Joep D
The CMSIS DSP 5 library
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Diff: functions/TransformFunctions/arm_cfft_radix4_f32.c
- Revision:
- 1:24714b45cd1b
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/functions/TransformFunctions/arm_cfft_radix4_f32.c Wed Jun 20 11:21:31 2018 +0000
@@ -0,0 +1,1209 @@
+/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_cfft_radix4_f32.c
+ * Description: Radix-4 Decimation in Frequency CFFT & CIFFT Floating point processing function
+ *
+ * $Date: 27. January 2017
+ * $Revision: V.1.5.1
+ *
+ * Target Processor: Cortex-M cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "arm_math.h"
+
+extern void arm_bitreversal_f32(
+float32_t * pSrc,
+uint16_t fftSize,
+uint16_t bitRevFactor,
+uint16_t * pBitRevTab);
+
+void arm_radix4_butterfly_f32(
+float32_t * pSrc,
+uint16_t fftLen,
+float32_t * pCoef,
+uint16_t twidCoefModifier);
+
+void arm_radix4_butterfly_inverse_f32(
+float32_t * pSrc,
+uint16_t fftLen,
+float32_t * pCoef,
+uint16_t twidCoefModifier,
+float32_t onebyfftLen);
+
+
+/**
+* @ingroup groupTransforms
+*/
+
+/**
+* @addtogroup ComplexFFT
+* @{
+*/
+
+/**
+* @details
+* @brief Processing function for the floating-point Radix-4 CFFT/CIFFT.
+* @deprecated Do not use this function. It has been superseded by \ref arm_cfft_f32 and will be removed
+* in the future.
+* @param[in] *S points to an instance of the floating-point Radix-4 CFFT/CIFFT structure.
+* @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.
+* @return none.
+*/
+
+void arm_cfft_radix4_f32(
+ const arm_cfft_radix4_instance_f32 * S,
+ float32_t * pSrc)
+{
+ if (S->ifftFlag == 1U)
+ {
+ /* Complex IFFT radix-4 */
+ arm_radix4_butterfly_inverse_f32(pSrc, S->fftLen, S->pTwiddle, S->twidCoefModifier, S->onebyfftLen);
+ }
+ else
+ {
+ /* Complex FFT radix-4 */
+ arm_radix4_butterfly_f32(pSrc, S->fftLen, S->pTwiddle, S->twidCoefModifier);
+ }
+
+ if (S->bitReverseFlag == 1U)
+ {
+ /* Bit Reversal */
+ arm_bitreversal_f32(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
+ }
+
+}
+
+/**
+* @} end of ComplexFFT group
+*/
+
+/* ----------------------------------------------------------------------
+ * Internal helper function used by the FFTs
+ * ---------------------------------------------------------------------- */
+
+/*
+* @brief Core function for the floating-point CFFT butterfly process.
+* @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
+* @param[in] fftLen length of the FFT.
+* @param[in] *pCoef points to the twiddle coefficient buffer.
+* @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
+* @return none.
+*/
+
+void arm_radix4_butterfly_f32(
+float32_t * pSrc,
+uint16_t fftLen,
+float32_t * pCoef,
+uint16_t twidCoefModifier)
+{
+
+ float32_t co1, co2, co3, si1, si2, si3;
+ uint32_t ia1, ia2, ia3;
+ uint32_t i0, i1, i2, i3;
+ uint32_t n1, n2, j, k;
+
+#if defined (ARM_MATH_DSP)
+
+ /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+ float32_t xaIn, yaIn, xbIn, ybIn, xcIn, ycIn, xdIn, ydIn;
+ float32_t Xaplusc, Xbplusd, Yaplusc, Ybplusd, Xaminusc, Xbminusd, Yaminusc,
+ Ybminusd;
+ float32_t Xb12C_out, Yb12C_out, Xc12C_out, Yc12C_out, Xd12C_out, Yd12C_out;
+ float32_t Xb12_out, Yb12_out, Xc12_out, Yc12_out, Xd12_out, Yd12_out;
+ float32_t *ptr1;
+ float32_t p0,p1,p2,p3,p4,p5;
+ float32_t a0,a1,a2,a3,a4,a5,a6,a7;
+
+ /* Initializations for the first stage */
+ n2 = fftLen;
+ n1 = n2;
+
+ /* n2 = fftLen/4 */
+ n2 >>= 2U;
+ i0 = 0U;
+ ia1 = 0U;
+
+ j = n2;
+
+ /* Calculation of first stage */
+ do
+ {
+ /* index calculation for the input as, */
+ /* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
