Senior Design: Sound Monitor / 4951

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Dependencies:   LCD_fonts SPI_TFT_ILI9341 CMSIS_DSP_401_without_cm4 mbed-src SDFileSystem wavfile

arm_cfft_f32.c@13:ab0285338951, 2015-12-14 (annotated)

Committer:
linx0576
Date:
Mon Dec 14 22:13:11 2015 +0000
Revision:
13:ab0285338951
Parent:
9:5a860b9c8a6a 
update

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EricLew 9:5a860b9c8a6a 1 /* ----------------------------------------------------------------------
EricLew 9:5a860b9c8a6a 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
EricLew 9:5a860b9c8a6a 3 *
EricLew 9:5a860b9c8a6a 4 * $Date: 19. March 2015
EricLew 9:5a860b9c8a6a 5 * $Revision: V.1.4.5
EricLew 9:5a860b9c8a6a 6 *
EricLew 9:5a860b9c8a6a 7 * Project: CMSIS DSP Library
EricLew 9:5a860b9c8a6a 8 * Title: arm_cfft_f32.c
EricLew 9:5a860b9c8a6a 9 *
EricLew 9:5a860b9c8a6a 10 * Description: Combined Radix Decimation in Frequency CFFT Floating point processing function
EricLew 9:5a860b9c8a6a 11 *
EricLew 9:5a860b9c8a6a 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
EricLew 9:5a860b9c8a6a 13 *
EricLew 9:5a860b9c8a6a 14 * Redistribution and use in source and binary forms, with or without
EricLew 9:5a860b9c8a6a 15 * modification, are permitted provided that the following conditions
EricLew 9:5a860b9c8a6a 16 * are met:
EricLew 9:5a860b9c8a6a 17 * - Redistributions of source code must retain the above copyright
EricLew 9:5a860b9c8a6a 18 * notice, this list of conditions and the following disclaimer.
EricLew 9:5a860b9c8a6a 19 * - Redistributions in binary form must reproduce the above copyright
EricLew 9:5a860b9c8a6a 20 * notice, this list of conditions and the following disclaimer in
EricLew 9:5a860b9c8a6a 21 * the documentation and/or other materials provided with the
EricLew 9:5a860b9c8a6a 22 * distribution.
EricLew 9:5a860b9c8a6a 23 * - Neither the name of ARM LIMITED nor the names of its contributors
EricLew 9:5a860b9c8a6a 24 * may be used to endorse or promote products derived from this
EricLew 9:5a860b9c8a6a 25 * software without specific prior written permission.
EricLew 9:5a860b9c8a6a 26 *
EricLew 9:5a860b9c8a6a 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
EricLew 9:5a860b9c8a6a 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
EricLew 9:5a860b9c8a6a 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
EricLew 9:5a860b9c8a6a 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
EricLew 9:5a860b9c8a6a 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
EricLew 9:5a860b9c8a6a 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
EricLew 9:5a860b9c8a6a 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
EricLew 9:5a860b9c8a6a 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
EricLew 9:5a860b9c8a6a 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
EricLew 9:5a860b9c8a6a 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
EricLew 9:5a860b9c8a6a 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
EricLew 9:5a860b9c8a6a 38 * POSSIBILITY OF SUCH DAMAGE.
EricLew 9:5a860b9c8a6a 39 * -------------------------------------------------------------------- */
EricLew 9:5a860b9c8a6a 40
EricLew 9:5a860b9c8a6a 41 #include "arm_math.h"
EricLew 9:5a860b9c8a6a 42 #include "arm_common_tables.h"
EricLew 9:5a860b9c8a6a 43
EricLew 9:5a860b9c8a6a 44 extern void arm_radix8_butterfly_f32(
EricLew 9:5a860b9c8a6a 45 float32_t * pSrc,
EricLew 9:5a860b9c8a6a 46 uint16_t fftLen,
EricLew 9:5a860b9c8a6a 47 const float32_t * pCoef,
EricLew 9:5a860b9c8a6a 48 uint16_t twidCoefModifier);
EricLew 9:5a860b9c8a6a 49
EricLew 9:5a860b9c8a6a 50 extern void arm_bitreversal_32(
EricLew 9:5a860b9c8a6a 51 uint32_t * pSrc,
EricLew 9:5a860b9c8a6a 52 const uint16_t bitRevLen,
EricLew 9:5a860b9c8a6a 53 const uint16_t * pBitRevTable);
EricLew 9:5a860b9c8a6a 54
EricLew 9:5a860b9c8a6a 55 /**
EricLew 9:5a860b9c8a6a 56 * @ingroup groupTransforms
EricLew 9:5a860b9c8a6a 57 */
EricLew 9:5a860b9c8a6a 58
EricLew 9:5a860b9c8a6a 59 /**
EricLew 9:5a860b9c8a6a 60 * @defgroup ComplexFFT Complex FFT Functions
EricLew 9:5a860b9c8a6a 61 *
EricLew 9:5a860b9c8a6a 62 * \par
EricLew 9:5a860b9c8a6a 63 * The Fast Fourier Transform (FFT) is an efficient algorithm for computing the
EricLew 9:5a860b9c8a6a 64 * Discrete Fourier Transform (DFT). The FFT can be orders of magnitude faster
EricLew 9:5a860b9c8a6a 65 * than the DFT, especially for long lengths.
EricLew 9:5a860b9c8a6a 66 * The algorithms described in this section
EricLew 9:5a860b9c8a6a 67 * operate on complex data. A separate set of functions is devoted to handling
EricLew 9:5a860b9c8a6a 68 * of real sequences.
EricLew 9:5a860b9c8a6a 69 * \par
EricLew 9:5a860b9c8a6a 70 * There are separate algorithms for handling floating-point, Q15, and Q31 data
EricLew 9:5a860b9c8a6a 71 * types. The algorithms available for each data type are described next.
EricLew 9:5a860b9c8a6a 72 * \par
EricLew 9:5a860b9c8a6a 73 * The FFT functions operate in-place. That is, the array holding the input data
EricLew 9:5a860b9c8a6a 74 * will also be used to hold the corresponding result. The input data is complex
EricLew 9:5a860b9c8a6a 75 * and contains <code>2*fftLen</code> interleaved values as shown below.
EricLew 9:5a860b9c8a6a 76 * <pre> {real[0], imag[0], real[1], imag[1],..} </pre>
EricLew 9:5a860b9c8a6a 77 * The FFT result will be contained in the same array and the frequency domain
EricLew 9:5a860b9c8a6a 78 * values will have the same interleaving.
