demayer 0:6bf0743ece18 280 /*
demayer 0:6bf0743ece18 281 outR = (pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] +
demayer 0:6bf0743ece18 282 pIn[2 * n - 2 * i] * pBTable[2 * i] -
demayer 0:6bf0743ece18 283 pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
demayer 0:6bf0743ece18 284
demayer 0:6bf0743ece18 285 outI = (pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] -
demayer 0:6bf0743ece18 286 pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
demayer 0:6bf0743ece18 287 pIn[2 * n - 2 * i + 1] * pBTable[2 * i]);
demayer 0:6bf0743ece18 288
demayer 0:6bf0743ece18 289 */
demayer 0:6bf0743ece18 290
demayer 0:6bf0743ece18 291 CoefA1 = *pCoefA++;
demayer 0:6bf0743ece18 292 CoefA2 = *pCoefA;
demayer 0:6bf0743ece18 293
demayer 0:6bf0743ece18 294 /* outR = (pSrc[2 * i] * CoefA1 */
demayer 0:6bf0743ece18 295 outR = *pSrc1 * CoefA1;
demayer 0:6bf0743ece18 296
demayer 0:6bf0743ece18 297 /* - pSrc[2 * i] * CoefA2 */
demayer 0:6bf0743ece18 298 outI = -(*pSrc1++) * CoefA2;
demayer 0:6bf0743ece18 299
demayer 0:6bf0743ece18 300 /* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */
demayer 0:6bf0743ece18 301 outR += (*pSrc1 + *pSrc2) * CoefA2;
demayer 0:6bf0743ece18 302
demayer 0:6bf0743ece18 303 /* pSrc[2 * i + 1] * CoefA1 */
demayer 0:6bf0743ece18 304 outI += (*pSrc1++) * CoefA1;
demayer 0:6bf0743ece18 305
demayer 0:6bf0743ece18 306 CoefB1 = *pCoefB;
demayer 0:6bf0743ece18 307
demayer 0:6bf0743ece18 308 /* - pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */
demayer 0:6bf0743ece18 309 outI -= *pSrc2-- * CoefB1;
demayer 0:6bf0743ece18 310
demayer 0:6bf0743ece18 311 /* pSrc[2 * fftLen - 2 * i] * CoefB1 */
demayer 0:6bf0743ece18 312 outR += *pSrc2 * CoefB1;
demayer 0:6bf0743ece18 313
demayer 0:6bf0743ece18 314 /* pSrc[2 * fftLen - 2 * i] * CoefA2 */
demayer 0:6bf0743ece18 315 outI += *pSrc2-- * CoefA2;
demayer 0:6bf0743ece18 316
demayer 0:6bf0743ece18 317 /* write output */
demayer 0:6bf0743ece18 318 *pDst++ = outR;
demayer 0:6bf0743ece18 319 *pDst++ = outI;
demayer 0:6bf0743ece18 320
demayer 0:6bf0743ece18 321 /* update coefficient pointer */
demayer 0:6bf0743ece18 322 pCoefB = pCoefB + (modifier * 2u);
demayer 0:6bf0743ece18 323 pCoefA = pCoefA + ((modifier * 2u) - 1u);
demayer 0:6bf0743ece18 324
demayer 0:6bf0743ece18 325 /* Decrement loop count */
demayer 0:6bf0743ece18 326 fftLen--;
demayer 0:6bf0743ece18 327 }
demayer 0:6bf0743ece18 328
demayer 0:6bf0743ece18 329 }