Eli Hughes / CMSIS_DSP_401

V4.0.1 of the ARM CMSIS DSP libraries. Note that arm_bitreversal2.s, arm_cfft_f32.c and arm_rfft_fast_f32.c had to be removed. arm_bitreversal2.s will not assemble with the online tools. So, the fast f32 FFT functions are not yet available. All the other FFT functions are available.

Dependents:   MPU9150_Example fir_f32 fir_f32 MPU9150_nucleo_noni2cdev ... more

TransformFunctions/arm_rfft_f32.c@0:3d9c67d97d6f, 2014-07-28 (annotated)

Committer:
emh203
Date:
Mon Jul 28 15:03:15 2014 +0000
Revision:
0:3d9c67d97d6f
1st working commit.   Had to remove arm_bitreversal2.s     arm_cfft_f32.c and arm_rfft_fast_f32.c.    The .s will not assemble.      For now I removed these functions so we could at least have a library for the other functions.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emh203 0:3d9c67d97d6f 1 /* ----------------------------------------------------------------------
emh203 0:3d9c67d97d6f 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
emh203 0:3d9c67d97d6f 3 *
emh203 0:3d9c67d97d6f 4 * $Date: 12. March 2014
emh203 0:3d9c67d97d6f 5 * $Revision: V1.4.3
emh203 0:3d9c67d97d6f 6 *
emh203 0:3d9c67d97d6f 7 * Project: CMSIS DSP Library
emh203 0:3d9c67d97d6f 8 * Title: arm_rfft_f32.c
emh203 0:3d9c67d97d6f 9 *
emh203 0:3d9c67d97d6f 10 * Description: RFFT & RIFFT Floating point process function
emh203 0:3d9c67d97d6f 11 *
emh203 0:3d9c67d97d6f 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emh203 0:3d9c67d97d6f 13 *
emh203 0:3d9c67d97d6f 14 * Redistribution and use in source and binary forms, with or without
emh203 0:3d9c67d97d6f 15 * modification, are permitted provided that the following conditions
emh203 0:3d9c67d97d6f 16 * are met:
emh203 0:3d9c67d97d6f 17 * - Redistributions of source code must retain the above copyright
emh203 0:3d9c67d97d6f 18 * notice, this list of conditions and the following disclaimer.
emh203 0:3d9c67d97d6f 19 * - Redistributions in binary form must reproduce the above copyright
emh203 0:3d9c67d97d6f 20 * notice, this list of conditions and the following disclaimer in
emh203 0:3d9c67d97d6f 21 * the documentation and/or other materials provided with the
emh203 0:3d9c67d97d6f 22 * distribution.
emh203 0:3d9c67d97d6f 23 * - Neither the name of ARM LIMITED nor the names of its contributors
emh203 0:3d9c67d97d6f 24 * may be used to endorse or promote products derived from this
emh203 0:3d9c67d97d6f 25 * software without specific prior written permission.
emh203 0:3d9c67d97d6f 26 *
emh203 0:3d9c67d97d6f 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
emh203 0:3d9c67d97d6f 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
emh203 0:3d9c67d97d6f 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
emh203 0:3d9c67d97d6f 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
emh203 0:3d9c67d97d6f 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
emh203 0:3d9c67d97d6f 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
emh203 0:3d9c67d97d6f 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
emh203 0:3d9c67d97d6f 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
emh203 0:3d9c67d97d6f 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
emh203 0:3d9c67d97d6f 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
emh203 0:3d9c67d97d6f 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
emh203 0:3d9c67d97d6f 38 * POSSIBILITY OF SUCH DAMAGE.
