/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_cfft_radix2_f32.c
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* Description: Radix-2 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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void arm_radix2_butterfly_f32(
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float32_t * pSrc,
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uint32_t fftLen,
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float32_t * pCoef,
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uint16_t twidCoefModifier);
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void arm_radix2_butterfly_inverse_f32(
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float32_t * pSrc,
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uint32_t fftLen,
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float32_t * pCoef,
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uint16_t twidCoefModifier,
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float32_t onebyfftLen);
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extern void arm_bitreversal_f32(
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float32_t * pSrc,
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uint16_t fftSize,
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uint16_t bitRevFactor,
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uint16_t * pBitRevTab);
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/**
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* @ingroup groupTransforms
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*/
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/**
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* @addtogroup ComplexFFT
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* @{
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*/
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/**
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* @details
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* @brief Radix-2 CFFT/CIFFT.
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* @deprecated Do not use this function. It has been superseded by \ref arm_cfft_f32 and will be removed
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* in the future.
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* @param[in] *S points to an instance of the floating-point Radix-2 CFFT/CIFFT structure.
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* @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.
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* @return none.
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*/
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void arm_cfft_radix2_f32(
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const arm_cfft_radix2_instance_f32 * S,
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float32_t * pSrc)
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{
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if (S->ifftFlag == 1U)
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{
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/* Complex IFFT radix-2 */
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arm_radix2_butterfly_inverse_f32(pSrc, S->fftLen, S->pTwiddle,
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S->twidCoefModifier, S->onebyfftLen);
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}
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else
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{
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/* Complex FFT radix-2 */
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arm_radix2_butterfly_f32(pSrc, S->fftLen, S->pTwiddle,
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S->twidCoefModifier);
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}
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if (S->bitReverseFlag == 1U)
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{
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/* Bit Reversal */
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arm_bitreversal_f32(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
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}
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}
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/**
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* @} end of ComplexFFT group
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*/
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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_radix2_butterfly_f32(
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float32_t * pSrc,
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uint32_t fftLen,
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float32_t * pCoef,
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uint16_t twidCoefModifier)
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{
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uint32_t i, j, k, l;
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uint32_t n1, n2, ia;
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float32_t xt, yt, cosVal, sinVal;
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float32_t p0, p1, p2, p3;
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float32_t a0, a1;
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#if defined (ARM_MATH_DSP)
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/* Initializations for the first stage */
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n2 = fftLen >> 1;
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ia = 0;
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i = 0;
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// loop for groups
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for (k = n2; k > 0; k--)
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{
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cosVal = pCoef[ia * 2];
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sinVal = pCoef[(ia * 2) + 1];
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/* Twiddle coefficients index modifier */
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ia += twidCoefModifier;
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/* index calculation for the input as, */
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/* pSrc[i + 0], pSrc[i + fftLen/1] */
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l = i + n2;
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/* Butterfly implementation */
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a0 = pSrc[2 * i] + pSrc[2 * l];
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xt = pSrc[2 * i] - pSrc[2 * l];
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yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
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a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
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p0 = xt * cosVal;
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p1 = yt * sinVal;
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p2 = yt * cosVal;
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p3 = xt * sinVal;
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pSrc[2 * i] = a0;
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pSrc[2 * i + 1] = a1;
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pSrc[2 * l] = p0 + p1;
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pSrc[2 * l + 1] = p2 - p3;
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i++;
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} // groups loop end
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twidCoefModifier <<= 1U;
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// loop for stage
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for (k = n2; k > 2; k = k >> 1)
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{
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n1 = n2;
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n2 = n2 >> 1;
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ia = 0;
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// loop for groups
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j = 0;
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do
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{
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cosVal = pCoef[ia * 2];
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sinVal = pCoef[(ia * 2) + 1];
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ia += twidCoefModifier;
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// loop for butterfly
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i = j;
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do
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{
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l = i + n2;
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a0 = pSrc[2 * i] + pSrc[2 * l];
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xt = pSrc[2 * i] - pSrc[2 * l];
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yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
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a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
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p0 = xt * cosVal;
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p1 = yt * sinVal;
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p2 = yt * cosVal;
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p3 = xt * sinVal;
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pSrc[2 * i] = a0;
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pSrc[2 * i + 1] = a1;
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pSrc[2 * l] = p0 + p1;
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pSrc[2 * l + 1] = p2 - p3;
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i += n1;
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} while ( i < fftLen ); // butterfly loop end
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j++;
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} while ( j < n2); // groups loop end
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twidCoefModifier <<= 1U;
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} // stages loop end
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// loop for butterfly
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for (i = 0; i < fftLen; i += 2)
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{
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a0 = pSrc[2 * i] + pSrc[2 * i + 2];
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xt = pSrc[2 * i] - pSrc[2 * i + 2];
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yt = pSrc[2 * i + 1] - pSrc[2 * i + 3];
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a1 = pSrc[2 * i + 3] + pSrc[2 * i + 1];
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pSrc[2 * i] = a0;
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pSrc[2 * i + 1] = a1;
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pSrc[2 * i + 2] = xt;
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pSrc[2 * i + 3] = yt;
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} // groups loop end
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#else
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n2 = fftLen;
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// loop for stage
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for (k = fftLen; k > 1; k = k >> 1)
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{
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n1 = n2;
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n2 = n2 >> 1;
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ia = 0;
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// loop for groups
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j = 0;
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do
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{
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cosVal = pCoef[ia * 2];
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sinVal = pCoef[(ia * 2) + 1];
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ia += twidCoefModifier;
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// loop for butterfly
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i = j;
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do
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{
