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CMSIS DSP library

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cmsis_dsp/TransformFunctions/arm_cfft_radix8_f32.c@5:3762170b6d4d, 2015-11-20 (annotated)

Committer:
mbed_official
Date:
Fri Nov 20 08:45:18 2015 +0000
Revision:
5:3762170b6d4d
Parent:
3:7a284390b0ce 
Synchronized with git revision 2eb940b9a73af188d3004a2575fdfbb05febe62b



Full URL: https://github.com/mbedmicro/mbed/commit/2eb940b9a73af188d3004a2575fdfbb05febe62b/



Added option to build rpc library. closes #1426

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 3:7a284390b0ce 1 /* ----------------------------------------------------------------------
mbed_official 5:3762170b6d4d 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
mbed_official 3:7a284390b0ce 3 *
mbed_official 5:3762170b6d4d 4 * $Date: 19. March 2015
mbed_official 5:3762170b6d4d 5 * $Revision: V.1.4.5
mbed_official 3:7a284390b0ce 6 *
mbed_official 3:7a284390b0ce 7 * Project: CMSIS DSP Library
mbed_official 3:7a284390b0ce 8 * Title: arm_cfft_radix8_f32.c
mbed_official 3:7a284390b0ce 9 *
mbed_official 3:7a284390b0ce 10 * Description: Radix-8 Decimation in Frequency CFFT & CIFFT 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 #include "arm_math.h"
mbed_official 3:7a284390b0ce 42
mbed_official 3:7a284390b0ce 43 /**
mbed_official 3:7a284390b0ce 44 * @ingroup groupTransforms
mbed_official 3:7a284390b0ce 45 */
mbed_official 3:7a284390b0ce 46
mbed_official 3:7a284390b0ce 47 /**
mbed_official 3:7a284390b0ce 48 * @defgroup Radix8_CFFT_CIFFT Radix-8 Complex FFT Functions
mbed_official 3:7a284390b0ce 49 *
mbed_official 3:7a284390b0ce 50 * \par
mbed_official 3:7a284390b0ce 51 * Complex Fast Fourier Transform(CFFT) and Complex Inverse Fast Fourier Transform(CIFFT) is an efficient algorithm to compute Discrete Fourier Transform(DFT) and Inverse Discrete Fourier Transform(IDFT).
mbed_official 3:7a284390b0ce 52 * Computational complexity of CFFT reduces drastically when compared to DFT.
mbed_official 3:7a284390b0ce 53 * \par
mbed_official 3:7a284390b0ce 54 * This set of functions implements CFFT/CIFFT
mbed_official 3:7a284390b0ce 55 * for floating-point data types. The functions operates on in-place buffer which uses same buffer for input and output.
mbed_official 3:7a284390b0ce 56 * Complex input is stored in input buffer in an interleaved fashion.
mbed_official 3:7a284390b0ce 57 *
mbed_official 3:7a284390b0ce 58 * \par
mbed_official 3:7a284390b0ce 59 * The functions operate on blocks of input and output data and each call to the function processes
mbed_official 3:7a284390b0ce 60 * <code>2*fftLen</code> samples through the transform. <code>pSrc</code> points to In-place arrays containing <code>2*fftLen</code> values.
mbed_official 3:7a284390b0ce 61 * \par
mbed_official 3:7a284390b0ce 62 * The <code>pSrc</code> points to the array of in-place buffer of size <code>2*fftLen</code> and inputs and outputs are stored in an interleaved fashion as shown below.
mbed_official 3:7a284390b0ce 63 * <pre> {real[0], imag[0], real[1], imag[1],..} </pre>
mbed_official 3:7a284390b0ce 64 *
mbed_official 3:7a284390b0ce 65 * \par Lengths supported by the transform:
mbed_official 3:7a284390b0ce 66 * \par
mbed_official 3:7a284390b0ce 67 * Internally, the function utilize a Radix-8 decimation in frequency(DIF) algorithm
mbed_official 3:7a284390b0ce 68 * and the size of the FFT supported are of the lengths [ 64, 512, 4096].
