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/* ----------------------------------------------------------------------

 * Project:      CMSIS DSP Library

 * Title:        arm_cfft_radix2_f32.c

 * Description:  Radix-2 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"

void arm_radix2_butterfly_f32(

  float32_t * pSrc,

  uint32_t fftLen,

  float32_t * pCoef,

  uint16_t twidCoefModifier);

void arm_radix2_butterfly_inverse_f32(

  float32_t * pSrc,

  uint32_t fftLen,

  float32_t * pCoef,

  uint16_t twidCoefModifier,

  float32_t onebyfftLen);

extern void arm_bitreversal_f32(

    float32_t * pSrc,

    uint16_t fftSize,

    uint16_t bitRevFactor,

    uint16_t * pBitRevTab);

/**

* @ingroup groupTransforms

*/

/**

* @addtogroup ComplexFFT

* @{

*/

/**

* @details

* @brief Radix-2 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  It has been superseded by \ref arm_cfft_f32 and will be removed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-2 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_f32(

const arm_cfft_radix2_instance_f32 * S,

float32_t * pSrc)

{

   if (S->ifftFlag == 1U)

   {

      /*  Complex IFFT radix-2  */

      arm_radix2_butterfly_inverse_f32(pSrc, S->fftLen, S->pTwiddle,

      S->twidCoefModifier, S->onebyfftLen);

   }

   else

   {

      /*  Complex FFT radix-2  */

      arm_radix2_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_radix2_butterfly_f32(

float32_t * pSrc,

uint32_t fftLen,

float32_t * pCoef,

uint16_t twidCoefModifier)

{

   uint32_t i, j, k, l;

   uint32_t n1, n2, ia;

   float32_t xt, yt, cosVal, sinVal;

   float32_t p0, p1, p2, p3;

   float32_t a0, a1;

#if defined (ARM_MATH_DSP)

   /*  Initializations for the first stage */

   n2 = fftLen >> 1;

   ia = 0;

   i = 0;

   // loop for groups

   for (k = n2; k > 0; k--)

   {

      cosVal = pCoef[ia * 2];

      sinVal = pCoef[(ia * 2) + 1];

      /*  Twiddle coefficients index modifier */

      ia += twidCoefModifier;

      /*  index calculation for the input as, */

      /*  pSrc[i + 0], pSrc[i + fftLen/1] */

      l = i + n2;

      /*  Butterfly implementation */

      a0 = pSrc[2 * i] + pSrc[2 * l];

      xt = pSrc[2 * i] - pSrc[2 * l];

      yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];

      a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

      p0 = xt * cosVal;

      p1 = yt * sinVal;

      p2 = yt * cosVal;

      p3 = xt * sinVal;

      pSrc[2 * i]     = a0;

      pSrc[2 * i + 1] = a1;

      pSrc[2 * l]     = p0 + p1;

      pSrc[2 * l + 1] = p2 - p3;

      i++;

   }                             // groups loop end

   twidCoefModifier <<= 1U;

   // loop for stage

   for (k = n2; k > 2; k = k >> 1)

   {

      n1 = n2;

      n2 = n2 >> 1;

      ia = 0;

      // loop for groups

      j = 0;

      do

      {

         cosVal = pCoef[ia * 2];

         sinVal = pCoef[(ia * 2) + 1];

         ia += twidCoefModifier;

         // loop for butterfly

         i = j;

         do

         {

            l = i + n2;

            a0 = pSrc[2 * i] + pSrc[2 * l];

            xt = pSrc[2 * i] - pSrc[2 * l];

            yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];

            a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

            p0 = xt * cosVal;

            p1 = yt * sinVal;

            p2 = yt * cosVal;

            p3 = xt * sinVal;

            pSrc[2 * i] = a0;

            pSrc[2 * i + 1] = a1;

            pSrc[2 * l]     = p0 + p1;

            pSrc[2 * l + 1] = p2 - p3;

            i += n1;

         } while ( i < fftLen );                        // butterfly loop end

         j++;

      } while ( j < n2);                          // groups loop end

      twidCoefModifier <<= 1U;

   }                             // stages loop end

   // loop for butterfly

   for (i = 0; i < fftLen; i += 2)

   {

      a0 = pSrc[2 * i] + pSrc[2 * i + 2];

      xt = pSrc[2 * i] - pSrc[2 * i + 2];

      yt = pSrc[2 * i + 1] - pSrc[2 * i + 3];

      a1 = pSrc[2 * i + 3] + pSrc[2 * i + 1];

      pSrc[2 * i] = a0;

      pSrc[2 * i + 1] = a1;

      pSrc[2 * i + 2] = xt;

      pSrc[2 * i + 3] = yt;

   }                             // groups loop end

#else

   n2 = fftLen;

   // loop for stage

   for (k = fftLen; k > 1; k = k >> 1)

   {

      n1 = n2;

      n2 = n2 >> 1;

      ia = 0;

      // loop for groups

      j = 0;

      do

      {

         cosVal = pCoef[ia * 2];

         sinVal = pCoef[(ia * 2) + 1];

         ia += twidCoefModifier;

         // loop for butterfly

         i = j;

         do

         {

            l = i + n2;

            a0 = pSrc[2 * i] + pSrc[2 * l];

            xt = pSrc[2 * i] - pSrc[2 * l];

            yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];

            a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

            p0 = xt * cosVal;

            p1 = yt * sinVal;

            p2 = yt * cosVal;

            p3 = xt * sinVal;

            pSrc[2 * i] = a0;

            pSrc[2 * i + 1] = a1;

            pSrc[2 * l]     = p0 + p1;

            pSrc[2 * l + 1] = p2 - p3;

            i += n1;

