| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_rfft_q15.c |
| * Description: RFFT & RIFFT Q15 process function |
| * |
| * $Date: 18. March 2019 |
| * $Revision: V1.6.0 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2019 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_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| const q15_t * pATable, |
| const q15_t * pBTable, |
| q15_t * pDst, |
| uint32_t modifier); |
| |
| void arm_split_rifft_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| const q15_t * pATable, |
| const q15_t * pBTable, |
| q15_t * pDst, |
| uint32_t modifier); |
| |
| /** |
| @addtogroup RealFFT |
| @{ |
| */ |
| |
| /** |
| @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 input buffer |
| @param[out] pDst points to output buffer |
| @return none |
| |
| @par Input an output formats |
| 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_instance_q15 *S_CFFT = S->pCfft; |
| uint32_t L2 = S->fftLenReal >> 1U; |
| uint32_t i; |
| |
| /* Calculation of RIFFT of input */ |
| if (S->ifftFlagR == 1U) |
| { |
| /* Real IFFT core process */ |
| arm_split_rifft_q15 (pSrc, L2, S->pTwiddleAReal, S->pTwiddleBReal, pDst, S->twidCoefRModifier); |
| |
| /* Complex IFFT process */ |
| arm_cfft_q15 (S_CFFT, pDst, S->ifftFlagR, S->bitReverseFlagR); |
| |
| for(i = 0; i < S->fftLenReal; i++) |
| { |
| pDst[i] = pDst[i] << 1U; |
| } |
| } |
| else |
| { |
| /* Calculation of RFFT of input */ |
| |
| /* Complex FFT process */ |
| arm_cfft_q15 (S_CFFT, pSrc, S->ifftFlagR, S->bitReverseFlagR); |
| |
| /* Real FFT core process */ |
| arm_split_rfft_q15 (pSrc, L2, S->pTwiddleAReal, S->pTwiddleBReal, pDst, S->twidCoefRModifier); |
| } |
| |
| } |
| |
| /** |
| @} end of RealFFT group |
| */ |
| |
| /** |
| @brief Core Real FFT process |
| @param[in] pSrc points to input buffer |
| @param[in] fftLen length of FFT |
| @param[in] pATable points to twiddle Coef A buffer |
| @param[in] pBTable points to twiddle Coef B buffer |
| @param[out] pDst points to output buffer |
| @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table |
| @return none |
| |
| @par |
| The function implements a Real FFT |
| */ |
| |
| void arm_split_rfft_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| const q15_t * pATable, |
| const q15_t * pBTable, |
| q15_t * pDst, |
| uint32_t modifier) |
| { |
| uint32_t i; /* Loop Counter */ |
| q31_t outR, outI; /* Temporary variables for output */ |
| const q15_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ |
| q15_t *pSrc1, *pSrc2; |
| #if defined (ARM_MATH_DSP) |
| q15_t *pD1, *pD2; |
| #endif |
| |
| /* Init coefficient pointers */ |
| pCoefA = &pATable[modifier * 2]; |
| pCoefB = &pBTable[modifier * 2]; |
| |
| pSrc1 = &pSrc[2]; |
| pSrc2 = &pSrc[(2U * fftLen) - 2U]; |
| |
| #if defined (ARM_MATH_DSP) |
| |
| i = 1U; |
| pD1 = pDst + 2; |
| pD2 = pDst + (4U * fftLen) - 2; |
| |
| for (i = fftLen - 1; i > 0; i--) |
| { |
| /* |
| 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]) |
| */ |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| /* pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1] */ |
| outR = __SMUSD(read_q15x2 (pSrc1), read_q15x2((q15_t *) pCoefA)); |
| #else |
| /* -(pSrc[2 * i + 1] * pATable[2 * i + 1] - pSrc[2 * i] * pATable[2 * i]) */ |
| outR = -(__SMUSD(read_q15x2 (pSrc1), read_q15x2((q15_t *) pCoefA))); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* pSrc[2 * n - 2 * i] * pBTable[2 * i] + pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]) */ |
| outR = __SMLAD(read_q15x2 (pSrc2), read_q15x2((q15_t *) pCoefB), outR) >> 16U; |
| |
| /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] - pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ |
| #ifndef ARM_MATH_BIG_ENDIAN |
| outI = __SMUSDX(read_q15x2_da (&pSrc2), read_q15x2((q15_t *) pCoefB)); |
| #else |
| outI = __SMUSDX(read_q15x2 ((q15_t *) pCoefB), read_q15x2_da (&pSrc2)); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] */ |
| outI = __SMLADX(read_q15x2_ia (&pSrc1), read_q15x2 ((q15_t *) pCoefA), outI); |
| |
| /* write output */ |
| *pD1++ = (q15_t) outR; |
| *pD1++ = outI >> 16U; |
| |
| /* write complex conjugate output */ |
| pD2[0] = (q15_t) outR; |
| pD2[1] = -(outI >> 16U); |
| pD2 -= 2; |
| |
| /* update coefficient pointer */ |
| pCoefB = pCoefB + (2U * modifier); |
