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The CMSIS DSP 5 library

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functions/TransformFunctions/arm_bitreversal.c@3:4098b9d3d571, 2018-06-21 (annotated)

Committer:
xorjoep
Date:
Thu Jun 21 11:56:27 2018 +0000
Revision:
3:4098b9d3d571
Parent:
1:24714b45cd1b 
headers is a folder not a library

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xorjoep 1:24714b45cd1b 1 /* ----------------------------------------------------------------------
xorjoep 1:24714b45cd1b 2 * Project: CMSIS DSP Library
xorjoep 1:24714b45cd1b 3 * Title: arm_bitreversal.c
xorjoep 1:24714b45cd1b 4 * Description: Bitreversal functions
xorjoep 1:24714b45cd1b 5 *
xorjoep 1:24714b45cd1b 6 * $Date: 27. January 2017
xorjoep 1:24714b45cd1b 7 * $Revision: V.1.5.1
xorjoep 1:24714b45cd1b 8 *
xorjoep 1:24714b45cd1b 9 * Target Processor: Cortex-M cores
xorjoep 1:24714b45cd1b 10 * -------------------------------------------------------------------- */
xorjoep 1:24714b45cd1b 11 /*
xorjoep 1:24714b45cd1b 12 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
xorjoep 1:24714b45cd1b 13 *
xorjoep 1:24714b45cd1b 14 * SPDX-License-Identifier: Apache-2.0
xorjoep 1:24714b45cd1b 15 *
xorjoep 1:24714b45cd1b 16 * Licensed under the Apache License, Version 2.0 (the License); you may
xorjoep 1:24714b45cd1b 17 * not use this file except in compliance with the License.
xorjoep 1:24714b45cd1b 18 * You may obtain a copy of the License at
xorjoep 1:24714b45cd1b 19 *
xorjoep 1:24714b45cd1b 20 * www.apache.org/licenses/LICENSE-2.0
xorjoep 1:24714b45cd1b 21 *
xorjoep 1:24714b45cd1b 22 * Unless required by applicable law or agreed to in writing, software
xorjoep 1:24714b45cd1b 23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
xorjoep 1:24714b45cd1b 24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
xorjoep 1:24714b45cd1b 25 * See the License for the specific language governing permissions and
xorjoep 1:24714b45cd1b 26 * limitations under the License.
xorjoep 1:24714b45cd1b 27 */
xorjoep 1:24714b45cd1b 28
xorjoep 1:24714b45cd1b 29 #include "arm_math.h"
xorjoep 1:24714b45cd1b 30 #include "arm_common_tables.h"
xorjoep 1:24714b45cd1b 31
xorjoep 1:24714b45cd1b 32 /*
xorjoep 1:24714b45cd1b 33 * @brief In-place bit reversal function.
xorjoep 1:24714b45cd1b 34 * @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
xorjoep 1:24714b45cd1b 35 * @param[in] fftSize length of the FFT.
xorjoep 1:24714b45cd1b 36 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table.
xorjoep 1:24714b45cd1b 37 * @param[in] *pBitRevTab points to the bit reversal table.
xorjoep 1:24714b45cd1b 38 * @return none.