+ i1 = i0 + n2;
+ i2 = i1 + n2;
+ i3 = i2 + n2;
+
+ xaIn = pSrc[(2U * i0)];
+ yaIn = pSrc[(2U * i0) + 1U];
+
+ xbIn = pSrc[(2U * i1)];
+ ybIn = pSrc[(2U * i1) + 1U];
+
+ xcIn = pSrc[(2U * i2)];
+ ycIn = pSrc[(2U * i2) + 1U];
+
+ xdIn = pSrc[(2U * i3)];
+ ydIn = pSrc[(2U * i3) + 1U];
+
+ /* xa + xc */
+ Xaplusc = xaIn + xcIn;
+ /* xb + xd */
+ Xbplusd = xbIn + xdIn;
+ /* ya + yc */
+ Yaplusc = yaIn + ycIn;
+ /* yb + yd */
+ Ybplusd = ybIn + ydIn;
+
+ /* index calculation for the coefficients */
+ ia2 = ia1 + ia1;
+ co2 = pCoef[ia2 * 2U];
+ si2 = pCoef[(ia2 * 2U) + 1U];
+
+ /* xa - xc */
+ Xaminusc = xaIn - xcIn;
+ /* xb - xd */
+ Xbminusd = xbIn - xdIn;
+ /* ya - yc */
+ Yaminusc = yaIn - ycIn;
+ /* yb - yd */
+ Ybminusd = ybIn - ydIn;
+
+ /* xa' = xa + xb + xc + xd */
+ pSrc[(2U * i0)] = Xaplusc + Xbplusd;
+ /* ya' = ya + yb + yc + yd */
+ pSrc[(2U * i0) + 1U] = Yaplusc + Ybplusd;
+
+ /* (xa - xc) + (yb - yd) */
+ Xb12C_out = (Xaminusc + Ybminusd);
+ /* (ya - yc) + (xb - xd) */
+ Yb12C_out = (Yaminusc - Xbminusd);
+ /* (xa + xc) - (xb + xd) */
+ Xc12C_out = (Xaplusc - Xbplusd);
+ /* (ya + yc) - (yb + yd) */
+ Yc12C_out = (Yaplusc - Ybplusd);
+ /* (xa - xc) - (yb - yd) */
+ Xd12C_out = (Xaminusc - Ybminusd);
+ /* (ya - yc) + (xb - xd) */
+ Yd12C_out = (Xbminusd + Yaminusc);
+
+ co1 = pCoef[ia1 * 2U];
+ si1 = pCoef[(ia1 * 2U) + 1U];
+
+ /* index calculation for the coefficients */
+ ia3 = ia2 + ia1;
+ co3 = pCoef[ia3 * 2U];
+ si3 = pCoef[(ia3 * 2U) + 1U];
+
+ Xb12_out = Xb12C_out * co1;
+ Yb12_out = Yb12C_out * co1;
+ Xc12_out = Xc12C_out * co2;
+ Yc12_out = Yc12C_out * co2;
+ Xd12_out = Xd12C_out * co3;
+ Yd12_out = Yd12C_out * co3;
+
+ /* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */
+ //Xb12_out -= Yb12C_out * si1;
+ p0 = Yb12C_out * si1;
+ /* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */
+ //Yb12_out += Xb12C_out * si1;
+ p1 = Xb12C_out * si1;
+ /* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */
+ //Xc12_out -= Yc12C_out * si2;
+ p2 = Yc12C_out * si2;
+ /* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */
+ //Yc12_out += Xc12C_out * si2;
+ p3 = Xc12C_out * si2;
+ /* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */
+ //Xd12_out -= Yd12C_out * si3;
+ p4 = Yd12C_out * si3;
+ /* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */
+ //Yd12_out += Xd12C_out * si3;
+ p5 = Xd12C_out * si3;
+
+ Xb12_out += p0;
+ Yb12_out -= p1;
+ Xc12_out += p2;
+ Yc12_out -= p3;
+ Xd12_out += p4;
+ Yd12_out -= p5;
+
+ /* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */
+ pSrc[2U * i1] = Xc12_out;
+
+ /* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */
+ pSrc[(2U * i1) + 1U] = Yc12_out;
+
+ /* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */
+ pSrc[2U * i2] = Xb12_out;
+
+ /* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */
+ pSrc[(2U * i2) + 1U] = Yb12_out;
+
+ /* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */
+ pSrc[2U * i3] = Xd12_out;
+
+ /* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */
+ pSrc[(2U * i3) + 1U] = Yd12_out;
+
+ /* Twiddle coefficients index modifier */
+ ia1 += twidCoefModifier;
+
+ /* Updating input index */
+ i0++;
+
+ }
+ while (--j);
+
+ twidCoefModifier <<= 2U;
+
+ /* Calculation of second stage to excluding last stage */
+ for (k = fftLen >> 2U; k > 4U; k >>= 2U)
+ {
+ /* Initializations for the first stage */
+ n1 = n2;
+ n2 >>= 2U;
+ ia1 = 0U;
+
+ /* Calculation of first stage */
+ j = 0;
+ do
+ {
+ /* index calculation for the coefficients */
+ ia2 = ia1 + ia1;
+ ia3 = ia2 + ia1;
+ co1 = pCoef[ia1 * 2U];
+ si1 = pCoef[(ia1 * 2U) + 1U];
+ co2 = pCoef[ia2 * 2U];