mbed_official 3:7a284390b0ce 69 *
mbed_official 3:7a284390b0ce 70 *
mbed_official 3:7a284390b0ce 71 * \par Algorithm:
mbed_official 3:7a284390b0ce 72 *
mbed_official 3:7a284390b0ce 73 * <b>Complex Fast Fourier Transform:</b>
mbed_official 3:7a284390b0ce 74 * \par
mbed_official 3:7a284390b0ce 75 * Input real and imaginary data:
mbed_official 3:7a284390b0ce 76 * <pre>
mbed_official 3:7a284390b0ce 77 * x(n) = xa + j * ya
mbed_official 3:7a284390b0ce 78 * x(n+N/4 ) = xb + j * yb
mbed_official 3:7a284390b0ce 79 * x(n+N/2 ) = xc + j * yc
mbed_official 3:7a284390b0ce 80 * x(n+3N 4) = xd + j * yd
mbed_official 3:7a284390b0ce 81 * </pre>
mbed_official 3:7a284390b0ce 82 * where N is length of FFT
mbed_official 3:7a284390b0ce 83 * \par
mbed_official 3:7a284390b0ce 84 * Output real and imaginary data:
mbed_official 3:7a284390b0ce 85 * <pre>
mbed_official 3:7a284390b0ce 86 * X(4r) = xa'+ j * ya'
mbed_official 3:7a284390b0ce 87 * X(4r+1) = xb'+ j * yb'
mbed_official 3:7a284390b0ce 88 * X(4r+2) = xc'+ j * yc'
mbed_official 3:7a284390b0ce 89 * X(4r+3) = xd'+ j * yd'
mbed_official 3:7a284390b0ce 90 * </pre>
mbed_official 3:7a284390b0ce 91 * \par
mbed_official 3:7a284390b0ce 92 * Twiddle factors for Radix-8 FFT:
mbed_official 3:7a284390b0ce 93 * <pre>
mbed_official 3:7a284390b0ce 94 * Wn = co1 + j * (- si1)
mbed_official 3:7a284390b0ce 95 * W2n = co2 + j * (- si2)
mbed_official 3:7a284390b0ce 96 * W3n = co3 + j * (- si3)
mbed_official 3:7a284390b0ce 97 * </pre>
mbed_official 3:7a284390b0ce 98 *
mbed_official 3:7a284390b0ce 99 * \par
mbed_official 3:7a284390b0ce 100 * \image html CFFT.gif "Radix-8 Decimation-in Frequency Complex Fast Fourier Transform"
mbed_official 3:7a284390b0ce 101 *
mbed_official 3:7a284390b0ce 102 * \par
mbed_official 3:7a284390b0ce 103 * Output from Radix-8 CFFT Results in Digit reversal order. Interchange middle two branches of every butterfly results in Bit reversed output.
mbed_official 3:7a284390b0ce 104 * \par
mbed_official 3:7a284390b0ce 105 * <b> Butterfly CFFT equations:</b>
mbed_official 3:7a284390b0ce 106 * <pre>
mbed_official 3:7a284390b0ce 107 * xa' = xa + xb + xc + xd
mbed_official 3:7a284390b0ce 108 * ya' = ya + yb + yc + yd
mbed_official 3:7a284390b0ce 109 * xc' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1)
mbed_official 3:7a284390b0ce 110 * yc' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1)
mbed_official 3:7a284390b0ce 111 * xb' = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2)
mbed_official 3:7a284390b0ce 112 * yb' = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2)
mbed_official 3:7a284390b0ce 113 * xd' = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3)
mbed_official 3:7a284390b0ce 114 * yd' = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3)
mbed_official 3:7a284390b0ce 115 * </pre>
mbed_official 3:7a284390b0ce 116 *
mbed_official 3:7a284390b0ce 117 * \par
mbed_official 3:7a284390b0ce 118 * where <code>fftLen</code> length of CFFT/CIFFT; <code>ifftFlag</code> Flag for selection of CFFT or CIFFT(Set ifftFlag to calculate CIFFT otherwise calculates CFFT);
mbed_official 3:7a284390b0ce 119 * <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 120 * <code>pTwiddle</code>points to array of twiddle coefficients; <code>pBitRevTable</code> points to the array of bit reversal table.