EricLew 9:5a860b9c8a6a 79 *
EricLew 9:5a860b9c8a6a 80 * \par Floating-point
EricLew 9:5a860b9c8a6a 81 * The floating-point complex FFT uses a mixed-radix algorithm. Multiple radix-8
EricLew 9:5a860b9c8a6a 82 * stages are performed along with a single radix-2 or radix-4 stage, as needed.
EricLew 9:5a860b9c8a6a 83 * The algorithm supports lengths of [16, 32, 64, ..., 4096] and each length uses
EricLew 9:5a860b9c8a6a 84 * a different twiddle factor table.
EricLew 9:5a860b9c8a6a 85 * \par
EricLew 9:5a860b9c8a6a 86 * The function uses the standard FFT definition and output values may grow by a
EricLew 9:5a860b9c8a6a 87 * factor of <code>fftLen</code> when computing the forward transform. The
EricLew 9:5a860b9c8a6a 88 * inverse transform includes a scale of <code>1/fftLen</code> as part of the
EricLew 9:5a860b9c8a6a 89 * calculation and this matches the textbook definition of the inverse FFT.
EricLew 9:5a860b9c8a6a 90 * \par
EricLew 9:5a860b9c8a6a 91 * Pre-initialized data structures containing twiddle factors and bit reversal
EricLew 9:5a860b9c8a6a 92 * tables are provided and defined in <code>arm_const_structs.h</code>. Include
EricLew 9:5a860b9c8a6a 93 * this header in your function and then pass one of the constant structures as
EricLew 9:5a860b9c8a6a 94 * an argument to arm_cfft_f32. For example:
EricLew 9:5a860b9c8a6a 95 * \par
EricLew 9:5a860b9c8a6a 96 * <code>arm_cfft_f32(arm_cfft_sR_f32_len64, pSrc, 1, 1)</code>
EricLew 9:5a860b9c8a6a 97 * \par
EricLew 9:5a860b9c8a6a 98 * computes a 64-point inverse complex FFT including bit reversal.
EricLew 9:5a860b9c8a6a 99 * The data structures are treated as constant data and not modified during the
EricLew 9:5a860b9c8a6a 100 * calculation. The same data structure can be reused for multiple transforms
EricLew 9:5a860b9c8a6a 101 * including mixing forward and inverse transforms.
EricLew 9:5a860b9c8a6a 102 * \par
EricLew 9:5a860b9c8a6a 103 * Earlier releases of the library provided separate radix-2 and radix-4
EricLew 9:5a860b9c8a6a 104 * algorithms that operated on floating-point data. These functions are still
EricLew 9:5a860b9c8a6a 105 * provided but are deprecated. The older functions are slower and less general
EricLew 9:5a860b9c8a6a 106 * than the new functions.
EricLew 9:5a860b9c8a6a 107 * \par
EricLew 9:5a860b9c8a6a 108 * An example of initialization of the constants for the arm_cfft_f32 function follows:
EricLew 9:5a860b9c8a6a 109 * \code
EricLew 9:5a860b9c8a6a 110 * const static arm_cfft_instance_f32 *S;
EricLew 9:5a860b9c8a6a 111 * ...
EricLew 9:5a860b9c8a6a 112 * switch (length) {
EricLew 9:5a860b9c8a6a 113 * case 16:
EricLew 9:5a860b9c8a6a 114 * S = &arm_cfft_sR_f32_len16;
EricLew 9:5a860b9c8a6a 115 * break;
EricLew 9:5a860b9c8a6a 116 * case 32:
EricLew 9:5a860b9c8a6a 117 * S = &arm_cfft_sR_f32_len32;
EricLew 9:5a860b9c8a6a 118 * break;
EricLew 9:5a860b9c8a6a 119 * case 64:
EricLew 9:5a860b9c8a6a 120 * S = &arm_cfft_sR_f32_len64;
EricLew 9:5a860b9c8a6a 121 * break;
EricLew 9:5a860b9c8a6a 122 * case 128:
EricLew 9:5a860b9c8a6a 123 * S = &arm_cfft_sR_f32_len128;
EricLew 9:5a860b9c8a6a 124 * break;
EricLew 9:5a860b9c8a6a 125 * case 256:
EricLew 9:5a860b9c8a6a 126 * S = &arm_cfft_sR_f32_len256;
EricLew 9:5a860b9c8a6a 127 * break;
EricLew 9:5a860b9c8a6a 128 * case 512:
EricLew 9:5a860b9c8a6a 129 * S = &arm_cfft_sR_f32_len512;
EricLew 9:5a860b9c8a6a 130 * break;
EricLew 9:5a860b9c8a6a 131 * case 1024:
EricLew 9:5a860b9c8a6a 132 * S = &arm_cfft_sR_f32_len1024;
EricLew 9:5a860b9c8a6a 133 * break;
EricLew 9:5a860b9c8a6a 134 * case 2048:
EricLew 9:5a860b9c8a6a 135 * S = &arm_cfft_sR_f32_len2048;
EricLew 9:5a860b9c8a6a 136 * break;
EricLew 9:5a860b9c8a6a 137 * case 4096:
EricLew 9:5a860b9c8a6a 138 * S = &arm_cfft_sR_f32_len4096;
EricLew 9:5a860b9c8a6a 139 * break;
EricLew 9:5a860b9c8a6a 140 * }
EricLew 9:5a860b9c8a6a 141 * \endcode
EricLew 9:5a860b9c8a6a 142 * \par Q15 and Q31
EricLew 9:5a860b9c8a6a 143 * The floating-point complex FFT uses a mixed-radix algorithm. Multiple radix-4
EricLew 9:5a860b9c8a6a 144 * stages are performed along with a single radix-2 stage, as needed.
EricLew 9:5a860b9c8a6a 145 * The algorithm supports lengths of [16, 32, 64, ..., 4096] and each length uses
EricLew 9:5a860b9c8a6a 146 * a different twiddle factor table.
EricLew 9:5a860b9c8a6a 147 * \par
EricLew 9:5a860b9c8a6a 148 * The function uses the standard FFT definition and output values may grow by a
EricLew 9:5a860b9c8a6a 149 * factor of <code>fftLen</code> when computing the forward transform. The
EricLew 9:5a860b9c8a6a 150 * inverse transform includes a scale of <code>1/fftLen</code> as part of the
EricLew 9:5a860b9c8a6a 151 * calculation and this matches the textbook definition of the inverse FFT.
