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Diffstat (limited to 'DSP_Lib/Source/TransformFunctions/arm_rfft_q31.c')
-rw-r--r-- | DSP_Lib/Source/TransformFunctions/arm_rfft_q31.c | 296 |
1 files changed, 296 insertions, 0 deletions
diff --git a/DSP_Lib/Source/TransformFunctions/arm_rfft_q31.c b/DSP_Lib/Source/TransformFunctions/arm_rfft_q31.c new file mode 100644 index 0000000..71bba21 --- /dev/null +++ b/DSP_Lib/Source/TransformFunctions/arm_rfft_q31.c @@ -0,0 +1,296 @@ +/* ---------------------------------------------------------------------- +* 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--; + } +} |