284 lines
8.9 KiB
C
284 lines
8.9 KiB
C
/* ----------------------------------------------------------------------
|
|
* Project: CMSIS DSP Library
|
|
* Title: arm_rfft_q31.c
|
|
* Description: FFT & RIFFT Q31 process function
|
|
*
|
|
* $Date: 27. January 2017
|
|
* $Revision: V.1.5.1
|
|
*
|
|
* Target Processor: Cortex-M cores
|
|
* -------------------------------------------------------------------- */
|
|
/*
|
|
* Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the License); you may
|
|
* not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#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--;
|
|
}
|
|
}
|