| /* ---------------------------------------------------------------------- |
| * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
| * |
| * $Date: 19. March 2015 |
| * $Revision: V.1.4.5 |
| * |
| * Project: CMSIS DSP Library |
| * Title: arm_rfft_f32.c |
| * |
| * Description: RFFT & RIFFT Floating point process function |
| * |
| * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * - Neither the name of ARM LIMITED nor the names of its contributors |
| * may be used to endorse or promote products derived from this |
| * software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
| * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| * POSSIBILITY OF SUCH DAMAGE. |
| * -------------------------------------------------------------------- */ |
| |
| #include "arm_math.h" |
| |
| extern void arm_radix4_butterfly_f32( |
| float32_t * pSrc, |
| uint16_t fftLen, |
| float32_t * pCoef, |
| uint16_t twidCoefModifier); |
| |
| extern void arm_radix4_butterfly_inverse_f32( |
| float32_t * pSrc, |
| uint16_t fftLen, |
| float32_t * pCoef, |
| uint16_t twidCoefModifier, |
| float32_t onebyfftLen); |
| |
| extern void arm_bitreversal_f32( |
| float32_t * pSrc, |
| uint16_t fftSize, |
| uint16_t bitRevFactor, |
| uint16_t * pBitRevTab); |
| |
| /** |
| * @ingroup groupTransforms |
| */ |
| |
| /*-------------------------------------------------------------------- |
| * Internal functions prototypes |
| *--------------------------------------------------------------------*/ |
| |
| void arm_split_rfft_f32( |
| float32_t * pSrc, |
| uint32_t fftLen, |
| float32_t * pATable, |
| float32_t * pBTable, |
| float32_t * pDst, |
| uint32_t modifier); |
| void arm_split_rifft_f32( |
| float32_t * pSrc, |
| uint32_t fftLen, |
| float32_t * pATable, |
| float32_t * pBTable, |
| float32_t * pDst, |
| uint32_t modifier); |
| |
| /** |
| * @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 the input buffer. |
| * @param[in] fftLen length of FFT. |
| * @param[in] *pATable points to the twiddle Coef A buffer. |
| * @param[in] *pBTable points to the twiddle Coef B buffer. |
| * @param[out] *pDst points to the 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, |
| float32_t * pATable, |
| float32_t * pBTable, |
| float32_t * pDst, |
| uint32_t modifier) |
| { |
| uint32_t i; /* Loop Counter */ |
| float32_t outR, outI; /* Temporary variables for output */ |
| 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 * 2u]; |
| pCoefB = &pBTable[modifier * 2u]; |
| |
| 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 the input buffer. |
| * @param[in] fftLen length of FFT. |
| * @param[in] *pATable points to the twiddle Coef A buffer. |
| * @param[in] *pBTable points to the twiddle Coef B buffer. |
| * @param[out] *pDst points to the 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, |
| float32_t * pATable, |
| float32_t * pBTable, |
| float32_t * pDst, |
| uint32_t modifier) |
| { |
| float32_t outR, outI; /* Temporary variables for output */ |
| 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 * 2u); |
| pCoefA = pCoefA + ((modifier * 2u) - 1u); |
| |
| /* Decrement loop count */ |
| fftLen--; |
| } |
| |
| } |
