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1 /* ----------------------------------------------------------------------
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2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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3 *
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4 * $Date: 19. March 2015
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5 * $Revision: V.1.4.5
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6 *
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7 * Project: CMSIS DSP Library
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8 * Title: arm_bitreversal.c
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9 *
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10 * Description: This file has common tables like Bitreverse, reciprocal etc which are used across different functions
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11 *
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12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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13 *
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14 * Redistribution and use in source and binary forms, with or without
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15 * modification, are permitted provided that the following conditions
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16 * are met:
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17 * - Redistributions of source code must retain the above copyright
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18 * notice, this list of conditions and the following disclaimer.
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19 * - Redistributions in binary form must reproduce the above copyright
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20 * notice, this list of conditions and the following disclaimer in
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21 * the documentation and/or other materials provided with the
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22 * distribution.
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23 * - Neither the name of ARM LIMITED nor the names of its contributors
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24 * may be used to endorse or promote products derived from this
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25 * software without specific prior written permission.
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26 *
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27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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38 * POSSIBILITY OF SUCH DAMAGE.
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39 * -------------------------------------------------------------------- */
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40
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41 #include "arm_math.h"
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42 #include "arm_common_tables.h"
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43
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44 /*
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45 * @brief In-place bit reversal function.
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46 * @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
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47 * @param[in] fftSize length of the FFT.
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48 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table.
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49 * @param[in] *pBitRevTab points to the bit reversal table.
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50 * @return none.
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51 */
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52
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53 void arm_bitreversal_f32(
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54 float32_t * pSrc,
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55 uint16_t fftSize,
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56 uint16_t bitRevFactor,
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57 uint16_t * pBitRevTab)
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58 {
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59 uint16_t fftLenBy2, fftLenBy2p1;
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60 uint16_t i, j;
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61 float32_t in;
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62
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63 /* Initializations */
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64 j = 0u;
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65 fftLenBy2 = fftSize >> 1u;
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66 fftLenBy2p1 = (fftSize >> 1u) + 1u;
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67
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68 /* Bit Reversal Implementation */
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69 for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
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70 {
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71 if(i < j)
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72 {
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73 /* pSrc[i] <-> pSrc[j]; */
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74 in = pSrc[2u * i];
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75 pSrc[2u * i] = pSrc[2u * j];
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76 pSrc[2u * j] = in;
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77
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78 /* pSrc[i+1u] <-> pSrc[j+1u] */
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79 in = pSrc[(2u * i) + 1u];
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80 pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
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81 pSrc[(2u * j) + 1u] = in;
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82
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83 /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
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84 in = pSrc[2u * (i + fftLenBy2p1)];
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85 pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
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86 pSrc[2u * (j + fftLenBy2p1)] = in;
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87
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88 /* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
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89 in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
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90 pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
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91 pSrc[(2u * (j + fftLenBy2p1)) + 1u];
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92 pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
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93
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94 }
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95
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96 /* pSrc[i+1u] <-> pSrc[j+1u] */
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97 in = pSrc[2u * (i + 1u)];
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98 pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
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99 pSrc[2u * (j + fftLenBy2)] = in;
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100
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101 /* pSrc[i+2u] <-> pSrc[j+2u] */
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102 in = pSrc[(2u * (i + 1u)) + 1u];
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103 pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
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104 pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
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105
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106 /* Reading the index for the bit reversal */
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107 j = *pBitRevTab;
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108
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109 /* Updating the bit reversal index depending on the fft length */
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110 pBitRevTab += bitRevFactor;
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111 }
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112 }
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113
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114
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115
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116 /*
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117 * @brief In-place bit reversal function.
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118 * @param[in, out] *pSrc points to the in-place buffer of Q31 data type.
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119 * @param[in] fftLen length of the FFT.
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120 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
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121 * @param[in] *pBitRevTab points to bit reversal table.
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122 * @return none.
