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CMSIS DSP library

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cmsis_dsp/TransformFunctions/arm_cfft_f32.c@3:7a284390b0ce, 2013-11-08 (annotated)

Committer:
mbed_official
Date:
Fri Nov 08 13:45:10 2013 +0000
Revision:
3:7a284390b0ce
Child:
5:3762170b6d4d
Synchronized with git revision e69956aba2f68a2a26ac26b051f8d349deaa1ce8

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 3:7a284390b0ce 1 /* ----------------------------------------------------------------------
mbed_official 3:7a284390b0ce 2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
mbed_official 3:7a284390b0ce 3 *
mbed_official 3:7a284390b0ce 4 * $Date: 17. January 2013
mbed_official 3:7a284390b0ce 5 * $Revision: V1.4.1
mbed_official 3:7a284390b0ce 6 *
mbed_official 3:7a284390b0ce 7 * Project: CMSIS DSP Library
mbed_official 3:7a284390b0ce 8 * Title: arm_cfft_f32.c
mbed_official 3:7a284390b0ce 9 *
mbed_official 3:7a284390b0ce 10 * Description: Combined Radix Decimation in Frequency CFFT Floating point processing function
mbed_official 3:7a284390b0ce 11 *
mbed_official 3:7a284390b0ce 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
mbed_official 3:7a284390b0ce 13 *
mbed_official 3:7a284390b0ce 14 * Redistribution and use in source and binary forms, with or without
mbed_official 3:7a284390b0ce 15 * modification, are permitted provided that the following conditions
mbed_official 3:7a284390b0ce 16 * are met:
mbed_official 3:7a284390b0ce 17 * - Redistributions of source code must retain the above copyright
mbed_official 3:7a284390b0ce 18 * notice, this list of conditions and the following disclaimer.
mbed_official 3:7a284390b0ce 19 * - Redistributions in binary form must reproduce the above copyright
mbed_official 3:7a284390b0ce 20 * notice, this list of conditions and the following disclaimer in
mbed_official 3:7a284390b0ce 21 * the documentation and/or other materials provided with the
mbed_official 3:7a284390b0ce 22 * distribution.
mbed_official 3:7a284390b0ce 23 * - Neither the name of ARM LIMITED nor the names of its contributors
mbed_official 3:7a284390b0ce 24 * may be used to endorse or promote products derived from this
mbed_official 3:7a284390b0ce 25 * software without specific prior written permission.
mbed_official 3:7a284390b0ce 26 *
mbed_official 3:7a284390b0ce 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
mbed_official 3:7a284390b0ce 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
mbed_official 3:7a284390b0ce 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
mbed_official 3:7a284390b0ce 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
mbed_official 3:7a284390b0ce 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
mbed_official 3:7a284390b0ce 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
mbed_official 3:7a284390b0ce 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
mbed_official 3:7a284390b0ce 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
mbed_official 3:7a284390b0ce 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
mbed_official 3:7a284390b0ce 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
mbed_official 3:7a284390b0ce 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
mbed_official 3:7a284390b0ce 38 * POSSIBILITY OF SUCH DAMAGE.
mbed_official 3:7a284390b0ce 39 * -------------------------------------------------------------------- */
mbed_official 3:7a284390b0ce 40
mbed_official 3:7a284390b0ce 41
mbed_official 3:7a284390b0ce 42 #include "arm_math.h"
mbed_official 3:7a284390b0ce 43 #include "arm_common_tables.h"
mbed_official 3:7a284390b0ce 44
mbed_official 3:7a284390b0ce 45 extern void arm_radix8_butterfly_f32(
mbed_official 3:7a284390b0ce 46 float32_t * pSrc,
mbed_official 3:7a284390b0ce 47 uint16_t fftLen,
mbed_official 3:7a284390b0ce 48 const float32_t * pCoef,
mbed_official 3:7a284390b0ce 49 uint16_t twidCoefModifier);
mbed_official 3:7a284390b0ce 50
mbed_official 3:7a284390b0ce 51 extern void arm_bitreversal_32(
mbed_official 3:7a284390b0ce 52 uint32_t * pSrc,
mbed_official 3:7a284390b0ce 53 const uint16_t bitRevLen,
mbed_official 3:7a284390b0ce 54 const uint16_t * pBitRevTable);
mbed_official 3:7a284390b0ce 55
mbed_official 3:7a284390b0ce 56 /**
mbed_official 3:7a284390b0ce 57 * @ingroup groupTransforms
mbed_official 3:7a284390b0ce 58 */
mbed_official 3:7a284390b0ce 59
mbed_official 3:7a284390b0ce 60 /**
mbed_official 3:7a284390b0ce 61 * @defgroup ComplexFFT Complex FFT Functions
mbed_official 3:7a284390b0ce 62 *
mbed_official 3:7a284390b0ce 63 * \par
mbed_official 3:7a284390b0ce 64 * The Fast Fourier Transform (FFT) is an efficient algorithm for computing the
mbed_official 3:7a284390b0ce 65 * Discrete Fourier Transform (DFT). The FFT can be orders of magnitude faster
mbed_official 3:7a284390b0ce 66 * than the DFT, especially for long lengths.
mbed_official 3:7a284390b0ce 67 * The algorithms described in this section
mbed_official 3:7a284390b0ce 68 * operate on complex data. A separate set of functions is devoted to handling
mbed_official 3:7a284390b0ce 69 * of real sequences.
mbed_official 3:7a284390b0ce 70 * \par
mbed_official 3:7a284390b0ce 71 * There are separate algorithms for handling floating-point, Q15, and Q31 data
mbed_official 3:7a284390b0ce 72 * types. The algorithms available for each data type are described next.
mbed_official 3:7a284390b0ce 73 * \par
mbed_official 3:7a284390b0ce 74 * The FFT functions operate in-place. That is, the array holding the input data
mbed_official 3:7a284390b0ce 75 * will also be used to hold the corresponding result. The input data is complex
mbed_official 3:7a284390b0ce 76 * and contains <code>2*fftLen</code> interleaved values as shown below.
mbed_official 3:7a284390b0ce 77 * <pre> {real[0], imag[0], real[1], imag[1],..} </pre>
mbed_official 3:7a284390b0ce 78 * The FFT result will be contained in the same array and the frequency domain
mbed_official 3:7a284390b0ce 79 * values will have the same interleaving.