xorjoep 1:24714b45cd1b 39 */
xorjoep 1:24714b45cd1b 40
xorjoep 1:24714b45cd1b 41 void arm_bitreversal_f32(
xorjoep 1:24714b45cd1b 42 float32_t * pSrc,
xorjoep 1:24714b45cd1b 43 uint16_t fftSize,
xorjoep 1:24714b45cd1b 44 uint16_t bitRevFactor,
xorjoep 1:24714b45cd1b 45 uint16_t * pBitRevTab)
xorjoep 1:24714b45cd1b 46 {
xorjoep 1:24714b45cd1b 47 uint16_t fftLenBy2, fftLenBy2p1;
xorjoep 1:24714b45cd1b 48 uint16_t i, j;
xorjoep 1:24714b45cd1b 49 float32_t in;
xorjoep 1:24714b45cd1b 50
xorjoep 1:24714b45cd1b 51 /* Initializations */
xorjoep 1:24714b45cd1b 52 j = 0U;
xorjoep 1:24714b45cd1b 53 fftLenBy2 = fftSize >> 1U;
xorjoep 1:24714b45cd1b 54 fftLenBy2p1 = (fftSize >> 1U) + 1U;
xorjoep 1:24714b45cd1b 55
xorjoep 1:24714b45cd1b 56 /* Bit Reversal Implementation */
xorjoep 1:24714b45cd1b 57 for (i = 0U; i <= (fftLenBy2 - 2U); i += 2U)
xorjoep 1:24714b45cd1b 58 {
xorjoep 1:24714b45cd1b 59 if (i < j)
xorjoep 1:24714b45cd1b 60 {
xorjoep 1:24714b45cd1b 61 /* pSrc[i] <-> pSrc[j]; */
xorjoep 1:24714b45cd1b 62 in = pSrc[2U * i];
xorjoep 1:24714b45cd1b 63 pSrc[2U * i] = pSrc[2U * j];
xorjoep 1:24714b45cd1b 64 pSrc[2U * j] = in;
xorjoep 1:24714b45cd1b 65
xorjoep 1:24714b45cd1b 66 /* pSrc[i+1U] <-> pSrc[j+1U] */
xorjoep 1:24714b45cd1b 67 in = pSrc[(2U * i) + 1U];
xorjoep 1:24714b45cd1b 68 pSrc[(2U * i) + 1U] = pSrc[(2U * j) + 1U];
xorjoep 1:24714b45cd1b 69 pSrc[(2U * j) + 1U] = in;
xorjoep 1:24714b45cd1b 70
xorjoep 1:24714b45cd1b 71 /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
xorjoep 1:24714b45cd1b 72 in = pSrc[2U * (i + fftLenBy2p1)];
xorjoep 1:24714b45cd1b 73 pSrc[2U * (i + fftLenBy2p1)] = pSrc[2U * (j + fftLenBy2p1)];
xorjoep 1:24714b45cd1b 74 pSrc[2U * (j + fftLenBy2p1)] = in;
xorjoep 1:24714b45cd1b 75
xorjoep 1:24714b45cd1b 76 /* pSrc[i+fftLenBy2p1+1U] <-> pSrc[j+fftLenBy2p1+1U] */
xorjoep 1:24714b45cd1b 77 in = pSrc[(2U * (i + fftLenBy2p1)) + 1U];
xorjoep 1:24714b45cd1b 78 pSrc[(2U * (i + fftLenBy2p1)) + 1U] =
xorjoep 1:24714b45cd1b 79 pSrc[(2U * (j + fftLenBy2p1)) + 1U];
xorjoep 1:24714b45cd1b 80 pSrc[(2U * (j + fftLenBy2p1)) + 1U] = in;
xorjoep 1:24714b45cd1b 81
xorjoep 1:24714b45cd1b 82 }
xorjoep 1:24714b45cd1b 83
xorjoep 1:24714b45cd1b 84 /* pSrc[i+1U] <-> pSrc[j+1U] */
xorjoep 1:24714b45cd1b 85 in = pSrc[2U * (i + 1U)];
xorjoep 1:24714b45cd1b 86 pSrc[2U * (i + 1U)] = pSrc[2U * (j + fftLenBy2)];
xorjoep 1:24714b45cd1b 87 pSrc[2U * (j + fftLenBy2)] = in;
xorjoep 1:24714b45cd1b 88
xorjoep 1:24714b45cd1b 89 /* pSrc[i+2U] <-> pSrc[j+2U] */
xorjoep 1:24714b45cd1b 90 in = pSrc[(2U * (i + 1U)) + 1U];
xorjoep 1:24714b45cd1b 91 pSrc[(2U * (i + 1U)) + 1U] = pSrc[(2U * (j + fftLenBy2)) + 1U];
xorjoep 1:24714b45cd1b 92 pSrc[(2U * (j + fftLenBy2)) + 1U] = in;
xorjoep 1:24714b45cd1b 93
xorjoep 1:24714b45cd1b 94 /* Reading the index for the bit reversal */
xorjoep 1:24714b45cd1b 95 j = *pBitRevTab;
xorjoep 1:24714b45cd1b 96
xorjoep 1:24714b45cd1b 97 /* Updating the bit reversal index depending on the fft length */
xorjoep 1:24714b45cd1b 98 pBitRevTab += bitRevFactor;
xorjoep 1:24714b45cd1b 99 }
xorjoep 1:24714b45cd1b 100 }
xorjoep 1:24714b45cd1b 101
xorjoep 1:24714b45cd1b 102
xorjoep 1:24714b45cd1b 103
xorjoep 1:24714b45cd1b 104 /*
xorjoep 1:24714b45cd1b 105 * @brief In-place bit reversal function.