EricLew 9:5a860b9c8a6a 152 * \par
EricLew 9:5a860b9c8a6a 153 * Pre-initialized data structures containing twiddle factors and bit reversal
EricLew 9:5a860b9c8a6a 154 * tables are provided and defined in <code>arm_const_structs.h</code>. Include
EricLew 9:5a860b9c8a6a 155 * this header in your function and then pass one of the constant structures as
EricLew 9:5a860b9c8a6a 156 * an argument to arm_cfft_q31. For example:
EricLew 9:5a860b9c8a6a 157 * \par
EricLew 9:5a860b9c8a6a 158 * <code>arm_cfft_q31(arm_cfft_sR_q31_len64, pSrc, 1, 1)</code>
EricLew 9:5a860b9c8a6a 159 * \par
EricLew 9:5a860b9c8a6a 160 * computes a 64-point inverse complex FFT including bit reversal.
EricLew 9:5a860b9c8a6a 161 * The data structures are treated as constant data and not modified during the
EricLew 9:5a860b9c8a6a 162 * calculation. The same data structure can be reused for multiple transforms
EricLew 9:5a860b9c8a6a 163 * including mixing forward and inverse transforms.
EricLew 9:5a860b9c8a6a 164 * \par
EricLew 9:5a860b9c8a6a 165 * Earlier releases of the library provided separate radix-2 and radix-4
EricLew 9:5a860b9c8a6a 166 * algorithms that operated on floating-point data. These functions are still
EricLew 9:5a860b9c8a6a 167 * provided but are deprecated. The older functions are slower and less general
EricLew 9:5a860b9c8a6a 168 * than the new functions.
EricLew 9:5a860b9c8a6a 169 * \par
EricLew 9:5a860b9c8a6a 170 * An example of initialization of the constants for the arm_cfft_q31 function follows:
EricLew 9:5a860b9c8a6a 171 * \code
EricLew 9:5a860b9c8a6a 172 * const static arm_cfft_instance_q31 *S;
EricLew 9:5a860b9c8a6a 173 * ...
EricLew 9:5a860b9c8a6a 174 * switch (length) {
EricLew 9:5a860b9c8a6a 175 * case 16:
EricLew 9:5a860b9c8a6a 176 * S = &arm_cfft_sR_q31_len16;
EricLew 9:5a860b9c8a6a 177 * break;
EricLew 9:5a860b9c8a6a 178 * case 32:
EricLew 9:5a860b9c8a6a 179 * S = &arm_cfft_sR_q31_len32;
EricLew 9:5a860b9c8a6a 180 * break;
EricLew 9:5a860b9c8a6a 181 * case 64:
EricLew 9:5a860b9c8a6a 182 * S = &arm_cfft_sR_q31_len64;
EricLew 9:5a860b9c8a6a 183 * break;
EricLew 9:5a860b9c8a6a 184 * case 128:
EricLew 9:5a860b9c8a6a 185 * S = &arm_cfft_sR_q31_len128;
EricLew 9:5a860b9c8a6a 186 * break;
EricLew 9:5a860b9c8a6a 187 * case 256:
EricLew 9:5a860b9c8a6a 188 * S = &arm_cfft_sR_q31_len256;
EricLew 9:5a860b9c8a6a 189 * break;
EricLew 9:5a860b9c8a6a 190 * case 512:
EricLew 9:5a860b9c8a6a 191 * S = &arm_cfft_sR_q31_len512;
EricLew 9:5a860b9c8a6a 192 * break;
EricLew 9:5a860b9c8a6a 193 * case 1024:
EricLew 9:5a860b9c8a6a 194 * S = &arm_cfft_sR_q31_len1024;
EricLew 9:5a860b9c8a6a 195 * break;
EricLew 9:5a860b9c8a6a 196 * case 2048:
EricLew 9:5a860b9c8a6a 197 * S = &arm_cfft_sR_q31_len2048;
EricLew 9:5a860b9c8a6a 198 * break;
EricLew 9:5a860b9c8a6a 199 * case 4096:
EricLew 9:5a860b9c8a6a 200 * S = &arm_cfft_sR_q31_len4096;
EricLew 9:5a860b9c8a6a 201 * break;
EricLew 9:5a860b9c8a6a 202 * }
EricLew 9:5a860b9c8a6a 203 * \endcode
EricLew 9:5a860b9c8a6a 204 *
EricLew 9:5a860b9c8a6a 205 */
EricLew 9:5a860b9c8a6a 206
EricLew 9:5a860b9c8a6a 207 void arm_cfft_radix8by2_f32( arm_cfft_instance_f32 * S, float32_t * p1)
EricLew 9:5a860b9c8a6a 208 {
EricLew 9:5a860b9c8a6a 209 uint32_t L = S->fftLen;
EricLew 9:5a860b9c8a6a 210 float32_t * pCol1, * pCol2, * pMid1, * pMid2;
EricLew 9:5a860b9c8a6a 211 float32_t * p2 = p1 + L;
EricLew 9:5a860b9c8a6a 212 const float32_t * tw = (float32_t *) S->pTwiddle;
EricLew 9:5a860b9c8a6a 213 float32_t t1[4], t2[4], t3[4], t4[4], twR, twI;
EricLew 9:5a860b9c8a6a 214 float32_t m0, m1, m2, m3;
EricLew 9:5a860b9c8a6a 215 uint32_t l;
EricLew 9:5a860b9c8a6a 216
EricLew 9:5a860b9c8a6a 217 pCol1 = p1;
EricLew 9:5a860b9c8a6a 218 pCol2 = p2;
EricLew 9:5a860b9c8a6a 219
EricLew 9:5a860b9c8a6a 220 // Define new length
EricLew 9:5a860b9c8a6a 221 L >>= 1;
EricLew 9:5a860b9c8a6a 222 // Initialize mid pointers
EricLew 9:5a860b9c8a6a 223 pMid1 = p1 + L;