mbed_official 3:7a284390b0ce 80 *
mbed_official 3:7a284390b0ce 81 * \par Floating-point
mbed_official 3:7a284390b0ce 82 * The floating-point complex FFT uses a mixed-radix algorithm. Multiple radix-8
mbed_official 3:7a284390b0ce 83 * stages are performed along with a single radix-2 or radix-4 stage, as needed.
mbed_official 3:7a284390b0ce 84 * The algorithm supports lengths of [16, 32, 64, ..., 4096] and each length uses
mbed_official 3:7a284390b0ce 85 * a different twiddle factor table.
mbed_official 3:7a284390b0ce 86 * \par
mbed_official 3:7a284390b0ce 87 * The function uses the standard FFT definition and output values may grow by a
mbed_official 3:7a284390b0ce 88 * factor of <code>fftLen</code> when computing the forward transform. The
mbed_official 3:7a284390b0ce 89 * inverse transform includes a scale of <code>1/fftLen</code> as part of the
mbed_official 3:7a284390b0ce 90 * calculation and this matches the textbook definition of the inverse FFT.
mbed_official 3:7a284390b0ce 91 * \par
mbed_official 3:7a284390b0ce 92 * Preinitialized data structures containing twiddle factors and bit reversal
mbed_official 3:7a284390b0ce 93 * tables are provided and defined in <code>arm_const_structs.h</code>. Include
mbed_official 3:7a284390b0ce 94 * this header in your function and then pass one of the constant structures as
mbed_official 3:7a284390b0ce 95 * an argument to arm_cfft_f32. For example:
mbed_official 3:7a284390b0ce 96 * \par
mbed_official 3:7a284390b0ce 97 * <code>arm_cfft_f32(arm_cfft_sR_f32_len64, pSrc, 1, 1)</code>
mbed_official 3:7a284390b0ce 98 * \par
mbed_official 3:7a284390b0ce 99 * computes a 64-point inverse complex FFT including bit reversal.
mbed_official 3:7a284390b0ce 100 * The data structures are treated as constant data and not modified during the
mbed_official 3:7a284390b0ce 101 * calculation. The same data structure can be reused for multiple transforms
mbed_official 3:7a284390b0ce 102 * including mixing forward and inverse transforms.
mbed_official 3:7a284390b0ce 103 * \par
mbed_official 3:7a284390b0ce 104 * Earlier releases of the library provided separate radix-2 and radix-4
mbed_official 3:7a284390b0ce 105 * algorithms that operated on floating-point data. These functions are still
mbed_official 3:7a284390b0ce 106 * provided but are deprecated. The older functions are slower and less general
mbed_official 3:7a284390b0ce 107 * than the new functions.
mbed_official 3:7a284390b0ce 108 * \par
mbed_official 3:7a284390b0ce 109 * An example of initialization of the constants for the arm_cfft_f32 function follows:
mbed_official 3:7a284390b0ce 110 * \par
mbed_official 3:7a284390b0ce 111 * const static arm_cfft_instance_f32 *S;
mbed_official 3:7a284390b0ce 112 * ...
mbed_official 3:7a284390b0ce 113 * switch (length) {
mbed_official 3:7a284390b0ce 114 * case 16:
mbed_official 3:7a284390b0ce 115 * S = & arm_cfft_sR_f32_len16;
mbed_official 3:7a284390b0ce 116 * break;
mbed_official 3:7a284390b0ce 117 * case 32:
mbed_official 3:7a284390b0ce 118 * S = & arm_cfft_sR_f32_len32;
mbed_official 3:7a284390b0ce 119 * break;
mbed_official 3:7a284390b0ce 120 * case 64:
mbed_official 3:7a284390b0ce 121 * S = & arm_cfft_sR_f32_len64;
mbed_official 3:7a284390b0ce 122 * break;
mbed_official 3:7a284390b0ce 123 * case 128:
mbed_official 3:7a284390b0ce 124 * S = & arm_cfft_sR_f32_len128;
mbed_official 3:7a284390b0ce 125 * break;
mbed_official 3:7a284390b0ce 126 * case 256:
mbed_official 3:7a284390b0ce 127 * S = & arm_cfft_sR_f32_len256;
mbed_official 3:7a284390b0ce 128 * break;
mbed_official 3:7a284390b0ce 129 * case 512:
mbed_official 3:7a284390b0ce 130 * S = & arm_cfft_sR_f32_len512;
mbed_official 3:7a284390b0ce 131 * break;
mbed_official 3:7a284390b0ce 132 * case 1024:
mbed_official 3:7a284390b0ce 133 * S = & arm_cfft_sR_f32_len1024;
mbed_official 3:7a284390b0ce 134 * break;
mbed_official 3:7a284390b0ce 135 * case 2048:
mbed_official 3:7a284390b0ce 136 * S = & arm_cfft_sR_f32_len2048;
mbed_official 3:7a284390b0ce 137 * break;
mbed_official 3:7a284390b0ce 138 * case 4096:
mbed_official 3:7a284390b0ce 139 * S = & arm_cfft_sR_f32_len4096;
mbed_official 3:7a284390b0ce 140 * break;
mbed_official 3:7a284390b0ce 141 * }
mbed_official 3:7a284390b0ce 142 * \par Q15 and Q31
mbed_official 3:7a284390b0ce 143 * The library provides radix-2 and radix-4 FFT algorithms for fixed-point data. The
mbed_official 3:7a284390b0ce 144 * radix-2 algorithm supports lengths of [16, 32, 64, ..., 4096]. The radix-4
mbed_official 3:7a284390b0ce 145 * algorithm supports lengths of [16, 64, 256, ..., 4096]. When possible, you
mbed_official 3:7a284390b0ce 146 * should use the radix-4 algorithm since it is faster than the radix-2 of the
mbed_official 3:7a284390b0ce 147 * same length.
mbed_official 3:7a284390b0ce 148 * \par
mbed_official 3:7a284390b0ce 149 * The forward FFTs include scaling in order to prevent results from overflowing.
mbed_official 3:7a284390b0ce 150 * Intermediate results are scaled down during each butterfly stage. In the
mbed_official 3:7a284390b0ce 151 * radix-2 algorithm, a scale of 0.5 is applied during each butterfly. In the
mbed_official 3:7a284390b0ce 152 * radix-4 algorithm, a scale of 0.25 is applied. The scaling applies to both
mbed_official 3:7a284390b0ce 153 * the forward and the inverse FFTs. Thus the forward FFT contains an additional
mbed_official 3:7a284390b0ce 154 * scale factor of <code>1/fftLen</code> as compared to the standard textbook
mbed_official 3:7a284390b0ce 155 * definition of the FFT. The inverse FFT also scales down during each butterfly
mbed_official 3:7a284390b0ce 156 * stage and this corresponds to the standard textbook definition.
