| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_bitreversal.c |
| * Description: Bitreversal functions |
| * |
| * $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" |
| #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; |
| } |
| } |