mbed_official 3:7a284390b0ce 121 * <code>twidCoefModifier</code> modifier for twiddle factor table which supports all FFT lengths with same table;
mbed_official 3:7a284390b0ce 122 * <code>pBitRevTable</code> modifier for bit reversal table which supports all FFT lengths with same table.
mbed_official 3:7a284390b0ce 123 * <code>onebyfftLen</code> value of 1/fftLen to calculate CIFFT;
mbed_official 3:7a284390b0ce 124 *
mbed_official 3:7a284390b0ce 125 * \par Fixed-Point Behavior
mbed_official 3:7a284390b0ce 126 * Care must be taken when using the fixed-point versions of the CFFT/CIFFT function.
mbed_official 3:7a284390b0ce 127 * Refer to the function specific documentation below for usage guidelines.
mbed_official 3:7a284390b0ce 128 */
mbed_official 3:7a284390b0ce 129
mbed_official 3:7a284390b0ce 130
mbed_official 3:7a284390b0ce 131 /*
mbed_official 3:7a284390b0ce 132 * @brief Core function for the floating-point CFFT butterfly process.
mbed_official 3:7a284390b0ce 133 * @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
mbed_official 3:7a284390b0ce 134 * @param[in] fftLen length of the FFT.
mbed_official 3:7a284390b0ce 135 * @param[in] *pCoef points to the twiddle coefficient buffer.
mbed_official 3:7a284390b0ce 136 * @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
mbed_official 3:7a284390b0ce 137 * @return none.
mbed_official 3:7a284390b0ce 138 */
mbed_official 3:7a284390b0ce 139
mbed_official 3:7a284390b0ce 140 void arm_radix8_butterfly_f32(
mbed_official 3:7a284390b0ce 141 float32_t * pSrc,
mbed_official 3:7a284390b0ce 142 uint16_t fftLen,
mbed_official 3:7a284390b0ce 143 const float32_t * pCoef,
mbed_official 3:7a284390b0ce 144 uint16_t twidCoefModifier)
mbed_official 3:7a284390b0ce 145 {
mbed_official 3:7a284390b0ce 146 uint32_t ia1, ia2, ia3, ia4, ia5, ia6, ia7;
mbed_official 3:7a284390b0ce 147 uint32_t i1, i2, i3, i4, i5, i6, i7, i8;
mbed_official 3:7a284390b0ce 148 uint32_t id;
mbed_official 3:7a284390b0ce 149 uint32_t n1, n2, j;
mbed_official 3:7a284390b0ce 150
mbed_official 3:7a284390b0ce 151 float32_t r1, r2, r3, r4, r5, r6, r7, r8;
mbed_official 3:7a284390b0ce 152 float32_t t1, t2;
mbed_official 3:7a284390b0ce 153 float32_t s1, s2, s3, s4, s5, s6, s7, s8;
mbed_official 3:7a284390b0ce 154 float32_t p1, p2, p3, p4;
mbed_official 3:7a284390b0ce 155 float32_t co2, co3, co4, co5, co6, co7, co8;