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123 */
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124
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125 void arm_bitreversal_q31(
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126 q31_t * pSrc,
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127 uint32_t fftLen,
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128 uint16_t bitRevFactor,
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129 uint16_t * pBitRevTable)
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130 {
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131 uint32_t fftLenBy2, fftLenBy2p1, i, j;
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132 q31_t in;
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133
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134 /* Initializations */
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135 j = 0u;
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136 fftLenBy2 = fftLen / 2u;
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137 fftLenBy2p1 = (fftLen / 2u) + 1u;
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138
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139 /* Bit Reversal Implementation */
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140 for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
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141 {
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142 if(i < j)
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143 {
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144 /* pSrc[i] <-> pSrc[j]; */
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145 in = pSrc[2u * i];
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146 pSrc[2u * i] = pSrc[2u * j];
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147 pSrc[2u * j] = in;
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148
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149 /* pSrc[i+1u] <-> pSrc[j+1u] */
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150 in = pSrc[(2u * i) + 1u];
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151 pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
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152 pSrc[(2u * j) + 1u] = in;
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153
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154 /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
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155 in = pSrc[2u * (i + fftLenBy2p1)];
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156 pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
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157 pSrc[2u * (j + fftLenBy2p1)] = in;
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158
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159 /* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
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160 in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
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161 pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
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162 pSrc[(2u * (j + fftLenBy2p1)) + 1u];
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163 pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
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164
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165 }
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166
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167 /* pSrc[i+1u] <-> pSrc[j+1u] */
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168 in = pSrc[2u * (i + 1u)];
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169 pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
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170 pSrc[2u * (j + fftLenBy2)] = in;
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171
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172 /* pSrc[i+2u] <-> pSrc[j+2u] */
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173 in = pSrc[(2u * (i + 1u)) + 1u];
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174 pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
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175 pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
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176
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177 /* Reading the index for the bit reversal */
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178 j = *pBitRevTable;
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179
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180 /* Updating the bit reversal index depending on the fft length */
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181 pBitRevTable += bitRevFactor;
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182 }
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183 }
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184
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185
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186
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187 /*
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188 * @brief In-place bit reversal function.
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189 * @param[in, out] *pSrc points to the in-place buffer of Q15 data type.
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190 * @param[in] fftLen length of the FFT.
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191 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
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192 * @param[in] *pBitRevTab points to bit reversal table.
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193 * @return none.
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194 */
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195
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196 void arm_bitreversal_q15(
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197 q15_t * pSrc16,
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198 uint32_t fftLen,
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199 uint16_t bitRevFactor,
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200 uint16_t * pBitRevTab)
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201 {
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202 q31_t *pSrc = (q31_t *) pSrc16;
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203 q31_t in;
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204 uint32_t fftLenBy2, fftLenBy2p1;
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205 uint32_t i, j;
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206
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207 /* Initializations */
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208 j = 0u;
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209 fftLenBy2 = fftLen / 2u;
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210 fftLenBy2p1 = (fftLen / 2u) + 1u;
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211
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212 /* Bit Reversal Implementation */
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213 for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
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214 {
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215 if(i < j)
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216 {
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217 /* pSrc[i] <-> pSrc[j]; */
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218 /* pSrc[i+1u] <-> pSrc[j+1u] */
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219 in = pSrc[i];
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220 pSrc[i] = pSrc[j];
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221 pSrc[j] = in;
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222
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223 /* pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1]; */
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224 /* pSrc[i + fftLenBy2p1+1u] <-> pSrc[j + fftLenBy2p1+1u] */
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225 in = pSrc[i + fftLenBy2p1];
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226 pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1];
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227 pSrc[j + fftLenBy2p1] = in;
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228 }
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229
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230 /* pSrc[i+1u] <-> pSrc[j+fftLenBy2]; */
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231 /* pSrc[i+2] <-> pSrc[j+fftLenBy2+1u] */
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232 in = pSrc[i + 1u];
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233 pSrc[i + 1u] = pSrc[j + fftLenBy2];
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234 pSrc[j + fftLenBy2] = in;
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235
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236 /* Reading the index for the bit reversal */
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237 j = *pBitRevTab;
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238
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239 /* Updating the bit reversal index depending on the fft length */
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240 pBitRevTab += bitRevFactor;
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241 }
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242 }
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