arm_rfft_q31.c
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CLexer
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r16 | /* ---------------------------------------------------------------------- | ||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 29. November 2010 | ||||
* $Revision: V1.0.3 | ||||
* | ||||
* Project: CMSIS DSP Library | ||||
* Title: arm_rfft_q31.c | ||||
* | ||||
* Description: RFFT & RIFFT Q31 process function | ||||
* | ||||
* | ||||
* Target Processor: Cortex-M4/Cortex-M3 | ||||
* | ||||
* 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--; | ||||
} | ||||
} | ||||