Vitaly Badeev / Mbed 2 deprecated Radar1

Radar1

Dependencies:   FT800_2 mbed Encoder

DSP/src/arm_cfft_radix8_f32.c@0:fda1a80ff1ac, 2019-04-25 (annotated)

Committer:
Vitan
Date:
Thu Apr 25 11:19:28 2019 +0000
Revision:
0:fda1a80ff1ac
Radar1

Who changed what in which revision?

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Vitan 0:fda1a80ff1ac 1 /* ----------------------------------------------------------------------
Vitan 0:fda1a80ff1ac 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
Vitan 0:fda1a80ff1ac 3 *
Vitan 0:fda1a80ff1ac 4 * $Date: 19. March 2015
Vitan 0:fda1a80ff1ac 5 * $Revision: V.1.4.5
Vitan 0:fda1a80ff1ac 6 *
Vitan 0:fda1a80ff1ac 7 * Project: CMSIS DSP Library
Vitan 0:fda1a80ff1ac 8 * Title: arm_cfft_radix8_f32.c
Vitan 0:fda1a80ff1ac 9 *
Vitan 0:fda1a80ff1ac 10 * Description: Radix-8 Decimation in Frequency CFFT & CIFFT Floating point processing function
Vitan 0:fda1a80ff1ac 11 *
Vitan 0:fda1a80ff1ac 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
Vitan 0:fda1a80ff1ac 13 *
Vitan 0:fda1a80ff1ac 14 * Redistribution and use in source and binary forms, with or without
Vitan 0:fda1a80ff1ac 15 * modification, are permitted provided that the following conditions
Vitan 0:fda1a80ff1ac 16 * are met:
Vitan 0:fda1a80ff1ac 17 * - Redistributions of source code must retain the above copyright
Vitan 0:fda1a80ff1ac 18 * notice, this list of conditions and the following disclaimer.
Vitan 0:fda1a80ff1ac 19 * - Redistributions in binary form must reproduce the above copyright
Vitan 0:fda1a80ff1ac 20 * notice, this list of conditions and the following disclaimer in
Vitan 0:fda1a80ff1ac 21 * the documentation and/or other materials provided with the
Vitan 0:fda1a80ff1ac 22 * distribution.
Vitan 0:fda1a80ff1ac 23 * - Neither the name of ARM LIMITED nor the names of its contributors
Vitan 0:fda1a80ff1ac 24 * may be used to endorse or promote products derived from this
Vitan 0:fda1a80ff1ac 25 * software without specific prior written permission.
Vitan 0:fda1a80ff1ac 26 *
Vitan 0:fda1a80ff1ac 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
Vitan 0:fda1a80ff1ac 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
Vitan 0:fda1a80ff1ac 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
Vitan 0:fda1a80ff1ac 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
Vitan 0:fda1a80ff1ac 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
Vitan 0:fda1a80ff1ac 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
Vitan 0:fda1a80ff1ac 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
Vitan 0:fda1a80ff1ac 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
Vitan 0:fda1a80ff1ac 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
Vitan 0:fda1a80ff1ac 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
Vitan 0:fda1a80ff1ac 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
Vitan 0:fda1a80ff1ac 38 * POSSIBILITY OF SUCH DAMAGE.
Vitan 0:fda1a80ff1ac 39 * -------------------------------------------------------------------- */
Vitan 0:fda1a80ff1ac 40
Vitan 0:fda1a80ff1ac 41 #include "arm_math.h"
Vitan 0:fda1a80ff1ac 42
Vitan 0:fda1a80ff1ac 43 /**
Vitan 0:fda1a80ff1ac 44 * @ingroup groupTransforms
Vitan 0:fda1a80ff1ac 45 */
Vitan 0:fda1a80ff1ac 46
Vitan 0:fda1a80ff1ac 47 /**
Vitan 0:fda1a80ff1ac 48 * @defgroup Radix8_CFFT_CIFFT Radix-8 Complex FFT Functions
Vitan 0:fda1a80ff1ac 49 *
Vitan 0:fda1a80ff1ac 50 * \par
Vitan 0:fda1a80ff1ac 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).
Vitan 0:fda1a80ff1ac 52 * Computational complexity of CFFT reduces drastically when compared to DFT.