xorjoep 1:24714b45cd1b 106 * @param[in, out] *pSrc points to the in-place buffer of Q31 data type.
xorjoep 1:24714b45cd1b 107 * @param[in] fftLen length of the FFT.
xorjoep 1:24714b45cd1b 108 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
xorjoep 1:24714b45cd1b 109 * @param[in] *pBitRevTab points to bit reversal table.
xorjoep 1:24714b45cd1b 110 * @return none.
xorjoep 1:24714b45cd1b 111 */
xorjoep 1:24714b45cd1b 112
xorjoep 1:24714b45cd1b 113 void arm_bitreversal_q31(
xorjoep 1:24714b45cd1b 114 q31_t * pSrc,
xorjoep 1:24714b45cd1b 115 uint32_t fftLen,
xorjoep 1:24714b45cd1b 116 uint16_t bitRevFactor,
xorjoep 1:24714b45cd1b 117 uint16_t * pBitRevTable)
xorjoep 1:24714b45cd1b 118 {
xorjoep 1:24714b45cd1b 119 uint32_t fftLenBy2, fftLenBy2p1, i, j;
xorjoep 1:24714b45cd1b 120 q31_t in;
xorjoep 1:24714b45cd1b 121
xorjoep 1:24714b45cd1b 122 /* Initializations */
xorjoep 1:24714b45cd1b 123 j = 0U;
xorjoep 1:24714b45cd1b 124 fftLenBy2 = fftLen / 2U;
xorjoep 1:24714b45cd1b 125 fftLenBy2p1 = (fftLen / 2U) + 1U;
xorjoep 1:24714b45cd1b 126
xorjoep 1:24714b45cd1b 127 /* Bit Reversal Implementation */
xorjoep 1:24714b45cd1b 128 for (i = 0U; i <= (fftLenBy2 - 2U); i += 2U)
xorjoep 1:24714b45cd1b 129 {
xorjoep 1:24714b45cd1b 130 if (i < j)
xorjoep 1:24714b45cd1b 131 {
xorjoep 1:24714b45cd1b 132 /* pSrc[i] <-> pSrc[j]; */
xorjoep 1:24714b45cd1b 133 in = pSrc[2U * i];
xorjoep 1:24714b45cd1b 134 pSrc[2U * i] = pSrc[2U * j];
xorjoep 1:24714b45cd1b 135 pSrc[2U * j] = in;
xorjoep 1:24714b45cd1b 136
xorjoep 1:24714b45cd1b 137 /* pSrc[i+1U] <-> pSrc[j+1U] */
xorjoep 1:24714b45cd1b 138 in = pSrc[(2U * i) + 1U];
xorjoep 1:24714b45cd1b 139 pSrc[(2U * i) + 1U] = pSrc[(2U * j) + 1U];
xorjoep 1:24714b45cd1b 140 pSrc[(2U * j) + 1U] = in;
xorjoep 1:24714b45cd1b 141
xorjoep 1:24714b45cd1b 142 /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
xorjoep 1:24714b45cd1b 143 in = pSrc[2U * (i + fftLenBy2p1)];
xorjoep 1:24714b45cd1b 144 pSrc[2U * (i + fftLenBy2p1)] = pSrc[2U * (j + fftLenBy2p1)];