mbed_official 3:7a284390b0ce 157 * \par
mbed_official 3:7a284390b0ce 158 * A separate instance structure must be defined for each transform used but
mbed_official 3:7a284390b0ce 159 * twiddle factor and bit reversal tables can be reused.
mbed_official 3:7a284390b0ce 160 * \par
mbed_official 3:7a284390b0ce 161 * There is also an associated initialization function for each data type.
mbed_official 3:7a284390b0ce 162 * The initialization function performs the following operations:
mbed_official 3:7a284390b0ce 163 * - Sets the values of the internal structure fields.
mbed_official 3:7a284390b0ce 164 * - Initializes twiddle factor table and bit reversal table pointers.
mbed_official 3:7a284390b0ce 165 * \par
mbed_official 3:7a284390b0ce 166 * Use of the initialization function is optional.
mbed_official 3:7a284390b0ce 167 * However, if the initialization function is used, then the instance structure
mbed_official 3:7a284390b0ce 168 * cannot be placed into a const data section. To place an instance structure
mbed_official 3:7a284390b0ce 169 * into a const data section, the instance structure should be manually
mbed_official 3:7a284390b0ce 170 * initialized as follows:
mbed_official 3:7a284390b0ce 171 * <pre>
mbed_official 3:7a284390b0ce 172 *arm_cfft_radix2_instance_q31 S = {fftLen, ifftFlag, bitReverseFlag, pTwiddle, pBitRevTable, twidCoefModifier, bitRevFactor};
mbed_official 3:7a284390b0ce 173 *arm_cfft_radix2_instance_q15 S = {fftLen, ifftFlag, bitReverseFlag, pTwiddle, pBitRevTable, twidCoefModifier, bitRevFactor};
mbed_official 3:7a284390b0ce 174 *arm_cfft_radix4_instance_q31 S = {fftLen, ifftFlag, bitReverseFlag, pTwiddle, pBitRevTable, twidCoefModifier, bitRevFactor};
mbed_official 3:7a284390b0ce 175 *arm_cfft_radix4_instance_q15 S = {fftLen, ifftFlag, bitReverseFlag, pTwiddle, pBitRevTable, twidCoefModifier, bitRevFactor};
mbed_official 3:7a284390b0ce 176 *arm_cfft_instance_f32 S = {fftLen, pTwiddle, pBitRevTable, bitRevLength};
mbed_official 3:7a284390b0ce 177 * </pre>
mbed_official 3:7a284390b0ce 178 * \par
mbed_official 3:7a284390b0ce 179 * where <code>fftLen</code> length of CFFT/CIFFT; <code>ifftFlag</code> Flag for
mbed_official 3:7a284390b0ce 180 * selection of forward or inverse transform. When ifftFlag is set the inverse
mbed_official 3:7a284390b0ce 181 * transform is calculated.
mbed_official 3:7a284390b0ce 182 * <code>bitReverseFlag</code> Flag for selection of output order (Set bitReverseFlag to output in normal order otherwise output in bit reversed order);
mbed_official 3:7a284390b0ce 183 * <code>pTwiddle</code>points to array of twiddle coefficients; <code>pBitRevTable</code> points to the bit reversal table.
mbed_official 3:7a284390b0ce 184 * <code>twidCoefModifier</code> modifier for twiddle factor table which supports all FFT lengths with same table;
mbed_official 3:7a284390b0ce 185 * <code>pBitRevTable</code> modifier for bit reversal table which supports all FFT lengths with same table.
mbed_official 3:7a284390b0ce 186 * <code>onebyfftLen</code> value of 1/fftLen to calculate CIFFT;
mbed_official 3:7a284390b0ce 187 * \par
mbed_official 3:7a284390b0ce 188 * The Q15 and Q31 FFT functions use a large bit reversal and twiddle factor
mbed_official 3:7a284390b0ce 189 * table. The tables are defined for the maximum length transform and a subset
mbed_official 3:7a284390b0ce 190 * of the coefficients are used in shorter transforms.
mbed_official 3:7a284390b0ce 191 *
mbed_official 3:7a284390b0ce 192 */
mbed_official 3:7a284390b0ce 193
mbed_official 3:7a284390b0ce 194 void arm_cfft_radix8by2_f32( arm_cfft_instance_f32 * S, float32_t * p1)
mbed_official 3:7a284390b0ce 195 {
mbed_official 3:7a284390b0ce 196 uint32_t L = S->fftLen;
mbed_official 3:7a284390b0ce 197 float32_t * pCol1, * pCol2, * pMid1, * pMid2;
mbed_official 3:7a284390b0ce 198 float32_t * p2 = p1 + L;
mbed_official 3:7a284390b0ce 199 const float32_t * tw = (float32_t *) S->pTwiddle;
mbed_official 3:7a284390b0ce 200 float32_t t1[4], t2[4], t3[4], t4[4], twR, twI;
mbed_official 3:7a284390b0ce 201 float32_t m0, m1, m2, m3;
mbed_official 3:7a284390b0ce 202 uint32_t l;
mbed_official 3:7a284390b0ce 203
mbed_official 3:7a284390b0ce 204 pCol1 = p1;
mbed_official 3:7a284390b0ce 205 pCol2 = p2;
