arm_rfft_q15.c
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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_q15.c | ||||
* | ||||
* Description: RFFT & RIFFT Q15 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_q15( | ||||
q15_t * pSrc, | ||||
uint32_t fftLen, | ||||
q15_t * pATable, | ||||
q15_t * pBTable, | ||||
q15_t * pDst, | ||||
uint32_t modifier); | ||||
void arm_split_rifft_q15( | ||||
q15_t * pSrc, | ||||
uint32_t fftLen, | ||||
q15_t * pATable, | ||||
q15_t * pBTable, | ||||
q15_t * pDst, | ||||
uint32_t modifier); | ||||
/** | ||||
* @addtogroup RFFT_RIFFT | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @brief Processing function for the Q15 RFFT/RIFFT. | ||||
* @param[in] *S points to an instance of the Q15 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 RFFTQ15.gif "Input and Output Formats for Q15 RFFT" | ||||
* \par | ||||
* \image html RIFFTQ15.gif "Input and Output Formats for Q15 RIFFT" | ||||
*/ | ||||
void arm_rfft_q15( | ||||
const arm_rfft_instance_q15 * S, | ||||
q15_t * pSrc, | ||||
q15_t * pDst) | ||||
{ | ||||
const arm_cfft_radix4_instance_q15 *S_CFFT = S->pCfft; | ||||
/* Calculation of RIFFT of input */ | ||||
if(S->ifftFlagR == 1u) | ||||
{ | ||||
/* Real IFFT core process */ | ||||
arm_split_rifft_q15(pSrc, S->fftLenBy2, S->pTwiddleAReal, | ||||
S->pTwiddleBReal, pDst, S->twidCoefRModifier); | ||||
/* Complex readix-4 IFFT process */ | ||||
arm_radix4_butterfly_inverse_q15(pDst, S_CFFT->fftLen, | ||||
S_CFFT->pTwiddle, | ||||
S_CFFT->twidCoefModifier); | ||||
/* Bit reversal process */ | ||||
if(S->bitReverseFlagR == 1u) | ||||
{ | ||||
arm_bitreversal_q15(pDst, S_CFFT->fftLen, | ||||
S_CFFT->bitRevFactor, S_CFFT->pBitRevTable); | ||||
} | ||||
} | ||||
else | ||||
{ | ||||
/* Calculation of RFFT of input */ | ||||
/* Complex readix-4 FFT process */ | ||||
arm_radix4_butterfly_q15(pSrc, S_CFFT->fftLen, | ||||
S_CFFT->pTwiddle, S_CFFT->twidCoefModifier); | ||||
/* Bit reversal process */ | ||||
if(S->bitReverseFlagR == 1u) | ||||
{ | ||||
arm_bitreversal_q15(pSrc, S_CFFT->fftLen, | ||||
S_CFFT->bitRevFactor, S_CFFT->pBitRevTable); | ||||
} | ||||
arm_split_rfft_q15(pSrc, S->fftLenBy2, S->pTwiddleAReal, | ||||
S->pTwiddleBReal, pDst, S->twidCoefRModifier); | ||||
} | ||||
} | ||||
/** | ||||
* @} end of RFFT_RIFFT group | ||||
*/ | ||||
/** | ||||
* @brief Core Real FFT process | ||||
* @param *pSrc points to the input buffer. | ||||
* @param fftLen length of FFT. | ||||
* @param *pATable points to the A twiddle Coef buffer. | ||||
* @param *pBTable points to the B twiddle Coef buffer. | ||||
* @param *pDst points to the output buffer. | ||||
* @param modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. | ||||
* @return none. | ||||
* The function implements a Real FFT | ||||
*/ | ||||
void arm_split_rfft_q15( | ||||
q15_t * pSrc, | ||||
uint32_t fftLen, | ||||
q15_t * pATable, | ||||
q15_t * pBTable, | ||||
q15_t * pDst, | ||||
uint32_t modifier) | ||||
{ | ||||
uint32_t i; /* Loop Counter */ | ||||
q31_t outR, outI; /* Temporary variables for output */ | ||||
q15_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ | ||||