         } while (i < fftLen);

         j++;

      } while (j < n2);

      twidCoefModifier <<= 1U;

   }

#endif //    #if defined (ARM_MATH_DSP)

}

void arm_radix2_butterfly_inverse_f32(

float32_t * pSrc,

uint32_t fftLen,

float32_t * pCoef,

uint16_t twidCoefModifier,

float32_t onebyfftLen)

{

   uint32_t i, j, k, l;

   uint32_t n1, n2, ia;

   float32_t xt, yt, cosVal, sinVal;

   float32_t p0, p1, p2, p3;

   float32_t a0, a1;

#if defined (ARM_MATH_DSP)

   n2 = fftLen >> 1;

   ia = 0;

   // loop for groups

   for (i = 0; i < n2; i++)

   {

      cosVal = pCoef[ia * 2];

      sinVal = pCoef[(ia * 2) + 1];

      ia += twidCoefModifier;

      l = i + n2;

      a0 = pSrc[2 * i] + pSrc[2 * l];

      xt = pSrc[2 * i] - pSrc[2 * l];

      yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];

      a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

      p0 = xt * cosVal;

      p1 = yt * sinVal;

      p2 = yt * cosVal;

      p3 = xt * sinVal;

      pSrc[2 * i] = a0;

      pSrc[2 * i + 1] = a1;

      pSrc[2 * l]     = p0 - p1;

      pSrc[2 * l + 1] = p2 + p3;

   }                             // groups loop end

   twidCoefModifier <<= 1U;

   // loop for stage

   for (k = fftLen / 2; k > 2; k = k >> 1)

   {

      n1 = n2;

      n2 = n2 >> 1;

      ia = 0;

      // loop for groups

      j = 0;

      do

      {

         cosVal = pCoef[ia * 2];

         sinVal = pCoef[(ia * 2) + 1];

         ia += twidCoefModifier;

         // loop for butterfly

         i = j;

         do

         {

            l = i + n2;

            a0 = pSrc[2 * i] + pSrc[2 * l];

            xt = pSrc[2 * i] - pSrc[2 * l];

            yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];

            a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

            p0 = xt * cosVal;

            p1 = yt * sinVal;

            p2 = yt * cosVal;

            p3 = xt * sinVal;

            pSrc[2 * i] = a0;

            pSrc[2 * i + 1] = a1;

            pSrc[2 * l]     = p0 - p1;

            pSrc[2 * l + 1] = p2 + p3;

            i += n1;

         } while ( i < fftLen );                 // butterfly loop end

         j++;

      } while (j < n2);                      // groups loop end

      twidCoefModifier <<= 1U;

   }                             // stages loop end

   // loop for butterfly

   for (i = 0; i < fftLen; i += 2)

   {

      a0 = pSrc[2 * i] + pSrc[2 * i + 2];

      xt = pSrc[2 * i] - pSrc[2 * i + 2];

      a1 = pSrc[2 * i + 3] + pSrc[2 * i + 1];

      yt = pSrc[2 * i + 1] - pSrc[2 * i + 3];

      p0 = a0 * onebyfftLen;

      p2 = xt * onebyfftLen;

      p1 = a1 * onebyfftLen;

      p3 = yt * onebyfftLen;

      pSrc[2 * i] = p0;

      pSrc[2 * i + 1] = p1;

      pSrc[2 * i + 2] = p2;

      pSrc[2 * i + 3] = p3;

   }                             // butterfly loop end

#else

   n2 = fftLen;

   // loop for stage

   for (k = fftLen; k > 2; k = k >> 1)

   {

      n1 = n2;

      n2 = n2 >> 1;

      ia = 0;

      // loop for groups

      j = 0;

      do

      {

         cosVal = pCoef[ia * 2];

         sinVal = pCoef[(ia * 2) + 1];

         ia = ia + twidCoefModifier;

         // loop for butterfly

         i = j;

         do

         {

            l = i + n2;

            a0 = pSrc[2 * i] + pSrc[2 * l];

            xt = pSrc[2 * i] - pSrc[2 * l];

            yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];

            a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

            p0 = xt * cosVal;

            p1 = yt * sinVal;

            p2 = yt * cosVal;

            p3 = xt * sinVal;

            pSrc[2 * i] = a0;

            pSrc[2 * i + 1] = a1;

            pSrc[2 * l]     = p0 - p1;

            pSrc[2 * l + 1] = p2 + p3;

            i += n1;

         } while ( i < fftLen );                    // butterfly loop end

         j++;

      } while ( j < n2 );                      // groups loop end

      twidCoefModifier = twidCoefModifier << 1U;

   }                             // stages loop end

   n1 = n2;

   n2 = n2 >> 1;

   // loop for butterfly

   for (i = 0; i < fftLen; i += n1)

   {

      l = i + n2;

      a0 = pSrc[2 * i] + pSrc[2 * l];

      xt = pSrc[2 * i] - pSrc[2 * l];

      a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

      yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];

      p0 = a0 * onebyfftLen;

      p2 = xt * onebyfftLen;

      p1 = a1 * onebyfftLen;

      p3 = yt * onebyfftLen;

      pSrc[2 * i] = p0;

      pSrc[2U * l] = p2;

      pSrc[2 * i + 1] = p1;

      pSrc[2U * l + 1U] = p3;

   }                             // butterfly loop end

#endif //      #if defined (ARM_MATH_DSP)

}