| /* ---------------------------------------------------------------------- |
| * 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_q31.c |
| * |
| * Description: RFFT & RIFFT Q31 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" |
| |
| /*-------------------------------------------------------------------- |
| * Internal functions prototypes |
| --------------------------------------------------------------------*/ |
| |
| void arm_split_rfft_q31( |
| q31_t * pSrc, |
| uint32_t fftLen, |
| q31_t * pATable, |
| q31_t * pBTable, |
| q31_t * pDst, |
| uint32_t modifier); |
| |
| void arm_split_rifft_q31( |
| q31_t * pSrc, |
| uint32_t fftLen, |
| q31_t * pATable, |
| q31_t * pBTable, |
| q31_t * pDst, |
| uint32_t modifier); |
| |
| /** |
| * @addtogroup RealFFT |
| * @{ |
| */ |
| |
| /** |
| * @brief Processing function for the Q31 RFFT/RIFFT. |
| * @param[in] *S points to an instance of the Q31 RFFT/RIFFT structure. |
| * @param[in] *pSrc points to the input buffer. |
| * @param[out] *pDst points to the output buffer. |
| * @return none. |
| * |
| * \par Input an output formats: |
| * \par |
| * Internally input is downscaled by 2 for every stage to avoid saturations inside CFFT/CIFFT process. |
| * Hence the output format is different for different RFFT sizes. |
| * The input and output formats for different RFFT sizes and number of bits to upscale are mentioned in the tables below for RFFT and RIFFT: |
| * \par |
| * \image html RFFTQ31.gif "Input and Output Formats for Q31 RFFT" |
| * |
| * \par |
| * \image html RIFFTQ31.gif "Input and Output Formats for Q31 RIFFT" |
| */ |
| void arm_rfft_q31( |
| const arm_rfft_instance_q31 * S, |
| q31_t * pSrc, |
| q31_t * pDst) |
| { |
| const arm_cfft_instance_q31 *S_CFFT = S->pCfft; |
| uint32_t i; |
| uint32_t L2 = S->fftLenReal >> 1; |
| |
| /* Calculation of RIFFT of input */ |
| if(S->ifftFlagR == 1u) |
| { |
| /* Real IFFT core process */ |
| arm_split_rifft_q31(pSrc, L2, S->pTwiddleAReal, |
| S->pTwiddleBReal, pDst, S->twidCoefRModifier); |
| |
| /* Complex IFFT process */ |
| arm_cfft_q31(S_CFFT, pDst, S->ifftFlagR, S->bitReverseFlagR); |
| |
| for(i=0;i<S->fftLenReal;i++) |
| { |
| pDst[i] = pDst[i] << 1; |
| } |
| } |
| else |
| { |
| /* Calculation of RFFT of input */ |
| |
| /* Complex FFT process */ |
| arm_cfft_q31(S_CFFT, pSrc, S->ifftFlagR, S->bitReverseFlagR); |
| |
| /* Real FFT core process */ |
| arm_split_rfft_q31(pSrc, L2, 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_q31( |
| q31_t * pSrc, |
| uint32_t fftLen, |
| q31_t * pATable, |
| q31_t * pBTable, |
| q31_t * pDst, |
| uint32_t modifier) |
| { |
| uint32_t i; /* Loop Counter */ |
| q31_t outR, outI; /* Temporary variables for output */ |
| q31_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ |
| q31_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */ |
| q31_t *pOut1 = &pDst[2], *pOut2 = &pDst[(4u * fftLen) - 1u]; |
| q31_t *pIn1 = &pSrc[2], *pIn2 = &pSrc[(2u * fftLen) - 1u]; |
| |
| /* 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]); */ |
| |
| CoefA1 = *pCoefA++; |
| CoefA2 = *pCoefA; |
| |
| /* outR = (pSrc[2 * i] * pATable[2 * i] */ |
| mult_32x32_keep32_R(outR, *pIn1, CoefA1); |
| |
| /* outI = pIn[2 * i] * pATable[2 * i + 1] */ |
| mult_32x32_keep32_R(outI, *pIn1++, CoefA2); |
| |
| /* - pSrc[2 * i + 1] * pATable[2 * i + 1] */ |
| multSub_32x32_keep32_R(outR, *pIn1, CoefA2); |
| |
| /* (pIn[2 * i + 1] * pATable[2 * i] */ |
| multAcc_32x32_keep32_R(outI, *pIn1++, CoefA1); |
| |
| /* pSrc[2 * n - 2 * i] * pBTable[2 * i] */ |
| multSub_32x32_keep32_R(outR, *pIn2, CoefA2); |
| CoefB1 = *pCoefB; |
| |
| /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */ |
| multSub_32x32_keep32_R(outI, *pIn2--, CoefB1); |
| |
| /* pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */ |
| multAcc_32x32_keep32_R(outR, *pIn2, CoefB1); |
| |
| /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ |
| multSub_32x32_keep32_R(outI, *pIn2--, CoefA2); |
| |
| /* write output */ |
| *pOut1++ = outR; |
| *pOut1++ = outI; |
| |
| /* write complex conjugate output */ |
| *pOut2-- = -outI; |
| *pOut2-- = outR; |
| |
| /* update coefficient pointer */ |
| pCoefB = pCoefB + (modifier * 2u); |
| pCoefA = pCoefA + ((modifier * 2u) - 1u); |
| |
| i--; |
| } |
| pDst[2u * fftLen] = (pSrc[0] - pSrc[1]) >> 1; |
| pDst[(2u * fftLen) + 1u] = 0; |
| |
| pDst[0] = (pSrc[0] + pSrc[1]) >> 1; |
| pDst[1] = 0; |
| } |
| |
| /** |
| * @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_q31( |
| q31_t * pSrc, |
| uint32_t fftLen, |
| q31_t * pATable, |
| q31_t * pBTable, |
| q31_t * pDst, |
| uint32_t modifier) |
| { |
| q31_t outR, outI; /* Temporary variables for output */ |
| q31_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ |
| q31_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */ |
| q31_t *pIn1 = &pSrc[0], *pIn2 = &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 = (pIn[2 * i] * pATable[2 * i] */ |
| mult_32x32_keep32_R(outR, *pIn1, CoefA1); |
| |
| /* - pIn[2 * i] * pATable[2 * i + 1] */ |
| mult_32x32_keep32_R(outI, *pIn1++, -CoefA2); |
| |
| /* pIn[2 * i + 1] * pATable[2 * i + 1] */ |
| multAcc_32x32_keep32_R(outR, *pIn1, CoefA2); |
| |
| /* pIn[2 * i + 1] * pATable[2 * i] */ |
| multAcc_32x32_keep32_R(outI, *pIn1++, CoefA1); |
| |
| /* pIn[2 * n - 2 * i] * pBTable[2 * i] */ |
| multAcc_32x32_keep32_R(outR, *pIn2, CoefA2); |
| CoefB1 = *pCoefB; |
| |
| /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */ |
| multSub_32x32_keep32_R(outI, *pIn2--, CoefB1); |
| |
| /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */ |
| multAcc_32x32_keep32_R(outR, *pIn2, CoefB1); |
| |
| /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ |
| multAcc_32x32_keep32_R(outI, *pIn2--, CoefA2); |
| |
| /* write output */ |
| *pDst++ = outR; |
| *pDst++ = outI; |
| |
| /* update coefficient pointer */ |
| pCoefB = pCoefB + (modifier * 2u); |
| pCoefA = pCoefA + ((modifier * 2u) - 1u); |
| |
| /* Decrement loop count */ |
| fftLen--; |
| } |
| } |