mbed_official 3:7a284390b0ce 156 float32_t si2, si3, si4, si5, si6, si7, si8;
mbed_official 3:7a284390b0ce 157 const float32_t C81 = 0.70710678118f;
mbed_official 3:7a284390b0ce 158
mbed_official 3:7a284390b0ce 159 n2 = fftLen;
mbed_official 3:7a284390b0ce 160
mbed_official 3:7a284390b0ce 161 do
mbed_official 3:7a284390b0ce 162 {
mbed_official 3:7a284390b0ce 163 n1 = n2;
mbed_official 3:7a284390b0ce 164 n2 = n2 >> 3;
mbed_official 3:7a284390b0ce 165 i1 = 0;
mbed_official 3:7a284390b0ce 166
mbed_official 3:7a284390b0ce 167 do
mbed_official 3:7a284390b0ce 168 {
mbed_official 3:7a284390b0ce 169 i2 = i1 + n2;
mbed_official 3:7a284390b0ce 170 i3 = i2 + n2;
mbed_official 3:7a284390b0ce 171 i4 = i3 + n2;
mbed_official 3:7a284390b0ce 172 i5 = i4 + n2;
mbed_official 3:7a284390b0ce 173 i6 = i5 + n2;
mbed_official 3:7a284390b0ce 174 i7 = i6 + n2;
mbed_official 3:7a284390b0ce 175 i8 = i7 + n2;
mbed_official 3:7a284390b0ce 176 r1 = pSrc[2 * i1] + pSrc[2 * i5];
mbed_official 3:7a284390b0ce 177 r5 = pSrc[2 * i1] - pSrc[2 * i5];
mbed_official 3:7a284390b0ce 178 r2 = pSrc[2 * i2] + pSrc[2 * i6];
mbed_official 3:7a284390b0ce 179 r6 = pSrc[2 * i2] - pSrc[2 * i6];
mbed_official 3:7a284390b0ce 180 r3 = pSrc[2 * i3] + pSrc[2 * i7];
mbed_official 3:7a284390b0ce 181 r7 = pSrc[2 * i3] - pSrc[2 * i7];
mbed_official 3:7a284390b0ce 182 r4 = pSrc[2 * i4] + pSrc[2 * i8];
mbed_official 3:7a284390b0ce 183 r8 = pSrc[2 * i4] - pSrc[2 * i8];
mbed_official 3:7a284390b0ce 184 t1 = r1 - r3;
mbed_official 3:7a284390b0ce 185 r1 = r1 + r3;
mbed_official 3:7a284390b0ce 186 r3 = r2 - r4;
mbed_official 3:7a284390b0ce 187 r2 = r2 + r4;
mbed_official 3:7a284390b0ce 188 pSrc[2 * i1] = r1 + r2;
mbed_official 3:7a284390b0ce 189 pSrc[2 * i5] = r1 - r2;
mbed_official 3:7a284390b0ce 190 r1 = pSrc[2 * i1 + 1] + pSrc[2 * i5 + 1];
mbed_official 3:7a284390b0ce 191 s5 = pSrc[2 * i1 + 1] - pSrc[2 * i5 + 1];
mbed_official 3:7a284390b0ce 192 r2 = pSrc[2 * i2 + 1] + pSrc[2 * i6 + 1];
mbed_official 3:7a284390b0ce 193 s6 = pSrc[2 * i2 + 1] - pSrc[2 * i6 + 1];
mbed_official 3:7a284390b0ce 194 s3 = pSrc[2 * i3 + 1] + pSrc[2 * i7 + 1];
mbed_official 3:7a284390b0ce 195 s7 = pSrc[2 * i3 + 1] - pSrc[2 * i7 + 1];
mbed_official 3:7a284390b0ce 196 r4 = pSrc[2 * i4 + 1] + pSrc[2 * i8 + 1];
mbed_official 3:7a284390b0ce 197 s8 = pSrc[2 * i4 + 1] - pSrc[2 * i8 + 1];
mbed_official 3:7a284390b0ce 198 t2 = r1 - s3;
mbed_official 3:7a284390b0ce 199 r1 = r1 + s3;
