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

* Copyright (C) 2010-2014 ARM Limited. All rights reserved.  

*  

* $Date:        19. March 2015

* $Revision:    V.1.4.5  

*  

* Project:          CMSIS DSP Library  

* Title:            arm_cfft_radix2_q31.c  

*  

* Description:  Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function  

*  

*  

* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0

*  

* Redistribution and use in source and binary forms, with or without

* modification, are permitted provided that the following conditions

* are met:

*   - Redistributions of source code must retain the above copyright

*     notice, this list of conditions and the following disclaimer.

*   - Redistributions in binary form must reproduce the above copyright

*     notice, this list of conditions and the following disclaimer in

*     the documentation and/or other materials provided with the

*     distribution.

*   - Neither the name of ARM LIMITED nor the names of its contributors

*     may be used to endorse or promote products derived from this

*     software without specific prior written permission.

*

* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,

* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,

* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

* POSSIBILITY OF SUCH DAMAGE.    

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

#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 

}