+ si2 = pCoef[(ia2 * 2U) + 1U];
+ co3 = pCoef[ia3 * 2U];
+ si3 = pCoef[(ia3 * 2U) + 1U];
+
+ /* Twiddle coefficients index modifier */
+ ia1 += twidCoefModifier;
+
+ i0 = j;
+ do
+ {
+ /* index calculation for the input as, */
+ /* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
+ i1 = i0 + n2;
+ i2 = i1 + n2;
+ i3 = i2 + n2;
+
+ xaIn = pSrc[(2U * i0)];
+ yaIn = pSrc[(2U * i0) + 1U];
+
+ xbIn = pSrc[(2U * i1)];
+ ybIn = pSrc[(2U * i1) + 1U];
+
+ xcIn = pSrc[(2U * i2)];
+ ycIn = pSrc[(2U * i2) + 1U];
+
+ xdIn = pSrc[(2U * i3)];
+ ydIn = pSrc[(2U * i3) + 1U];
+
+ /* xa - xc */
+ Xaminusc = xaIn - xcIn;
+ /* (xb - xd) */
+ Xbminusd = xbIn - xdIn;
+ /* ya - yc */
+ Yaminusc = yaIn - ycIn;
+ /* (yb - yd) */
+ Ybminusd = ybIn - ydIn;
+
+ /* xa + xc */
+ Xaplusc = xaIn + xcIn;
+ /* xb + xd */
+ Xbplusd = xbIn + xdIn;
+ /* ya + yc */
+ Yaplusc = yaIn + ycIn;
+ /* yb + yd */
+ Ybplusd = ybIn + ydIn;
+
+ /* (xa - xc) + (yb - yd) */
+ Xb12C_out = (Xaminusc + Ybminusd);
+ /* (ya - yc) - (xb - xd) */
+ Yb12C_out = (Yaminusc - Xbminusd);
+ /* xa + xc -(xb + xd) */
+ Xc12C_out = (Xaplusc - Xbplusd);
+ /* (ya + yc) - (yb + yd) */
+ Yc12C_out = (Yaplusc - Ybplusd);
+ /* (xa - xc) - (yb - yd) */
+ Xd12C_out = (Xaminusc - Ybminusd);
+ /* (ya - yc) + (xb - xd) */
+ Yd12C_out = (Xbminusd + Yaminusc);
+
+ pSrc[(2U * i0)] = Xaplusc + Xbplusd;
+ pSrc[(2U * i0) + 1U] = Yaplusc + Ybplusd;
+
+ Xb12_out = Xb12C_out * co1;
+ Yb12_out = Yb12C_out * co1;
+ Xc12_out = Xc12C_out * co2;
+ Yc12_out = Yc12C_out * co2;
+ Xd12_out = Xd12C_out * co3;
+ Yd12_out = Yd12C_out * co3;
+
+ /* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */
+ //Xb12_out -= Yb12C_out * si1;
+ p0 = Yb12C_out * si1;
+ /* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */
+ //Yb12_out += Xb12C_out * si1;
+ p1 = Xb12C_out * si1;
+ /* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */
+ //Xc12_out -= Yc12C_out * si2;
+ p2 = Yc12C_out * si2;
+ /* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */
+ //Yc12_out += Xc12C_out * si2;
+ p3 = Xc12C_out * si2;
+ /* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */
+ //Xd12_out -= Yd12C_out * si3;
+ p4 = Yd12C_out * si3;
+ /* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */
+ //Yd12_out += Xd12C_out * si3;
+ p5 = Xd12C_out * si3;
+
+ Xb12_out += p0;
+ Yb12_out -= p1;
+ Xc12_out += p2;
+ Yc12_out -= p3;
+ Xd12_out += p4;
+ Yd12_out -= p5;
+
+ /* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */
+ pSrc[2U * i1] = Xc12_out;
+
+ /* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */
+ pSrc[(2U * i1) + 1U] = Yc12_out;
+
+ /* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */
+ pSrc[2U * i2] = Xb12_out;
+
+ /* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */
+ pSrc[(2U * i2) + 1U] = Yb12_out;
+
+ /* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */
+ pSrc[2U * i3] = Xd12_out;
+
+ /* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */
+ pSrc[(2U * i3) + 1U] = Yd12_out;
+
+ i0 += n1;
+ } while (i0 < fftLen);
+ j++;
+ } while (j <= (n2 - 1U));
+ twidCoefModifier <<= 2U;
+ }
+
+ j = fftLen >> 2;
+ ptr1 = &pSrc[0];
+
+ /* Calculations of last stage */
+ do
+ {
+ xaIn = ptr1[0];
+ yaIn = ptr1[1];
+ xbIn = ptr1[2];
+ ybIn = ptr1[3];
+ xcIn = ptr1[4];
+ ycIn = ptr1[5];
+ xdIn = ptr1[6];
+ ydIn = ptr1[7];
+
+ /* xa + xc */
+ Xaplusc = xaIn + xcIn;
+
+ /* xa - xc */
+ Xaminusc = xaIn - xcIn;
+
+ /* ya + yc */
+ Yaplusc = yaIn + ycIn;
+
+ /* ya - yc */
+ Yaminusc = yaIn - ycIn;
+
+ /* xb + xd */
+ Xbplusd = xbIn + xdIn;
+
+ /* yb + yd */
+ Ybplusd = ybIn + ydIn;
+
+ /* (xb-xd) */
+ Xbminusd = xbIn - xdIn;
+
+ /* (yb-yd) */