EricLew 9:5a860b9c8a6a 224 pMid2 = p2 + L;
EricLew 9:5a860b9c8a6a 225
EricLew 9:5a860b9c8a6a 226 // do two dot Fourier transform
EricLew 9:5a860b9c8a6a 227 for ( l = L >> 2; l > 0; l-- )
EricLew 9:5a860b9c8a6a 228 {
EricLew 9:5a860b9c8a6a 229 t1[0] = p1[0];
EricLew 9:5a860b9c8a6a 230 t1[1] = p1[1];
EricLew 9:5a860b9c8a6a 231 t1[2] = p1[2];
EricLew 9:5a860b9c8a6a 232 t1[3] = p1[3];
EricLew 9:5a860b9c8a6a 233
EricLew 9:5a860b9c8a6a 234 t2[0] = p2[0];
EricLew 9:5a860b9c8a6a 235 t2[1] = p2[1];
EricLew 9:5a860b9c8a6a 236 t2[2] = p2[2];
EricLew 9:5a860b9c8a6a 237 t2[3] = p2[3];
EricLew 9:5a860b9c8a6a 238
EricLew 9:5a860b9c8a6a 239 t3[0] = pMid1[0];
EricLew 9:5a860b9c8a6a 240 t3[1] = pMid1[1];
EricLew 9:5a860b9c8a6a 241 t3[2] = pMid1[2];
EricLew 9:5a860b9c8a6a 242 t3[3] = pMid1[3];
EricLew 9:5a860b9c8a6a 243
EricLew 9:5a860b9c8a6a 244 t4[0] = pMid2[0];
EricLew 9:5a860b9c8a6a 245 t4[1] = pMid2[1];
EricLew 9:5a860b9c8a6a 246 t4[2] = pMid2[2];
EricLew 9:5a860b9c8a6a 247 t4[3] = pMid2[3];
EricLew 9:5a860b9c8a6a 248
EricLew 9:5a860b9c8a6a 249 *p1++ = t1[0] + t2[0];
EricLew 9:5a860b9c8a6a 250 *p1++ = t1[1] + t2[1];
EricLew 9:5a860b9c8a6a 251 *p1++ = t1[2] + t2[2];
EricLew 9:5a860b9c8a6a 252 *p1++ = t1[3] + t2[3]; // col 1
EricLew 9:5a860b9c8a6a 253
EricLew 9:5a860b9c8a6a 254 t2[0] = t1[0] - t2[0];
EricLew 9:5a860b9c8a6a 255 t2[1] = t1[1] - t2[1];
EricLew 9:5a860b9c8a6a 256 t2[2] = t1[2] - t2[2];
EricLew 9:5a860b9c8a6a 257 t2[3] = t1[3] - t2[3]; // for col 2
EricLew 9:5a860b9c8a6a 258
EricLew 9:5a860b9c8a6a 259 *pMid1++ = t3[0] + t4[0];
EricLew 9:5a860b9c8a6a 260 *pMid1++ = t3[1] + t4[1];
EricLew 9:5a860b9c8a6a 261 *pMid1++ = t3[2] + t4[2];
EricLew 9:5a860b9c8a6a 262 *pMid1++ = t3[3] + t4[3]; // col 1
EricLew 9:5a860b9c8a6a 263
EricLew 9:5a860b9c8a6a 264 t4[0] = t4[0] - t3[0];
EricLew 9:5a860b9c8a6a 265 t4[1] = t4[1] - t3[1];
EricLew 9:5a860b9c8a6a 266 t4[2] = t4[2] - t3[2];
EricLew 9:5a860b9c8a6a 267 t4[3] = t4[3] - t3[3]; // for col 2
EricLew 9:5a860b9c8a6a 268
EricLew 9:5a860b9c8a6a 269 twR = *tw++;
EricLew 9:5a860b9c8a6a 270 twI = *tw++;
EricLew 9:5a860b9c8a6a 271
EricLew 9:5a860b9c8a6a 272 // multiply by twiddle factors
EricLew 9:5a860b9c8a6a 273 m0 = t2[0] * twR;
EricLew 9:5a860b9c8a6a 274 m1 = t2[1] * twI;
EricLew 9:5a860b9c8a6a 275 m2 = t2[1] * twR;
EricLew 9:5a860b9c8a6a 276 m3 = t2[0] * twI;
EricLew 9:5a860b9c8a6a 277
EricLew 9:5a860b9c8a6a 278 // R = R * Tr - I * Ti
EricLew 9:5a860b9c8a6a 279 *p2++ = m0 + m1;
EricLew 9:5a860b9c8a6a 280 // I = I * Tr + R * Ti
EricLew 9:5a860b9c8a6a 281 *p2++ = m2 - m3;
EricLew 9:5a860b9c8a6a 282
EricLew 9:5a860b9c8a6a 283 // use vertical symmetry
EricLew 9:5a860b9c8a6a 284 // 0.9988 - 0.0491i <==> -0.0491 - 0.9988i
EricLew 9:5a860b9c8a6a 285 m0 = t4[0] * twI;
EricLew 9:5a860b9c8a6a 286 m1 = t4[1] * twR;
EricLew 9:5a860b9c8a6a 287 m2 = t4[1] * twI;
EricLew 9:5a860b9c8a6a 288 m3 = t4[0] * twR;
EricLew 9:5a860b9c8a6a 289
EricLew 9:5a860b9c8a6a 290 *pMid2++ = m0 - m1;
EricLew 9:5a860b9c8a6a 291 *pMid2++ = m2 + m3;
EricLew 9:5a860b9c8a6a 292
EricLew 9:5a860b9c8a6a 293 twR = *tw++;
EricLew 9:5a860b9c8a6a 294 twI = *tw++;
EricLew 9:5a860b9c8a6a 295
EricLew 9:5a860b9c8a6a 296 m0 = t2[2] * twR;
EricLew 9:5a860b9c8a6a 297 m1 = t2[3] * twI;
EricLew 9:5a860b9c8a6a 298 m2 = t2[3] * twR;
EricLew 9:5a860b9c8a6a 299 m3 = t2[2] * twI;
EricLew 9:5a860b9c8a6a 300
EricLew 9:5a860b9c8a6a 301 *p2++ = m0 + m1;
EricLew 9:5a860b9c8a6a 302 *p2++ = m2 - m3;
EricLew 9:5a860b9c8a6a 303
EricLew 9:5a860b9c8a6a 304 m0 = t4[2] * twI;
EricLew 9:5a860b9c8a6a 305 m1 = t4[3] * twR;
EricLew 9:5a860b9c8a6a 306 m2 = t4[3] * twI;
EricLew 9:5a860b9c8a6a 307 m3 = t4[2] * twR;
EricLew 9:5a860b9c8a6a 308
EricLew 9:5a860b9c8a6a 309 *pMid2++ = m0 - m1;
EricLew 9:5a860b9c8a6a 310 *pMid2++ = m2 + m3;
EricLew 9:5a860b9c8a6a 311 }
EricLew 9:5a860b9c8a6a 312
EricLew 9:5a860b9c8a6a 313 // first col
EricLew 9:5a860b9c8a6a 314 arm_radix8_butterfly_f32( pCol1, L, (float32_t *) S->pTwiddle, 2u);