emh203 0:3d9c67d97d6f 39 * -------------------------------------------------------------------- */
emh203 0:3d9c67d97d6f 40
emh203 0:3d9c67d97d6f 41 #include "arm_math.h"
emh203 0:3d9c67d97d6f 42
emh203 0:3d9c67d97d6f 43 extern void arm_radix4_butterfly_f32(
emh203 0:3d9c67d97d6f 44 float32_t * pSrc,
emh203 0:3d9c67d97d6f 45 uint16_t fftLen,
emh203 0:3d9c67d97d6f 46 float32_t * pCoef,
emh203 0:3d9c67d97d6f 47 uint16_t twidCoefModifier);
emh203 0:3d9c67d97d6f 48
emh203 0:3d9c67d97d6f 49 extern void arm_radix4_butterfly_inverse_f32(
emh203 0:3d9c67d97d6f 50 float32_t * pSrc,
emh203 0:3d9c67d97d6f 51 uint16_t fftLen,
emh203 0:3d9c67d97d6f 52 float32_t * pCoef,
emh203 0:3d9c67d97d6f 53 uint16_t twidCoefModifier,
emh203 0:3d9c67d97d6f 54 float32_t onebyfftLen);
emh203 0:3d9c67d97d6f 55
emh203 0:3d9c67d97d6f 56 extern void arm_bitreversal_f32(
emh203 0:3d9c67d97d6f 57 float32_t * pSrc,
emh203 0:3d9c67d97d6f 58 uint16_t fftSize,
emh203 0:3d9c67d97d6f 59 uint16_t bitRevFactor,
emh203 0:3d9c67d97d6f 60 uint16_t * pBitRevTab);
emh203 0:3d9c67d97d6f 61
emh203 0:3d9c67d97d6f 62 /**
emh203 0:3d9c67d97d6f 63 * @ingroup groupTransforms
emh203 0:3d9c67d97d6f 64 */
emh203 0:3d9c67d97d6f 65
emh203 0:3d9c67d97d6f 66 /*--------------------------------------------------------------------
emh203 0:3d9c67d97d6f 67 * Internal functions prototypes
emh203 0:3d9c67d97d6f 68 *--------------------------------------------------------------------*/
emh203 0:3d9c67d97d6f 69
emh203 0:3d9c67d97d6f 70 void arm_split_rfft_f32(
emh203 0:3d9c67d97d6f 71 float32_t * pSrc,
emh203 0:3d9c67d97d6f 72 uint32_t fftLen,
emh203 0:3d9c67d97d6f 73 float32_t * pATable,
emh203 0:3d9c67d97d6f 74 float32_t * pBTable,
emh203 0:3d9c67d97d6f 75 float32_t * pDst,
emh203 0:3d9c67d97d6f 76 uint32_t modifier);
emh203 0:3d9c67d97d6f 77 void arm_split_rifft_f32(
emh203 0:3d9c67d97d6f 78 float32_t * pSrc,
emh203 0:3d9c67d97d6f 79 uint32_t fftLen,
emh203 0:3d9c67d97d6f 80 float32_t * pATable,
emh203 0:3d9c67d97d6f 81 float32_t * pBTable,
emh203 0:3d9c67d97d6f 82 float32_t * pDst,
emh203 0:3d9c67d97d6f 83 uint32_t modifier);
emh203 0:3d9c67d97d6f 84
emh203 0:3d9c67d97d6f 85 /**
emh203 0:3d9c67d97d6f 86 * @addtogroup RealFFT
emh203 0:3d9c67d97d6f 87 * @{
emh203 0:3d9c67d97d6f 88 */
emh203 0:3d9c67d97d6f 89
emh203 0:3d9c67d97d6f 90 /**
emh203 0:3d9c67d97d6f 91 * @brief Processing function for the floating-point RFFT/RIFFT.
emh203 0:3d9c67d97d6f 92 * @deprecated Do not use this function. It has been superceded by \ref arm_rfft_fast_f32 and will be removed
emh203 0:3d9c67d97d6f 93 * in the future.
emh203 0:3d9c67d97d6f 94 * @param[in] *S points to an instance of the floating-point RFFT/RIFFT structure.
emh203 0:3d9c67d97d6f 95 * @param[in] *pSrc points to the input buffer.
emh203 0:3d9c67d97d6f 96 * @param[out] *pDst points to the output buffer.
emh203 0:3d9c67d97d6f 97 * @return none.