+ Ybminusd = ybIn - ydIn;
+
+ /* xa' = xa + xb + xc + xd */
+ a0 = (Xaplusc + Xbplusd);
+ /* ya' = ya + yb + yc + yd */
+ a1 = (Yaplusc + Ybplusd);
+ /* xc' = (xa-xb+xc-xd) */
+ a2 = (Xaplusc - Xbplusd);
+ /* yc' = (ya-yb+yc-yd) */
+ a3 = (Yaplusc - Ybplusd);
+ /* xb' = (xa+yb-xc-yd) */
+ a4 = (Xaminusc + Ybminusd);
+ /* yb' = (ya-xb-yc+xd) */
+ a5 = (Yaminusc - Xbminusd);
+ /* xd' = (xa-yb-xc+yd)) */
+ a6 = (Xaminusc - Ybminusd);
+ /* yd' = (ya+xb-yc-xd) */
+ a7 = (Xbminusd + Yaminusc);
+
+ ptr1[0] = a0;
+ ptr1[1] = a1;
+ ptr1[2] = a2;
+ ptr1[3] = a3;
+ ptr1[4] = a4;
+ ptr1[5] = a5;
+ ptr1[6] = a6;
+ ptr1[7] = a7;
+
+ /* increment pointer by 8 */
+ ptr1 += 8U;
+ } while (--j);
+
+#else
+
+ float32_t t1, t2, r1, r2, s1, s2;
+
+ /* Run the below code for Cortex-M0 */
+
+ /* Initializations for the fft calculation */
+ n2 = fftLen;
+ n1 = n2;
+ for (k = fftLen; k > 1U; k >>= 2U)
+ {
+ /* Initializations for the fft calculation */
+ n1 = n2;
+ n2 >>= 2U;
+ ia1 = 0U;
+
+ /* FFT Calculation */
+ j = 0;
+ do
+ {
+ /* index calculation for the coefficients */
+ ia2 = ia1 + ia1;
+ ia3 = ia2 + ia1;
+ co1 = pCoef[ia1 * 2U];
+ si1 = pCoef[(ia1 * 2U) + 1U];
+ co2 = pCoef[ia2 * 2U];
+ si2 = pCoef[(ia2 * 2U) + 1U];
+ co3 = pCoef[ia3 * 2U];
+ si3 = pCoef[(ia3 * 2U) + 1U];
+
+ /* Twiddle coefficients index modifier */
+ ia1 = ia1 + twidCoefModifier;
+
+ i0 = j;
+ do
+ {
+ /* index calculation for the input as, */
+ /* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
+ i1 = i0 + n2;
+ i2 = i1 + n2;
+ i3 = i2 + n2;
+
+ /* xa + xc */
+ r1 = pSrc[(2U * i0)] + pSrc[(2U * i2)];
+
+ /* xa - xc */
+ r2 = pSrc[(2U * i0)] - pSrc[(2U * i2)];
+
+ /* ya + yc */
+ s1 = pSrc[(2U * i0) + 1U] + pSrc[(2U * i2) + 1U];
+
+ /* ya - yc */
+ s2 = pSrc[(2U * i0) + 1U] - pSrc[(2U * i2) + 1U];
+
+ /* xb + xd */
+ t1 = pSrc[2U * i1] + pSrc[2U * i3];
+
+ /* xa' = xa + xb + xc + xd */
+ pSrc[2U * i0] = r1 + t1;
+
+ /* xa + xc -(xb + xd) */
+ r1 = r1 - t1;
+
+ /* yb + yd */
+ t2 = pSrc[(2U * i1) + 1U] + pSrc[(2U * i3) + 1U];
+
+ /* ya' = ya + yb + yc + yd */
+ pSrc[(2U * i0) + 1U] = s1 + t2;
+
+ /* (ya + yc) - (yb + yd) */
+ s1 = s1 - t2;
+
+ /* (yb - yd) */
+ t1 = pSrc[(2U * i1) + 1U] - pSrc[(2U * i3) + 1U];
+
+ /* (xb - xd) */
+ t2 = pSrc[2U * i1] - pSrc[2U * i3];
+
+ /* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */
+ pSrc[2U * i1] = (r1 * co2) + (s1 * si2);
+
+ /* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */
+ pSrc[(2U * i1) + 1U] = (s1 * co2) - (r1 * si2);
+
+ /* (xa - xc) + (yb - yd) */
+ r1 = r2 + t1;
+
+ /* (xa - xc) - (yb - yd) */
+ r2 = r2 - t1;
+
+ /* (ya - yc) - (xb - xd) */
+ s1 = s2 - t2;
+
+ /* (ya - yc) + (xb - xd) */
+ s2 = s2 + t2;
+
+ /* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */
+ pSrc[2U * i2] = (r1 * co1) + (s1 * si1);
+
+ /* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */
+ pSrc[(2U * i2) + 1U] = (s1 * co1) - (r1 * si1);
+
+ /* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */
+ pSrc[2U * i3] = (r2 * co3) + (s2 * si3);
+
+ /* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */
+ pSrc[(2U * i3) + 1U] = (s2 * co3) - (r2 * si3);
+
+ i0 += n1;
+ } while ( i0 < fftLen);
+ j++;
+ } while (j <= (n2 - 1U));
+ twidCoefModifier <<= 2U;
+ }
+
+#endif /* #if defined (ARM_MATH_DSP) */
+
+}
+
+/*
+* @brief Core function for the floating-point CIFFT butterfly process.
+* @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
+* @param[in] fftLen length of the FFT.
+* @param[in] *pCoef points to twiddle coefficient buffer.
+* @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
+* @param[in] onebyfftLen value of 1/fftLen.
+* @return none.