Vitan 0:fda1a80ff1ac 53 * \par
Vitan 0:fda1a80ff1ac 54 * This set of functions implements CFFT/CIFFT
Vitan 0:fda1a80ff1ac 55 * for floating-point data types. The functions operates on in-place buffer which uses same buffer for input and output.
Vitan 0:fda1a80ff1ac 56 * Complex input is stored in input buffer in an interleaved fashion.
Vitan 0:fda1a80ff1ac 57 *
Vitan 0:fda1a80ff1ac 58 * \par
Vitan 0:fda1a80ff1ac 59 * The functions operate on blocks of input and output data and each call to the function processes
Vitan 0:fda1a80ff1ac 60 * <code>2*fftLen</code> samples through the transform. <code>pSrc</code> points to In-place arrays containing <code>2*fftLen</code> values.
Vitan 0:fda1a80ff1ac 61 * \par
Vitan 0:fda1a80ff1ac 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.
Vitan 0:fda1a80ff1ac 63 * <pre> {real[0], imag[0], real[1], imag[1],..} </pre>
Vitan 0:fda1a80ff1ac 64 *
Vitan 0:fda1a80ff1ac 65 * \par Lengths supported by the transform:
Vitan 0:fda1a80ff1ac 66 * \par
Vitan 0:fda1a80ff1ac 67 * Internally, the function utilize a Radix-8 decimation in frequency(DIF) algorithm
Vitan 0:fda1a80ff1ac 68 * and the size of the FFT supported are of the lengths [ 64, 512, 4096].
Vitan 0:fda1a80ff1ac 69 *
Vitan 0:fda1a80ff1ac 70 *
Vitan 0:fda1a80ff1ac 71 * \par Algorithm:
Vitan 0:fda1a80ff1ac 72 *
Vitan 0:fda1a80ff1ac 73 * <b>Complex Fast Fourier Transform:</b>
Vitan 0:fda1a80ff1ac 74 * \par
Vitan 0:fda1a80ff1ac 75 * Input real and imaginary data:
Vitan 0:fda1a80ff1ac 76 * <pre>
Vitan 0:fda1a80ff1ac 77 * x(n) = xa + j * ya
Vitan 0:fda1a80ff1ac 78 * x(n+N/4 ) = xb + j * yb
Vitan 0:fda1a80ff1ac 79 * x(n+N/2 ) = xc + j * yc
Vitan 0:fda1a80ff1ac 80 * x(n+3N 4) = xd + j * yd
Vitan 0:fda1a80ff1ac 81 * </pre>
Vitan 0:fda1a80ff1ac 82 * where N is length of FFT
Vitan 0:fda1a80ff1ac 83 * \par
Vitan 0:fda1a80ff1ac 84 * Output real and imaginary data:
Vitan 0:fda1a80ff1ac 85 * <pre>
Vitan 0:fda1a80ff1ac 86 * X(4r) = xa'+ j * ya'
Vitan 0:fda1a80ff1ac 87 * X(4r+1) = xb'+ j * yb'
Vitan 0:fda1a80ff1ac 88 * X(4r+2) = xc'+ j * yc'
Vitan 0:fda1a80ff1ac 89 * X(4r+3) = xd'+ j * yd'
Vitan 0:fda1a80ff1ac 90 * </pre>
Vitan 0:fda1a80ff1ac 91 * \par
Vitan 0:fda1a80ff1ac 92 * Twiddle factors for Radix-8 FFT:
Vitan 0:fda1a80ff1ac 93 * <pre>
Vitan 0:fda1a80ff1ac 94 * Wn = co1 + j * (- si1)
Vitan 0:fda1a80ff1ac 95 * W2n = co2 + j * (- si2)
Vitan 0:fda1a80ff1ac 96 * W3n = co3 + j * (- si3)
Vitan 0:fda1a80ff1ac 97 * </pre>
Vitan 0:fda1a80ff1ac 98 *
Vitan 0:fda1a80ff1ac 99 * \par
Vitan 0:fda1a80ff1ac 100 * \image html CFFT.gif "Radix-8 Decimation-in Frequency Complex Fast Fourier Transform"
Vitan 0:fda1a80ff1ac 101 *
Vitan 0:fda1a80ff1ac 102 * \par
Vitan 0:fda1a80ff1ac 103 * Output from Radix-8 CFFT Results in Digit reversal order. Interchange middle two branches of every butterfly results in Bit reversed output.