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l = i + n2;
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a0 = pSrc[2 * i] + pSrc[2 * l];
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xt = pSrc[2 * i] - pSrc[2 * l];
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yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
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a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
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p0 = xt * cosVal;
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p1 = yt * sinVal;
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p2 = yt * cosVal;
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p3 = xt * sinVal;
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pSrc[2 * i] = a0;
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pSrc[2 * i + 1] = a1;
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pSrc[2 * l] = p0 + p1;
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pSrc[2 * l + 1] = p2 - p3;
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i += n1;
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} while (i < fftLen);
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j++;
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} while (j < n2);
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twidCoefModifier <<= 1U;
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}
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#endif // #if defined (ARM_MATH_DSP)
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}
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void arm_radix2_butterfly_inverse_f32(
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float32_t * pSrc,
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uint32_t fftLen,
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float32_t * pCoef,
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uint16_t twidCoefModifier,
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float32_t onebyfftLen)
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{
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uint32_t i, j, k, l;
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uint32_t n1, n2, ia;
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float32_t xt, yt, cosVal, sinVal;
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float32_t p0, p1, p2, p3;
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float32_t a0, a1;
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#if defined (ARM_MATH_DSP)
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n2 = fftLen >> 1;
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ia = 0;
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// loop for groups
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for (i = 0; i < n2; i++)
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{
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cosVal = pCoef[ia * 2];
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sinVal = pCoef[(ia * 2) + 1];
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ia += twidCoefModifier;
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l = i + n2;
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a0 = pSrc[2 * i] + pSrc[2 * l];
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xt = pSrc[2 * i] - pSrc[2 * l];
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yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
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a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
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p0 = xt * cosVal;
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p1 = yt * sinVal;
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p2 = yt * cosVal;
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p3 = xt * sinVal;
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pSrc[2 * i] = a0;
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pSrc[2 * i + 1] = a1;
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pSrc[2 * l] = p0 - p1;
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pSrc[2 * l + 1] = p2 + p3;
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} // groups loop end
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twidCoefModifier <<= 1U;
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// loop for stage
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for (k = fftLen / 2; k > 2; k = k >> 1)
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{
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n1 = n2;
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n2 = n2 >> 1;
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ia = 0;
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// loop for groups
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j = 0;
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do
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{
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cosVal = pCoef[ia * 2];
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sinVal = pCoef[(ia * 2) + 1];
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ia += twidCoefModifier;
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// loop for butterfly
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i = j;
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do
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{
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l = i + n2;
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a0 = pSrc[2 * i] + pSrc[2 * l];
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xt = pSrc[2 * i] - pSrc[2 * l];
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yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
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a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
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p0 = xt * cosVal;
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p1 = yt * sinVal;
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p2 = yt * cosVal;
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p3 = xt * sinVal;
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pSrc[2 * i] = a0;
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pSrc[2 * i + 1] = a1;
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pSrc[2 * l] = p0 - p1;
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pSrc[2 * l + 1] = p2 + p3;
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i += n1;
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} while ( i < fftLen ); // butterfly loop end
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j++;
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} while (j < n2); // groups loop end
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twidCoefModifier <<= 1U;
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} // stages loop end
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// loop for butterfly
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for (i = 0; i < fftLen; i += 2)
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{
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a0 = pSrc[2 * i] + pSrc[2 * i + 2];
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xt = pSrc[2 * i] - pSrc[2 * i + 2];
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a1 = pSrc[2 * i + 3] + pSrc[2 * i + 1];
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yt = pSrc[2 * i + 1] - pSrc[2 * i + 3];
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p0 = a0 * onebyfftLen;
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p2 = xt * onebyfftLen;
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p1 = a1 * onebyfftLen;
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p3 = yt * onebyfftLen;
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pSrc[2 * i] = p0;
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pSrc[2 * i + 1] = p1;
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pSrc[2 * i + 2] = p2;
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pSrc[2 * i + 3] = p3;
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} // butterfly loop end
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#else
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n2 = fftLen;
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// loop for stage
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for (k = fftLen; k > 2; k = k >> 1)
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{
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n1 = n2;
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n2 = n2 >> 1;
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ia = 0;
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// loop for groups
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j = 0;
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do
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{
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cosVal = pCoef[ia * 2];
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sinVal = pCoef[(ia * 2) + 1];
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ia = ia + twidCoefModifier;
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// loop for butterfly
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i = j;
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do
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{
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l = i + n2;
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a0 = pSrc[2 * i] + pSrc[2 * l];
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xt = pSrc[2 * i] - pSrc[2 * l];
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yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
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a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
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p0 = xt * cosVal;
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p1 = yt * sinVal;
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p2 = yt * cosVal;
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p3 = xt * sinVal;
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pSrc[2 * i] = a0;
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pSrc[2 * i + 1] = a1;
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pSrc[2 * l] = p0 - p1;
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pSrc[2 * l + 1] = p2 + p3;
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i += n1;
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} while ( i < fftLen ); // butterfly loop end
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j++;
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} while ( j < n2 ); // groups loop end
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twidCoefModifier = twidCoefModifier << 1U;
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} // stages loop end
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n1 = n2;
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n2 = n2 >> 1;
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// loop for butterfly
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for (i = 0; i < fftLen; i += n1)
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{
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l = i + n2;
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a0 = pSrc[2 * i] + pSrc[2 * l];
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xt = pSrc[2 * i] - pSrc[2 * l];
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a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
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yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
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p0 = a0 * onebyfftLen;
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p2 = xt * onebyfftLen;
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p1 = a1 * onebyfftLen;
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p3 = yt * onebyfftLen;
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pSrc[2 * i] = p0;
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pSrc[2U * l] = p2;
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pSrc[2 * i + 1] = p1;
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pSrc[2U * l + 1U] = p3;
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} // butterfly loop end
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#endif // #if defined (ARM_MATH_DSP)
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}
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