mbed_official 3:7a284390b0ce 206
mbed_official 3:7a284390b0ce 207 // Define new length
mbed_official 3:7a284390b0ce 208 L >>= 1;
mbed_official 3:7a284390b0ce 209 // Initialize mid pointers
mbed_official 3:7a284390b0ce 210 pMid1 = p1 + L;
mbed_official 3:7a284390b0ce 211 pMid2 = p2 + L;
mbed_official 3:7a284390b0ce 212
mbed_official 3:7a284390b0ce 213 // do two dot Fourier transform
mbed_official 3:7a284390b0ce 214 for ( l = L >> 2; l > 0; l-- )
mbed_official 3:7a284390b0ce 215 {
mbed_official 3:7a284390b0ce 216 t1[0] = p1[0];
mbed_official 3:7a284390b0ce 217 t1[1] = p1[1];
mbed_official 3:7a284390b0ce 218 t1[2] = p1[2];
mbed_official 3:7a284390b0ce 219 t1[3] = p1[3];
mbed_official 3:7a284390b0ce 220
mbed_official 3:7a284390b0ce 221 t2[0] = p2[0];
mbed_official 3:7a284390b0ce 222 t2[1] = p2[1];
mbed_official 3:7a284390b0ce 223 t2[2] = p2[2];
mbed_official 3:7a284390b0ce 224 t2[3] = p2[3];
mbed_official 3:7a284390b0ce 225
mbed_official 3:7a284390b0ce 226 t3[0] = pMid1[0];
mbed_official 3:7a284390b0ce 227 t3[1] = pMid1[1];
mbed_official 3:7a284390b0ce 228 t3[2] = pMid1[2];
mbed_official 3:7a284390b0ce 229 t3[3] = pMid1[3];
mbed_official 3:7a284390b0ce 230
mbed_official 3:7a284390b0ce 231 t4[0] = pMid2[0];
mbed_official 3:7a284390b0ce 232 t4[1] = pMid2[1];
mbed_official 3:7a284390b0ce 233 t4[2] = pMid2[2];
mbed_official 3:7a284390b0ce 234 t4[3] = pMid2[3];
mbed_official 3:7a284390b0ce 235
mbed_official 3:7a284390b0ce 236 *p1++ = t1[0] + t2[0];
mbed_official 3:7a284390b0ce 237 *p1++ = t1[1] + t2[1];
mbed_official 3:7a284390b0ce 238 *p1++ = t1[2] + t2[2];
mbed_official 3:7a284390b0ce 239 *p1++ = t1[3] + t2[3]; // col 1
mbed_official 3:7a284390b0ce 240
mbed_official 3:7a284390b0ce 241 t2[0] = t1[0] - t2[0];
mbed_official 3:7a284390b0ce 242 t2[1] = t1[1] - t2[1];
mbed_official 3:7a284390b0ce 243 t2[2] = t1[2] - t2[2];
mbed_official 3:7a284390b0ce 244 t2[3] = t1[3] - t2[3]; // for col 2
mbed_official 3:7a284390b0ce 245
mbed_official 3:7a284390b0ce 246 *pMid1++ = t3[0] + t4[0];
mbed_official 3:7a284390b0ce 247 *pMid1++ = t3[1] + t4[1];
mbed_official 3:7a284390b0ce 248 *pMid1++ = t3[2] + t4[2];
mbed_official 3:7a284390b0ce 249 *pMid1++ = t3[3] + t4[3]; // col 1
mbed_official 3:7a284390b0ce 250
mbed_official 3:7a284390b0ce 251 t4[0] = t4[0] - t3[0];
mbed_official 3:7a284390b0ce 252 t4[1] = t4[1] - t3[1];
mbed_official 3:7a284390b0ce 253 t4[2] = t4[2] - t3[2];
mbed_official 3:7a284390b0ce 254 t4[3] = t4[3] - t3[3]; // for col 2
mbed_official 3:7a284390b0ce 255
mbed_official 3:7a284390b0ce 256 twR = *tw++;
mbed_official 3:7a284390b0ce 257 twI = *tw++;
mbed_official 3:7a284390b0ce 258
mbed_official 3:7a284390b0ce 259 // multiply by twiddle factors
mbed_official 3:7a284390b0ce 260 m0 = t2[0] * twR;
mbed_official 3:7a284390b0ce 261 m1 = t2[1] * twI;
mbed_official 3:7a284390b0ce 262 m2 = t2[1] * twR;
mbed_official 3:7a284390b0ce 263 m3 = t2[0] * twI;
mbed_official 3:7a284390b0ce 264
mbed_official 3:7a284390b0ce 265 // R = R * Tr - I * Ti
mbed_official 3:7a284390b0ce 266 *p2++ = m0 + m1;
mbed_official 3:7a284390b0ce 267 // I = I * Tr + R * Ti
mbed_official 3:7a284390b0ce 268 *p2++ = m2 - m3;
mbed_official 3:7a284390b0ce 269
mbed_official 3:7a284390b0ce 270 // use vertical symmetry
mbed_official 3:7a284390b0ce 271 // 0.9988 - 0.0491i <==> -0.0491 - 0.9988i
mbed_official 3:7a284390b0ce 272 m0 = t4[0] * twI;
mbed_official 3:7a284390b0ce 273 m1 = t4[1] * twR;
mbed_official 3:7a284390b0ce 274 m2 = t4[1] * twI;
mbed_official 3:7a284390b0ce 275 m3 = t4[0] * twR;
mbed_official 3:7a284390b0ce 276
mbed_official 3:7a284390b0ce 277 *pMid2++ = m0 - m1;
mbed_official 3:7a284390b0ce 278 *pMid2++ = m2 + m3;
mbed_official 3:7a284390b0ce 279
mbed_official 3:7a284390b0ce 280 twR = *tw++;
mbed_official 3:7a284390b0ce 281 twI = *tw++;
mbed_official 3:7a284390b0ce 282
mbed_official 3:7a284390b0ce 283 m0 = t2[2] * twR;
mbed_official 3:7a284390b0ce 284 m1 = t2[3] * twI;
mbed_official 3:7a284390b0ce 285 m2 = t2[3] * twR;
mbed_official 3:7a284390b0ce 286 m3 = t2[2] * twI;
mbed_official 3:7a284390b0ce 287
mbed_official 3:7a284390b0ce 288 *p2++ = m0 + m1;
mbed_official 3:7a284390b0ce 289 *p2++ = m2 - m3;
mbed_official 3:7a284390b0ce 290
mbed_official 3:7a284390b0ce 291 m0 = t4[2] * twI;