Vitan 0:fda1a80ff1ac 104 * \par
Vitan 0:fda1a80ff1ac 105 * <b> Butterfly CFFT equations:</b>
Vitan 0:fda1a80ff1ac 106 * <pre>
Vitan 0:fda1a80ff1ac 107 * xa' = xa + xb + xc + xd
Vitan 0:fda1a80ff1ac 108 * ya' = ya + yb + yc + yd
Vitan 0:fda1a80ff1ac 109 * xc' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1)
Vitan 0:fda1a80ff1ac 110 * yc' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1)
Vitan 0:fda1a80ff1ac 111 * xb' = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2)
Vitan 0:fda1a80ff1ac 112 * yb' = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2)
Vitan 0:fda1a80ff1ac 113 * xd' = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3)
Vitan 0:fda1a80ff1ac 114 * yd' = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3)
Vitan 0:fda1a80ff1ac 115 * </pre>
Vitan 0:fda1a80ff1ac 116 *
Vitan 0:fda1a80ff1ac 117 * \par
Vitan 0:fda1a80ff1ac 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);
Vitan 0:fda1a80ff1ac 119 * <code>bitReverseFlag</code> Flag for selection of output order(Set bitReverseFlag to output in normal order otherwise output in bit reversed order);
Vitan 0:fda1a80ff1ac 120 * <code>pTwiddle</code>points to array of twiddle coefficients; <code>pBitRevTable</code> points to the array of bit reversal table.
Vitan 0:fda1a80ff1ac 121 * <code>twidCoefModifier</code> modifier for twiddle factor table which supports all FFT lengths with same table;
Vitan 0:fda1a80ff1ac 122 * <code>pBitRevTable</code> modifier for bit reversal table which supports all FFT lengths with same table.
Vitan 0:fda1a80ff1ac 123 * <code>onebyfftLen</code> value of 1/fftLen to calculate CIFFT;
Vitan 0:fda1a80ff1ac 124 *
Vitan 0:fda1a80ff1ac 125 * \par Fixed-Point Behavior
Vitan 0:fda1a80ff1ac 126 * Care must be taken when using the fixed-point versions of the CFFT/CIFFT function.
Vitan 0:fda1a80ff1ac 127 * Refer to the function specific documentation below for usage guidelines.
Vitan 0:fda1a80ff1ac 128 */
Vitan 0:fda1a80ff1ac 129
Vitan 0:fda1a80ff1ac 130
Vitan 0:fda1a80ff1ac 131 /*
Vitan 0:fda1a80ff1ac 132 * @brief Core function for the floating-point CFFT butterfly process.
Vitan 0:fda1a80ff1ac 133 * @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
Vitan 0:fda1a80ff1ac 134 * @param[in] fftLen length of the FFT.
Vitan 0:fda1a80ff1ac 135 * @param[in] *pCoef points to the twiddle coefficient buffer.
Vitan 0:fda1a80ff1ac 136 * @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
Vitan 0:fda1a80ff1ac 137 * @return none.