emh203 0:3d9c67d97d6f 98 */
emh203 0:3d9c67d97d6f 99
emh203 0:3d9c67d97d6f 100 void arm_rfft_f32(
emh203 0:3d9c67d97d6f 101 const arm_rfft_instance_f32 * S,
emh203 0:3d9c67d97d6f 102 float32_t * pSrc,
emh203 0:3d9c67d97d6f 103 float32_t * pDst)
emh203 0:3d9c67d97d6f 104 {
emh203 0:3d9c67d97d6f 105 const arm_cfft_radix4_instance_f32 *S_CFFT = S->pCfft;
emh203 0:3d9c67d97d6f 106
emh203 0:3d9c67d97d6f 107
emh203 0:3d9c67d97d6f 108 /* Calculation of Real IFFT of input */
emh203 0:3d9c67d97d6f 109 if(S->ifftFlagR == 1u)
emh203 0:3d9c67d97d6f 110 {
emh203 0:3d9c67d97d6f 111 /* Real IFFT core process */
emh203 0:3d9c67d97d6f 112 arm_split_rifft_f32(pSrc, S->fftLenBy2, S->pTwiddleAReal,
emh203 0:3d9c67d97d6f 113 S->pTwiddleBReal, pDst, S->twidCoefRModifier);
emh203 0:3d9c67d97d6f 114
emh203 0:3d9c67d97d6f 115
emh203 0:3d9c67d97d6f 116 /* Complex radix-4 IFFT process */
emh203 0:3d9c67d97d6f 117 arm_radix4_butterfly_inverse_f32(pDst, S_CFFT->fftLen,
emh203 0:3d9c67d97d6f 118 S_CFFT->pTwiddle,
emh203 0:3d9c67d97d6f 119 S_CFFT->twidCoefModifier,
emh203 0:3d9c67d97d6f 120 S_CFFT->onebyfftLen);
emh203 0:3d9c67d97d6f 121
emh203 0:3d9c67d97d6f 122 /* Bit reversal process */
emh203 0:3d9c67d97d6f 123 if(S->bitReverseFlagR == 1u)
emh203 0:3d9c67d97d6f 124 {
emh203 0:3d9c67d97d6f 125 arm_bitreversal_f32(pDst, S_CFFT->fftLen,
emh203 0:3d9c67d97d6f 126 S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
emh203 0:3d9c67d97d6f 127 }
emh203 0:3d9c67d97d6f 128 }
emh203 0:3d9c67d97d6f 129 else
emh203 0:3d9c67d97d6f 130 {
emh203 0:3d9c67d97d6f 131
emh203 0:3d9c67d97d6f 132 /* Calculation of RFFT of input */
emh203 0:3d9c67d97d6f 133
emh203 0:3d9c67d97d6f 134 /* Complex radix-4 FFT process */
emh203 0:3d9c67d97d6f 135 arm_radix4_butterfly_f32(pSrc, S_CFFT->fftLen,
emh203 0:3d9c67d97d6f 136 S_CFFT->pTwiddle, S_CFFT->twidCoefModifier);
emh203 0:3d9c67d97d6f 137
emh203 0:3d9c67d97d6f 138 /* Bit reversal process */
emh203 0:3d9c67d97d6f 139 if(S->bitReverseFlagR == 1u)
emh203 0:3d9c67d97d6f 140 {
emh203 0:3d9c67d97d6f 141 arm_bitreversal_f32(pSrc, S_CFFT->fftLen,
emh203 0:3d9c67d97d6f 142 S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
emh203 0:3d9c67d97d6f 143 }
emh203 0:3d9c67d97d6f 144
emh203 0:3d9c67d97d6f 145
emh203 0:3d9c67d97d6f 146 /* Real FFT core process */
emh203 0:3d9c67d97d6f 147 arm_split_rfft_f32(pSrc, S->fftLenBy2, S->pTwiddleAReal,
emh203 0:3d9c67d97d6f 148 S->pTwiddleBReal, pDst, S->twidCoefRModifier);
emh203 0:3d9c67d97d6f 149 }
emh203 0:3d9c67d97d6f 150
emh203 0:3d9c67d97d6f 151 }
emh203 0:3d9c67d97d6f 152
emh203 0:3d9c67d97d6f 153 /**
emh203 0:3d9c67d97d6f 154 * @} end of RealFFT group
emh203 0:3d9c67d97d6f 155 */
emh203 0:3d9c67d97d6f 156
emh203 0:3d9c67d97d6f 157 /**
emh203 0:3d9c67d97d6f 158 * @brief Core Real FFT process
emh203 0:3d9c67d97d6f 159 * @param[in] *pSrc points to the input buffer.
emh203 0:3d9c67d97d6f 160 * @param[in] fftLen length of FFT.
emh203 0:3d9c67d97d6f 161 * @param[in] *pATable points to the twiddle Coef A buffer.
