/*Copyright (c) 2003-2004, Mark Borgerding

  Lots of modifications by Jean-Marc Valin

  Copyright (c) 2005-2007, Xiph.Org Foundation

  Copyright (c) 2008,      Xiph.Org Foundation, CSIRO

  All rights reserved.

  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.

  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 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

  CONTRACT, STRICT 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.*/

/* This code is originally from Mark Borgerding's KISS-FFT but has been

   heavily modified to better suit Opus */

#ifndef SKIP_CONFIG_H

#  ifdef HAVE_CONFIG_H

#    include "config.h"

#  endif

#endif

#include "_kiss_fft_guts.h"

#include "arch.h"

#include "os_support.h"

#include "mathops.h"

#include "stack_alloc.h"

#if defined(CUSTOM_MODES) || defined(ENABLE_OPUS_CUSTOM_API)

#define OPUS_CUSTOM 1

#endif

#if defined(ENABLE_PFA)

extern void opus_fft_pfa_c(const kiss_fft_state *st, const kiss_fft_cpx *fin, kiss_fft_cpx *fout ARG_FIXED(int downshift));

extern void opus_ifft_pfa_c(const kiss_fft_state *st, const kiss_fft_cpx *fin, kiss_fft_cpx *fout ARG_FIXED(int fft_shift));

#endif

#ifndef M_PI

#define M_PI 3.141592653

#endif

/* The guts header contains all the multiplication and addition macros that are defined for

   complex numbers.  It also declares the kf_ internal functions.

*/

#if !defined(ENABLE_PFA) || defined(OPUS_CUSTOM) || defined(ENABLE_DEEP_PLC)

static void kf_bfly2(

                     kiss_fft_cpx * Fout,

                     int m,

                     int N

                    )

{

   kiss_fft_cpx * Fout2;

   int i;

   (void)m;

#ifdef CUSTOM_MODES

   if (m==1)

   {

      celt_assert(m==1);

      for (i=0;i<N;i++)

      {

         kiss_fft_cpx t;

         Fout2 = Fout + 1;

         t = *Fout2;

         C_SUB( *Fout2 ,  *Fout , t );

         C_ADDTO( *Fout ,  t );

         Fout += 2;

      }

   } else

#endif

   {

      celt_coef tw;

      tw = QCONST32(0.7071067812f, COEF_SHIFT-1);

      /* We know that m==4 here because the radix-2 is just after a radix-4 */

      celt_assert(m==4);

      for (i=0;i<N;i++)

      {

         kiss_fft_cpx t;

         Fout2 = Fout + 4;

         t = Fout2[0];

         C_SUB( Fout2[0] ,  Fout[0] , t );

         C_ADDTO( Fout[0] ,  t );

         t.r = S_MUL(ADD32_ovflw(Fout2[1].r, Fout2[1].i), tw);

         t.i = S_MUL(SUB32_ovflw(Fout2[1].i, Fout2[1].r), tw);

         C_SUB( Fout2[1] ,  Fout[1] , t );

         C_ADDTO( Fout[1] ,  t );

         t.r = Fout2[2].i;

         t.i = NEG32_ovflw(Fout2[2].r);

         C_SUB( Fout2[2] ,  Fout[2] , t );

         C_ADDTO( Fout[2] ,  t );

         t.r = S_MUL(SUB32_ovflw(Fout2[3].i, Fout2[3].r), tw);

         t.i = S_MUL(NEG32_ovflw(ADD32_ovflw(Fout2[3].i, Fout2[3].r)), tw);

         C_SUB( Fout2[3] ,  Fout[3] , t );

         C_ADDTO( Fout[3] ,  t );

         Fout += 8;

      }

   }

}

static void kf_bfly4(

                     kiss_fft_cpx * Fout,

                     const size_t fstride,

                     const kiss_fft_state *st,

                     int m,

                     int N,

                     int mm

                    )

{

   int i;

   if (m==1)