Vitan 0:fda1a80ff1ac 138 */
Vitan 0:fda1a80ff1ac 139
Vitan 0:fda1a80ff1ac 140 void arm_radix8_butterfly_f32(
Vitan 0:fda1a80ff1ac 141 float32_t * pSrc,
Vitan 0:fda1a80ff1ac 142 uint16_t fftLen,
Vitan 0:fda1a80ff1ac 143 const float32_t * pCoef,
Vitan 0:fda1a80ff1ac 144 uint16_t twidCoefModifier)
Vitan 0:fda1a80ff1ac 145 {
Vitan 0:fda1a80ff1ac 146 uint32_t ia1, ia2, ia3, ia4, ia5, ia6, ia7;
Vitan 0:fda1a80ff1ac 147 uint32_t i1, i2, i3, i4, i5, i6, i7, i8;
Vitan 0:fda1a80ff1ac 148 uint32_t id;
Vitan 0:fda1a80ff1ac 149 uint32_t n1, n2, j;
Vitan 0:fda1a80ff1ac 150
Vitan 0:fda1a80ff1ac 151 float32_t r1, r2, r3, r4, r5, r6, r7, r8;
Vitan 0:fda1a80ff1ac 152 float32_t t1, t2;
Vitan 0:fda1a80ff1ac 153 float32_t s1, s2, s3, s4, s5, s6, s7, s8;
Vitan 0:fda1a80ff1ac 154 float32_t p1, p2, p3, p4;
Vitan 0:fda1a80ff1ac 155 float32_t co2, co3, co4, co5, co6, co7, co8;
Vitan 0:fda1a80ff1ac 156 float32_t si2, si3, si4, si5, si6, si7, si8;
Vitan 0:fda1a80ff1ac 157 const float32_t C81 = 0.70710678118f;
Vitan 0:fda1a80ff1ac 158
Vitan 0:fda1a80ff1ac 159 n2 = fftLen;
Vitan 0:fda1a80ff1ac 160
Vitan 0:fda1a80ff1ac 161 do
Vitan 0:fda1a80ff1ac 162 {
Vitan 0:fda1a80ff1ac 163 n1 = n2;
Vitan 0:fda1a80ff1ac 164 n2 = n2 >> 3;
Vitan 0:fda1a80ff1ac 165 i1 = 0;
Vitan 0:fda1a80ff1ac 166
Vitan 0:fda1a80ff1ac 167 do
Vitan 0:fda1a80ff1ac 168 {
Vitan 0:fda1a80ff1ac 169 i2 = i1 + n2;
Vitan 0:fda1a80ff1ac 170 i3 = i2 + n2;
Vitan 0:fda1a80ff1ac 171 i4 = i3 + n2;
Vitan 0:fda1a80ff1ac 172 i5 = i4 + n2;
Vitan 0:fda1a80ff1ac 173 i6 = i5 + n2;
Vitan 0:fda1a80ff1ac 174 i7 = i6 + n2;
Vitan 0:fda1a80ff1ac 175 i8 = i7 + n2;
Vitan 0:fda1a80ff1ac 176 r1 = pSrc[2 * i1] + pSrc[2 * i5];
Vitan 0:fda1a80ff1ac 177 r5 = pSrc[2 * i1] - pSrc[2 * i5];
Vitan 0:fda1a80ff1ac 178 r2 = pSrc[2 * i2] + pSrc[2 * i6];
Vitan 0:fda1a80ff1ac 179 r6 = pSrc[2 * i2] - pSrc[2 * i6];
Vitan 0:fda1a80ff1ac 180 r3 = pSrc[2 * i3] + pSrc[2 * i7];
Vitan 0:fda1a80ff1ac 181 r7 = pSrc[2 * i3] - pSrc[2 * i7];
Vitan 0:fda1a80ff1ac 182 r4 = pSrc[2 * i4] + pSrc[2 * i8];
Vitan 0:fda1a80ff1ac 183 r8 = pSrc[2 * i4] - pSrc[2 * i8];
Vitan 0:fda1a80ff1ac 184 t1 = r1 - r3;
Vitan 0:fda1a80ff1ac 185 r1 = r1 + r3;
Vitan 0:fda1a80ff1ac 186 r3 = r2 - r4;