emh203 0:3d9c67d97d6f 162 * @param[in] *pBTable points to the twiddle Coef B buffer.
emh203 0:3d9c67d97d6f 163 * @param[out] *pDst points to the output buffer.
emh203 0:3d9c67d97d6f 164 * @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
emh203 0:3d9c67d97d6f 165 * @return none.
emh203 0:3d9c67d97d6f 166 */
emh203 0:3d9c67d97d6f 167
emh203 0:3d9c67d97d6f 168 void arm_split_rfft_f32(
emh203 0:3d9c67d97d6f 169 float32_t * pSrc,
emh203 0:3d9c67d97d6f 170 uint32_t fftLen,
emh203 0:3d9c67d97d6f 171 float32_t * pATable,
emh203 0:3d9c67d97d6f 172 float32_t * pBTable,
emh203 0:3d9c67d97d6f 173 float32_t * pDst,
emh203 0:3d9c67d97d6f 174 uint32_t modifier)
emh203 0:3d9c67d97d6f 175 {
emh203 0:3d9c67d97d6f 176 uint32_t i; /* Loop Counter */
emh203 0:3d9c67d97d6f 177 float32_t outR, outI; /* Temporary variables for output */
emh203 0:3d9c67d97d6f 178 float32_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */
emh203 0:3d9c67d97d6f 179 float32_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */
emh203 0:3d9c67d97d6f 180 float32_t *pDst1 = &pDst[2], *pDst2 = &pDst[(4u * fftLen) - 1u]; /* temp pointers for output buffer */
emh203 0:3d9c67d97d6f 181 float32_t *pSrc1 = &pSrc[2], *pSrc2 = &pSrc[(2u * fftLen) - 1u]; /* temp pointers for input buffer */
emh203 0:3d9c67d97d6f 182
emh203 0:3d9c67d97d6f 183 /* Init coefficient pointers */
emh203 0:3d9c67d97d6f 184 pCoefA = &pATable[modifier * 2u];
emh203 0:3d9c67d97d6f 185 pCoefB = &pBTable[modifier * 2u];
emh203 0:3d9c67d97d6f 186
emh203 0:3d9c67d97d6f 187 i = fftLen - 1u;
emh203 0:3d9c67d97d6f 188
emh203 0:3d9c67d97d6f 189 while(i > 0u)
emh203 0:3d9c67d97d6f 190 {
emh203 0:3d9c67d97d6f 191 /*
emh203 0:3d9c67d97d6f 192 outR = (pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1]
emh203 0:3d9c67d97d6f 193 + pSrc[2 * n - 2 * i] * pBTable[2 * i] +
emh203 0:3d9c67d97d6f 194 pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
emh203 0:3d9c67d97d6f 195 */
emh203 0:3d9c67d97d6f 196
emh203 0:3d9c67d97d6f 197 /* outI = (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] +
emh203 0:3d9c67d97d6f 198 pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
emh203 0:3d9c67d97d6f 199 pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); */
emh203 0:3d9c67d97d6f 200
emh203 0:3d9c67d97d6f 201 /* read pATable[2 * i] */
emh203 0:3d9c67d97d6f 202 CoefA1 = *pCoefA++;
emh203 0:3d9c67d97d6f 203 /* pATable[2 * i + 1] */
emh203 0:3d9c67d97d6f 204 CoefA2 = *pCoefA;
emh203 0:3d9c67d97d6f 205
emh203 0:3d9c67d97d6f 206 /* pSrc[2 * i] * pATable[2 * i] */