mbed_official 3:7a284390b0ce 292 m1 = t4[3] * twR;
mbed_official 3:7a284390b0ce 293 m2 = t4[3] * twI;
mbed_official 3:7a284390b0ce 294 m3 = t4[2] * twR;
mbed_official 3:7a284390b0ce 295
mbed_official 3:7a284390b0ce 296 *pMid2++ = m0 - m1;
mbed_official 3:7a284390b0ce 297 *pMid2++ = m2 + m3;
mbed_official 3:7a284390b0ce 298 }
mbed_official 3:7a284390b0ce 299
mbed_official 3:7a284390b0ce 300 // first col
mbed_official 3:7a284390b0ce 301 arm_radix8_butterfly_f32( pCol1, L, (float32_t *) S->pTwiddle, 2u);
mbed_official 3:7a284390b0ce 302 // second col
mbed_official 3:7a284390b0ce 303 arm_radix8_butterfly_f32( pCol2, L, (float32_t *) S->pTwiddle, 2u);
mbed_official 3:7a284390b0ce 304
mbed_official 3:7a284390b0ce 305 }
mbed_official 3:7a284390b0ce 306
mbed_official 3:7a284390b0ce 307 void arm_cfft_radix8by4_f32( arm_cfft_instance_f32 * S, float32_t * p1)
mbed_official 3:7a284390b0ce 308 {
mbed_official 3:7a284390b0ce 309 uint32_t L = S->fftLen >> 1;
mbed_official 3:7a284390b0ce 310 float32_t * pCol1, *pCol2, *pCol3, *pCol4, *pEnd1, *pEnd2, *pEnd3, *pEnd4;
mbed_official 3:7a284390b0ce 311 const float32_t *tw2, *tw3, *tw4;
mbed_official 3:7a284390b0ce 312 float32_t * p2 = p1 + L;
mbed_official 3:7a284390b0ce 313 float32_t * p3 = p2 + L;
mbed_official 3:7a284390b0ce 314 float32_t * p4 = p3 + L;
mbed_official 3:7a284390b0ce 315 float32_t t2[4], t3[4], t4[4], twR, twI;
mbed_official 3:7a284390b0ce 316 float32_t p1ap3_0, p1sp3_0, p1ap3_1, p1sp3_1;
mbed_official 3:7a284390b0ce 317 float32_t m0, m1, m2, m3;
mbed_official 3:7a284390b0ce 318 uint32_t l, twMod2, twMod3, twMod4;
mbed_official 3:7a284390b0ce 319
mbed_official 3:7a284390b0ce 320 pCol1 = p1; // points to real values by default
mbed_official 3:7a284390b0ce 321 pCol2 = p2;
mbed_official 3:7a284390b0ce 322 pCol3 = p3;
mbed_official 3:7a284390b0ce 323 pCol4 = p4;
mbed_official 3:7a284390b0ce 324 pEnd1 = p2 - 1; // points to imaginary values by default
mbed_official 3:7a284390b0ce 325 pEnd2 = p3 - 1;
mbed_official 3:7a284390b0ce 326 pEnd3 = p4 - 1;
mbed_official 3:7a284390b0ce 327 pEnd4 = pEnd3 + L;
mbed_official 3:7a284390b0ce 328
mbed_official 3:7a284390b0ce 329 tw2 = tw3 = tw4 = (float32_t *) S->pTwiddle;
mbed_official 3:7a284390b0ce 330
mbed_official 3:7a284390b0ce 331 L >>= 1;
mbed_official 3:7a284390b0ce 332
mbed_official 3:7a284390b0ce 333 // do four dot Fourier transform
mbed_official 3:7a284390b0ce 334
mbed_official 3:7a284390b0ce 335 twMod2 = 2;
mbed_official 3:7a284390b0ce 336 twMod3 = 4;
mbed_official 3:7a284390b0ce 337 twMod4 = 6;
mbed_official 3:7a284390b0ce 338
mbed_official 3:7a284390b0ce 339 // TOP
mbed_official 3:7a284390b0ce 340 p1ap3_0 = p1[0] + p3[0];
mbed_official 3:7a284390b0ce 341 p1sp3_0 = p1[0] - p3[0];
mbed_official 3:7a284390b0ce 342 p1ap3_1 = p1[1] + p3[1];
mbed_official 3:7a284390b0ce 343 p1sp3_1 = p1[1] - p3[1];
mbed_official 3:7a284390b0ce 344
mbed_official 3:7a284390b0ce 345 // col 2
mbed_official 3:7a284390b0ce 346 t2[0] = p1sp3_0 + p2[1] - p4[1];
mbed_official 3:7a284390b0ce 347 t2[1] = p1sp3_1 - p2[0] + p4[0];
mbed_official 3:7a284390b0ce 348 // col 3
mbed_official 3:7a284390b0ce 349 t3[0] = p1ap3_0 - p2[0] - p4[0];
mbed_official 3:7a284390b0ce 350 t3[1] = p1ap3_1 - p2[1] - p4[1];
mbed_official 3:7a284390b0ce 351 // col 4
mbed_official 3:7a284390b0ce 352 t4[0] = p1sp3_0 - p2[1] + p4[1];
mbed_official 3:7a284390b0ce 353 t4[1] = p1sp3_1 + p2[0] - p4[0];
mbed_official 3:7a284390b0ce 354 // col 1
mbed_official 3:7a284390b0ce 355 *p1++ = p1ap3_0 + p2[0] + p4[0];
mbed_official 3:7a284390b0ce 356 *p1++ = p1ap3_1 + p2[1] + p4[1];
mbed_official 3:7a284390b0ce 357
mbed_official 3:7a284390b0ce 358 // Twiddle factors are ones
mbed_official 3:7a284390b0ce 359 *p2++ = t2[0];
mbed_official 3:7a284390b0ce 360 *p2++ = t2[1];
mbed_official 3:7a284390b0ce 361 *p3++ = t3[0];
mbed_official 3:7a284390b0ce 362 *p3++ = t3[1];
mbed_official 3:7a284390b0ce 363 *p4++ = t4[0];
mbed_official 3:7a284390b0ce 364 *p4++ = t4[1];
mbed_official 3:7a284390b0ce 365
mbed_official 3:7a284390b0ce 366 tw2 += twMod2;
mbed_official 3:7a284390b0ce 367 tw3 += twMod3;
mbed_official 3:7a284390b0ce 368 tw4 += twMod4;
mbed_official 3:7a284390b0ce 369
mbed_official 3:7a284390b0ce 370 for (l = (L - 2) >> 1; l > 0; l-- )
mbed_official 3:7a284390b0ce 371 {