Vitan 0:fda1a80ff1ac 187 r2 = r2 + r4;
Vitan 0:fda1a80ff1ac 188 pSrc[2 * i1] = r1 + r2;
Vitan 0:fda1a80ff1ac 189 pSrc[2 * i5] = r1 - r2;
Vitan 0:fda1a80ff1ac 190 r1 = pSrc[2 * i1 + 1] + pSrc[2 * i5 + 1];
Vitan 0:fda1a80ff1ac 191 s5 = pSrc[2 * i1 + 1] - pSrc[2 * i5 + 1];
Vitan 0:fda1a80ff1ac 192 r2 = pSrc[2 * i2 + 1] + pSrc[2 * i6 + 1];
Vitan 0:fda1a80ff1ac 193 s6 = pSrc[2 * i2 + 1] - pSrc[2 * i6 + 1];
Vitan 0:fda1a80ff1ac 194 s3 = pSrc[2 * i3 + 1] + pSrc[2 * i7 + 1];
Vitan 0:fda1a80ff1ac 195 s7 = pSrc[2 * i3 + 1] - pSrc[2 * i7 + 1];
Vitan 0:fda1a80ff1ac 196 r4 = pSrc[2 * i4 + 1] + pSrc[2 * i8 + 1];
Vitan 0:fda1a80ff1ac 197 s8 = pSrc[2 * i4 + 1] - pSrc[2 * i8 + 1];
Vitan 0:fda1a80ff1ac 198 t2 = r1 - s3;
Vitan 0:fda1a80ff1ac 199 r1 = r1 + s3;
Vitan 0:fda1a80ff1ac 200 s3 = r2 - r4;
Vitan 0:fda1a80ff1ac 201 r2 = r2 + r4;
Vitan 0:fda1a80ff1ac 202 pSrc[2 * i1 + 1] = r1 + r2;
Vitan 0:fda1a80ff1ac 203 pSrc[2 * i5 + 1] = r1 - r2;
Vitan 0:fda1a80ff1ac 204 pSrc[2 * i3] = t1 + s3;
Vitan 0:fda1a80ff1ac 205 pSrc[2 * i7] = t1 - s3;
Vitan 0:fda1a80ff1ac 206 pSrc[2 * i3 + 1] = t2 - r3;
Vitan 0:fda1a80ff1ac 207 pSrc[2 * i7 + 1] = t2 + r3;
Vitan 0:fda1a80ff1ac 208 r1 = (r6 - r8) * C81;
Vitan 0:fda1a80ff1ac 209 r6 = (r6 + r8) * C81;
Vitan 0:fda1a80ff1ac 210 r2 = (s6 - s8) * C81;
Vitan 0:fda1a80ff1ac 211 s6 = (s6 + s8) * C81;
Vitan 0:fda1a80ff1ac 212 t1 = r5 - r1;
Vitan 0:fda1a80ff1ac 213 r5 = r5 + r1;
Vitan 0:fda1a80ff1ac 214 r8 = r7 - r6;
Vitan 0:fda1a80ff1ac 215 r7 = r7 + r6;
Vitan 0:fda1a80ff1ac 216 t2 = s5 - r2;
Vitan 0:fda1a80ff1ac 217 s5 = s5 + r2;
Vitan 0:fda1a80ff1ac 218 s8 = s7 - s6;
Vitan 0:fda1a80ff1ac 219 s7 = s7 + s6;
Vitan 0:fda1a80ff1ac 220 pSrc[2 * i2] = r5 + s7;
Vitan 0:fda1a80ff1ac 221 pSrc[2 * i8] = r5 - s7;
Vitan 0:fda1a80ff1ac 222 pSrc[2 * i6] = t1 + s8;
Vitan 0:fda1a80ff1ac 223 pSrc[2 * i4] = t1 - s8;
Vitan 0:fda1a80ff1ac 224 pSrc[2 * i2 + 1] = s5 - r7;
Vitan 0:fda1a80ff1ac 225 pSrc[2 * i8 + 1] = s5 + r7;
Vitan 0:fda1a80ff1ac 226 pSrc[2 * i6 + 1] = t2 - r8;
Vitan 0:fda1a80ff1ac 227 pSrc[2 * i4 + 1] = t2 + r8;
Vitan 0:fda1a80ff1ac 228
Vitan 0:fda1a80ff1ac 229 i1 += n1;
Vitan 0:fda1a80ff1ac 230 } while(i1 < fftLen);
Vitan 0:fda1a80ff1ac 231
Vitan 0:fda1a80ff1ac 232 if(n2 < 8)