q15_t *pSrc1, *pSrc2; | ||||
pSrc[2u * fftLen] = pSrc[0]; | ||||
pSrc[(2u * fftLen) + 1u] = pSrc[1]; | ||||
pCoefA = &pATable[modifier * 2u]; | ||||
pCoefB = &pBTable[modifier * 2u]; | ||||
pSrc1 = &pSrc[2]; | ||||
pSrc2 = &pSrc[(2u * fftLen) - 2u]; | ||||
i = 1u; | ||||
while(i < fftLen) | ||||
{ | ||||
/* | ||||
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]); */ | ||||
/* pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1] */ | ||||
outR = __SMUSD(*__SIMD32(pSrc1), *__SIMD32(pCoefA)); | ||||
/* pSrc[2 * n - 2 * i] * pBTable[2 * i] + | ||||
pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]) */ | ||||
outR = __SMLAD(*__SIMD32(pSrc2), *__SIMD32(pCoefB), outR) >> 15u; | ||||
/* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] - | ||||
pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ | ||||
outI = __SMUSDX(*__SIMD32(pSrc2)--, *__SIMD32(pCoefB)); | ||||
/* (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] */ | ||||
outI = __SMLADX(*__SIMD32(pSrc1)++, *__SIMD32(pCoefA), outI); | ||||
/* write output */ | ||||
pDst[2u * i] = (q15_t) outR; | ||||
pDst[(2u * i) + 1u] = outI >> 15u; | ||||
/* write complex conjugate output */ | ||||
pDst[(4u * fftLen) - (2u * i)] = (q15_t) outR; | ||||
pDst[((4u * fftLen) - (2u * i)) + 1u] = -(outI >> 15u); | ||||
/* update coefficient pointer */ | ||||
pCoefB = pCoefB + (2u * modifier); | ||||
pCoefA = pCoefA + (2u * modifier); | ||||
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. | ||||
* The function implements a Real IFFT | ||||
*/ | ||||
void arm_split_rifft_q15( | ||||
q15_t * pSrc, | ||||
uint32_t fftLen, | ||||
q15_t * pATable, | ||||
q15_t * pBTable, | ||||
q15_t * pDst, | ||||
uint32_t modifier) | ||||
{ | ||||
uint32_t i; /* Loop Counter */ | ||||
q31_t outR, outI; /* Temporary variables for output */ | ||||
q15_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ | ||||
q15_t *pSrc1, *pSrc2; | ||||
q15_t *pDst1 = &pDst[0]; | ||||
pCoefA = &pATable[0]; | ||||
pCoefB = &pBTable[0]; | ||||
pSrc1 = &pSrc[0]; | ||||
pSrc2 = &pSrc[2u * fftLen]; | ||||
i = fftLen; | ||||
while(i > 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]); | ||||
*/ | ||||
/* pIn[2 * n - 2 * i] * pBTable[2 * i] - | ||||
pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]) */ | ||||
outR = __SMUSD(*__SIMD32(pSrc2), *__SIMD32(pCoefB)); | ||||
/* pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] + | ||||
pIn[2 * n - 2 * i] * pBTable[2 * i] */ | ||||
outR = __SMLAD(*__SIMD32(pSrc1), *__SIMD32(pCoefA), outR) >> 15u; | ||||
/* | ||||
-pIn[2 * n - 2 * i] * pBTable[2 * i + 1] + | ||||
pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ | ||||
outI = __SMUADX(*__SIMD32(pSrc2)--, *__SIMD32(pCoefB)); | ||||
/* pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] */ | ||||
outI = __SMLSDX(*__SIMD32(pCoefA), *__SIMD32(pSrc1)++, -outI); | ||||
/* write output */ | ||||
*__SIMD32(pDst1)++ = | ||||
(q31_t) ((outI << 1u) & 0xFFFF0000) | (outR & 0x0000FFFF); | ||||
/* update coefficient pointer */ | ||||
pCoefB = pCoefB + (2u * modifier); | ||||
pCoefA = pCoefA + (2u * modifier); | ||||
i--; | ||||
} | ||||
} | ||||