| /* ---------------------------------------------------------------------- |
| * Copyright (C) 2010 ARM Limited. All rights reserved. |
| * |
| * $Date: 15. July 2011 |
| * $Revision: V1.0.10 |
| * |
| * Project: CMSIS DSP Library |
| * Title: arm_rfft_q31.c |
| * |
| * Description: RFFT & RIFFT Q31 process function |
| * |
| * |
| * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
| * |
| * Version 1.0.10 2011/7/15 |
| * Big Endian support added and Merged M0 and M3/M4 Source code. |
| * |
| * Version 1.0.3 2010/11/29 |
| * Re-organized the CMSIS folders and updated documentation. |
| * |
| * Version 1.0.2 2010/11/11 |
| * Documentation updated. |
| * |
| * Version 1.0.1 2010/10/05 |
| * Production release and review comments incorporated. |
| * |
| * Version 1.0.0 2010/09/20 |
| * Production release and review comments incorporated. |
| * |
| * Version 0.0.7 2010/06/10 |
| * Misra-C changes done |
| * -------------------------------------------------------------------- */ |
| |
| #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 RFFT_RIFFT |
| * @{ |
| */ |
| |
| /** |
| * @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_radix4_instance_q31 *S_CFFT = S->pCfft; |
| |
| /* Calculation of RIFFT of input */ |
| if(S->ifftFlagR == 1u) |
| { |
| /* Real IFFT core process */ |
| arm_split_rifft_q31(pSrc, S->fftLenBy2, S->pTwiddleAReal, |
| S->pTwiddleBReal, pDst, S->twidCoefRModifier); |
| |
| /* Complex readix-4 IFFT process */ |
| arm_radix4_butterfly_inverse_q31(pDst, S_CFFT->fftLen, |
| S_CFFT->pTwiddle, |
| S_CFFT->twidCoefModifier); |
| /* Bit reversal process */ |
| if(S->bitReverseFlagR == 1u) |
| { |
| arm_bitreversal_q31(pDst, S_CFFT->fftLen, |
| S_CFFT->bitRevFactor, S_CFFT->pBitRevTable); |
| } |
| } |
| else |
| { |
| /* Calculation of RFFT of input */ |
| |
| /* Complex readix-4 FFT process */ |
| arm_radix4_butterfly_q31(pSrc, S_CFFT->fftLen, |
| S_CFFT->pTwiddle, S_CFFT->twidCoefModifier); |
| |
| /* Bit reversal process */ |
| if(S->bitReverseFlagR == 1u) |
| { |
| arm_bitreversal_q31(pSrc, S_CFFT->fftLen, |
| S_CFFT->bitRevFactor, S_CFFT->pBitRevTable); |
| } |
| |
| /* Real FFT core process */ |
| arm_split_rfft_q31(pSrc, S->fftLenBy2, S->pTwiddleAReal, |
| S->pTwiddleBReal, pDst, S->twidCoefRModifier); |
| } |
| |
| } |
| |
| |
| /** |
| * @} end of RFFT_RIFFT 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]; |
| |
| pSrc[2u * fftLen] = pSrc[0]; |
| pSrc[(2u * fftLen) + 1u] = pSrc[1]; |
| |
| /* 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] */ |
| outR = ((int32_t) (((q63_t) * pIn1 * CoefA1) >> 32)); |
| |
| /* outI = pIn[2 * i] * pATable[2 * i + 1] */ |
| outI = ((int32_t) (((q63_t) * pIn1++ * CoefA2) >> 32)); |
| |
| /* - pSrc[2 * i + 1] * pATable[2 * i + 1] */ |
| outR = |
| (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn1 * (-CoefA2))) >> 32); |
| |
| /* (pIn[2 * i + 1] * pATable[2 * i] */ |
| outI = |
| (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn1++ * (CoefA1))) >> 32); |
| |
| /* pSrc[2 * n - 2 * i] * pBTable[2 * i] */ |
| outR = |
| (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn2 * (-CoefA2))) >> 32); |
| CoefB1 = *pCoefB; |
| |
| /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */ |
| outI = |
| (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn2-- * (-CoefB1))) >> 32); |
| |
| /* pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */ |
| outR = |
| (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn2 * (CoefB1))) >> 32); |
| |
| /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ |
| outI = |
| (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn2-- * (-CoefA2))) >> 32); |
| |
| /* write output */ |
| *pOut1++ = (outR << 1u); |
| *pOut1++ = (outI << 1u); |
| |
| /* write complex conjugate output */ |
| *pOut2-- = -(outI << 1u); |
| *pOut2-- = (outR << 1u); |
| |
| /* 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; |
| |
| pDst[0] = pSrc[0] + pSrc[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] */ |
| outR = ((int32_t) (((q63_t) * pIn1 * CoefA1) >> 32)); |
| |
| /* - pIn[2 * i] * pATable[2 * i + 1] */ |
| outI = -((int32_t) (((q63_t) * pIn1++ * CoefA2) >> 32)); |
| |
| /* pIn[2 * i + 1] * pATable[2 * i + 1] */ |
| outR = |
| (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn1 * (CoefA2))) >> 32); |
| |
| /* pIn[2 * i + 1] * pATable[2 * i] */ |
| outI = |
| (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn1++ * (CoefA1))) >> 32); |
| |
| /* pIn[2 * n - 2 * i] * pBTable[2 * i] */ |
| outR = |
| (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn2 * (CoefA2))) >> 32); |
| |
| CoefB1 = *pCoefB; |
| |
| /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */ |
| outI = |
| (q31_t) ((((q63_t) outI << 32) - ((q63_t) * pIn2-- * (CoefB1))) >> 32); |
| |
| /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */ |
| outR = |
| (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn2 * (CoefB1))) >> 32); |
| |
| /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ |
| outI = |
| (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn2-- * (CoefA2))) >> 32); |
| |
| /* write output */ |
| *pDst++ = (outR << 1u); |
| *pDst++ = (outI << 1u); |
| |
| /* update coefficient pointer */ |
| pCoefB = pCoefB + (modifier * 2u); |
| pCoefA = pCoefA + ((modifier * 2u) - 1u); |
| |
| /* Decrement loop count */ |
| fftLen--; |
| |
| } |
| |
| |
| } |