Vitan 0:fda1a80ff1ac 233 break;
Vitan 0:fda1a80ff1ac 234
Vitan 0:fda1a80ff1ac 235 ia1 = 0;
Vitan 0:fda1a80ff1ac 236 j = 1;
Vitan 0:fda1a80ff1ac 237
Vitan 0:fda1a80ff1ac 238 do
Vitan 0:fda1a80ff1ac 239 {
Vitan 0:fda1a80ff1ac 240 /* index calculation for the coefficients */
Vitan 0:fda1a80ff1ac 241 id = ia1 + twidCoefModifier;
Vitan 0:fda1a80ff1ac 242 ia1 = id;
Vitan 0:fda1a80ff1ac 243 ia2 = ia1 + id;
Vitan 0:fda1a80ff1ac 244 ia3 = ia2 + id;
Vitan 0:fda1a80ff1ac 245 ia4 = ia3 + id;
Vitan 0:fda1a80ff1ac 246 ia5 = ia4 + id;
Vitan 0:fda1a80ff1ac 247 ia6 = ia5 + id;
Vitan 0:fda1a80ff1ac 248 ia7 = ia6 + id;
Vitan 0:fda1a80ff1ac 249
Vitan 0:fda1a80ff1ac 250 co2 = pCoef[2 * ia1];
Vitan 0:fda1a80ff1ac 251 co3 = pCoef[2 * ia2];
Vitan 0:fda1a80ff1ac 252 co4 = pCoef[2 * ia3];
Vitan 0:fda1a80ff1ac 253 co5 = pCoef[2 * ia4];
Vitan 0:fda1a80ff1ac 254 co6 = pCoef[2 * ia5];
Vitan 0:fda1a80ff1ac 255 co7 = pCoef[2 * ia6];
Vitan 0:fda1a80ff1ac 256 co8 = pCoef[2 * ia7];
Vitan 0:fda1a80ff1ac 257 si2 = pCoef[2 * ia1 + 1];
Vitan 0:fda1a80ff1ac 258 si3 = pCoef[2 * ia2 + 1];
Vitan 0:fda1a80ff1ac 259 si4 = pCoef[2 * ia3 + 1];
Vitan 0:fda1a80ff1ac 260 si5 = pCoef[2 * ia4 + 1];
Vitan 0:fda1a80ff1ac 261 si6 = pCoef[2 * ia5 + 1];
Vitan 0:fda1a80ff1ac 262 si7 = pCoef[2 * ia6 + 1];
Vitan 0:fda1a80ff1ac 263 si8 = pCoef[2 * ia7 + 1];
Vitan 0:fda1a80ff1ac 264
Vitan 0:fda1a80ff1ac 265 i1 = j;
Vitan 0:fda1a80ff1ac 266
Vitan 0:fda1a80ff1ac 267 do
Vitan 0:fda1a80ff1ac 268 {
Vitan 0:fda1a80ff1ac 269 /* index calculation for the input */
Vitan 0:fda1a80ff1ac 270 i2 = i1 + n2;
Vitan 0:fda1a80ff1ac 271 i3 = i2 + n2;
Vitan 0:fda1a80ff1ac 272 i4 = i3 + n2;
Vitan 0:fda1a80ff1ac 273 i5 = i4 + n2;
Vitan 0:fda1a80ff1ac 274 i6 = i5 + n2;
Vitan 0:fda1a80ff1ac 275 i7 = i6 + n2;
Vitan 0:fda1a80ff1ac 276 i8 = i7 + n2;
Vitan 0:fda1a80ff1ac 277 r1 = pSrc[2 * i1] + pSrc[2 * i5];
Vitan 0:fda1a80ff1ac 278 r5 = pSrc[2 * i1] - pSrc[2 * i5];
Vitan 0:fda1a80ff1ac 279 r2 = pSrc[2 * i2] + pSrc[2 * i6];
Vitan 0:fda1a80ff1ac 280 r6 = pSrc[2 * i2] - pSrc[2 * i6];
Vitan 0:fda1a80ff1ac 281 r3 = pSrc[2 * i3] + pSrc[2 * i7];
Vitan 0:fda1a80ff1ac 282 r7 = pSrc[2 * i3] - pSrc[2 * i7];
Vitan 0:fda1a80ff1ac 283 r4 = pSrc[2 * i4] + pSrc[2 * i8];