mbed_official 3:7a284390b0ce 372
mbed_official 3:7a284390b0ce 373 // TOP
mbed_official 3:7a284390b0ce 374 p1ap3_0 = p1[0] + p3[0];
mbed_official 3:7a284390b0ce 375 p1sp3_0 = p1[0] - p3[0];
mbed_official 3:7a284390b0ce 376 p1ap3_1 = p1[1] + p3[1];
mbed_official 3:7a284390b0ce 377 p1sp3_1 = p1[1] - p3[1];
mbed_official 3:7a284390b0ce 378 // col 2
mbed_official 3:7a284390b0ce 379 t2[0] = p1sp3_0 + p2[1] - p4[1];
mbed_official 3:7a284390b0ce 380 t2[1] = p1sp3_1 - p2[0] + p4[0];
mbed_official 3:7a284390b0ce 381 // col 3
mbed_official 3:7a284390b0ce 382 t3[0] = p1ap3_0 - p2[0] - p4[0];
mbed_official 3:7a284390b0ce 383 t3[1] = p1ap3_1 - p2[1] - p4[1];
mbed_official 3:7a284390b0ce 384 // col 4
mbed_official 3:7a284390b0ce 385 t4[0] = p1sp3_0 - p2[1] + p4[1];
mbed_official 3:7a284390b0ce 386 t4[1] = p1sp3_1 + p2[0] - p4[0];
mbed_official 3:7a284390b0ce 387 // col 1 - top
mbed_official 3:7a284390b0ce 388 *p1++ = p1ap3_0 + p2[0] + p4[0];
mbed_official 3:7a284390b0ce 389 *p1++ = p1ap3_1 + p2[1] + p4[1];
mbed_official 3:7a284390b0ce 390
mbed_official 3:7a284390b0ce 391 // BOTTOM
mbed_official 3:7a284390b0ce 392 p1ap3_1 = pEnd1[-1] + pEnd3[-1];
mbed_official 3:7a284390b0ce 393 p1sp3_1 = pEnd1[-1] - pEnd3[-1];
mbed_official 3:7a284390b0ce 394 p1ap3_0 = pEnd1[0] + pEnd3[0];
mbed_official 3:7a284390b0ce 395 p1sp3_0 = pEnd1[0] - pEnd3[0];
mbed_official 3:7a284390b0ce 396 // col 2
mbed_official 3:7a284390b0ce 397 t2[2] = pEnd2[0] - pEnd4[0] + p1sp3_1;
mbed_official 3:7a284390b0ce 398 t2[3] = pEnd1[0] - pEnd3[0] - pEnd2[-1] + pEnd4[-1];
mbed_official 3:7a284390b0ce 399 // col 3
mbed_official 3:7a284390b0ce 400 t3[2] = p1ap3_1 - pEnd2[-1] - pEnd4[-1];
mbed_official 3:7a284390b0ce 401 t3[3] = p1ap3_0 - pEnd2[0] - pEnd4[0];
mbed_official 3:7a284390b0ce 402 // col 4
mbed_official 3:7a284390b0ce 403 t4[2] = pEnd2[0] - pEnd4[0] - p1sp3_1;
mbed_official 3:7a284390b0ce 404 t4[3] = pEnd4[-1] - pEnd2[-1] - p1sp3_0;
mbed_official 3:7a284390b0ce 405 // col 1 - Bottom
mbed_official 3:7a284390b0ce 406 *pEnd1-- = p1ap3_0 + pEnd2[0] + pEnd4[0];
mbed_official 3:7a284390b0ce 407 *pEnd1-- = p1ap3_1 + pEnd2[-1] + pEnd4[-1];
mbed_official 3:7a284390b0ce 408
mbed_official 3:7a284390b0ce 409 // COL 2
mbed_official 3:7a284390b0ce 410 // read twiddle factors
mbed_official 3:7a284390b0ce 411 twR = *tw2++;
mbed_official 3:7a284390b0ce 412 twI = *tw2++;
mbed_official 3:7a284390b0ce 413 // multiply by twiddle factors
mbed_official 3:7a284390b0ce 414 // let Z1 = a + i(b), Z2 = c + i(d)
mbed_official 3:7a284390b0ce 415 // => Z1 * Z2 = (a*c - b*d) + i(b*c + a*d)
mbed_official 3:7a284390b0ce 416 // Top
mbed_official 3:7a284390b0ce 417 m0 = t2[0] * twR;
mbed_official 3:7a284390b0ce 418 m1 = t2[1] * twI;
mbed_official 3:7a284390b0ce 419 m2 = t2[1] * twR;
mbed_official 3:7a284390b0ce 420 m3 = t2[0] * twI;
mbed_official 3:7a284390b0ce 421
mbed_official 3:7a284390b0ce 422 *p2++ = m0 + m1;
mbed_official 3:7a284390b0ce 423 *p2++ = m2 - m3;
mbed_official 3:7a284390b0ce 424 // use vertical symmetry col 2
mbed_official 3:7a284390b0ce 425 // 0.9997 - 0.0245i <==> 0.0245 - 0.9997i
mbed_official 3:7a284390b0ce 426 // Bottom
mbed_official 3:7a284390b0ce 427 m0 = t2[3] * twI;
mbed_official 3:7a284390b0ce 428 m1 = t2[2] * twR;
mbed_official 3:7a284390b0ce 429 m2 = t2[2] * twI;
mbed_official 3:7a284390b0ce 430 m3 = t2[3] * twR;
mbed_official 3:7a284390b0ce 431
mbed_official 3:7a284390b0ce 432 *pEnd2-- = m0 - m1;
mbed_official 3:7a284390b0ce 433 *pEnd2-- = m2 + m3;
mbed_official 3:7a284390b0ce 434
mbed_official 3:7a284390b0ce 435 // COL 3
mbed_official 3:7a284390b0ce 436 twR = tw3[0];
mbed_official 3:7a284390b0ce 437 twI = tw3[1];
mbed_official 3:7a284390b0ce 438 tw3 += twMod3;
mbed_official 3:7a284390b0ce 439 // Top
mbed_official 3:7a284390b0ce 440 m0 = t3[0] * twR;
mbed_official 3:7a284390b0ce 441 m1 = t3[1] * twI;
mbed_official 3:7a284390b0ce 442 m2 = t3[1] * twR;
mbed_official 3:7a284390b0ce 443 m3 = t3[0] * twI;
mbed_official 3:7a284390b0ce 444
mbed_official 3:7a284390b0ce 445 *p3++ = m0 + m1;
mbed_official 3:7a284390b0ce 446 *p3++ = m2 - m3;
mbed_official 3:7a284390b0ce 447 // use vertical symmetry col 3
mbed_official 3:7a284390b0ce 448 // 0.9988 - 0.0491i <==> -0.9988 - 0.0491i
mbed_official 3:7a284390b0ce 449 // Bottom
