diff options
Diffstat (limited to 'Drivers/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix2_q15.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix2_q15.c | 689 |
1 files changed, 689 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix2_q15.c b/Drivers/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix2_q15.c new file mode 100644 index 0000000..fbb809e --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix2_q15.c @@ -0,0 +1,689 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_cfft_radix2_q15.c
+ * Description: Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function
+ *
+ * $Date: 18. March 2019
+ * $Revision: V1.6.0
+ *
+ * Target Processor: Cortex-M cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2019 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"
+
+void arm_radix2_butterfly_q15(
+ q15_t * pSrc,
+ uint32_t fftLen,
+ const q15_t * pCoef,
+ uint16_t twidCoefModifier);
+
+void arm_radix2_butterfly_inverse_q15(
+ q15_t * pSrc,
+ uint32_t fftLen,
+ const q15_t * pCoef,
+ uint16_t twidCoefModifier);
+
+void arm_bitreversal_q15(
+ q15_t * pSrc,
+ uint32_t fftLen,
+ uint16_t bitRevFactor,
+ const uint16_t * pBitRevTab);
+
+/**
+ @ingroup groupTransforms
+ */
+
+/**
+ @addtogroup ComplexFFT
+ @{
+ */
+
+/**
+ @brief Processing function for the fixed-point CFFT/CIFFT.
+ @deprecated Do not use this function. It has been superseded by \ref arm_cfft_q15 and will be removed in the future.
+ @param[in] S points to an instance of the fixed-point 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_radix2_q15(
+ const arm_cfft_radix2_instance_q15 * S,
+ q15_t * pSrc)
+{
+
+ if (S->ifftFlag == 1U)
+ {
+ arm_radix2_butterfly_inverse_q15 (pSrc, S->fftLen, S->pTwiddle, S->twidCoefModifier);
+ }
+ else
+ {
+ arm_radix2_butterfly_q15 (pSrc, S->fftLen, S->pTwiddle, S->twidCoefModifier);
+ }
+
+ arm_bitreversal_q15(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
+}
+
+/**
+ @} end of ComplexFFT group
+ */
+
+void arm_radix2_butterfly_q15(
+ q15_t * pSrc,
+ uint32_t fftLen,
+ const q15_t * pCoef,
+ uint16_t twidCoefModifier)
+{
+#if defined (ARM_MATH_DSP)
+
+ uint32_t i, j, k, l;
+ uint32_t n1, n2, ia;
+ q15_t in;
+ q31_t T, S, R;
+ q31_t coeff, out1, out2;
+
+ //N = fftLen;
+ n2 = fftLen;
+
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ // loop for groups
+ for (i = 0; i < n2; i++)
+ {
+ coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U));
+
+ ia = ia + twidCoefModifier;
+
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+ in = ((int16_t) (T & 0xFFFF)) >> 1;
+ T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
+
+ S = read_q15x2 (pSrc + (2 * l));
+ in = ((int16_t) (S & 0xFFFF)) >> 1;
+ S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __SHADD16(T, S));
+
+#ifndef ARM_MATH_BIG_ENDIAN
+ out1 = __SMUAD(coeff, R) >> 16;
+ out2 = __SMUSDX(coeff, R);
+#else
+ out1 = __SMUSDX(R, coeff) >> 16U;
+ out2 = __SMUAD(coeff, R);
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ write_q15x2 (pSrc + (2U * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));
+
+ coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U));
+
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ i++;
+ l++;
+
+ T = read_q15x2 (pSrc + (2 * i));
+ in = ((int16_t) (T & 0xFFFF)) >> 1;
+ T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
+
+ S = read_q15x2 (pSrc + (2 * l));
+ in = ((int16_t) (S & 0xFFFF)) >> 1;
+ S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __SHADD16(T, S));
+
+#ifndef ARM_MATH_BIG_ENDIAN
+ out1 = __SMUAD(coeff, R) >> 16;
+ out2 = __SMUSDX(coeff, R);
+#else
+
+ out1 = __SMUSDX(R, coeff) >> 16U;
+ out2 = __SMUAD(coeff, R);
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ write_q15x2 (pSrc + (2U * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+
+ /* loop for stage */
+ for (k = fftLen / 2; k > 2; k = k >> 1)
+ {
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (j = 0; j < n2; j++)
+ {
+ coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U));
+
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = j; i < fftLen; i += n1)
+ {
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+
+ S = read_q15x2 (pSrc + (2 * l));
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __SHADD16(T, S));
+
+#ifndef ARM_MATH_BIG_ENDIAN
+ out1 = __SMUAD(coeff, R) >> 16;
+ out2 = __SMUSDX(coeff, R);
+#else
+ out1 = __SMUSDX(R, coeff) >> 16U;
+ out2 = __SMUAD(coeff, R);
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ write_q15x2 (pSrc + (2U * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));
+
+ i += n1;
+
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+
+ S = read_q15x2 (pSrc + (2 * l));
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __SHADD16(T, S));
+
+#ifndef ARM_MATH_BIG_ENDIAN
+ out1 = __SMUAD(coeff, R) >> 16;