xorjoep 1:24714b45cd1b 145 pSrc[2U * (j + fftLenBy2p1)] = in;
xorjoep 1:24714b45cd1b 146
xorjoep 1:24714b45cd1b 147 /* pSrc[i+fftLenBy2p1+1U] <-> pSrc[j+fftLenBy2p1+1U] */
xorjoep 1:24714b45cd1b 148 in = pSrc[(2U * (i + fftLenBy2p1)) + 1U];
xorjoep 1:24714b45cd1b 149 pSrc[(2U * (i + fftLenBy2p1)) + 1U] =
xorjoep 1:24714b45cd1b 150 pSrc[(2U * (j + fftLenBy2p1)) + 1U];
xorjoep 1:24714b45cd1b 151 pSrc[(2U * (j + fftLenBy2p1)) + 1U] = in;
xorjoep 1:24714b45cd1b 152
xorjoep 1:24714b45cd1b 153 }
xorjoep 1:24714b45cd1b 154
xorjoep 1:24714b45cd1b 155 /* pSrc[i+1U] <-> pSrc[j+1U] */
xorjoep 1:24714b45cd1b 156 in = pSrc[2U * (i + 1U)];
xorjoep 1:24714b45cd1b 157 pSrc[2U * (i + 1U)] = pSrc[2U * (j + fftLenBy2)];
xorjoep 1:24714b45cd1b 158 pSrc[2U * (j + fftLenBy2)] = in;
xorjoep 1:24714b45cd1b 159
xorjoep 1:24714b45cd1b 160 /* pSrc[i+2U] <-> pSrc[j+2U] */
xorjoep 1:24714b45cd1b 161 in = pSrc[(2U * (i + 1U)) + 1U];
xorjoep 1:24714b45cd1b 162 pSrc[(2U * (i + 1U)) + 1U] = pSrc[(2U * (j + fftLenBy2)) + 1U];
xorjoep 1:24714b45cd1b 163 pSrc[(2U * (j + fftLenBy2)) + 1U] = in;
xorjoep 1:24714b45cd1b 164
xorjoep 1:24714b45cd1b 165 /* Reading the index for the bit reversal */
xorjoep 1:24714b45cd1b 166 j = *pBitRevTable;
xorjoep 1:24714b45cd1b 167
xorjoep 1:24714b45cd1b 168 /* Updating the bit reversal index depending on the fft length */
xorjoep 1:24714b45cd1b 169 pBitRevTable += bitRevFactor;
xorjoep 1:24714b45cd1b 170 }
xorjoep 1:24714b45cd1b 171 }
xorjoep 1:24714b45cd1b 172
xorjoep 1:24714b45cd1b 173
xorjoep 1:24714b45cd1b 174
xorjoep 1:24714b45cd1b 175 /*
xorjoep 1:24714b45cd1b 176 * @brief In-place bit reversal function.
xorjoep 1:24714b45cd1b 177 * @param[in, out] *pSrc points to the in-place buffer of Q15 data type.
xorjoep 1:24714b45cd1b 178 * @param[in] fftLen length of the FFT.
xorjoep 1:24714b45cd1b 179 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
xorjoep 1:24714b45cd1b 180 * @param[in] *pBitRevTab points to bit reversal table.
xorjoep 1:24714b45cd1b 181 * @return none.