EricLew 9:5a860b9c8a6a 315 // second col
EricLew 9:5a860b9c8a6a 316 arm_radix8_butterfly_f32( pCol2, L, (float32_t *) S->pTwiddle, 2u);
EricLew 9:5a860b9c8a6a 317 }
EricLew 9:5a860b9c8a6a 318
EricLew 9:5a860b9c8a6a 319 void arm_cfft_radix8by4_f32( arm_cfft_instance_f32 * S, float32_t * p1)
EricLew 9:5a860b9c8a6a 320 {
EricLew 9:5a860b9c8a6a 321 uint32_t L = S->fftLen >> 1;
EricLew 9:5a860b9c8a6a 322 float32_t * pCol1, *pCol2, *pCol3, *pCol4, *pEnd1, *pEnd2, *pEnd3, *pEnd4;
EricLew 9:5a860b9c8a6a 323 const float32_t *tw2, *tw3, *tw4;
EricLew 9:5a860b9c8a6a 324 float32_t * p2 = p1 + L;
EricLew 9:5a860b9c8a6a 325 float32_t * p3 = p2 + L;
EricLew 9:5a860b9c8a6a 326 float32_t * p4 = p3 + L;
EricLew 9:5a860b9c8a6a 327 float32_t t2[4], t3[4], t4[4], twR, twI;
EricLew 9:5a860b9c8a6a 328 float32_t p1ap3_0, p1sp3_0, p1ap3_1, p1sp3_1;
EricLew 9:5a860b9c8a6a 329 float32_t m0, m1, m2, m3;
EricLew 9:5a860b9c8a6a 330 uint32_t l, twMod2, twMod3, twMod4;
EricLew 9:5a860b9c8a6a 331
EricLew 9:5a860b9c8a6a 332 pCol1 = p1; // points to real values by default
EricLew 9:5a860b9c8a6a 333 pCol2 = p2;
EricLew 9:5a860b9c8a6a 334 pCol3 = p3;
EricLew 9:5a860b9c8a6a 335 pCol4 = p4;
EricLew 9:5a860b9c8a6a 336 pEnd1 = p2 - 1; // points to imaginary values by default
EricLew 9:5a860b9c8a6a 337 pEnd2 = p3 - 1;
EricLew 9:5a860b9c8a6a 338 pEnd3 = p4 - 1;
EricLew 9:5a860b9c8a6a 339 pEnd4 = pEnd3 + L;
EricLew 9:5a860b9c8a6a 340
EricLew 9:5a860b9c8a6a 341 tw2 = tw3 = tw4 = (float32_t *) S->pTwiddle;
EricLew 9:5a860b9c8a6a 342
EricLew 9:5a860b9c8a6a 343 L >>= 1;
EricLew 9:5a860b9c8a6a 344
EricLew 9:5a860b9c8a6a 345 // do four dot Fourier transform
EricLew 9:5a860b9c8a6a 346
EricLew 9:5a860b9c8a6a 347 twMod2 = 2;
EricLew 9:5a860b9c8a6a 348 twMod3 = 4;
EricLew 9:5a860b9c8a6a 349 twMod4 = 6;
EricLew 9:5a860b9c8a6a 350
EricLew 9:5a860b9c8a6a 351 // TOP
EricLew 9:5a860b9c8a6a 352 p1ap3_0 = p1[0] + p3[0];
EricLew 9:5a860b9c8a6a 353 p1sp3_0 = p1[0] - p3[0];
EricLew 9:5a860b9c8a6a 354 p1ap3_1 = p1[1] + p3[1];
EricLew 9:5a860b9c8a6a 355 p1sp3_1 = p1[1] - p3[1];
EricLew 9:5a860b9c8a6a 356
EricLew 9:5a860b9c8a6a 357 // col 2
EricLew 9:5a860b9c8a6a 358 t2[0] = p1sp3_0 + p2[1] - p4[1];
EricLew 9:5a860b9c8a6a 359 t2[1] = p1sp3_1 - p2[0] + p4[0];
EricLew 9:5a860b9c8a6a 360 // col 3
EricLew 9:5a860b9c8a6a 361 t3[0] = p1ap3_0 - p2[0] - p4[0];
EricLew 9:5a860b9c8a6a 362 t3[1] = p1ap3_1 - p2[1] - p4[1];
EricLew 9:5a860b9c8a6a 363 // col 4
EricLew 9:5a860b9c8a6a 364 t4[0] = p1sp3_0 - p2[1] + p4[1];
EricLew 9:5a860b9c8a6a 365 t4[1] = p1sp3_1 + p2[0] - p4[0];
EricLew 9:5a860b9c8a6a 366 // col 1
EricLew 9:5a860b9c8a6a 367 *p1++ = p1ap3_0 + p2[0] + p4[0];
EricLew 9:5a860b9c8a6a 368 *p1++ = p1ap3_1 + p2[1] + p4[1];
EricLew 9:5a860b9c8a6a 369
EricLew 9:5a860b9c8a6a 370 // Twiddle factors are ones
EricLew 9:5a860b9c8a6a 371 *p2++ = t2[0];
EricLew 9:5a860b9c8a6a 372 *p2++ = t2[1];
EricLew 9:5a860b9c8a6a 373 *p3++ = t3[0];
EricLew 9:5a860b9c8a6a 374 *p3++ = t3[1];
EricLew 9:5a860b9c8a6a 375 *p4++ = t4[0];
EricLew 9:5a860b9c8a6a 376 *p4++ = t4[1];
EricLew 9:5a860b9c8a6a 377
EricLew 9:5a860b9c8a6a 378 tw2 += twMod2;
EricLew 9:5a860b9c8a6a 379 tw3 += twMod3;
EricLew 9:5a860b9c8a6a 380 tw4 += twMod4;
EricLew 9:5a860b9c8a6a 381
EricLew 9:5a860b9c8a6a 382 for (l = (L - 2) >> 1; l > 0; l-- )
EricLew 9:5a860b9c8a6a 383 {
EricLew 9:5a860b9c8a6a 384 // TOP
EricLew 9:5a860b9c8a6a 385 p1ap3_0 = p1[0] + p3[0];
EricLew 9:5a860b9c8a6a 386 p1sp3_0 = p1[0] - p3[0];
EricLew 9:5a860b9c8a6a 387 p1ap3_1 = p1[1] + p3[1];
EricLew 9:5a860b9c8a6a 388 p1sp3_1 = p1[1] - p3[1];
EricLew 9:5a860b9c8a6a 389 // col 2
EricLew 9:5a860b9c8a6a 390 t2[0] = p1sp3_0 + p2[1] - p4[1];
EricLew 9:5a860b9c8a6a 391 t2[1] = p1sp3_1 - p2[0] + p4[0];
EricLew 9:5a860b9c8a6a 392 // col 3
EricLew 9:5a860b9c8a6a 393 t3[0] = p1ap3_0 - p2[0] - p4[0];
EricLew 9:5a860b9c8a6a 394 t3[1] = p1ap3_1 - p2[1] - p4[1];
EricLew 9:5a860b9c8a6a 395 // col 4
