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

 * Project:      CMSIS DSP Library

 * Title:        arm_cfft_radix2_q31.c

 * Description:  Radix-2 Decimation in Frequency CFFT & CIFFT Fixed 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_q31(

  q31_t * pSrc,

  uint32_t fftLen,

  q31_t * pCoef,

  uint16_t twidCoefModifier);

void arm_radix2_butterfly_inverse_q31(

  q31_t * pSrc,

  uint32_t fftLen,

  q31_t * pCoef,

  uint16_t twidCoefModifier);

void arm_bitreversal_q31(

  q31_t * pSrc,

  uint32_t fftLen,

  uint16_t bitRevFactor,

  uint16_t * pBitRevTab);

/**

* @ingroup groupTransforms

*/

/**

* @addtogroup ComplexFFT

* @{

*/

/**

* @details

* @brief Processing function for the fixed-point CFFT/CIFFT.

* @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_q31 and will be removed

* @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_q31(

const arm_cfft_radix2_instance_q31 * S,

q31_t * pSrc)

{

   if (S->ifftFlag == 1U)

   {

      arm_radix2_butterfly_inverse_q31(pSrc, S->fftLen,

      S->pTwiddle, S->twidCoefModifier);

   }

   else

   {

      arm_radix2_butterfly_q31(pSrc, S->fftLen,

      S->pTwiddle, S->twidCoefModifier);

   }

   arm_bitreversal_q31(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);

}

/**

* @} end of ComplexFFT group

*/

void arm_radix2_butterfly_q31(

q31_t * pSrc,

uint32_t fftLen,

q31_t * pCoef,

uint16_t twidCoefModifier)

{

   unsigned i, j, k, l, m;

   unsigned n1, n2, ia;

   q31_t xt, yt, cosVal, sinVal;

   q31_t p0, p1;

   //N = fftLen;

   n2 = fftLen;

   n1 = n2;

   n2 = n2 >> 1;

   ia = 0;

   // loop for groups

   for (i = 0; i < n2; i++)

   {

      cosVal = pCoef[ia * 2];

      sinVal = pCoef[(ia * 2) + 1];

      ia = ia + twidCoefModifier;

      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;

      mult_32x32_keep32_R(p0, xt, cosVal);

      mult_32x32_keep32_R(p1, yt, cosVal);

      multAcc_32x32_keep32_R(p0, yt, sinVal);

      multSub_32x32_keep32_R(p1, xt, sinVal);

      pSrc[2U * l] = p0;

      pSrc[2U * l + 1U] = p1;

   }                             // 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

      for (j = 0; j < n2; j++)

      {

         cosVal = pCoef[ia * 2];

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

         ia = ia + twidCoefModifier;

         // loop for butterfly

         i = j;

         m = fftLen / n1;

         do

         {

            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;

            mult_32x32_keep32_R(p0, xt, cosVal);

            mult_32x32_keep32_R(p1, yt, cosVal);

            multAcc_32x32_keep32_R(p0, yt, sinVal);

            multSub_32x32_keep32_R(p1, xt, sinVal);

            pSrc[2U * l] = p0;

            pSrc[2U * l + 1U] = p1;

            i += n1;

            m--;

         } while ( m > 0);                   // butterfly loop end

      }                           // groups loop end

      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[2U * l] = xt;

      pSrc[2U * l + 1U] = yt;

      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[2U * l] = xt;

      pSrc[2U * l + 1U] = yt;

   }                             // butterfly loop end

}

void arm_radix2_butterfly_inverse_q31(

q31_t * pSrc,

uint32_t fftLen,

q31_t * pCoef,

uint16_t twidCoefModifier)

{

   unsigned i, j, k, l;

   unsigned n1, n2, ia;

   q31_t xt, yt, cosVal, sinVal;

   q31_t p0, p1;

   //N = fftLen;

   n2 = fftLen;

   n1 = n2;

   n2 = n2 >> 1;

   ia = 0;

   // loop for groups

   for (i = 0; i < n2; i++)

   {

      cosVal = pCoef[ia * 2];

      sinVal = pCoef[(ia * 2) + 1];

      ia = ia + twidCoefModifier;

      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;

      mult_32x32_keep32_R(p0, xt, cosVal);

      mult_32x32_keep32_R(p1, yt, cosVal);

      multSub_32x32_keep32_R(p0, yt, sinVal);

      multAcc_32x32_keep32_R(p1, xt, sinVal);

      pSrc[2U * l] = p0;

      pSrc[2U * l + 1U] = p1;

   }                             // 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;

            mult_32x32_keep32_R(p0, xt, cosVal);

            mult_32x32_keep32_R(p1, yt, cosVal);

            multSub_32x32_keep32_R(p0, yt, sinVal);

            multAcc_32x32_keep32_R(p1, xt, sinVal);

            pSrc[2U * l] = p0;

            pSrc[2U * l + 1U] = p1;

         }                         // 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[2U * l] = xt;

      pSrc[2U * l + 1U] = yt;

      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[2U * l] = xt;

      pSrc[2U * l + 1U] = yt;

   }                             // butterfly loop end

}