mbed_official 3:7a284390b0ce 200 s3 = r2 - r4;
mbed_official 3:7a284390b0ce 201 r2 = r2 + r4;
mbed_official 3:7a284390b0ce 202 pSrc[2 * i1 + 1] = r1 + r2;
mbed_official 3:7a284390b0ce 203 pSrc[2 * i5 + 1] = r1 - r2;
mbed_official 3:7a284390b0ce 204 pSrc[2 * i3] = t1 + s3;
mbed_official 3:7a284390b0ce 205 pSrc[2 * i7] = t1 - s3;
mbed_official 3:7a284390b0ce 206 pSrc[2 * i3 + 1] = t2 - r3;
mbed_official 3:7a284390b0ce 207 pSrc[2 * i7 + 1] = t2 + r3;
mbed_official 3:7a284390b0ce 208 r1 = (r6 - r8) * C81;
mbed_official 3:7a284390b0ce 209 r6 = (r6 + r8) * C81;
mbed_official 3:7a284390b0ce 210 r2 = (s6 - s8) * C81;
mbed_official 3:7a284390b0ce 211 s6 = (s6 + s8) * C81;
mbed_official 3:7a284390b0ce 212 t1 = r5 - r1;
mbed_official 3:7a284390b0ce 213 r5 = r5 + r1;
mbed_official 3:7a284390b0ce 214 r8 = r7 - r6;
mbed_official 3:7a284390b0ce 215 r7 = r7 + r6;
mbed_official 3:7a284390b0ce 216 t2 = s5 - r2;
mbed_official 3:7a284390b0ce 217 s5 = s5 + r2;
mbed_official 3:7a284390b0ce 218 s8 = s7 - s6;
mbed_official 3:7a284390b0ce 219 s7 = s7 + s6;
mbed_official 3:7a284390b0ce 220 pSrc[2 * i2] = r5 + s7;
mbed_official 3:7a284390b0ce 221 pSrc[2 * i8] = r5 - s7;
mbed_official 3:7a284390b0ce 222 pSrc[2 * i6] = t1 + s8;
mbed_official 3:7a284390b0ce 223 pSrc[2 * i4] = t1 - s8;
mbed_official 3:7a284390b0ce 224 pSrc[2 * i2 + 1] = s5 - r7;
mbed_official 3:7a284390b0ce 225 pSrc[2 * i8 + 1] = s5 + r7;
mbed_official 3:7a284390b0ce 226 pSrc[2 * i6 + 1] = t2 - r8;
mbed_official 3:7a284390b0ce 227 pSrc[2 * i4 + 1] = t2 + r8;
mbed_official 3:7a284390b0ce 228
mbed_official 3:7a284390b0ce 229 i1 += n1;
mbed_official 3:7a284390b0ce 230 } while(i1 < fftLen);
mbed_official 3:7a284390b0ce 231
mbed_official 3:7a284390b0ce 232 if(n2 < 8)
mbed_official 3:7a284390b0ce 233 break;
mbed_official 3:7a284390b0ce 234
mbed_official 3:7a284390b0ce 235 ia1 = 0;
mbed_official 3:7a284390b0ce 236 j = 1;
mbed_official 3:7a284390b0ce 237
mbed_official 3:7a284390b0ce 238 do
mbed_official 3:7a284390b0ce 239 {
mbed_official 3:7a284390b0ce 240 /* index calculation for the coefficients */
mbed_official 3:7a284390b0ce 241 id = ia1 + twidCoefModifier;
mbed_official 3:7a284390b0ce 242 ia1 = id;
mbed_official 3:7a284390b0ce 243 ia2 = ia1 + id;
mbed_official 3:7a284390b0ce 244 ia3 = ia2 + id;
mbed_official 3:7a284390b0ce 245 ia4 = ia3 + id;
mbed_official 3:7a284390b0ce 246 ia5 = ia4 + id;