mbed_official 3:7a284390b0ce 450 m0 = -t3[3] * twR;
mbed_official 3:7a284390b0ce 451 m1 = t3[2] * twI;
mbed_official 3:7a284390b0ce 452 m2 = t3[2] * twR;
mbed_official 3:7a284390b0ce 453 m3 = t3[3] * twI;
mbed_official 3:7a284390b0ce 454
mbed_official 3:7a284390b0ce 455 *pEnd3-- = m0 - m1;
mbed_official 3:7a284390b0ce 456 *pEnd3-- = m3 - m2;
mbed_official 3:7a284390b0ce 457
mbed_official 3:7a284390b0ce 458 // COL 4
mbed_official 3:7a284390b0ce 459 twR = tw4[0];
mbed_official 3:7a284390b0ce 460 twI = tw4[1];
mbed_official 3:7a284390b0ce 461 tw4 += twMod4;
mbed_official 3:7a284390b0ce 462 // Top
mbed_official 3:7a284390b0ce 463 m0 = t4[0] * twR;
mbed_official 3:7a284390b0ce 464 m1 = t4[1] * twI;
mbed_official 3:7a284390b0ce 465 m2 = t4[1] * twR;
mbed_official 3:7a284390b0ce 466 m3 = t4[0] * twI;
mbed_official 3:7a284390b0ce 467
mbed_official 3:7a284390b0ce 468 *p4++ = m0 + m1;
mbed_official 3:7a284390b0ce 469 *p4++ = m2 - m3;
mbed_official 3:7a284390b0ce 470 // use vertical symmetry col 4
mbed_official 3:7a284390b0ce 471 // 0.9973 - 0.0736i <==> -0.0736 + 0.9973i
mbed_official 3:7a284390b0ce 472 // Bottom
mbed_official 3:7a284390b0ce 473 m0 = t4[3] * twI;
mbed_official 3:7a284390b0ce 474 m1 = t4[2] * twR;
mbed_official 3:7a284390b0ce 475 m2 = t4[2] * twI;
mbed_official 3:7a284390b0ce 476 m3 = t4[3] * twR;
mbed_official 3:7a284390b0ce 477
mbed_official 3:7a284390b0ce 478 *pEnd4-- = m0 - m1;
mbed_official 3:7a284390b0ce 479 *pEnd4-- = m2 + m3;
mbed_official 3:7a284390b0ce 480 }
mbed_official 3:7a284390b0ce 481
mbed_official 3:7a284390b0ce 482 //MIDDLE
mbed_official 3:7a284390b0ce 483 // Twiddle factors are
mbed_official 3:7a284390b0ce 484 // 1.0000 0.7071-0.7071i -1.0000i -0.7071-0.7071i
mbed_official 3:7a284390b0ce 485 p1ap3_0 = p1[0] + p3[0];
mbed_official 3:7a284390b0ce 486 p1sp3_0 = p1[0] - p3[0];
mbed_official 3:7a284390b0ce 487 p1ap3_1 = p1[1] + p3[1];
mbed_official 3:7a284390b0ce 488 p1sp3_1 = p1[1] - p3[1];
mbed_official 3:7a284390b0ce 489
mbed_official 3:7a284390b0ce 490 // col 2
mbed_official 3:7a284390b0ce 491 t2[0] = p1sp3_0 + p2[1] - p4[1];
mbed_official 3:7a284390b0ce 492 t2[1] = p1sp3_1 - p2[0] + p4[0];
mbed_official 3:7a284390b0ce 493 // col 3
mbed_official 3:7a284390b0ce 494 t3[0] = p1ap3_0 - p2[0] - p4[0];
mbed_official 3:7a284390b0ce 495 t3[1] = p1ap3_1 - p2[1] - p4[1];
mbed_official 3:7a284390b0ce 496 // col 4
mbed_official 3:7a284390b0ce 497 t4[0] = p1sp3_0 - p2[1] + p4[1];
mbed_official 3:7a284390b0ce 498 t4[1] = p1sp3_1 + p2[0] - p4[0];
mbed_official 3:7a284390b0ce 499 // col 1 - Top
mbed_official 3:7a284390b0ce 500 *p1++ = p1ap3_0 + p2[0] + p4[0];
mbed_official 3:7a284390b0ce 501 *p1++ = p1ap3_1 + p2[1] + p4[1];
mbed_official 3:7a284390b0ce 502
mbed_official 3:7a284390b0ce 503 // COL 2
mbed_official 3:7a284390b0ce 504 twR = tw2[0];
mbed_official 3:7a284390b0ce 505 twI = tw2[1];
mbed_official 3:7a284390b0ce 506
mbed_official 3:7a284390b0ce 507 m0 = t2[0] * twR;
mbed_official 3:7a284390b0ce 508 m1 = t2[1] * twI;
mbed_official 3:7a284390b0ce 509 m2 = t2[1] * twR;
mbed_official 3:7a284390b0ce 510 m3 = t2[0] * twI;
mbed_official 3:7a284390b0ce 511
mbed_official 3:7a284390b0ce 512 *p2++ = m0 + m1;
mbed_official 3:7a284390b0ce 513 *p2++ = m2 - m3;
mbed_official 3:7a284390b0ce 514 // COL 3
mbed_official 3:7a284390b0ce 515 twR = tw3[0];
mbed_official 3:7a284390b0ce 516 twI = tw3[1];
mbed_official 3:7a284390b0ce 517
mbed_official 3:7a284390b0ce 518 m0 = t3[0] * twR;
mbed_official 3:7a284390b0ce 519 m1 = t3[1] * twI;
mbed_official 3:7a284390b0ce 520 m2 = t3[1] * twR;
mbed_official 3:7a284390b0ce 521 m3 = t3[0] * twI;
mbed_official 3:7a284390b0ce 522
mbed_official 3:7a284390b0ce 523 *p3++ = m0 + m1;
mbed_official 3:7a284390b0ce 524 *p3++ = m2 - m3;
mbed_official 3:7a284390b0ce 525 // COL 4
mbed_official 3:7a284390b0ce 526 twR = tw4[0];
mbed_official 3:7a284390b0ce 527 twI = tw4[1];
mbed_official 3:7a284390b0ce 528
mbed_official 3:7a284390b0ce 529 m0 = t4[0] * twR;
mbed_official 3:7a284390b0ce 530 m1 = t4[1] * twI;
mbed_official 3:7a284390b0ce 531 m2 = t4[1] * twR;
mbed_official 3:7a284390b0ce 532 m3 = t4[0] * twI;
mbed_official 3:7a284390b0ce 533
mbed_official 3:7a284390b0ce 534 *p4++ = m0 + m1;
mbed_official 3:7a284390b0ce 535 *p4++ = m2 - m3;
mbed_official 3:7a284390b0ce 536