   {

      /* Degenerate case where all the twiddles are 1. */

      for (i=0;i<N;i++)

      {

         kiss_fft_cpx scratch0, scratch1;

         C_SUB( scratch0 , *Fout, Fout[2] );

         C_ADDTO(*Fout, Fout[2]);

         C_ADD( scratch1 , Fout[1] , Fout[3] );

         C_SUB( Fout[2], *Fout, scratch1 );

         C_ADDTO( *Fout , scratch1 );

         C_SUB( scratch1 , Fout[1] , Fout[3] );

         Fout[1].r = ADD32_ovflw(scratch0.r, scratch1.i);

         Fout[1].i = SUB32_ovflw(scratch0.i, scratch1.r);

         Fout[3].r = SUB32_ovflw(scratch0.r, scratch1.i);

         Fout[3].i = ADD32_ovflw(scratch0.i, scratch1.r);

         Fout+=4;

      }

   } else {

      int j;

      kiss_fft_cpx scratch[6];

      const kiss_twiddle_cpx *tw1,*tw2,*tw3;

      const int m2=2*m;

      const int m3=3*m;

      kiss_fft_cpx * Fout_beg = Fout;

      for (i=0;i<N;i++)

      {

         Fout = Fout_beg + i*mm;

         tw3 = tw2 = tw1 = st->twiddles;

         /* m is guaranteed to be a multiple of 4. */

         for (j=0;j<m;j++)

         {

            C_MUL(scratch[0],Fout[m] , *tw1 );

            C_MUL(scratch[1],Fout[m2] , *tw2 );

            C_MUL(scratch[2],Fout[m3] , *tw3 );

            C_SUB( scratch[5] , *Fout, scratch[1] );

            C_ADDTO(*Fout, scratch[1]);

            C_ADD( scratch[3] , scratch[0] , scratch[2] );

            C_SUB( scratch[4] , scratch[0] , scratch[2] );

            C_SUB( Fout[m2], *Fout, scratch[3] );

            tw1 += fstride;

            tw2 += fstride*2;

            tw3 += fstride*3;

            C_ADDTO( *Fout , scratch[3] );

            Fout[m].r = ADD32_ovflw(scratch[5].r, scratch[4].i);

            Fout[m].i = SUB32_ovflw(scratch[5].i, scratch[4].r);

            Fout[m3].r = SUB32_ovflw(scratch[5].r, scratch[4].i);

            Fout[m3].i = ADD32_ovflw(scratch[5].i, scratch[4].r);

            ++Fout;

         }

      }

   }

}

#ifndef RADIX_TWO_ONLY

static void kf_bfly3(

                     kiss_fft_cpx * Fout,

                     const size_t fstride,

                     const kiss_fft_state *st,

                     int m,

                     int N,

                     int mm

                    )

{

   int i;

   size_t k;

   const size_t m2 = 2*m;

   const kiss_twiddle_cpx *tw1,*tw2;

   kiss_fft_cpx scratch[5];

   kiss_twiddle_cpx epi3;

   kiss_fft_cpx * Fout_beg = Fout;

#ifdef FIXED_POINT

   /*epi3.r = -16384;*/ /* Unused */

   epi3.i = -QCONST32(0.86602540f, COEF_SHIFT-1);

#else

   epi3 = st->twiddles[fstride*m];

#endif

   for (i=0;i<N;i++)

   {

      Fout = Fout_beg + i*mm;

      tw1=tw2=st->twiddles;

      /* For non-custom modes, m is guaranteed to be a multiple of 4. */

      k=m;

      do {

         C_MUL(scratch[1],Fout[m] , *tw1);

         C_MUL(scratch[2],Fout[m2] , *tw2);

         C_ADD(scratch[3],scratch[1],scratch[2]);

         C_SUB(scratch[0],scratch[1],scratch[2]);

         tw1 += fstride;

         tw2 += fstride*2;

         Fout[m].r = SUB32_ovflw(Fout->r, HALF_OF(scratch[3].r));