mbed_official 3:7a284390b0ce 247 ia6 = ia5 + id;
mbed_official 3:7a284390b0ce 248 ia7 = ia6 + id;
mbed_official 3:7a284390b0ce 249
mbed_official 3:7a284390b0ce 250 co2 = pCoef[2 * ia1];
mbed_official 3:7a284390b0ce 251 co3 = pCoef[2 * ia2];
mbed_official 3:7a284390b0ce 252 co4 = pCoef[2 * ia3];
mbed_official 3:7a284390b0ce 253 co5 = pCoef[2 * ia4];
mbed_official 3:7a284390b0ce 254 co6 = pCoef[2 * ia5];
mbed_official 3:7a284390b0ce 255 co7 = pCoef[2 * ia6];
mbed_official 3:7a284390b0ce 256 co8 = pCoef[2 * ia7];
mbed_official 3:7a284390b0ce 257 si2 = pCoef[2 * ia1 + 1];
mbed_official 3:7a284390b0ce 258 si3 = pCoef[2 * ia2 + 1];
mbed_official 3:7a284390b0ce 259 si4 = pCoef[2 * ia3 + 1];
mbed_official 3:7a284390b0ce 260 si5 = pCoef[2 * ia4 + 1];
mbed_official 3:7a284390b0ce 261 si6 = pCoef[2 * ia5 + 1];
mbed_official 3:7a284390b0ce 262 si7 = pCoef[2 * ia6 + 1];
mbed_official 3:7a284390b0ce 263 si8 = pCoef[2 * ia7 + 1];
mbed_official 3:7a284390b0ce 264
mbed_official 3:7a284390b0ce 265 i1 = j;
mbed_official 3:7a284390b0ce 266
mbed_official 3:7a284390b0ce 267 do
mbed_official 3:7a284390b0ce 268 {
mbed_official 3:7a284390b0ce 269 /* index calculation for the input */
mbed_official 3:7a284390b0ce 270 i2 = i1 + n2;
mbed_official 3:7a284390b0ce 271 i3 = i2 + n2;
mbed_official 3:7a284390b0ce 272 i4 = i3 + n2;
mbed_official 3:7a284390b0ce 273 i5 = i4 + n2;
mbed_official 3:7a284390b0ce 274 i6 = i5 + n2;
mbed_official 3:7a284390b0ce 275 i7 = i6 + n2;
mbed_official 3:7a284390b0ce 276 i8 = i7 + n2;
mbed_official 3:7a284390b0ce 277 r1 = pSrc[2 * i1] + pSrc[2 * i5];
mbed_official 3:7a284390b0ce 278 r5 = pSrc[2 * i1] - pSrc[2 * i5];
mbed_official 3:7a284390b0ce 279 r2 = pSrc[2 * i2] + pSrc[2 * i6];
mbed_official 3:7a284390b0ce 280 r6 = pSrc[2 * i2] - pSrc[2 * i6];
mbed_official 3:7a284390b0ce 281 r3 = pSrc[2 * i3] + pSrc[2 * i7];
mbed_official 3:7a284390b0ce 282 r7 = pSrc[2 * i3] - pSrc[2 * i7];
mbed_official 3:7a284390b0ce 283 r4 = pSrc[2 * i4] + pSrc[2 * i8];
mbed_official 3:7a284390b0ce 284 r8 = pSrc[2 * i4] - pSrc[2 * i8];
mbed_official 3:7a284390b0ce 285 t1 = r1 - r3;
mbed_official 3:7a284390b0ce 286 r1 = r1 + r3;
mbed_official 3:7a284390b0ce 287 r3 = r2 - r4;
mbed_official 3:7a284390b0ce 288 r2 = r2 + r4;
mbed_official 3:7a284390b0ce 289 pSrc[2 * i1] = r1 + r2;
mbed_official 3:7a284390b0ce 290 r2 = r1 - r2;
mbed_official 3:7a284390b0ce 291 s1 = pSrc[2 * i1 + 1] + pSrc[2 * i5 + 1];