EricLew 9:5a860b9c8a6a 396 t4[0] = p1sp3_0 - p2[1] + p4[1];
EricLew 9:5a860b9c8a6a 397 t4[1] = p1sp3_1 + p2[0] - p4[0];
EricLew 9:5a860b9c8a6a 398 // col 1 - top
EricLew 9:5a860b9c8a6a 399 *p1++ = p1ap3_0 + p2[0] + p4[0];
EricLew 9:5a860b9c8a6a 400 *p1++ = p1ap3_1 + p2[1] + p4[1];
EricLew 9:5a860b9c8a6a 401
EricLew 9:5a860b9c8a6a 402 // BOTTOM
EricLew 9:5a860b9c8a6a 403 p1ap3_1 = pEnd1[-1] + pEnd3[-1];
EricLew 9:5a860b9c8a6a 404 p1sp3_1 = pEnd1[-1] - pEnd3[-1];
EricLew 9:5a860b9c8a6a 405 p1ap3_0 = pEnd1[0] + pEnd3[0];
EricLew 9:5a860b9c8a6a 406 p1sp3_0 = pEnd1[0] - pEnd3[0];
EricLew 9:5a860b9c8a6a 407 // col 2
EricLew 9:5a860b9c8a6a 408 t2[2] = pEnd2[0] - pEnd4[0] + p1sp3_1;
EricLew 9:5a860b9c8a6a 409 t2[3] = pEnd1[0] - pEnd3[0] - pEnd2[-1] + pEnd4[-1];
EricLew 9:5a860b9c8a6a 410 // col 3
EricLew 9:5a860b9c8a6a 411 t3[2] = p1ap3_1 - pEnd2[-1] - pEnd4[-1];
EricLew 9:5a860b9c8a6a 412 t3[3] = p1ap3_0 - pEnd2[0] - pEnd4[0];
EricLew 9:5a860b9c8a6a 413 // col 4
EricLew 9:5a860b9c8a6a 414 t4[2] = pEnd2[0] - pEnd4[0] - p1sp3_1;
EricLew 9:5a860b9c8a6a 415 t4[3] = pEnd4[-1] - pEnd2[-1] - p1sp3_0;
EricLew 9:5a860b9c8a6a 416 // col 1 - Bottom
EricLew 9:5a860b9c8a6a 417 *pEnd1-- = p1ap3_0 + pEnd2[0] + pEnd4[0];
EricLew 9:5a860b9c8a6a 418 *pEnd1-- = p1ap3_1 + pEnd2[-1] + pEnd4[-1];
EricLew 9:5a860b9c8a6a 419
EricLew 9:5a860b9c8a6a 420 // COL 2
EricLew 9:5a860b9c8a6a 421 // read twiddle factors
EricLew 9:5a860b9c8a6a 422 twR = *tw2++;
EricLew 9:5a860b9c8a6a 423 twI = *tw2++;
EricLew 9:5a860b9c8a6a 424 // multiply by twiddle factors
EricLew 9:5a860b9c8a6a 425 // let Z1 = a + i(b), Z2 = c + i(d)
EricLew 9:5a860b9c8a6a 426 // => Z1 * Z2 = (a*c - b*d) + i(b*c + a*d)
EricLew 9:5a860b9c8a6a 427
EricLew 9:5a860b9c8a6a 428 // Top
EricLew 9:5a860b9c8a6a 429 m0 = t2[0] * twR;
EricLew 9:5a860b9c8a6a 430 m1 = t2[1] * twI;
EricLew 9:5a860b9c8a6a 431 m2 = t2[1] * twR;
EricLew 9:5a860b9c8a6a 432 m3 = t2[0] * twI;
EricLew 9:5a860b9c8a6a 433
EricLew 9:5a860b9c8a6a 434 *p2++ = m0 + m1;
EricLew 9:5a860b9c8a6a 435 *p2++ = m2 - m3;
EricLew 9:5a860b9c8a6a 436 // use vertical symmetry col 2
EricLew 9:5a860b9c8a6a 437 // 0.9997 - 0.0245i <==> 0.0245 - 0.9997i
EricLew 9:5a860b9c8a6a 438 // Bottom
EricLew 9:5a860b9c8a6a 439 m0 = t2[3] * twI;
EricLew 9:5a860b9c8a6a 440 m1 = t2[2] * twR;
EricLew 9:5a860b9c8a6a 441 m2 = t2[2] * twI;
EricLew 9:5a860b9c8a6a 442 m3 = t2[3] * twR;
EricLew 9:5a860b9c8a6a 443
EricLew 9:5a860b9c8a6a 444 *pEnd2-- = m0 - m1;
EricLew 9:5a860b9c8a6a 445 *pEnd2-- = m2 + m3;
EricLew 9:5a860b9c8a6a 446
EricLew 9:5a860b9c8a6a 447 // COL 3
EricLew 9:5a860b9c8a6a 448 twR = tw3[0];
EricLew 9:5a860b9c8a6a 449 twI = tw3[1];
EricLew 9:5a860b9c8a6a 450 tw3 += twMod3;
EricLew 9:5a860b9c8a6a 451 // Top
EricLew 9:5a860b9c8a6a 452 m0 = t3[0] * twR;
EricLew 9:5a860b9c8a6a 453 m1 = t3[1] * twI;
EricLew 9:5a860b9c8a6a 454 m2 = t3[1] * twR;
EricLew 9:5a860b9c8a6a 455 m3 = t3[0] * twI;
EricLew 9:5a860b9c8a6a 456
EricLew 9:5a860b9c8a6a 457 *p3++ = m0 + m1;
EricLew 9:5a860b9c8a6a 458 *p3++ = m2 - m3;
EricLew 9:5a860b9c8a6a 459 // use vertical symmetry col 3
EricLew 9:5a860b9c8a6a 460 // 0.9988 - 0.0491i <==> -0.9988 - 0.0491i
EricLew 9:5a860b9c8a6a 461 // Bottom
EricLew 9:5a860b9c8a6a 462 m0 = -t3[3] * twR;
EricLew 9:5a860b9c8a6a 463 m1 = t3[2] * twI;
EricLew 9:5a860b9c8a6a 464 m2 = t3[2] * twR;
EricLew 9:5a860b9c8a6a 465 m3 = t3[3] * twI;
EricLew 9:5a860b9c8a6a 466
EricLew 9:5a860b9c8a6a 467 *pEnd3-- = m0 - m1;
EricLew 9:5a860b9c8a6a 468 *pEnd3-- = m3 - m2;
EricLew 9:5a860b9c8a6a 469
EricLew 9:5a860b9c8a6a 470 // COL 4
EricLew 9:5a860b9c8a6a 471 twR = tw4[0];
EricLew 9:5a860b9c8a6a 472 twI = tw4[1];
EricLew 9:5a860b9c8a6a 473 tw4 += twMod4;
EricLew 9:5a860b9c8a6a 474 // Top
EricLew 9:5a860b9c8a6a 475 m0 = t4[0] * twR;
EricLew 9:5a860b9c8a6a 476 m1 = t4[1] * twI;
EricLew 9:5a860b9c8a6a 477 m2 = t4[1] * twR;
EricLew 9:5a860b9c8a6a 478 m3 = t4[0] * twI;
EricLew 9:5a860b9c8a6a 479
EricLew 9:5a860b9c8a6a 480 *p4++ = m0 + m1;