Vitan 0:fda1a80ff1ac 284 r8 = pSrc[2 * i4] - pSrc[2 * i8];
Vitan 0:fda1a80ff1ac 285 t1 = r1 - r3;
Vitan 0:fda1a80ff1ac 286 r1 = r1 + r3;
Vitan 0:fda1a80ff1ac 287 r3 = r2 - r4;
Vitan 0:fda1a80ff1ac 288 r2 = r2 + r4;
Vitan 0:fda1a80ff1ac 289 pSrc[2 * i1] = r1 + r2;
Vitan 0:fda1a80ff1ac 290 r2 = r1 - r2;
Vitan 0:fda1a80ff1ac 291 s1 = pSrc[2 * i1 + 1] + pSrc[2 * i5 + 1];
Vitan 0:fda1a80ff1ac 292 s5 = pSrc[2 * i1 + 1] - pSrc[2 * i5 + 1];
Vitan 0:fda1a80ff1ac 293 s2 = pSrc[2 * i2 + 1] + pSrc[2 * i6 + 1];
Vitan 0:fda1a80ff1ac 294 s6 = pSrc[2 * i2 + 1] - pSrc[2 * i6 + 1];
Vitan 0:fda1a80ff1ac 295 s3 = pSrc[2 * i3 + 1] + pSrc[2 * i7 + 1];
Vitan 0:fda1a80ff1ac 296 s7 = pSrc[2 * i3 + 1] - pSrc[2 * i7 + 1];
Vitan 0:fda1a80ff1ac 297 s4 = pSrc[2 * i4 + 1] + pSrc[2 * i8 + 1];
Vitan 0:fda1a80ff1ac 298 s8 = pSrc[2 * i4 + 1] - pSrc[2 * i8 + 1];
Vitan 0:fda1a80ff1ac 299 t2 = s1 - s3;
Vitan 0:fda1a80ff1ac 300 s1 = s1 + s3;
Vitan 0:fda1a80ff1ac 301 s3 = s2 - s4;
Vitan 0:fda1a80ff1ac 302 s2 = s2 + s4;
Vitan 0:fda1a80ff1ac 303 r1 = t1 + s3;
Vitan 0:fda1a80ff1ac 304 t1 = t1 - s3;
Vitan 0:fda1a80ff1ac 305 pSrc[2 * i1 + 1] = s1 + s2;
Vitan 0:fda1a80ff1ac 306 s2 = s1 - s2;
Vitan 0:fda1a80ff1ac 307 s1 = t2 - r3;
Vitan 0:fda1a80ff1ac 308 t2 = t2 + r3;
Vitan 0:fda1a80ff1ac 309 p1 = co5 * r2;
Vitan 0:fda1a80ff1ac 310 p2 = si5 * s2;
Vitan 0:fda1a80ff1ac 311 p3 = co5 * s2;
Vitan 0:fda1a80ff1ac 312 p4 = si5 * r2;
Vitan 0:fda1a80ff1ac 313 pSrc[2 * i5] = p1 + p2;
Vitan 0:fda1a80ff1ac 314 pSrc[2 * i5 + 1] = p3 - p4;
Vitan 0:fda1a80ff1ac 315 p1 = co3 * r1;
Vitan 0:fda1a80ff1ac 316 p2 = si3 * s1;
Vitan 0:fda1a80ff1ac 317 p3 = co3 * s1;
Vitan 0:fda1a80ff1ac 318 p4 = si3 * r1;
Vitan 0:fda1a80ff1ac 319 pSrc[2 * i3] = p1 + p2;
Vitan 0:fda1a80ff1ac 320 pSrc[2 * i3 + 1] = p3 - p4;
Vitan 0:fda1a80ff1ac 321 p1 = co7 * t1;
Vitan 0:fda1a80ff1ac 322 p2 = si7 * t2;
Vitan 0:fda1a80ff1ac 323 p3 = co7 * t2;
Vitan 0:fda1a80ff1ac 324 p4 = si7 * t1;
Vitan 0:fda1a80ff1ac 325 pSrc[2 * i7] = p1 + p2;
Vitan 0:fda1a80ff1ac 326 pSrc[2 * i7 + 1] = p3 - p4;
Vitan 0:fda1a80ff1ac 327 r1 = (r6 - r8) * C81;
Vitan 0:fda1a80ff1ac 328 r6 = (r6 + r8) * C81;
Vitan 0:fda1a80ff1ac 329 s1 = (s6 - s8) * C81;