mbed_official 3:7a284390b0ce 292 s5 = pSrc[2 * i1 + 1] - pSrc[2 * i5 + 1];
mbed_official 3:7a284390b0ce 293 s2 = pSrc[2 * i2 + 1] + pSrc[2 * i6 + 1];
mbed_official 3:7a284390b0ce 294 s6 = pSrc[2 * i2 + 1] - pSrc[2 * i6 + 1];
mbed_official 3:7a284390b0ce 295 s3 = pSrc[2 * i3 + 1] + pSrc[2 * i7 + 1];
mbed_official 3:7a284390b0ce 296 s7 = pSrc[2 * i3 + 1] - pSrc[2 * i7 + 1];
mbed_official 3:7a284390b0ce 297 s4 = pSrc[2 * i4 + 1] + pSrc[2 * i8 + 1];
mbed_official 3:7a284390b0ce 298 s8 = pSrc[2 * i4 + 1] - pSrc[2 * i8 + 1];
mbed_official 3:7a284390b0ce 299 t2 = s1 - s3;
mbed_official 3:7a284390b0ce 300 s1 = s1 + s3;
mbed_official 3:7a284390b0ce 301 s3 = s2 - s4;
mbed_official 3:7a284390b0ce 302 s2 = s2 + s4;
mbed_official 3:7a284390b0ce 303 r1 = t1 + s3;
mbed_official 3:7a284390b0ce 304 t1 = t1 - s3;
mbed_official 3:7a284390b0ce 305 pSrc[2 * i1 + 1] = s1 + s2;
mbed_official 3:7a284390b0ce 306 s2 = s1 - s2;
mbed_official 3:7a284390b0ce 307 s1 = t2 - r3;
mbed_official 3:7a284390b0ce 308 t2 = t2 + r3;
mbed_official 3:7a284390b0ce 309 p1 = co5 * r2;
mbed_official 3:7a284390b0ce 310 p2 = si5 * s2;
mbed_official 3:7a284390b0ce 311 p3 = co5 * s2;
mbed_official 3:7a284390b0ce 312 p4 = si5 * r2;
mbed_official 3:7a284390b0ce 313 pSrc[2 * i5] = p1 + p2;
mbed_official 3:7a284390b0ce 314 pSrc[2 * i5 + 1] = p3 - p4;
mbed_official 3:7a284390b0ce 315 p1 = co3 * r1;
mbed_official 3:7a284390b0ce 316 p2 = si3 * s1;
mbed_official 3:7a284390b0ce 317 p3 = co3 * s1;
mbed_official 3:7a284390b0ce 318 p4 = si3 * r1;
mbed_official 3:7a284390b0ce 319 pSrc[2 * i3] = p1 + p2;
mbed_official 3:7a284390b0ce 320 pSrc[2 * i3 + 1] = p3 - p4;
mbed_official 3:7a284390b0ce 321 p1 = co7 * t1;
mbed_official 3:7a284390b0ce 322 p2 = si7 * t2;
mbed_official 3:7a284390b0ce 323 p3 = co7 * t2;
mbed_official 3:7a284390b0ce 324 p4 = si7 * t1;
mbed_official 3:7a284390b0ce 325 pSrc[2 * i7] = p1 + p2;
mbed_official 3:7a284390b0ce 326 pSrc[2 * i7 + 1] = p3 - p4;
mbed_official 3:7a284390b0ce 327 r1 = (r6 - r8) * C81;
mbed_official 3:7a284390b0ce 328 r6 = (r6 + r8) * C81;
mbed_official 3:7a284390b0ce 329 s1 = (s6 - s8) * C81;
mbed_official 3:7a284390b0ce 330 s6 = (s6 + s8) * C81;
mbed_official 3:7a284390b0ce 331 t1 = r5 - r1;
mbed_official 3:7a284390b0ce 332 r5 = r5 + r1;
mbed_official 3:7a284390b0ce 333 r8 = r7 - r6;
mbed_official 3:7a284390b0ce 334 r7 = r7 + r6;
