/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_cfft_radix8_f32.c
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* Description: Radix-8 Decimation in Frequency CFFT & CIFFT Floating point processing function
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*
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* $Date: 27. January 2017
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* $Revision: V.1.5.1
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*
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* Target Processor: Cortex-M cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "arm_math.h"
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/* ----------------------------------------------------------------------
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* Internal helper function used by the FFTs
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* -------------------------------------------------------------------- */
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/*
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* @brief Core function for the floating-point CFFT butterfly process.
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* @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
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* @param[in] fftLen length of the FFT.
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* @param[in] *pCoef points to the twiddle coefficient buffer.
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* @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
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* @return none.
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*/
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void arm_radix8_butterfly_f32(
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float32_t * pSrc,
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uint16_t fftLen,
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const float32_t * pCoef,
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uint16_t twidCoefModifier)
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{
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uint32_t ia1, ia2, ia3, ia4, ia5, ia6, ia7;
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uint32_t i1, i2, i3, i4, i5, i6, i7, i8;
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uint32_t id;
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uint32_t n1, n2, j;
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float32_t r1, r2, r3, r4, r5, r6, r7, r8;
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float32_t t1, t2;
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float32_t s1, s2, s3, s4, s5, s6, s7, s8;
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float32_t p1, p2, p3, p4;
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float32_t co2, co3, co4, co5, co6, co7, co8;
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float32_t si2, si3, si4, si5, si6, si7, si8;
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const float32_t C81 = 0.70710678118f;
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n2 = fftLen;
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do
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{
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n1 = n2;
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n2 = n2 >> 3;
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i1 = 0;
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do
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{
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i2 = i1 + n2;
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i3 = i2 + n2;
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i4 = i3 + n2;
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i5 = i4 + n2;
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i6 = i5 + n2;
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i7 = i6 + n2;
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i8 = i7 + n2;
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r1 = pSrc[2 * i1] + pSrc[2 * i5];
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r5 = pSrc[2 * i1] - pSrc[2 * i5];
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r2 = pSrc[2 * i2] + pSrc[2 * i6];
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r6 = pSrc[2 * i2] - pSrc[2 * i6];
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r3 = pSrc[2 * i3] + pSrc[2 * i7];
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r7 = pSrc[2 * i3] - pSrc[2 * i7];
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r4 = pSrc[2 * i4] + pSrc[2 * i8];
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r8 = pSrc[2 * i4] - pSrc[2 * i8];
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t1 = r1 - r3;
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r1 = r1 + r3;
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r3 = r2 - r4;
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r2 = r2 + r4;
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pSrc[2 * i1] = r1 + r2;
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pSrc[2 * i5] = r1 - r2;
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r1 = pSrc[2 * i1 + 1] + pSrc[2 * i5 + 1];
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s5 = pSrc[2 * i1 + 1] - pSrc[2 * i5 + 1];
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r2 = pSrc[2 * i2 + 1] + pSrc[2 * i6 + 1];
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s6 = pSrc[2 * i2 + 1] - pSrc[2 * i6 + 1];
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s3 = pSrc[2 * i3 + 1] + pSrc[2 * i7 + 1];
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s7 = pSrc[2 * i3 + 1] - pSrc[2 * i7 + 1];
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r4 = pSrc[2 * i4 + 1] + pSrc[2 * i8 + 1];
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s8 = pSrc[2 * i4 + 1] - pSrc[2 * i8 + 1];
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t2 = r1 - s3;
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r1 = r1 + s3;
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s3 = r2 - r4;
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r2 = r2 + r4;
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pSrc[2 * i1 + 1] = r1 + r2;
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pSrc[2 * i5 + 1] = r1 - r2;
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pSrc[2 * i3] = t1 + s3;
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pSrc[2 * i7] = t1 - s3;
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pSrc[2 * i3 + 1] = t2 - r3;
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pSrc[2 * i7 + 1] = t2 + r3;
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r1 = (r6 - r8) * C81;
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r6 = (r6 + r8) * C81;
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r2 = (s6 - s8) * C81;
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s6 = (s6 + s8) * C81;
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t1 = r5 - r1;
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r5 = r5 + r1;
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r8 = r7 - r6;
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r7 = r7 + r6;
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t2 = s5 - r2;
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s5 = s5 + r2;
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s8 = s7 - s6;
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s7 = s7 + s6;
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pSrc[2 * i2] = r5 + s7;
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pSrc[2 * i8] = r5 - s7;
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pSrc[2 * i6] = t1 + s8;
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pSrc[2 * i4] = t1 - s8;
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pSrc[2 * i2 + 1] = s5 - r7;
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pSrc[2 * i8 + 1] = s5 + r7;
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pSrc[2 * i6 + 1] = t2 - r8;
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pSrc[2 * i4 + 1] = t2 + r8;
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i1 += n1;
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} while (i1 < fftLen);
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if (n2 < 8)
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break;
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ia1 = 0;
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j = 1;
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do
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{
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/* index calculation for the coefficients */
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id = ia1 + twidCoefModifier;
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ia1 = id;
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ia2 = ia1 + id;
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ia3 = ia2 + id;
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ia4 = ia3 + id;
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ia5 = ia4 + id;
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ia6 = ia5 + id;
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ia7 = ia6 + id;