xorjoep 1:24714b45cd1b 182 */
xorjoep 1:24714b45cd1b 183
xorjoep 1:24714b45cd1b 184 void arm_bitreversal_q15(
xorjoep 1:24714b45cd1b 185 q15_t * pSrc16,
xorjoep 1:24714b45cd1b 186 uint32_t fftLen,
xorjoep 1:24714b45cd1b 187 uint16_t bitRevFactor,
xorjoep 1:24714b45cd1b 188 uint16_t * pBitRevTab)
xorjoep 1:24714b45cd1b 189 {
xorjoep 1:24714b45cd1b 190 q31_t *pSrc = (q31_t *) pSrc16;
xorjoep 1:24714b45cd1b 191 q31_t in;
xorjoep 1:24714b45cd1b 192 uint32_t fftLenBy2, fftLenBy2p1;
xorjoep 1:24714b45cd1b 193 uint32_t i, j;
xorjoep 1:24714b45cd1b 194
xorjoep 1:24714b45cd1b 195 /* Initializations */
xorjoep 1:24714b45cd1b 196 j = 0U;
xorjoep 1:24714b45cd1b 197 fftLenBy2 = fftLen / 2U;
xorjoep 1:24714b45cd1b 198 fftLenBy2p1 = (fftLen / 2U) + 1U;
xorjoep 1:24714b45cd1b 199
xorjoep 1:24714b45cd1b 200 /* Bit Reversal Implementation */
xorjoep 1:24714b45cd1b 201 for (i = 0U; i <= (fftLenBy2 - 2U); i += 2U)
xorjoep 1:24714b45cd1b 202 {
xorjoep 1:24714b45cd1b 203 if (i < j)
xorjoep 1:24714b45cd1b 204 {
xorjoep 1:24714b45cd1b 205 /* pSrc[i] <-> pSrc[j]; */
xorjoep 1:24714b45cd1b 206 /* pSrc[i+1U] <-> pSrc[j+1U] */
xorjoep 1:24714b45cd1b 207 in = pSrc[i];
xorjoep 1:24714b45cd1b 208 pSrc[i] = pSrc[j];
xorjoep 1:24714b45cd1b 209 pSrc[j] = in;
xorjoep 1:24714b45cd1b 210
xorjoep 1:24714b45cd1b 211 /* pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1]; */
xorjoep 1:24714b45cd1b 212 /* pSrc[i + fftLenBy2p1+1U] <-> pSrc[j + fftLenBy2p1+1U] */
xorjoep 1:24714b45cd1b 213 in = pSrc[i + fftLenBy2p1];
xorjoep 1:24714b45cd1b 214 pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1];
xorjoep 1:24714b45cd1b 215 pSrc[j + fftLenBy2p1] = in;
xorjoep 1:24714b45cd1b 216 }
xorjoep 1:24714b45cd1b 217
xorjoep 1:24714b45cd1b 218 /* pSrc[i+1U] <-> pSrc[j+fftLenBy2]; */
xorjoep 1:24714b45cd1b 219 /* pSrc[i+2] <-> pSrc[j+fftLenBy2+1U] */
xorjoep 1:24714b45cd1b 220 in = pSrc[i + 1U];
xorjoep 1:24714b45cd1b 221 pSrc[i + 1U] = pSrc[j + fftLenBy2];
xorjoep 1:24714b45cd1b 222 pSrc[j + fftLenBy2] = in;
xorjoep 1:24714b45cd1b 223
xorjoep 1:24714b45cd1b 224 /* Reading the index for the bit reversal */
xorjoep 1:24714b45cd1b 225 j = *pBitRevTab;
xorjoep 1:24714b45cd1b 226
xorjoep 1:24714b45cd1b 227 /* Updating the bit reversal index depending on the fft length */
xorjoep 1:24714b45cd1b 228 pBitRevTab += bitRevFactor;
xorjoep 1:24714b45cd1b 229 }
xorjoep 1:24714b45cd1b 230 }