| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_rfft_f32.c |
| * Description: RFFT & RIFFT Floating point process function |
| * |
| * $Date: 18. March 2019 |
| * $Revision: V1.6.0 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the License); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "arm_math.h" |
| |
| /* ---------------------------------------------------------------------- |
| * Internal functions prototypes |
| * -------------------------------------------------------------------- */ |
| |
| extern void arm_radix4_butterfly_f32( |
| float32_t * pSrc, |
| uint16_t fftLen, |
| const float32_t * pCoef, |
| uint16_t twidCoefModifier); |
| |
| extern void arm_radix4_butterfly_inverse_f32( |
| float32_t * pSrc, |
| uint16_t fftLen, |
| const float32_t * pCoef, |
| uint16_t twidCoefModifier, |
| float32_t onebyfftLen); |
| |
| extern void arm_bitreversal_f32( |
| float32_t * pSrc, |
| uint16_t fftSize, |
| uint16_t bitRevFactor, |
| const uint16_t * pBitRevTab); |
| |
| void arm_split_rfft_f32( |
| float32_t * pSrc, |
| uint32_t fftLen, |
| const float32_t * pATable, |
| const float32_t * pBTable, |
| float32_t * pDst, |
| uint32_t modifier); |
| |
| void arm_split_rifft_f32( |
| float32_t * pSrc, |
| uint32_t fftLen, |
| const float32_t * pATable, |
| const float32_t * pBTable, |
| float32_t * pDst, |
| uint32_t modifier); |
| |
| /** |
| @ingroup groupTransforms |
| */ |
| |
| /** |
| @addtogroup RealFFT |
| @{ |
| */ |
| |
| /** |
| @brief Processing function for the floating-point RFFT/RIFFT. |
| @deprecated Do not use this function. It has been superceded by \ref arm_rfft_fast_f32 and will be removed in the future. |
| @param[in] S points to an instance of the floating-point RFFT/RIFFT structure |
| @param[in] pSrc points to the input buffer |
| @param[out] pDst points to the output buffer |
| @return none |
| */ |
| |
| void arm_rfft_f32( |
| const arm_rfft_instance_f32 * S, |
| float32_t * pSrc, |
| float32_t * pDst) |
| { |
| const arm_cfft_radix4_instance_f32 *S_CFFT = S->pCfft; |
| |
| /* Calculation of Real IFFT of input */ |
| if (S->ifftFlagR == 1U) |
| { |
| /* Real IFFT core process */ |
| arm_split_rifft_f32 (pSrc, S->fftLenBy2, S->pTwiddleAReal, S->pTwiddleBReal, pDst, S->twidCoefRModifier); |
| |
| |
| /* Complex radix-4 IFFT process */ |
| arm_radix4_butterfly_inverse_f32 (pDst, S_CFFT->fftLen, S_CFFT->pTwiddle, S_CFFT->twidCoefModifier, S_CFFT->onebyfftLen); |
| |
| /* Bit reversal process */ |
| if (S->bitReverseFlagR == 1U) |
| { |
| arm_bitreversal_f32 (pDst, S_CFFT->fftLen, S_CFFT->bitRevFactor, S_CFFT->pBitRevTable); |
| } |
| } |
| else |
| { |
| /* Calculation of RFFT of input */ |
| |
| /* Complex radix-4 FFT process */ |
| arm_radix4_butterfly_f32 (pSrc, S_CFFT->fftLen, S_CFFT->pTwiddle, S_CFFT->twidCoefModifier); |
| |
| /* Bit reversal process */ |
| if (S->bitReverseFlagR == 1U) |
| { |
| arm_bitreversal_f32 (pSrc, S_CFFT->fftLen, S_CFFT->bitRevFactor, S_CFFT->pBitRevTable); |
| } |
| |
| /* Real FFT core process */ |
| arm_split_rfft_f32 (pSrc, S->fftLenBy2, S->pTwiddleAReal, S->pTwiddleBReal, pDst, S->twidCoefRModifier); |
| } |
| |
| } |
| |
| /** |
| @} end of RealFFT group |
| */ |
| |
| /** |
| @brief Core Real FFT process |
| @param[in] pSrc points to input buffer |
| @param[in] fftLen length of FFT |
| @param[in] pATable points to twiddle Coef A buffer |
| @param[in] pBTable points to twiddle Coef B buffer |
| @param[out] pDst points to output buffer |
| @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table |
| @return none |
| */ |
| |
| void arm_split_rfft_f32( |
| float32_t * pSrc, |
| uint32_t fftLen, |
| const float32_t * pATable, |
| const float32_t * pBTable, |
| float32_t * pDst, |
| uint32_t modifier) |
| { |
| uint32_t i; /* Loop Counter */ |
| float32_t outR, outI; /* Temporary variables for output */ |
| const float32_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ |
| float32_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */ |
| float32_t *pDst1 = &pDst[2], *pDst2 = &pDst[(4U * fftLen) - 1U]; /* temp pointers for output buffer */ |