+ out2 = __SMUSDX(coeff, R);
+#else
+ out1 = __SMUSDX(R, coeff) >> 16U;
+ out2 = __SMUAD(coeff, R);
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ write_q15x2 (pSrc + (2U * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));
+
+ } /* butterfly loop end */
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+ } /* stages loop end */
+
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U));
+
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = 0; i < fftLen; i += n1)
+ {
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+
+ S = read_q15x2 (pSrc + (2 * l));
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __QADD16(T, S));
+
+ write_q15x2 (pSrc + (2 * l), R);
+
+ i += n1;
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+
+ S = read_q15x2 (pSrc + (2 * l));
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __QADD16(T, S));
+
+ write_q15x2 (pSrc + (2 * l), R);
+
+ } /* groups loop end */
+
+
+#else /* #if defined (ARM_MATH_DSP) */
+
+ uint32_t i, j, k, l;
+ uint32_t n1, n2, ia;
+ q15_t xt, yt, cosVal, sinVal;
+
+
+ // N = fftLen;
+ n2 = fftLen;
+
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (j = 0; j < n2; j++)
+ {
+ cosVal = pCoef[(ia * 2)];
+ sinVal = pCoef[(ia * 2) + 1];
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = j; i < fftLen; i += n1)
+ {
+ l = i + n2;
+ xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);
+ pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U;
+
+ yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U);
+ pSrc[2 * i + 1] = ((pSrc[2 * l + 1] >> 1U) +
+ (pSrc[2 * i + 1] >> 1U) ) >> 1U;
+
+ pSrc[2 * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +
+ ((int16_t) (((q31_t) yt * sinVal) >> 16)));
+
+ pSrc[2U * l + 1] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -
+ ((int16_t) (((q31_t) xt * sinVal) >> 16)));
+
+ } /* butterfly loop end */
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+
+ /* loop for stage */
+ for (k = fftLen / 2; k > 2; k = k >> 1)
+ {
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (j = 0; j < n2; j++)
+ {
+ cosVal = pCoef[ia * 2];
+ sinVal = pCoef[(ia * 2) + 1];
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = j; i < fftLen; i += n1)
+ {
+ l = i + n2;
+ xt = pSrc[2 * i] - pSrc[2 * l];
+ pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;
+
+ yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+ pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;
+
+ pSrc[2 * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +
+ ((int16_t) (((q31_t) yt * sinVal) >> 16)));
+
+ pSrc[2U * l + 1] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -
+ ((int16_t) (((q31_t) xt * sinVal) >> 16)));
+
+ } /* butterfly loop end */
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+ } /* stages loop end */
+
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (j = 0; j < n2; j++)
+ {
+ cosVal = pCoef[ia * 2];
+ sinVal = pCoef[(ia * 2) + 1];
+
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = j; i < fftLen; i += n1)
+ {
+ l = i + n2;
+ xt = pSrc[2 * i] - pSrc[2 * l];
+ pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
+
+ yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+ pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
+
+ pSrc[2 * l] = xt;
+
+ pSrc[2 * l + 1] = yt;
+
+ } /* butterfly loop end */
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+
+#endif /* #if defined (ARM_MATH_DSP) */
+
+}
+
+
+void arm_radix2_butterfly_inverse_q15(
+ q15_t * pSrc,
+ uint32_t fftLen,
+ const q15_t * pCoef,
+ uint16_t twidCoefModifier)
+{
+#if defined (ARM_MATH_DSP)
+
+ uint32_t i, j, k, l;
+ uint32_t n1, n2, ia;
+ q15_t in;
+ q31_t T, S, R;
+ q31_t coeff, out1, out2;
+
+ // N = fftLen;
+ n2 = fftLen;
+
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (i = 0; i < n2; i++)
+ {
+ coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U));
+
+ ia = ia + twidCoefModifier;
+
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+ in = ((int16_t) (T & 0xFFFF)) >> 1;
+ T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
+
+ S = read_q15x2 (pSrc + (2 * l));
+ in = ((int16_t) (S & 0xFFFF)) >> 1;
+ S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __SHADD16(T, S));
+
+#ifndef ARM_MATH_BIG_ENDIAN
+ out1 = __SMUSD(coeff, R) >> 16;
+ out2 = __SMUADX(coeff, R);
+#else
+ out1 = __SMUADX(R, coeff) >> 16U;
+ out2 = __SMUSD(__QSUB(0, coeff), R);
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ write_q15x2 (pSrc + (2 * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));
+
+ coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U));
+
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ i++;
+ l++;
+
+ T = read_q15x2 (pSrc + (2 * i));
+ in = ((int16_t) (T & 0xFFFF)) >> 1;
+ T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
+
+ S = read_q15x2 (pSrc + (2 * l));