emh203 0:3d9c67d97d6f 207 outR = *pSrc1 * CoefA1;
emh203 0:3d9c67d97d6f 208 /* pSrc[2 * i] * CoefA2 */
emh203 0:3d9c67d97d6f 209 outI = *pSrc1++ * CoefA2;
emh203 0:3d9c67d97d6f 210
emh203 0:3d9c67d97d6f 211 /* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */
emh203 0:3d9c67d97d6f 212 outR -= (*pSrc1 + *pSrc2) * CoefA2;
emh203 0:3d9c67d97d6f 213 /* pSrc[2 * i + 1] * CoefA1 */
emh203 0:3d9c67d97d6f 214 outI += *pSrc1++ * CoefA1;
emh203 0:3d9c67d97d6f 215
emh203 0:3d9c67d97d6f 216 CoefB1 = *pCoefB;
emh203 0:3d9c67d97d6f 217
emh203 0:3d9c67d97d6f 218 /* pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */
emh203 0:3d9c67d97d6f 219 outI -= *pSrc2-- * CoefB1;
emh203 0:3d9c67d97d6f 220 /* pSrc[2 * fftLen - 2 * i] * CoefA2 */
emh203 0:3d9c67d97d6f 221 outI -= *pSrc2 * CoefA2;
emh203 0:3d9c67d97d6f 222
emh203 0:3d9c67d97d6f 223 /* pSrc[2 * fftLen - 2 * i] * CoefB1 */
emh203 0:3d9c67d97d6f 224 outR += *pSrc2-- * CoefB1;
emh203 0:3d9c67d97d6f 225
emh203 0:3d9c67d97d6f 226 /* write output */
emh203 0:3d9c67d97d6f 227 *pDst1++ = outR;
emh203 0:3d9c67d97d6f 228 *pDst1++ = outI;
emh203 0:3d9c67d97d6f 229
emh203 0:3d9c67d97d6f 230 /* write complex conjugate output */
emh203 0:3d9c67d97d6f 231 *pDst2-- = -outI;
emh203 0:3d9c67d97d6f 232 *pDst2-- = outR;
emh203 0:3d9c67d97d6f 233
emh203 0:3d9c67d97d6f 234 /* update coefficient pointer */
emh203 0:3d9c67d97d6f 235 pCoefB = pCoefB + (modifier * 2u);
emh203 0:3d9c67d97d6f 236 pCoefA = pCoefA + ((modifier * 2u) - 1u);
emh203 0:3d9c67d97d6f 237
emh203 0:3d9c67d97d6f 238 i--;
emh203 0:3d9c67d97d6f 239
emh203 0:3d9c67d97d6f 240 }
emh203 0:3d9c67d97d6f 241
emh203 0:3d9c67d97d6f 242 pDst[2u * fftLen] = pSrc[0] - pSrc[1];
emh203 0:3d9c67d97d6f 243 pDst[(2u * fftLen) + 1u] = 0.0f;
emh203 0:3d9c67d97d6f 244
emh203 0:3d9c67d97d6f 245 pDst[0] = pSrc[0] + pSrc[1];
emh203 0:3d9c67d97d6f 246 pDst[1] = 0.0f;
emh203 0:3d9c67d97d6f 247
emh203 0:3d9c67d97d6f 248 }
emh203 0:3d9c67d97d6f 249
emh203 0:3d9c67d97d6f 250
emh203 0:3d9c67d97d6f 251 /**
emh203 0:3d9c67d97d6f 252 * @brief Core Real IFFT process
emh203 0:3d9c67d97d6f 253 * @param[in] *pSrc points to the input buffer.
emh203 0:3d9c67d97d6f 254 * @param[in] fftLen length of FFT.
emh203 0:3d9c67d97d6f 255 * @param[in] *pATable points to the twiddle Coef A buffer.
emh203 0:3d9c67d97d6f 256 * @param[in] *pBTable points to the twiddle Coef B buffer.
emh203 0:3d9c67d97d6f 257 * @param[out] *pDst points to the output buffer.
emh203 0:3d9c67d97d6f 258 * @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
emh203 0:3d9c67d97d6f 259 * @return none.