mbed_official 3:7a284390b0ce 537 // first col
mbed_official 3:7a284390b0ce 538 arm_radix8_butterfly_f32( pCol1, L, (float32_t *) S->pTwiddle, 4u);
mbed_official 3:7a284390b0ce 539 // second col
mbed_official 3:7a284390b0ce 540 arm_radix8_butterfly_f32( pCol2, L, (float32_t *) S->pTwiddle, 4u);
mbed_official 3:7a284390b0ce 541 // third col
mbed_official 3:7a284390b0ce 542 arm_radix8_butterfly_f32( pCol3, L, (float32_t *) S->pTwiddle, 4u);
mbed_official 3:7a284390b0ce 543 // fourth col
mbed_official 3:7a284390b0ce 544 arm_radix8_butterfly_f32( pCol4, L, (float32_t *) S->pTwiddle, 4u);
mbed_official 3:7a284390b0ce 545
mbed_official 3:7a284390b0ce 546 }
mbed_official 3:7a284390b0ce 547
mbed_official 3:7a284390b0ce 548 /**
mbed_official 3:7a284390b0ce 549 * @addtogroup ComplexFFT
mbed_official 3:7a284390b0ce 550 * @{
mbed_official 3:7a284390b0ce 551 */
mbed_official 3:7a284390b0ce 552
mbed_official 3:7a284390b0ce 553 /**
mbed_official 3:7a284390b0ce 554 * @details
mbed_official 3:7a284390b0ce 555 * @brief Processing function for the floating-point complex FFT.
mbed_official 3:7a284390b0ce 556 * @param[in] *S points to an instance of the floating-point CFFT structure.
mbed_official 3:7a284390b0ce 557 * @param[in, out] *p1 points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.
mbed_official 3:7a284390b0ce 558 * @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
mbed_official 3:7a284390b0ce 559 * @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
mbed_official 3:7a284390b0ce 560 * @return none.
mbed_official 3:7a284390b0ce 561 */
mbed_official 3:7a284390b0ce 562
mbed_official 3:7a284390b0ce 563 void arm_cfft_f32(
mbed_official 3:7a284390b0ce 564 const arm_cfft_instance_f32 * S,
mbed_official 3:7a284390b0ce 565 float32_t * p1,
mbed_official 3:7a284390b0ce 566 uint8_t ifftFlag,
mbed_official 3:7a284390b0ce 567 uint8_t bitReverseFlag)
mbed_official 3:7a284390b0ce 568 {
mbed_official 3:7a284390b0ce 569
mbed_official 3:7a284390b0ce 570 uint32_t L = S->fftLen, l;
mbed_official 3:7a284390b0ce 571 float32_t invL, * pSrc;
mbed_official 3:7a284390b0ce 572
mbed_official 3:7a284390b0ce 573 if(ifftFlag == 1u)
mbed_official 3:7a284390b0ce 574 {
mbed_official 3:7a284390b0ce 575 /* Conjugate input data */
mbed_official 3:7a284390b0ce 576 pSrc = p1 + 1;
mbed_official 3:7a284390b0ce 577 for(l=0; l<L; l++) {
mbed_official 3:7a284390b0ce 578 *pSrc = -*pSrc;
mbed_official 3:7a284390b0ce 579 pSrc += 2;
mbed_official 3:7a284390b0ce 580 }
mbed_official 3:7a284390b0ce 581 }
mbed_official 3:7a284390b0ce 582
mbed_official 3:7a284390b0ce 583 switch (L) {
mbed_official 3:7a284390b0ce 584 case 16:
mbed_official 3:7a284390b0ce 585 case 128:
mbed_official 3:7a284390b0ce 586 case 1024:
mbed_official 3:7a284390b0ce 587 arm_cfft_radix8by2_f32 ( (arm_cfft_instance_f32 *) S, p1);
mbed_official 3:7a284390b0ce 588 break;
mbed_official 3:7a284390b0ce 589 case 32:
mbed_official 3:7a284390b0ce 590 case 256:
mbed_official 3:7a284390b0ce 591 case 2048:
mbed_official 3:7a284390b0ce 592 arm_cfft_radix8by4_f32 ( (arm_cfft_instance_f32 *) S, p1);
mbed_official 3:7a284390b0ce 593 break;
mbed_official 3:7a284390b0ce 594 case 64:
mbed_official 3:7a284390b0ce 595 case 512:
mbed_official 3:7a284390b0ce 596 case 4096:
mbed_official 3:7a284390b0ce 597 arm_radix8_butterfly_f32( p1, L, (float32_t *) S->pTwiddle, 1);
mbed_official 3:7a284390b0ce 598 break;
mbed_official 3:7a284390b0ce 599 }
mbed_official 3:7a284390b0ce 600
mbed_official 3:7a284390b0ce 601 if( bitReverseFlag )
mbed_official 3:7a284390b0ce 602 arm_bitreversal_32((uint32_t*)p1,S->bitRevLength,S->pBitRevTable);
mbed_official 3:7a284390b0ce 603
mbed_official 3:7a284390b0ce 604 if(ifftFlag == 1u)
mbed_official 3:7a284390b0ce 605 {
mbed_official 3:7a284390b0ce 606 invL = 1.0f/(float32_t)L;
mbed_official 3:7a284390b0ce 607 /* Conjugate and scale output data */
mbed_official 3:7a284390b0ce 608 pSrc = p1;
mbed_official 3:7a284390b0ce 609 for(l=0; l<L; l++) {
mbed_official 3:7a284390b0ce 610 *pSrc++ *= invL ;
mbed_official 3:7a284390b0ce 611 *pSrc = -(*pSrc) * invL;
mbed_official 3:7a284390b0ce 612 pSrc++;
mbed_official 3:7a284390b0ce 613 }
mbed_official 3:7a284390b0ce 614 }
mbed_official 3:7a284390b0ce 615 }
mbed_official 3:7a284390b0ce 616