+ in = ((int16_t) (S & 0xFFFF)) >> 1;
+ S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __SHADD16(T, S));
+
+#ifndef ARM_MATH_BIG_ENDIAN
+ out1 = __SMUSD(coeff, R) >> 16;
+ out2 = __SMUADX(coeff, R);
+#else
+ out1 = __SMUADX(R, coeff) >> 16U;
+ out2 = __SMUSD(__QSUB(0, coeff), R);
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ write_q15x2 (pSrc + (2 * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+
+ /* loop for stage */
+ for (k = fftLen / 2; k > 2; k = k >> 1)
+ {
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (j = 0; j < n2; j++)
+ {
+ coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U));
+
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = j; i < fftLen; i += n1)
+ {
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+
+ S = read_q15x2 (pSrc + (2 * l));
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __SHADD16(T, S));
+
+#ifndef ARM_MATH_BIG_ENDIAN
+ out1 = __SMUSD(coeff, R) >> 16;
+ out2 = __SMUADX(coeff, R);
+#else
+ out1 = __SMUADX(R, coeff) >> 16U;
+ out2 = __SMUSD(__QSUB(0, coeff), R);
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ write_q15x2 (pSrc + (2 * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));
+
+ i += n1;
+
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+
+ S = read_q15x2 (pSrc + (2 * l));
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __SHADD16(T, S));
+
+#ifndef ARM_MATH_BIG_ENDIAN
+ out1 = __SMUSD(coeff, R) >> 16;
+ out2 = __SMUADX(coeff, R);
+#else
+ out1 = __SMUADX(R, coeff) >> 16U;
+ out2 = __SMUSD(__QSUB(0, coeff), R);
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ write_q15x2 (pSrc + (2 * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));
+
+ } /* butterfly loop end */
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+ } /* stages loop end */
+
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (j = 0; j < n2; j++)
+ {
+ coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U));
+
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = j; i < fftLen; i += n1)
+ {
+ l = i + n2;
+
+ T = read_q15x2 (pSrc + (2 * i));
+
+ S = read_q15x2 (pSrc + (2 * l));
+
+ R = __QSUB16(T, S);
+
+ write_q15x2 (pSrc + (2 * i), __QADD16(T, S));
+
+ write_q15x2 (pSrc + (2 * l), R);
+
+ } /* butterfly loop end */
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+
+#else /* #if defined (ARM_MATH_DSP) */
+
+ uint32_t i, j, k, l;
+ uint32_t n1, n2, ia;
+ q15_t xt, yt, cosVal, sinVal;
+
+ // N = fftLen;
+ n2 = fftLen;
+
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (j = 0; j < n2; j++)
+ {
+ cosVal = pCoef[(ia * 2)];
+ sinVal = pCoef[(ia * 2) + 1];
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = j; i < fftLen; i += n1)
+ {
+ l = i + n2;
+ xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);
+ pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U;
+
+ yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U);
+ pSrc[2 * i + 1] = ((pSrc[2 * l + 1] >> 1U) +
+ (pSrc[2 * i + 1] >> 1U) ) >> 1U;
+
+ pSrc[2 * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -
+ ((int16_t) (((q31_t) yt * sinVal) >> 16)));
+
+ pSrc[2 * l + 1] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +
+ ((int16_t) (((q31_t) xt * sinVal) >> 16)));
+
+ } /* butterfly loop end */
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+
+ /* loop for stage */
+ for (k = fftLen / 2; k > 2; k = k >> 1)
+ {
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ /* loop for groups */
+ for (j = 0; j < n2; j++)
+ {
+ cosVal = pCoef[(ia * 2)];
+ sinVal = pCoef[(ia * 2) + 1];
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = j; i < fftLen; i += n1)
+ {
+ l = i + n2;
+ xt = pSrc[2 * i] - pSrc[2 * l];
+ pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;
+
+ yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+ pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;
+
+ pSrc[2 * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -
+ ((int16_t) (((q31_t) yt * sinVal) >> 16)) );
+
+ pSrc[2 * l + 1] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +
+ ((int16_t) (((q31_t) xt * sinVal) >> 16)) );
+
+ } /* butterfly loop end */
+
+ } /* groups loop end */
+
+ twidCoefModifier = twidCoefModifier << 1U;
+ } /* stages loop end */
+
+ n1 = n2;
+ n2 = n2 >> 1;
+ ia = 0;
+
+ cosVal = pCoef[(ia * 2)];
+ sinVal = pCoef[(ia * 2) + 1];
+
+ ia = ia + twidCoefModifier;
+
+ /* loop for butterfly */
+ for (i = 0; i < fftLen; i += n1)
+ {
+ l = i + n2;
+ xt = pSrc[2 * i] - pSrc[2 * l];
+ pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
+
+ yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+ pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
+
+ pSrc[2 * l] = xt;
+
+ pSrc[2 * l + 1] = yt;
+
+ } /* groups loop end */
+
+
+#endif /* #if defined (ARM_MATH_DSP) */
+
+}
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