+*/
+
+void arm_radix4_butterfly_inverse_f32(
+float32_t * pSrc,
+uint16_t fftLen,
+float32_t * pCoef,
+uint16_t twidCoefModifier,
+float32_t onebyfftLen)
+{
+ float32_t co1, co2, co3, si1, si2, si3;
+ uint32_t ia1, ia2, ia3;
+ uint32_t i0, i1, i2, i3;
+ uint32_t n1, n2, j, k;
+
+#if defined (ARM_MATH_DSP)
+
+ float32_t xaIn, yaIn, xbIn, ybIn, xcIn, ycIn, xdIn, ydIn;
+ float32_t Xaplusc, Xbplusd, Yaplusc, Ybplusd, Xaminusc, Xbminusd, Yaminusc,
+ Ybminusd;
+ float32_t Xb12C_out, Yb12C_out, Xc12C_out, Yc12C_out, Xd12C_out, Yd12C_out;
+ float32_t Xb12_out, Yb12_out, Xc12_out, Yc12_out, Xd12_out, Yd12_out;
+ float32_t *ptr1;
+ float32_t p0,p1,p2,p3,p4,p5,p6,p7;
+ float32_t a0,a1,a2,a3,a4,a5,a6,a7;
+
+
+ /* Initializations for the first stage */
+ n2 = fftLen;
+ n1 = n2;
+
+ /* n2 = fftLen/4 */
+ n2 >>= 2U;
+ i0 = 0U;
+ ia1 = 0U;
+
+ j = n2;
+
+ /* Calculation of first stage */
+ do
+ {
+ /* index calculation for the input as, */
+ /* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
+ i1 = i0 + n2;
+ i2 = i1 + n2;
+ i3 = i2 + n2;
+
+ /* Butterfly implementation */
+ xaIn = pSrc[(2U * i0)];
+ yaIn = pSrc[(2U * i0) + 1U];
+
+ xcIn = pSrc[(2U * i2)];
+ ycIn = pSrc[(2U * i2) + 1U];
+
+ xbIn = pSrc[(2U * i1)];
+ ybIn = pSrc[(2U * i1) + 1U];
+
+ xdIn = pSrc[(2U * i3)];
+ ydIn = pSrc[(2U * i3) + 1U];
+
+ /* xa + xc */
+ Xaplusc = xaIn + xcIn;
+ /* xb + xd */
+ Xbplusd = xbIn + xdIn;
+ /* ya + yc */
+ Yaplusc = yaIn + ycIn;
+ /* yb + yd */
+ Ybplusd = ybIn + ydIn;
+
+ /* index calculation for the coefficients */
+ ia2 = ia1 + ia1;
+ co2 = pCoef[ia2 * 2U];
+ si2 = pCoef[(ia2 * 2U) + 1U];
+
+ /* xa - xc */
+ Xaminusc = xaIn - xcIn;
+ /* xb - xd */
+ Xbminusd = xbIn - xdIn;
+ /* ya - yc */
+ Yaminusc = yaIn - ycIn;
+ /* yb - yd */
+ Ybminusd = ybIn - ydIn;
+
+ /* xa' = xa + xb + xc + xd */
+ pSrc[(2U * i0)] = Xaplusc + Xbplusd;
+
+ /* ya' = ya + yb + yc + yd */
+ pSrc[(2U * i0) + 1U] = Yaplusc + Ybplusd;
+
+ /* (xa - xc) - (yb - yd) */
+ Xb12C_out = (Xaminusc - Ybminusd);
+ /* (ya - yc) + (xb - xd) */
+ Yb12C_out = (Yaminusc + Xbminusd);
+ /* (xa + xc) - (xb + xd) */
+ Xc12C_out = (Xaplusc - Xbplusd);
+ /* (ya + yc) - (yb + yd) */
+ Yc12C_out = (Yaplusc - Ybplusd);
+ /* (xa - xc) + (yb - yd) */
+ Xd12C_out = (Xaminusc + Ybminusd);
+ /* (ya - yc) - (xb - xd) */
+ Yd12C_out = (Yaminusc - Xbminusd);
+
+ co1 = pCoef[ia1 * 2U];
+ si1 = pCoef[(ia1 * 2U) + 1U];
+
+ /* index calculation for the coefficients */
+ ia3 = ia2 + ia1;
+ co3 = pCoef[ia3 * 2U];
+ si3 = pCoef[(ia3 * 2U) + 1U];
+
+ Xb12_out = Xb12C_out * co1;
+ Yb12_out = Yb12C_out * co1;
+ Xc12_out = Xc12C_out * co2;
+ Yc12_out = Yc12C_out * co2;
+ Xd12_out = Xd12C_out * co3;
+ Yd12_out = Yd12C_out * co3;
+
+ /* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */
+ //Xb12_out -= Yb12C_out * si1;
+ p0 = Yb12C_out * si1;
+ /* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */
+ //Yb12_out += Xb12C_out * si1;
+ p1 = Xb12C_out * si1;
+ /* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */
+ //Xc12_out -= Yc12C_out * si2;
+ p2 = Yc12C_out * si2;
+ /* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */
+ //Yc12_out += Xc12C_out * si2;
+ p3 = Xc12C_out * si2;
+ /* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */
+ //Xd12_out -= Yd12C_out * si3;
+ p4 = Yd12C_out * si3;
+ /* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */
+ //Yd12_out += Xd12C_out * si3;
+ p5 = Xd12C_out * si3;
+
+ Xb12_out -= p0;
+ Yb12_out += p1;
+ Xc12_out -= p2;
+ Yc12_out += p3;
+ Xd12_out -= p4;
+ Yd12_out += p5;
+
+ /* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */
+ pSrc[2U * i1] = Xc12_out;
+
+ /* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */
+ pSrc[(2U * i1) + 1U] = Yc12_out;
+
+ /* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */
+ pSrc[2U * i2] = Xb12_out;
+
+ /* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */
+ pSrc[(2U * i2) + 1U] = Yb12_out;
+
+ /* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */
+ pSrc[2U * i3] = Xd12_out;
+
+ /* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */
+ pSrc[(2U * i3) + 1U] = Yd12_out;
+
+ /* Twiddle coefficients index modifier */
+ ia1 = ia1 + twidCoefModifier;
+
+ /* Updating input index */
+ i0 = i0 + 1U;
+
+ } while (--j);
+
+ twidCoefModifier <<= 2U;
+
+ /* Calculation of second stage to excluding last stage */
+ for (k = fftLen >> 2U; k > 4U; k >>= 2U)
+ {
+ /* Initializations for the first stage */
+ n1 = n2;
+ n2 >>= 2U;
+ ia1 = 0U;
+
+ /* Calculation of first stage */
+ j = 0;
+ do
+ {
+ /* index calculation for the coefficients */
+ ia2 = ia1 + ia1;
+ ia3 = ia2 + ia1;
+ co1 = pCoef[ia1 * 2U];
+ si1 = pCoef[(ia1 * 2U) + 1U];
+ co2 = pCoef[ia2 * 2U];
+ si2 = pCoef[(ia2 * 2U) + 1U];
+ co3 = pCoef[ia3 * 2U];
+ si3 = pCoef[(ia3 * 2U) + 1U];
+
+ /* Twiddle coefficients index modifier */
+ ia1 = ia1 + twidCoefModifier;
+
+ i0 = j;
+ do
+ {
+ /* index calculation for the input as, */
+ /* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
+ i1 = i0 + n2;
+ i2 = i1 + n2;
+ i3 = i2 + n2;
+
+ xaIn = pSrc[(2U * i0)];
+ yaIn = pSrc[(2U * i0) + 1U];
+
+ xbIn = pSrc[(2U * i1)];
+ ybIn = pSrc[(2U * i1) + 1U];
+
+ xcIn = pSrc[(2U * i2)];
+ ycIn = pSrc[(2U * i2) + 1U];
+
+ xdIn = pSrc[(2U * i3)];
+ ydIn = pSrc[(2U * i3) + 1U];
+
+ /* xa - xc */
+ Xaminusc = xaIn - xcIn;
+ /* (xb - xd) */
+ Xbminusd = xbIn - xdIn;
+ /* ya - yc */
+ Yaminusc = yaIn - ycIn;
+ /* (yb - yd) */
+ Ybminusd = ybIn - ydIn;
+
+ /* xa + xc */
+ Xaplusc = xaIn + xcIn;
+ /* xb + xd */
+ Xbplusd = xbIn + xdIn;
+ /* ya + yc */
+ Yaplusc = yaIn + ycIn;
+ /* yb + yd */
+ Ybplusd = ybIn + ydIn;
+
+ /* (xa - xc) - (yb - yd) */
+ Xb12C_out = (Xaminusc - Ybminusd);
+ /* (ya - yc) + (xb - xd) */
+ Yb12C_out = (Yaminusc + Xbminusd);
+ /* xa + xc -(xb + xd) */
+ Xc12C_out = (Xaplusc - Xbplusd);
+ /* (ya + yc) - (yb + yd) */
+ Yc12C_out = (Yaplusc - Ybplusd);
+ /* (xa - xc) + (yb - yd) */
+ Xd12C_out = (Xaminusc + Ybminusd);
+ /* (ya - yc) - (xb - xd) */
+ Yd12C_out = (Yaminusc - Xbminusd);
+
+ pSrc[(2U * i0)] = Xaplusc + Xbplusd;
+ pSrc[(2U * i0) + 1U] = Yaplusc + Ybplusd;
+
+ Xb12_out = Xb12C_out * co1;
+ Yb12_out = Yb12C_out * co1;
+ Xc12_out = Xc12C_out * co2;
+ Yc12_out = Yc12C_out * co2;
+ Xd12_out = Xd12C_out * co3;
+ Yd12_out = Yd12C_out * co3;
+
+ /* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */
+ //Xb12_out -= Yb12C_out * si1;
+ p0 = Yb12C_out * si1;
+ /* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */
+ //Yb12_out += Xb12C_out * si1;
+ p1 = Xb12C_out * si1;
+ /* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */
+ //Xc12_out -= Yc12C_out * si2;
+ p2 = Yc12C_out * si2;
+ /* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */
+ //Yc12_out += Xc12C_out * si2;
+ p3 = Xc12C_out * si2;
+ /* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */
+ //Xd12_out -= Yd12C_out * si3;
+ p4 = Yd12C_out * si3;
+ /* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */
+ //Yd12_out += Xd12C_out * si3;
+ p5 = Xd12C_out * si3;
+
+ Xb12_out -= p0;
+ Yb12_out += p1;
+ Xc12_out -= p2;
+ Yc12_out += p3;
+ Xd12_out -= p4;
+ Yd12_out += p5;
+
+ /* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */
+ pSrc[2U * i1] = Xc12_out;
+
+ /* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */
+ pSrc[(2U * i1) + 1U] = Yc12_out;
+
+ /* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */
+ pSrc[2U * i2] = Xb12_out;
+
+ /* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */
+ pSrc[(2U * i2) + 1U] = Yb12_out;
+
+ /* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */
+ pSrc[2U * i3] = Xd12_out;
+
+ /* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */
+ pSrc[(2U * i3) + 1U] = Yd12_out;
+
+ i0 += n1;
+ } while (i0 < fftLen);
+ j++;
+ } while (j <= (n2 - 1U));
+ twidCoefModifier <<= 2U;
+ }
+ /* Initializations of last stage */
+
+ j = fftLen >> 2;
+ ptr1 = &pSrc[0];
+
+ /* Calculations of last stage */
+ do
+ {
+ xaIn = ptr1[0];
+ yaIn = ptr1[1];
+ xbIn = ptr1[2];
+ ybIn = ptr1[3];
+ xcIn = ptr1[4];
+ ycIn = ptr1[5];
+ xdIn = ptr1[6];
+ ydIn = ptr1[7];
+
+ /* Butterfly implementation */
+ /* xa + xc */
+ Xaplusc = xaIn + xcIn;
+
+ /* xa - xc */
+ Xaminusc = xaIn - xcIn;
+
+ /* ya + yc */
+ Yaplusc = yaIn + ycIn;
+
+ /* ya - yc */
+ Yaminusc = yaIn - ycIn;
+
+ /* xb + xd */
+ Xbplusd = xbIn + xdIn;
+
+ /* yb + yd */
+ Ybplusd = ybIn + ydIn;
+
+ /* (xb-xd) */
+ Xbminusd = xbIn - xdIn;
+
+ /* (yb-yd) */
+ Ybminusd = ybIn - ydIn;
+
+ /* xa' = (xa+xb+xc+xd) * onebyfftLen */
+ a0 = (Xaplusc + Xbplusd);
+ /* ya' = (ya+yb+yc+yd) * onebyfftLen */
+ a1 = (Yaplusc + Ybplusd);
+ /* xc' = (xa-xb+xc-xd) * onebyfftLen */
+ a2 = (Xaplusc - Xbplusd);
+ /* yc' = (ya-yb+yc-yd) * onebyfftLen */
+ a3 = (Yaplusc - Ybplusd);
+ /* xb' = (xa-yb-xc+yd) * onebyfftLen */
+ a4 = (Xaminusc - Ybminusd);
+ /* yb' = (ya+xb-yc-xd) * onebyfftLen */
+ a5 = (Yaminusc + Xbminusd);
+ /* xd' = (xa-yb-xc+yd) * onebyfftLen */
+ a6 = (Xaminusc + Ybminusd);
+ /* yd' = (ya-xb-yc+xd) * onebyfftLen */
+ a7 = (Yaminusc - Xbminusd);
+
+ p0 = a0 * onebyfftLen;
+ p1 = a1 * onebyfftLen;
+ p2 = a2 * onebyfftLen;
+ p3 = a3 * onebyfftLen;
+ p4 = a4 * onebyfftLen;
+ p5 = a5 * onebyfftLen;
+ p6 = a6 * onebyfftLen;
+ p7 = a7 * onebyfftLen;
+
+ /* xa' = (xa+xb+xc+xd) * onebyfftLen */
+ ptr1[0] = p0;
+ /* ya' = (ya+yb+yc+yd) * onebyfftLen */
+ ptr1[1] = p1;
+ /* xc' = (xa-xb+xc-xd) * onebyfftLen */
+ ptr1[2] = p2;
+ /* yc' = (ya-yb+yc-yd) * onebyfftLen */
+ ptr1[3] = p3;
+ /* xb' = (xa-yb-xc+yd) * onebyfftLen */
+ ptr1[4] = p4;
+ /* yb' = (ya+xb-yc-xd) * onebyfftLen */
+ ptr1[5] = p5;
+ /* xd' = (xa-yb-xc+yd) * onebyfftLen */
+ ptr1[6] = p6;
+ /* yd' = (ya-xb-yc+xd) * onebyfftLen */
+ ptr1[7] = p7;
+
+ /* increment source pointer by 8 for next calculations */
+ ptr1 = ptr1 + 8U;
+
+ } while (--j);
+
+#else
+
+ float32_t t1, t2, r1, r2, s1, s2;
+
+ /* Run the below code for Cortex-M0 */
+
+ /* Initializations for the first stage */
+ n2 = fftLen;
+ n1 = n2;
+
+ /* Calculation of first stage */
+ for (k = fftLen; k > 4U; k >>= 2U)
+ {
+ /* Initializations for the first stage */
+ n1 = n2;
+ n2 >>= 2U;
+ ia1 = 0U;
+
+ /* Calculation of first stage */
+ j = 0;
+ do
+ {
+ /* index calculation for the coefficients */
+ ia2 = ia1 + ia1;
+ ia3 = ia2 + ia1;
+ co1 = pCoef[ia1 * 2U];
+ si1 = pCoef[(ia1 * 2U) + 1U];
+ co2 = pCoef[ia2 * 2U];
+ si2 = pCoef[(ia2 * 2U) + 1U];
+ co3 = pCoef[ia3 * 2U];
+ si3 = pCoef[(ia3 * 2U) + 1U];
+
+ /* Twiddle coefficients index modifier */
+ ia1 = ia1 + twidCoefModifier;
+
+ i0 = j;
+ do
+ {
+ /* index calculation for the input as, */
+ /* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
+ i1 = i0 + n2;
+ i2 = i1 + n2;
+ i3 = i2 + n2;
+
+ /* xa + xc */
+ r1 = pSrc[(2U * i0)] + pSrc[(2U * i2)];
+
+ /* xa - xc */