| pCoefA = pCoefA + (2U * modifier); |
| } |
| |
| pDst[2U * fftLen] = (pSrc[0] - pSrc[1]) >> 1U; |
| pDst[2U * fftLen + 1U] = 0; |
| |
| pDst[0] = (pSrc[0] + pSrc[1]) >> 1U; |
| pDst[1] = 0; |
| |
| #else |
| |
| 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]); |
| */ |
| |
| outR = *pSrc1 * *pCoefA; |
| outR = outR - (*(pSrc1 + 1) * *(pCoefA + 1)); |
| outR = outR + (*pSrc2 * *pCoefB); |
| outR = (outR + (*(pSrc2 + 1) * *(pCoefB + 1))) >> 16; |
| |
| /* |
| 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]); |
| */ |
| |
| outI = *pSrc2 * *(pCoefB + 1); |
| outI = outI - (*(pSrc2 + 1) * *pCoefB); |
| outI = outI + (*(pSrc1 + 1) * *pCoefA); |
| outI = outI + (*pSrc1 * *(pCoefA + 1)); |
| |
| /* update input pointers */ |
| pSrc1 += 2U; |
| pSrc2 -= 2U; |
| |
| /* write output */ |
| pDst[2U * i] = (q15_t) outR; |
| pDst[2U * i + 1U] = outI >> 16U; |
| |
| /* write complex conjugate output */ |
| pDst[(4U * fftLen) - (2U * i)] = (q15_t) outR; |
| pDst[((4U * fftLen) - (2U * i)) + 1U] = -(outI >> 16U); |
| |
| /* update coefficient pointer */ |
| pCoefB = pCoefB + (2U * modifier); |
| pCoefA = pCoefA + (2U * modifier); |
| |
| i++; |
| } |
| |
| pDst[2U * fftLen] = (pSrc[0] - pSrc[1]) >> 1; |
| pDst[2U * fftLen + 1U] = 0; |
| |
| pDst[0] = (pSrc[0] + pSrc[1]) >> 1; |
| pDst[1] = 0; |
| |
| #endif /* #if defined (ARM_MATH_DSP) */ |
| } |
| |
| |
| /** |
| @brief Core Real IFFT process |
| @param[in] pSrc points to input buffer |
| @param[in] fftLen length of FFT |
| @param[in] pATable points to twiddle Coef A buffer |
| @param[in] pBTable points to twiddle Coef B buffer |
| @param[out] pDst points to output buffer |
| @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table |
| @return none |
| |
| @par |
| The function implements a Real IFFT |
| */ |
| |
| void arm_split_rifft_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| const q15_t * pATable, |
| const q15_t * pBTable, |
| q15_t * pDst, |
| uint32_t modifier) |
| { |
| uint32_t i; /* Loop Counter */ |
| q31_t outR, outI; /* Temporary variables for output */ |
| const 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[2 * 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]); |
| */ |
| |
| #if defined (ARM_MATH_DSP) |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| /* pIn[2 * n - 2 * i] * pBTable[2 * i] - pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]) */ |
| outR = __SMUSD(read_q15x2(pSrc2), read_q15x2((q15_t *) pCoefB)); |
| #else |
| /* -(-pIn[2 * n - 2 * i] * pBTable[2 * i] + pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1])) */ |
| outR = -(__SMUSD(read_q15x2(pSrc2), read_q15x2((q15_t *) pCoefB))); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] + pIn[2 * n - 2 * i] * pBTable[2 * i] */ |
| outR = __SMLAD(read_q15x2(pSrc1), read_q15x2 ((q15_t *) pCoefA), outR) >> 16U; |
| |
| /* -pIn[2 * n - 2 * i] * pBTable[2 * i + 1] + pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ |
| outI = __SMUADX(read_q15x2_da (&pSrc2), read_q15x2((q15_t *) pCoefB)); |
| |
| /* pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] */ |
| #ifndef ARM_MATH_BIG_ENDIAN |
| outI = __SMLSDX(read_q15x2 ((q15_t *) pCoefA), read_q15x2_ia (&pSrc1), -outI); |
| #else |
| outI = __SMLSDX(read_q15x2_ia (&pSrc1), read_q15x2 ((q15_t *) pCoefA), -outI); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* write output */ |
| #ifndef ARM_MATH_BIG_ENDIAN |
| write_q15x2_ia (&pDst1, __PKHBT(outR, (outI >> 16U), 16)); |
| #else |
| write_q15x2_ia (&pDst1, __PKHBT((outI >> 16U), outR, 16)); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| |
| #else /* #if defined (ARM_MATH_DSP) */ |
| |
| outR = *pSrc2 * *pCoefB; |
| outR = outR - (*(pSrc2 + 1) * *(pCoefB + 1)); |
| outR = outR + (*pSrc1 * *pCoefA); |
| outR = (outR + (*(pSrc1 + 1) * *(pCoefA + 1))) >> 16; |
| |
| outI = *(pSrc1 + 1) * *pCoefA; |
| outI = outI - (*pSrc1 * *(pCoefA + 1)); |
| outI = outI - (*pSrc2 * *(pCoefB + 1)); |
| outI = outI - (*(pSrc2 + 1) * *(pCoefB)); |
| |
| /* update input pointers */ |
| pSrc1 += 2U; |
| pSrc2 -= 2U; |
| |
| /* write output */ |
| *pDst1++ = (q15_t) outR; |
| *pDst1++ = (q15_t) (outI >> 16); |
| |
| #endif /* #if defined (ARM_MATH_DSP) */ |
| |
| /* update coefficient pointer */ |
| pCoefB = pCoefB + (2 * modifier); |
| pCoefA = pCoefA + (2 * modifier); |
| |
| i--; |
| } |
| |
| } |