Vitan 0:fda1a80ff1ac 330 s6 = (s6 + s8) * C81;
Vitan 0:fda1a80ff1ac 331 t1 = r5 - r1;
Vitan 0:fda1a80ff1ac 332 r5 = r5 + r1;
Vitan 0:fda1a80ff1ac 333 r8 = r7 - r6;
Vitan 0:fda1a80ff1ac 334 r7 = r7 + r6;
Vitan 0:fda1a80ff1ac 335 t2 = s5 - s1;
Vitan 0:fda1a80ff1ac 336 s5 = s5 + s1;
Vitan 0:fda1a80ff1ac 337 s8 = s7 - s6;
Vitan 0:fda1a80ff1ac 338 s7 = s7 + s6;
Vitan 0:fda1a80ff1ac 339 r1 = r5 + s7;
Vitan 0:fda1a80ff1ac 340 r5 = r5 - s7;
Vitan 0:fda1a80ff1ac 341 r6 = t1 + s8;
Vitan 0:fda1a80ff1ac 342 t1 = t1 - s8;
Vitan 0:fda1a80ff1ac 343 s1 = s5 - r7;
Vitan 0:fda1a80ff1ac 344 s5 = s5 + r7;
Vitan 0:fda1a80ff1ac 345 s6 = t2 - r8;
Vitan 0:fda1a80ff1ac 346 t2 = t2 + r8;
Vitan 0:fda1a80ff1ac 347 p1 = co2 * r1;
Vitan 0:fda1a80ff1ac 348 p2 = si2 * s1;
Vitan 0:fda1a80ff1ac 349 p3 = co2 * s1;
Vitan 0:fda1a80ff1ac 350 p4 = si2 * r1;
Vitan 0:fda1a80ff1ac 351 pSrc[2 * i2] = p1 + p2;
Vitan 0:fda1a80ff1ac 352 pSrc[2 * i2 + 1] = p3 - p4;
Vitan 0:fda1a80ff1ac 353 p1 = co8 * r5;
Vitan 0:fda1a80ff1ac 354 p2 = si8 * s5;
Vitan 0:fda1a80ff1ac 355 p3 = co8 * s5;
Vitan 0:fda1a80ff1ac 356 p4 = si8 * r5;
Vitan 0:fda1a80ff1ac 357 pSrc[2 * i8] = p1 + p2;
Vitan 0:fda1a80ff1ac 358 pSrc[2 * i8 + 1] = p3 - p4;
Vitan 0:fda1a80ff1ac 359 p1 = co6 * r6;
Vitan 0:fda1a80ff1ac 360 p2 = si6 * s6;
Vitan 0:fda1a80ff1ac 361 p3 = co6 * s6;
Vitan 0:fda1a80ff1ac 362 p4 = si6 * r6;
Vitan 0:fda1a80ff1ac 363 pSrc[2 * i6] = p1 + p2;
Vitan 0:fda1a80ff1ac 364 pSrc[2 * i6 + 1] = p3 - p4;
Vitan 0:fda1a80ff1ac 365 p1 = co4 * t1;
Vitan 0:fda1a80ff1ac 366 p2 = si4 * t2;
Vitan 0:fda1a80ff1ac 367 p3 = co4 * t2;
Vitan 0:fda1a80ff1ac 368 p4 = si4 * t1;
Vitan 0:fda1a80ff1ac 369 pSrc[2 * i4] = p1 + p2;
Vitan 0:fda1a80ff1ac 370 pSrc[2 * i4 + 1] = p3 - p4;
Vitan 0:fda1a80ff1ac 371
Vitan 0:fda1a80ff1ac 372 i1 += n1;
Vitan 0:fda1a80ff1ac 373 } while(i1 < fftLen);
Vitan 0:fda1a80ff1ac 374
Vitan 0:fda1a80ff1ac 375 j++;
Vitan 0:fda1a80ff1ac 376 } while(j < n2);
Vitan 0:fda1a80ff1ac 377
Vitan 0:fda1a80ff1ac 378 twidCoefModifier <<= 3;
Vitan 0:fda1a80ff1ac 379 } while(n2 > 7);
Vitan 0:fda1a80ff1ac 380 }
Vitan 0:fda1a80ff1ac 381
Vitan 0:fda1a80ff1ac 382 /**
Vitan 0:fda1a80ff1ac 383 * @} end of Radix8_CFFT_CIFFT group
Vitan 0:fda1a80ff1ac 384 */