mirror of https://github.com/ARMmbed/mbed-os.git
223 lines
6.3 KiB
C
223 lines
6.3 KiB
C
/* ----------------------------------------------------------------------
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* Copyright (C) 2010 ARM Limited. All rights reserved.
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*
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* $Date: 15. February 2012
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* $Revision: V1.1.0
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*
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* Project: CMSIS DSP Library
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* Title: arm_bitreversal.c
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*
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* Description: This file has common tables like Bitreverse, reciprocal etc which are used across different functions
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Version 1.1.0 2012/02/15
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* Updated with more optimizations, bug fixes and minor API changes.
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*
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* Version 1.0.10 2011/7/15
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* Initial Version
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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#include "arm_common_tables.h"
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/*
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* @brief In-place bit reversal function.
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* @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
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* @param[in] fftSize length of the FFT.
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* @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table.
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* @param[in] *pBitRevTab points to the bit reversal table.
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* @return none.
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*/
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void arm_bitreversal_f32(
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float32_t * pSrc,
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uint16_t fftSize,
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uint16_t bitRevFactor,
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uint16_t * pBitRevTab)
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{
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uint16_t fftLenBy2, fftLenBy2p1;
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uint16_t i, j;
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float32_t in;
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/* Initializations */
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j = 0u;
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fftLenBy2 = fftSize >> 1u;
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fftLenBy2p1 = (fftSize >> 1u) + 1u;
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/* Bit Reversal Implementation */
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for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
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{
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if(i < j)
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{
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/* pSrc[i] <-> pSrc[j]; */
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in = pSrc[2u * i];
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pSrc[2u * i] = pSrc[2u * j];
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pSrc[2u * j] = in;
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/* pSrc[i+1u] <-> pSrc[j+1u] */
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in = pSrc[(2u * i) + 1u];
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pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
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pSrc[(2u * j) + 1u] = in;
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/* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
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in = pSrc[2u * (i + fftLenBy2p1)];
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pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
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pSrc[2u * (j + fftLenBy2p1)] = in;
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/* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
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in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
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pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
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pSrc[(2u * (j + fftLenBy2p1)) + 1u];
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pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
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}
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/* pSrc[i+1u] <-> pSrc[j+1u] */
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in = pSrc[2u * (i + 1u)];
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pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
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pSrc[2u * (j + fftLenBy2)] = in;
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/* pSrc[i+2u] <-> pSrc[j+2u] */
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in = pSrc[(2u * (i + 1u)) + 1u];
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pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
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pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
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/* Reading the index for the bit reversal */
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j = *pBitRevTab;
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/* Updating the bit reversal index depending on the fft length */
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pBitRevTab += bitRevFactor;
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}
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}
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/*
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* @brief In-place bit reversal function.
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* @param[in, out] *pSrc points to the in-place buffer of Q31 data type.
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* @param[in] fftLen length of the FFT.
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* @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
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* @param[in] *pBitRevTab points to bit reversal table.
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* @return none.
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*/
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void arm_bitreversal_q31(
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q31_t * pSrc,
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uint32_t fftLen,
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uint16_t bitRevFactor,
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uint16_t * pBitRevTable)
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{
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uint32_t fftLenBy2, fftLenBy2p1, i, j;
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q31_t in;
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/* Initializations */
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j = 0u;
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fftLenBy2 = fftLen / 2u;
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fftLenBy2p1 = (fftLen / 2u) + 1u;
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/* Bit Reversal Implementation */
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for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
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{
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if(i < j)
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{
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/* pSrc[i] <-> pSrc[j]; */
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in = pSrc[2u * i];
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pSrc[2u * i] = pSrc[2u * j];
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pSrc[2u * j] = in;
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/* pSrc[i+1u] <-> pSrc[j+1u] */
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in = pSrc[(2u * i) + 1u];
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pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
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pSrc[(2u * j) + 1u] = in;
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/* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
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in = pSrc[2u * (i + fftLenBy2p1)];
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pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
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pSrc[2u * (j + fftLenBy2p1)] = in;
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/* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
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in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
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pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
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pSrc[(2u * (j + fftLenBy2p1)) + 1u];
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pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
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}
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/* pSrc[i+1u] <-> pSrc[j+1u] */
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in = pSrc[2u * (i + 1u)];
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pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
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pSrc[2u * (j + fftLenBy2)] = in;
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/* pSrc[i+2u] <-> pSrc[j+2u] */
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in = pSrc[(2u * (i + 1u)) + 1u];
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pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
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pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
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/* Reading the index for the bit reversal */
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j = *pBitRevTable;
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/* Updating the bit reversal index depending on the fft length */
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pBitRevTable += bitRevFactor;
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}
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}
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/*
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* @brief In-place bit reversal function.
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* @param[in, out] *pSrc points to the in-place buffer of Q15 data type.
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* @param[in] fftLen length of the FFT.
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* @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
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* @param[in] *pBitRevTab points to bit reversal table.
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* @return none.
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*/
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void arm_bitreversal_q15(
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q15_t * pSrc16,
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uint32_t fftLen,
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uint16_t bitRevFactor,
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uint16_t * pBitRevTab)
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{
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q31_t *pSrc = (q31_t *) pSrc16;
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q31_t in;
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uint32_t fftLenBy2, fftLenBy2p1;
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uint32_t i, j;
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/* Initializations */
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j = 0u;
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fftLenBy2 = fftLen / 2u;
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fftLenBy2p1 = (fftLen / 2u) + 1u;
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/* Bit Reversal Implementation */
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for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
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{
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if(i < j)
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{
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/* pSrc[i] <-> pSrc[j]; */
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/* pSrc[i+1u] <-> pSrc[j+1u] */
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in = pSrc[i];
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pSrc[i] = pSrc[j];
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pSrc[j] = in;
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/* pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1]; */
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/* pSrc[i + fftLenBy2p1+1u] <-> pSrc[j + fftLenBy2p1+1u] */
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in = pSrc[i + fftLenBy2p1];
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pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1];
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pSrc[j + fftLenBy2p1] = in;
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}
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/* pSrc[i+1u] <-> pSrc[j+fftLenBy2]; */
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/* pSrc[i+2] <-> pSrc[j+fftLenBy2+1u] */
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in = pSrc[i + 1u];
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pSrc[i + 1u] = pSrc[j + fftLenBy2];
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pSrc[j + fftLenBy2] = in;
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/* Reading the index for the bit reversal */
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j = *pBitRevTab;
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/* Updating the bit reversal index depending on the fft length */
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pBitRevTab += bitRevFactor;
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}
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}
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