+ r2 = pSrc[(2U * i0)] - pSrc[(2U * i2)];
+
+ /* ya + yc */
+ s1 = pSrc[(2U * i0) + 1U] + pSrc[(2U * i2) + 1U];
+
+ /* ya - yc */
+ s2 = pSrc[(2U * i0) + 1U] - pSrc[(2U * i2) + 1U];
+
+ /* xb + xd */
+ t1 = pSrc[2U * i1] + pSrc[2U * i3];
+
+ /* xa' = xa + xb + xc + xd */
+ pSrc[2U * i0] = r1 + t1;
+
+ /* xa + xc -(xb + xd) */
+ r1 = r1 - t1;
+
+ /* yb + yd */
+ t2 = pSrc[(2U * i1) + 1U] + pSrc[(2U * i3) + 1U];
+
+ /* ya' = ya + yb + yc + yd */
+ pSrc[(2U * i0) + 1U] = s1 + t2;
+
+ /* (ya + yc) - (yb + yd) */
+ s1 = s1 - t2;
+
+ /* (yb - yd) */
+ t1 = pSrc[(2U * i1) + 1U] - pSrc[(2U * i3) + 1U];
+
+ /* (xb - xd) */
+ t2 = pSrc[2U * i1] - pSrc[2U * i3];
+
+ /* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */
+ pSrc[2U * i1] = (r1 * co2) - (s1 * si2);
+
+ /* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */
+ pSrc[(2U * i1) + 1U] = (s1 * co2) + (r1 * si2);
+
+ /* (xa - xc) - (yb - yd) */
+ r1 = r2 - t1;
+
+ /* (xa - xc) + (yb - yd) */
+ r2 = r2 + t1;
+
+ /* (ya - yc) + (xb - xd) */
+ s1 = s2 + t2;
+
+ /* (ya - yc) - (xb - xd) */
+ s2 = s2 - t2;
+
+ /* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */
+ pSrc[2U * i2] = (r1 * co1) - (s1 * si1);
+
+ /* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */
+ pSrc[(2U * i2) + 1U] = (s1 * co1) + (r1 * si1);
+
+ /* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */
+ pSrc[2U * i3] = (r2 * co3) - (s2 * si3);
+
+ /* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */
+ pSrc[(2U * i3) + 1U] = (s2 * co3) + (r2 * si3);
+
+ i0 += n1;
+ } while ( i0 < fftLen);
+ j++;
+ } while (j <= (n2 - 1U));
+ twidCoefModifier <<= 2U;
+ }
+ /* Initializations of last stage */
+ n1 = n2;
+ n2 >>= 2U;
+
+ /* Calculations of last stage */
+ for (i0 = 0U; i0 <= (fftLen - n1); i0 += n1)
+ {
+ /* index calculation for the input as, */
+ /* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
+ i1 = i0 + n2;
+ i2 = i1 + n2;
+ i3 = i2 + n2;
+
+ /* Butterfly implementation */
+ /* xa + xc */
+ r1 = pSrc[2U * i0] + pSrc[2U * i2];
+
+ /* xa - xc */
+ r2 = pSrc[2U * i0] - pSrc[2U * i2];
+
+ /* ya + yc */
+ s1 = pSrc[(2U * i0) + 1U] + pSrc[(2U * i2) + 1U];
+
+ /* ya - yc */
+ s2 = pSrc[(2U * i0) + 1U] - pSrc[(2U * i2) + 1U];
+
+ /* xc + xd */
+ t1 = pSrc[2U * i1] + pSrc[2U * i3];
+
+ /* xa' = xa + xb + xc + xd */
+ pSrc[2U * i0] = (r1 + t1) * onebyfftLen;
+
+ /* (xa + xb) - (xc + xd) */
+ r1 = r1 - t1;
+
+ /* yb + yd */
+ t2 = pSrc[(2U * i1) + 1U] + pSrc[(2U * i3) + 1U];
+
+ /* ya' = ya + yb + yc + yd */
+ pSrc[(2U * i0) + 1U] = (s1 + t2) * onebyfftLen;
+
+ /* (ya + yc) - (yb + yd) */
+ s1 = s1 - t2;
+
+ /* (yb-yd) */
+ t1 = pSrc[(2U * i1) + 1U] - pSrc[(2U * i3) + 1U];
+
+ /* (xb-xd) */
+ t2 = pSrc[2U * i1] - pSrc[2U * i3];
+
+ /* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */
+ pSrc[2U * i1] = r1 * onebyfftLen;
+
+ /* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */
+ pSrc[(2U * i1) + 1U] = s1 * onebyfftLen;
+
+ /* (xa - xc) - (yb-yd) */
+ r1 = r2 - t1;
+
+ /* (xa - xc) + (yb-yd) */
+ r2 = r2 + t1;
+
+ /* (ya - yc) + (xb-xd) */
+ s1 = s2 + t2;
+
+ /* (ya - yc) - (xb-xd) */
+ s2 = s2 - t2;
+
+ /* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */
+ pSrc[2U * i2] = r1 * onebyfftLen;
+
+ /* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */
+ pSrc[(2U * i2) + 1U] = s1 * onebyfftLen;
+
+ /* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */
+ pSrc[2U * i3] = r2 * onebyfftLen;
+
+ /* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */
+ pSrc[(2U * i3) + 1U] = s2 * onebyfftLen;
+ }
+
+#endif /* #if defined (ARM_MATH_DSP) */
+}
+
+