EricLew 9:5a860b9c8a6a 481 *p4++ = m2 - m3;
EricLew 9:5a860b9c8a6a 482 // use vertical symmetry col 4
EricLew 9:5a860b9c8a6a 483 // 0.9973 - 0.0736i <==> -0.0736 + 0.9973i
EricLew 9:5a860b9c8a6a 484 // Bottom
EricLew 9:5a860b9c8a6a 485 m0 = t4[3] * twI;
EricLew 9:5a860b9c8a6a 486 m1 = t4[2] * twR;
EricLew 9:5a860b9c8a6a 487 m2 = t4[2] * twI;
EricLew 9:5a860b9c8a6a 488 m3 = t4[3] * twR;
EricLew 9:5a860b9c8a6a 489
EricLew 9:5a860b9c8a6a 490 *pEnd4-- = m0 - m1;
EricLew 9:5a860b9c8a6a 491 *pEnd4-- = m2 + m3;
EricLew 9:5a860b9c8a6a 492 }
EricLew 9:5a860b9c8a6a 493
EricLew 9:5a860b9c8a6a 494 //MIDDLE
EricLew 9:5a860b9c8a6a 495 // Twiddle factors are
EricLew 9:5a860b9c8a6a 496 // 1.0000 0.7071-0.7071i -1.0000i -0.7071-0.7071i
EricLew 9:5a860b9c8a6a 497 p1ap3_0 = p1[0] + p3[0];
EricLew 9:5a860b9c8a6a 498 p1sp3_0 = p1[0] - p3[0];
EricLew 9:5a860b9c8a6a 499 p1ap3_1 = p1[1] + p3[1];
EricLew 9:5a860b9c8a6a 500 p1sp3_1 = p1[1] - p3[1];
EricLew 9:5a860b9c8a6a 501
EricLew 9:5a860b9c8a6a 502 // col 2
EricLew 9:5a860b9c8a6a 503 t2[0] = p1sp3_0 + p2[1] - p4[1];
EricLew 9:5a860b9c8a6a 504 t2[1] = p1sp3_1 - p2[0] + p4[0];
EricLew 9:5a860b9c8a6a 505 // col 3
EricLew 9:5a860b9c8a6a 506 t3[0] = p1ap3_0 - p2[0] - p4[0];
EricLew 9:5a860b9c8a6a 507 t3[1] = p1ap3_1 - p2[1] - p4[1];
EricLew 9:5a860b9c8a6a 508 // col 4
EricLew 9:5a860b9c8a6a 509 t4[0] = p1sp3_0 - p2[1] + p4[1];
EricLew 9:5a860b9c8a6a 510 t4[1] = p1sp3_1 + p2[0] - p4[0];
EricLew 9:5a860b9c8a6a 511 // col 1 - Top
EricLew 9:5a860b9c8a6a 512 *p1++ = p1ap3_0 + p2[0] + p4[0];
EricLew 9:5a860b9c8a6a 513 *p1++ = p1ap3_1 + p2[1] + p4[1];
EricLew 9:5a860b9c8a6a 514
EricLew 9:5a860b9c8a6a 515 // COL 2
EricLew 9:5a860b9c8a6a 516 twR = tw2[0];
EricLew 9:5a860b9c8a6a 517 twI = tw2[1];
EricLew 9:5a860b9c8a6a 518
EricLew 9:5a860b9c8a6a 519 m0 = t2[0] * twR;
EricLew 9:5a860b9c8a6a 520 m1 = t2[1] * twI;
EricLew 9:5a860b9c8a6a 521 m2 = t2[1] * twR;
EricLew 9:5a860b9c8a6a 522 m3 = t2[0] * twI;
EricLew 9:5a860b9c8a6a 523
EricLew 9:5a860b9c8a6a 524 *p2++ = m0 + m1;
EricLew 9:5a860b9c8a6a 525 *p2++ = m2 - m3;
EricLew 9:5a860b9c8a6a 526 // COL 3
EricLew 9:5a860b9c8a6a 527 twR = tw3[0];
EricLew 9:5a860b9c8a6a 528 twI = tw3[1];
EricLew 9:5a860b9c8a6a 529
EricLew 9:5a860b9c8a6a 530 m0 = t3[0] * twR;
EricLew 9:5a860b9c8a6a 531 m1 = t3[1] * twI;
EricLew 9:5a860b9c8a6a 532 m2 = t3[1] * twR;
EricLew 9:5a860b9c8a6a 533 m3 = t3[0] * twI;
EricLew 9:5a860b9c8a6a 534
EricLew 9:5a860b9c8a6a 535 *p3++ = m0 + m1;
EricLew 9:5a860b9c8a6a 536 *p3++ = m2 - m3;
EricLew 9:5a860b9c8a6a 537 // COL 4
EricLew 9:5a860b9c8a6a 538 twR = tw4[0];
EricLew 9:5a860b9c8a6a 539 twI = tw4[1];
EricLew 9:5a860b9c8a6a 540
EricLew 9:5a860b9c8a6a 541 m0 = t4[0] * twR;
EricLew 9:5a860b9c8a6a 542 m1 = t4[1] * twI;
EricLew 9:5a860b9c8a6a 543 m2 = t4[1] * twR;
EricLew 9:5a860b9c8a6a 544 m3 = t4[0] * twI;
EricLew 9:5a860b9c8a6a 545
EricLew 9:5a860b9c8a6a 546 *p4++ = m0 + m1;
EricLew 9:5a860b9c8a6a 547 *p4++ = m2 - m3;
EricLew 9:5a860b9c8a6a 548
EricLew 9:5a860b9c8a6a 549 // first col
EricLew 9:5a860b9c8a6a 550 arm_radix8_butterfly_f32( pCol1, L, (float32_t *) S->pTwiddle, 4u);
EricLew 9:5a860b9c8a6a 551 // second col
EricLew 9:5a860b9c8a6a 552 arm_radix8_butterfly_f32( pCol2, L, (float32_t *) S->pTwiddle, 4u);
EricLew 9:5a860b9c8a6a 553 // third col
EricLew 9:5a860b9c8a6a 554 arm_radix8_butterfly_f32( pCol3, L, (float32_t *) S->pTwiddle, 4u);
EricLew 9:5a860b9c8a6a 555 // fourth col
EricLew 9:5a860b9c8a6a 556 arm_radix8_butterfly_f32( pCol4, L, (float32_t *) S->pTwiddle, 4u);
EricLew 9:5a860b9c8a6a 557 }
EricLew 9:5a860b9c8a6a 558
EricLew 9:5a860b9c8a6a 559 /**
EricLew 9:5a860b9c8a6a 560 * @addtogroup ComplexFFT
EricLew 9:5a860b9c8a6a 561 * @{
EricLew 9:5a860b9c8a6a 562 */
EricLew 9:5a860b9c8a6a 563
EricLew 9:5a860b9c8a6a 564 /**
EricLew 9:5a860b9c8a6a 565 * @details
EricLew 9:5a860b9c8a6a 566 * @brief Processing function for the floating-point complex FFT.