mbed_official 3:7a284390b0ce 335 t2 = s5 - s1;
mbed_official 3:7a284390b0ce 336 s5 = s5 + s1;
mbed_official 3:7a284390b0ce 337 s8 = s7 - s6;
mbed_official 3:7a284390b0ce 338 s7 = s7 + s6;
mbed_official 3:7a284390b0ce 339 r1 = r5 + s7;
mbed_official 3:7a284390b0ce 340 r5 = r5 - s7;
mbed_official 3:7a284390b0ce 341 r6 = t1 + s8;
mbed_official 3:7a284390b0ce 342 t1 = t1 - s8;
mbed_official 3:7a284390b0ce 343 s1 = s5 - r7;
mbed_official 3:7a284390b0ce 344 s5 = s5 + r7;
mbed_official 3:7a284390b0ce 345 s6 = t2 - r8;
mbed_official 3:7a284390b0ce 346 t2 = t2 + r8;
mbed_official 3:7a284390b0ce 347 p1 = co2 * r1;
mbed_official 3:7a284390b0ce 348 p2 = si2 * s1;
mbed_official 3:7a284390b0ce 349 p3 = co2 * s1;
mbed_official 3:7a284390b0ce 350 p4 = si2 * r1;
mbed_official 3:7a284390b0ce 351 pSrc[2 * i2] = p1 + p2;
mbed_official 3:7a284390b0ce 352 pSrc[2 * i2 + 1] = p3 - p4;
mbed_official 3:7a284390b0ce 353 p1 = co8 * r5;
mbed_official 3:7a284390b0ce 354 p2 = si8 * s5;
mbed_official 3:7a284390b0ce 355 p3 = co8 * s5;
mbed_official 3:7a284390b0ce 356 p4 = si8 * r5;
mbed_official 3:7a284390b0ce 357 pSrc[2 * i8] = p1 + p2;
mbed_official 3:7a284390b0ce 358 pSrc[2 * i8 + 1] = p3 - p4;
mbed_official 3:7a284390b0ce 359 p1 = co6 * r6;
mbed_official 3:7a284390b0ce 360 p2 = si6 * s6;
mbed_official 3:7a284390b0ce 361 p3 = co6 * s6;
mbed_official 3:7a284390b0ce 362 p4 = si6 * r6;
mbed_official 3:7a284390b0ce 363 pSrc[2 * i6] = p1 + p2;
mbed_official 3:7a284390b0ce 364 pSrc[2 * i6 + 1] = p3 - p4;
mbed_official 3:7a284390b0ce 365 p1 = co4 * t1;
mbed_official 3:7a284390b0ce 366 p2 = si4 * t2;
mbed_official 3:7a284390b0ce 367 p3 = co4 * t2;
mbed_official 3:7a284390b0ce 368 p4 = si4 * t1;
mbed_official 3:7a284390b0ce 369 pSrc[2 * i4] = p1 + p2;
mbed_official 3:7a284390b0ce 370 pSrc[2 * i4 + 1] = p3 - p4;
mbed_official 3:7a284390b0ce 371
mbed_official 3:7a284390b0ce 372 i1 += n1;
mbed_official 3:7a284390b0ce 373 } while(i1 < fftLen);
mbed_official 3:7a284390b0ce 374
mbed_official 3:7a284390b0ce 375 j++;
mbed_official 3:7a284390b0ce 376 } while(j < n2);
mbed_official 3:7a284390b0ce 377
mbed_official 3:7a284390b0ce 378 twidCoefModifier <<= 3;
mbed_official 3:7a284390b0ce 379 } while(n2 > 7);
mbed_official 3:7a284390b0ce 380 }
mbed_official 3:7a284390b0ce 381
mbed_official 3:7a284390b0ce 382 /**
mbed_official 3:7a284390b0ce 383 * @} end of Radix8_CFFT_CIFFT group
mbed_official 3:7a284390b0ce 384 */