/* ---------------------------------------------------------------------- * Copyright (C) 2010-2013 ARM Limited. All rights reserved. * * $Date: 17. January 2013 * $Revision: V1.4.1 * * Project: CMSIS DSP Library * Title: arm_bitreversal.c * * Description: This file has common tables like Bitreverse, reciprocal etc which are used across different functions * * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * - Neither the name of ARM LIMITED nor the names of its contributors * may be used to endorse or promote products derived from this * software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * -------------------------------------------------------------------- */ #include "arm_math.h" #include "arm_common_tables.h" /* * @brief In-place bit reversal function. * @param[in, out] *pSrc points to the in-place buffer of floating-point data type. * @param[in] fftSize length of the FFT. * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table. * @param[in] *pBitRevTab points to the bit reversal table. * @return none. */ void arm_bitreversal_f32( float32_t * pSrc, uint16_t fftSize, uint16_t bitRevFactor, uint16_t * pBitRevTab) { uint16_t fftLenBy2, fftLenBy2p1; uint16_t i, j; float32_t in; /* Initializations */ j = 0u; fftLenBy2 = fftSize >> 1u; fftLenBy2p1 = (fftSize >> 1u) + 1u; /* Bit Reversal Implementation */ for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u) { if(i < j) { /* pSrc[i] <-> pSrc[j]; */ in = pSrc[2u * i]; pSrc[2u * i] = pSrc[2u * j]; pSrc[2u * j] = in; /* pSrc[i+1u] <-> pSrc[j+1u] */ in = pSrc[(2u * i) + 1u]; pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u]; pSrc[(2u * j) + 1u] = in; /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */ in = pSrc[2u * (i + fftLenBy2p1)]; pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)]; pSrc[2u * (j + fftLenBy2p1)] = in; /* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */ in = pSrc[(2u * (i + fftLenBy2p1)) + 1u]; pSrc[(2u * (i + fftLenBy2p1)) + 1u] = pSrc[(2u * (j + fftLenBy2p1)) + 1u]; pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in; } /* pSrc[i+1u] <-> pSrc[j+1u] */ in = pSrc[2u * (i + 1u)]; pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)]; pSrc[2u * (j + fftLenBy2)] = in; /* pSrc[i+2u] <-> pSrc[j+2u] */ in = pSrc[(2u * (i + 1u)) + 1u]; pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u]; pSrc[(2u * (j + fftLenBy2)) + 1u] = in; /* Reading the index for the bit reversal */ j = *pBitRevTab; /* Updating the bit reversal index depending on the fft length */ pBitRevTab += bitRevFactor; } } /* * @brief In-place bit reversal function. * @param[in, out] *pSrc points to the in-place buffer of Q31 data type. * @param[in] fftLen length of the FFT. * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table * @param[in] *pBitRevTab points to bit reversal table. * @return none. */ void arm_bitreversal_q31( q31_t * pSrc, uint32_t fftLen, uint16_t bitRevFactor, uint16_t * pBitRevTable) { uint32_t fftLenBy2, fftLenBy2p1, i, j; q31_t in; /* Initializations */ j = 0u; fftLenBy2 = fftLen / 2u; fftLenBy2p1 = (fftLen / 2u) + 1u; /* Bit Reversal Implementation */ for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u) { if(i < j) { /* pSrc[i] <-> pSrc[j]; */ in = pSrc[2u * i]; pSrc[2u * i] = pSrc[2u * j]; pSrc[2u * j] = in; /* pSrc[i+1u] <-> pSrc[j+1u] */ in = pSrc[(2u * i) + 1u]; pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u]; pSrc[(2u * j) + 1u] = in; /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */ in = pSrc[2u * (i + fftLenBy2p1)]; pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)]; pSrc[2u * (j + fftLenBy2p1)] = in; /* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */ in = pSrc[(2u * (i + fftLenBy2p1)) + 1u]; pSrc[(2u * (i + fftLenBy2p1)) + 1u] = pSrc[(2u * (j + fftLenBy2p1)) + 1u]; pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in; } /* pSrc[i+1u] <-> pSrc[j+1u] */ in = pSrc[2u * (i + 1u)]; pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)]; pSrc[2u * (j + fftLenBy2)] = in; /* pSrc[i+2u] <-> pSrc[j+2u] */ in = pSrc[(2u * (i + 1u)) + 1u]; pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u]; pSrc[(2u * (j + fftLenBy2)) + 1u] = in; /* Reading the index for the bit reversal */ j = *pBitRevTable; /* Updating the bit reversal index depending on the fft length */ pBitRevTable += bitRevFactor; } } /* * @brief In-place bit reversal function. * @param[in, out] *pSrc points to the in-place buffer of Q15 data type. * @param[in] fftLen length of the FFT. * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table * @param[in] *pBitRevTab points to bit reversal table. * @return none. */ void arm_bitreversal_q15( q15_t * pSrc16, uint32_t fftLen, uint16_t bitRevFactor, uint16_t * pBitRevTab) { q31_t *pSrc = (q31_t *) pSrc16; q31_t in; uint32_t fftLenBy2, fftLenBy2p1; uint32_t i, j; /* Initializations */ j = 0u; fftLenBy2 = fftLen / 2u; fftLenBy2p1 = (fftLen / 2u) + 1u; /* Bit Reversal Implementation */ for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u) { if(i < j) { /* pSrc[i] <-> pSrc[j]; */ /* pSrc[i+1u] <-> pSrc[j+1u] */ in = pSrc[i]; pSrc[i] = pSrc[j]; pSrc[j] = in; /* pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1]; */ /* pSrc[i + fftLenBy2p1+1u] <-> pSrc[j + fftLenBy2p1+1u] */ in = pSrc[i + fftLenBy2p1]; pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1]; pSrc[j + fftLenBy2p1] = in; } /* pSrc[i+1u] <-> pSrc[j+fftLenBy2]; */ /* pSrc[i+2] <-> pSrc[j+fftLenBy2+1u] */ in = pSrc[i + 1u]; pSrc[i + 1u] = pSrc[j + fftLenBy2]; pSrc[j + fftLenBy2] = in; /* Reading the index for the bit reversal */ j = *pBitRevTab; /* Updating the bit reversal index depending on the fft length */ pBitRevTab += bitRevFactor; } }