EricLew 9:5a860b9c8a6a 567 * @param[in] *S points to an instance of the floating-point CFFT structure.
EricLew 9:5a860b9c8a6a 568 * @param[in, out] *p1 points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.
EricLew 9:5a860b9c8a6a 569 * @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
EricLew 9:5a860b9c8a6a 570 * @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
EricLew 9:5a860b9c8a6a 571 * @return none.
EricLew 9:5a860b9c8a6a 572 */
EricLew 9:5a860b9c8a6a 573
EricLew 9:5a860b9c8a6a 574 void arm_cfft_f32(
EricLew 9:5a860b9c8a6a 575 const arm_cfft_instance_f32 * S,
EricLew 9:5a860b9c8a6a 576 float32_t * p1,
EricLew 9:5a860b9c8a6a 577 uint8_t ifftFlag,
EricLew 9:5a860b9c8a6a 578 uint8_t bitReverseFlag)
EricLew 9:5a860b9c8a6a 579 {
EricLew 9:5a860b9c8a6a 580 uint32_t L = S->fftLen, l;
EricLew 9:5a860b9c8a6a 581 float32_t invL, * pSrc;
EricLew 9:5a860b9c8a6a 582
EricLew 9:5a860b9c8a6a 583 if(ifftFlag == 1u)
EricLew 9:5a860b9c8a6a 584 {
EricLew 9:5a860b9c8a6a 585 /* Conjugate input data */
EricLew 9:5a860b9c8a6a 586 pSrc = p1 + 1;
EricLew 9:5a860b9c8a6a 587 for(l=0; l<L; l++)
EricLew 9:5a860b9c8a6a 588 {
EricLew 9:5a860b9c8a6a 589 *pSrc = -*pSrc;
EricLew 9:5a860b9c8a6a 590 pSrc += 2;
EricLew 9:5a860b9c8a6a 591 }
EricLew 9:5a860b9c8a6a 592 }
EricLew 9:5a860b9c8a6a 593
EricLew 9:5a860b9c8a6a 594 switch (L)
EricLew 9:5a860b9c8a6a 595 {
EricLew 9:5a860b9c8a6a 596 case 16:
EricLew 9:5a860b9c8a6a 597 case 128:
EricLew 9:5a860b9c8a6a 598 case 1024:
EricLew 9:5a860b9c8a6a 599 arm_cfft_radix8by2_f32 ( (arm_cfft_instance_f32 *) S, p1);
EricLew 9:5a860b9c8a6a 600 break;
EricLew 9:5a860b9c8a6a 601 case 32:
EricLew 9:5a860b9c8a6a 602 case 256:
EricLew 9:5a860b9c8a6a 603 case 2048:
EricLew 9:5a860b9c8a6a 604 arm_cfft_radix8by4_f32 ( (arm_cfft_instance_f32 *) S, p1);
EricLew 9:5a860b9c8a6a 605 break;
EricLew 9:5a860b9c8a6a 606 case 64:
EricLew 9:5a860b9c8a6a 607 case 512:
EricLew 9:5a860b9c8a6a 608 case 4096:
EricLew 9:5a860b9c8a6a 609 arm_radix8_butterfly_f32( p1, L, (float32_t *) S->pTwiddle, 1);
EricLew 9:5a860b9c8a6a 610 break;
EricLew 9:5a860b9c8a6a 611 }
EricLew 9:5a860b9c8a6a 612
EricLew 9:5a860b9c8a6a 613 // if( bitReverseFlag )
EricLew 9:5a860b9c8a6a 614 // arm_bitreversal_32((uint32_t*)p1,S->bitRevLength,S->pBitRevTable);
EricLew 9:5a860b9c8a6a 615
EricLew 9:5a860b9c8a6a 616 if(ifftFlag == 1u)
EricLew 9:5a860b9c8a6a 617 {
EricLew 9:5a860b9c8a6a 618 invL = 1.0f/(float32_t)L;
EricLew 9:5a860b9c8a6a 619 /* Conjugate and scale output data */
EricLew 9:5a860b9c8a6a 620 pSrc = p1;
EricLew 9:5a860b9c8a6a 621 for(l=0; l<L; l++)
EricLew 9:5a860b9c8a6a 622 {
EricLew 9:5a860b9c8a6a 623 *pSrc++ *= invL ;
EricLew 9:5a860b9c8a6a 624 *pSrc = -(*pSrc) * invL;
EricLew 9:5a860b9c8a6a 625 pSrc++;
EricLew 9:5a860b9c8a6a 626 }
EricLew 9:5a860b9c8a6a 627 }
EricLew 9:5a860b9c8a6a 628 }
EricLew 9:5a860b9c8a6a 629
EricLew 9:5a860b9c8a6a 630 /**
EricLew 9:5a860b9c8a6a 631 * @} end of ComplexFFT group
EricLew 9:5a860b9c8a6a 632 */