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co2 = pCoef[2 * ia1];
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co3 = pCoef[2 * ia2];
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co4 = pCoef[2 * ia3];
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co5 = pCoef[2 * ia4];
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co6 = pCoef[2 * ia5];
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co7 = pCoef[2 * ia6];
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co8 = pCoef[2 * ia7];
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si2 = pCoef[2 * ia1 + 1];
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si3 = pCoef[2 * ia2 + 1];
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si4 = pCoef[2 * ia3 + 1];
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si5 = pCoef[2 * ia4 + 1];
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si6 = pCoef[2 * ia5 + 1];
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si7 = pCoef[2 * ia6 + 1];
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si8 = pCoef[2 * ia7 + 1];
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i1 = j;
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do
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{
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/* index calculation for the input */
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i2 = i1 + n2;
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i3 = i2 + n2;
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i4 = i3 + n2;
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i5 = i4 + n2;
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i6 = i5 + n2;
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i7 = i6 + n2;
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i8 = i7 + n2;
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r1 = pSrc[2 * i1] + pSrc[2 * i5];
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r5 = pSrc[2 * i1] - pSrc[2 * i5];
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r2 = pSrc[2 * i2] + pSrc[2 * i6];
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r6 = pSrc[2 * i2] - pSrc[2 * i6];
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r3 = pSrc[2 * i3] + pSrc[2 * i7];
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r7 = pSrc[2 * i3] - pSrc[2 * i7];
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r4 = pSrc[2 * i4] + pSrc[2 * i8];
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r8 = pSrc[2 * i4] - pSrc[2 * i8];
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t1 = r1 - r3;
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r1 = r1 + r3;
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r3 = r2 - r4;
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r2 = r2 + r4;
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pSrc[2 * i1] = r1 + r2;
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r2 = r1 - r2;
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s1 = pSrc[2 * i1 + 1] + pSrc[2 * i5 + 1];
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s5 = pSrc[2 * i1 + 1] - pSrc[2 * i5 + 1];
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s2 = pSrc[2 * i2 + 1] + pSrc[2 * i6 + 1];
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s6 = pSrc[2 * i2 + 1] - pSrc[2 * i6 + 1];
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s3 = pSrc[2 * i3 + 1] + pSrc[2 * i7 + 1];
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s7 = pSrc[2 * i3 + 1] - pSrc[2 * i7 + 1];
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s4 = pSrc[2 * i4 + 1] + pSrc[2 * i8 + 1];
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s8 = pSrc[2 * i4 + 1] - pSrc[2 * i8 + 1];
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t2 = s1 - s3;
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s1 = s1 + s3;
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s3 = s2 - s4;
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s2 = s2 + s4;
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r1 = t1 + s3;
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t1 = t1 - s3;
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pSrc[2 * i1 + 1] = s1 + s2;
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s2 = s1 - s2;
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s1 = t2 - r3;
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t2 = t2 + r3;
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p1 = co5 * r2;
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p2 = si5 * s2;
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p3 = co5 * s2;
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p4 = si5 * r2;
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pSrc[2 * i5] = p1 + p2;
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pSrc[2 * i5 + 1] = p3 - p4;
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p1 = co3 * r1;
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p2 = si3 * s1;
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p3 = co3 * s1;
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p4 = si3 * r1;
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pSrc[2 * i3] = p1 + p2;
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pSrc[2 * i3 + 1] = p3 - p4;
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p1 = co7 * t1;
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p2 = si7 * t2;
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p3 = co7 * t2;
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p4 = si7 * t1;
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pSrc[2 * i7] = p1 + p2;
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pSrc[2 * i7 + 1] = p3 - p4;
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r1 = (r6 - r8) * C81;
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r6 = (r6 + r8) * C81;
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s1 = (s6 - s8) * C81;
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s6 = (s6 + s8) * C81;
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t1 = r5 - r1;
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r5 = r5 + r1;
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r8 = r7 - r6;
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r7 = r7 + r6;
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t2 = s5 - s1;
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s5 = s5 + s1;
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s8 = s7 - s6;
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s7 = s7 + s6;
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r1 = r5 + s7;
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r5 = r5 - s7;
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r6 = t1 + s8;
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t1 = t1 - s8;
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s1 = s5 - r7;
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s5 = s5 + r7;
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s6 = t2 - r8;
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t2 = t2 + r8;
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p1 = co2 * r1;
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p2 = si2 * s1;
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p3 = co2 * s1;
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p4 = si2 * r1;
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pSrc[2 * i2] = p1 + p2;
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pSrc[2 * i2 + 1] = p3 - p4;
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p1 = co8 * r5;
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p2 = si8 * s5;
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p3 = co8 * s5;
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p4 = si8 * r5;
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pSrc[2 * i8] = p1 + p2;
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pSrc[2 * i8 + 1] = p3 - p4;
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p1 = co6 * r6;
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p2 = si6 * s6;
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p3 = co6 * s6;
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p4 = si6 * r6;
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pSrc[2 * i6] = p1 + p2;
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pSrc[2 * i6 + 1] = p3 - p4;
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p1 = co4 * t1;
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p2 = si4 * t2;
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p3 = co4 * t2;
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p4 = si4 * t1;
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pSrc[2 * i4] = p1 + p2;
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pSrc[2 * i4 + 1] = p3 - p4;
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i1 += n1;
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} while (i1 < fftLen);
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j++;
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} while (j < n2);
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twidCoefModifier <<= 3;
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} while (n2 > 7);
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}
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