| float32_t *pSrc1 = &pSrc[2], *pSrc2 = &pSrc[(2U * fftLen) - 1U]; /* temp pointers for input buffer */ |
| |
| /* Init coefficient pointers */ |
| pCoefA = &pATable[modifier * 2]; |
| pCoefB = &pBTable[modifier * 2]; |
| |
| i = fftLen - 1U; |
| |
| while (i > 0U) |
| { |
| /* |
| outR = ( pSrc[2 * i] * pATable[2 * i] |
| - pSrc[2 * i + 1] * pATable[2 * i + 1] |
| + pSrc[2 * n - 2 * i] * pBTable[2 * i] |
| + pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]); |
| |
| outI = ( pIn[2 * i + 1] * pATable[2 * i] |
| + pIn[2 * i] * pATable[2 * i + 1] |
| + pIn[2 * n - 2 * i] * pBTable[2 * i + 1] |
| - pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); |
| */ |
| |
| /* read pATable[2 * i] */ |
| CoefA1 = *pCoefA++; |
| /* pATable[2 * i + 1] */ |
| CoefA2 = *pCoefA; |
| |
| /* pSrc[2 * i] * pATable[2 * i] */ |
| outR = *pSrc1 * CoefA1; |
| /* pSrc[2 * i] * CoefA2 */ |
| outI = *pSrc1++ * CoefA2; |
| |
| /* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */ |
| outR -= (*pSrc1 + *pSrc2) * CoefA2; |
| /* pSrc[2 * i + 1] * CoefA1 */ |
| outI += *pSrc1++ * CoefA1; |
| |
| CoefB1 = *pCoefB; |
| |
| /* pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */ |
| outI -= *pSrc2-- * CoefB1; |
| /* pSrc[2 * fftLen - 2 * i] * CoefA2 */ |
| outI -= *pSrc2 * CoefA2; |
| |
| /* pSrc[2 * fftLen - 2 * i] * CoefB1 */ |
| outR += *pSrc2-- * CoefB1; |
| |
| /* write output */ |
| *pDst1++ = outR; |
| *pDst1++ = outI; |
| |
| /* write complex conjugate output */ |
| *pDst2-- = -outI; |
| *pDst2-- = outR; |
| |
| /* update coefficient pointer */ |
| pCoefB = pCoefB + (modifier * 2U); |
| pCoefA = pCoefA + ((modifier * 2U) - 1U); |
| |
| i--; |
| |
| } |
| |
| pDst[2U * fftLen] = pSrc[0] - pSrc[1]; |
| pDst[(2U * fftLen) + 1U] = 0.0f; |
| |
| pDst[0] = pSrc[0] + pSrc[1]; |
| pDst[1] = 0.0f; |
| |
| } |
| |
| |
| /** |
| @brief Core Real IFFT process |
| @param[in] pSrc points to input buffer |
| @param[in] fftLen length of FFT |
| @param[in] pATable points to twiddle Coef A buffer |
| @param[in] pBTable points to twiddle Coef B buffer |
| @param[out] pDst points to output buffer |
| @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table |
| @return none |
| */ |
| |
| void arm_split_rifft_f32( |
| float32_t * pSrc, |
| uint32_t fftLen, |
| const float32_t * pATable, |
| const float32_t * pBTable, |
| float32_t * pDst, |
| uint32_t modifier) |
| { |
| float32_t outR, outI; /* Temporary variables for output */ |
| const float32_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ |
| float32_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */ |
| float32_t *pSrc1 = &pSrc[0], *pSrc2 = &pSrc[(2U * fftLen) + 1U]; |
| |
| pCoefA = &pATable[0]; |
| pCoefB = &pBTable[0]; |
| |
| while (fftLen > 0U) |
| { |
| /* |
| outR = ( pIn[2 * i] * pATable[2 * i] |
| + pIn[2 * i + 1] * pATable[2 * i + 1] |
| + pIn[2 * n - 2 * i] * pBTable[2 * i] |
| - pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]); |
| |
| outI = ( pIn[2 * i + 1] * pATable[2 * i] |
| - pIn[2 * i] * pATable[2 * i + 1] |
| - pIn[2 * n - 2 * i] * pBTable[2 * i + 1] |
| - pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); |
| */ |
| |
| CoefA1 = *pCoefA++; |
| CoefA2 = *pCoefA; |
| |
| /* outR = (pSrc[2 * i] * CoefA1 */ |
| outR = *pSrc1 * CoefA1; |
| |
| /* - pSrc[2 * i] * CoefA2 */ |
| outI = -(*pSrc1++) * CoefA2; |
| |
| /* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */ |
| outR += (*pSrc1 + *pSrc2) * CoefA2; |
| |
| /* pSrc[2 * i + 1] * CoefA1 */ |
| outI += (*pSrc1++) * CoefA1; |
| |
| CoefB1 = *pCoefB; |
| |
| /* - pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */ |
| outI -= *pSrc2-- * CoefB1; |
| |
| /* pSrc[2 * fftLen - 2 * i] * CoefB1 */ |
| outR += *pSrc2 * CoefB1; |
| |
| /* pSrc[2 * fftLen - 2 * i] * CoefA2 */ |
| outI += *pSrc2-- * CoefA2; |
| |
| /* write output */ |
| *pDst++ = outR; |
| *pDst++ = outI; |
| |
| /* update coefficient pointer */ |
| pCoefB = pCoefB + (modifier * 2); |
| pCoefA = pCoefA + (modifier * 2 - 1); |
| |
| /* Decrement loop count */ |
| fftLen--; |
| } |
| |
| } |