emh203 0:3d9c67d97d6f 260 */
emh203 0:3d9c67d97d6f 261
emh203 0:3d9c67d97d6f 262 void arm_split_rifft_f32(
emh203 0:3d9c67d97d6f 263 float32_t * pSrc,
emh203 0:3d9c67d97d6f 264 uint32_t fftLen,
emh203 0:3d9c67d97d6f 265 float32_t * pATable,
emh203 0:3d9c67d97d6f 266 float32_t * pBTable,
emh203 0:3d9c67d97d6f 267 float32_t * pDst,
emh203 0:3d9c67d97d6f 268 uint32_t modifier)
emh203 0:3d9c67d97d6f 269 {
emh203 0:3d9c67d97d6f 270 float32_t outR, outI; /* Temporary variables for output */
emh203 0:3d9c67d97d6f 271 float32_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */
emh203 0:3d9c67d97d6f 272 float32_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */
emh203 0:3d9c67d97d6f 273 float32_t *pSrc1 = &pSrc[0], *pSrc2 = &pSrc[(2u * fftLen) + 1u];
emh203 0:3d9c67d97d6f 274
emh203 0:3d9c67d97d6f 275 pCoefA = &pATable[0];
emh203 0:3d9c67d97d6f 276 pCoefB = &pBTable[0];
emh203 0:3d9c67d97d6f 277
emh203 0:3d9c67d97d6f 278 while(fftLen > 0u)
emh203 0:3d9c67d97d6f 279 {
emh203 0:3d9c67d97d6f 280 /*
emh203 0:3d9c67d97d6f 281 outR = (pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] +
emh203 0:3d9c67d97d6f 282 pIn[2 * n - 2 * i] * pBTable[2 * i] -
emh203 0:3d9c67d97d6f 283 pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
emh203 0:3d9c67d97d6f 284
emh203 0:3d9c67d97d6f 285 outI = (pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] -
emh203 0:3d9c67d97d6f 286 pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
emh203 0:3d9c67d97d6f 287 pIn[2 * n - 2 * i + 1] * pBTable[2 * i]);
emh203 0:3d9c67d97d6f 288
emh203 0:3d9c67d97d6f 289 */
emh203 0:3d9c67d97d6f 290
emh203 0:3d9c67d97d6f 291 CoefA1 = *pCoefA++;
emh203 0:3d9c67d97d6f 292 CoefA2 = *pCoefA;
emh203 0:3d9c67d97d6f 293
emh203 0:3d9c67d97d6f 294 /* outR = (pSrc[2 * i] * CoefA1 */
emh203 0:3d9c67d97d6f 295 outR = *pSrc1 * CoefA1;
emh203 0:3d9c67d97d6f 296
emh203 0:3d9c67d97d6f 297 /* - pSrc[2 * i] * CoefA2 */
emh203 0:3d9c67d97d6f 298 outI = -(*pSrc1++) * CoefA2;
emh203 0:3d9c67d97d6f 299
emh203 0:3d9c67d97d6f 300 /* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */
emh203 0:3d9c67d97d6f 301 outR += (*pSrc1 + *pSrc2) * CoefA2;
emh203 0:3d9c67d97d6f 302
emh203 0:3d9c67d97d6f 303 /* pSrc[2 * i + 1] * CoefA1 */
emh203 0:3d9c67d97d6f 304 outI += (*pSrc1++) * CoefA1;
emh203 0:3d9c67d97d6f 305
emh203 0:3d9c67d97d6f 306 CoefB1 = *pCoefB;
emh203 0:3d9c67d97d6f 307
emh203 0:3d9c67d97d6f 308 /* - pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */
emh203 0:3d9c67d97d6f 309 outI -= *pSrc2-- * CoefB1;
emh203 0:3d9c67d97d6f 310
emh203 0:3d9c67d97d6f 311 /* pSrc[2 * fftLen - 2 * i] * CoefB1 */
emh203 0:3d9c67d97d6f 312 outR += *pSrc2 * CoefB1;
emh203 0:3d9c67d97d6f 313
emh203 0:3d9c67d97d6f 314 /* pSrc[2 * fftLen - 2 * i] * CoefA2 */
emh203 0:3d9c67d97d6f 315 outI += *pSrc2-- * CoefA2;
emh203 0:3d9c67d97d6f 316
emh203 0:3d9c67d97d6f 317 /* write output */
emh203 0:3d9c67d97d6f 318 *pDst++ = outR;
emh203 0:3d9c67d97d6f 319 *pDst++ = outI;
emh203 0:3d9c67d97d6f 320
emh203 0:3d9c67d97d6f 321 /* update coefficient pointer */
emh203 0:3d9c67d97d6f 322 pCoefB = pCoefB + (modifier * 2u);
emh203 0:3d9c67d97d6f 323 pCoefA = pCoefA + ((modifier * 2u) - 1u);
emh203 0:3d9c67d97d6f 324
emh203 0:3d9c67d97d6f 325 /* Decrement loop count */
emh203 0:3d9c67d97d6f 326 fftLen--;
emh203 0:3d9c67d97d6f 327 }
emh203 0:3d9c67d97d6f 328
emh203 0:3d9c67d97d6f 329 }