         Fout[m].i = SUB32_ovflw(Fout->i, HALF_OF(scratch[3].i));

         C_MULBYSCALAR( scratch[0] , epi3.i );

         C_ADDTO(*Fout,scratch[3]);

         Fout[m2].r = ADD32_ovflw(Fout[m].r, scratch[0].i);

         Fout[m2].i = SUB32_ovflw(Fout[m].i, scratch[0].r);

         Fout[m].r = SUB32_ovflw(Fout[m].r, scratch[0].i);

         Fout[m].i = ADD32_ovflw(Fout[m].i, scratch[0].r);

         ++Fout;

      } while(--k);

   }

}

#ifndef OVERRIDE_kf_bfly5

static void kf_bfly5(

                     kiss_fft_cpx * Fout,

                     const size_t fstride,

                     const kiss_fft_state *st,

                     int m,

                     int N,

                     int mm

                    )

{

   kiss_fft_cpx *Fout0,*Fout1,*Fout2,*Fout3,*Fout4;

   int i, u;

   kiss_fft_cpx scratch[13];

   const kiss_twiddle_cpx *tw;

   kiss_twiddle_cpx ya,yb;

   kiss_fft_cpx * Fout_beg = Fout;

#ifdef FIXED_POINT

   ya.r = QCONST32(0.30901699f, COEF_SHIFT-1);

   ya.i = -QCONST32(0.95105652f, COEF_SHIFT-1);

   yb.r = -QCONST32(0.80901699f, COEF_SHIFT-1);

   yb.i = -QCONST32(0.58778525f, COEF_SHIFT-1);

#else

   ya = st->twiddles[fstride*m];

   yb = st->twiddles[fstride*2*m];

#endif

   tw=st->twiddles;

   for (i=0;i<N;i++)

   {

      Fout = Fout_beg + i*mm;

      Fout0=Fout;

      Fout1=Fout0+m;

      Fout2=Fout0+2*m;

      Fout3=Fout0+3*m;

      Fout4=Fout0+4*m;

      /* For non-custom modes, m is guaranteed to be a multiple of 4. */

      for ( u=0; u<m; ++u ) {

         scratch[0] = *Fout0;

         C_MUL(scratch[1] ,*Fout1, tw[u*fstride]);

         C_MUL(scratch[2] ,*Fout2, tw[2*u*fstride]);

         C_MUL(scratch[3] ,*Fout3, tw[3*u*fstride]);

         C_MUL(scratch[4] ,*Fout4, tw[4*u*fstride]);

         C_ADD( scratch[7],scratch[1],scratch[4]);

         C_SUB( scratch[10],scratch[1],scratch[4]);

         C_ADD( scratch[8],scratch[2],scratch[3]);

         C_SUB( scratch[9],scratch[2],scratch[3]);

         Fout0->r = ADD32_ovflw(Fout0->r, ADD32_ovflw(scratch[7].r, scratch[8].r));

         Fout0->i = ADD32_ovflw(Fout0->i, ADD32_ovflw(scratch[7].i, scratch[8].i));

         scratch[5].r = ADD32_ovflw(scratch[0].r, ADD32_ovflw(S_MUL(scratch[7].r,ya.r), S_MUL(scratch[8].r,yb.r)));

         scratch[5].i = ADD32_ovflw(scratch[0].i, ADD32_ovflw(S_MUL(scratch[7].i,ya.r), S_MUL(scratch[8].i,yb.r)));

         scratch[6].r =  ADD32_ovflw(S_MUL(scratch[10].i,ya.i), S_MUL(scratch[9].i,yb.i));

         scratch[6].i = NEG32_ovflw(ADD32_ovflw(S_MUL(scratch[10].r,ya.i), S_MUL(scratch[9].r,yb.i)));

         C_SUB(*Fout1,scratch[5],scratch[6]);

         C_ADD(*Fout4,scratch[5],scratch[6]);

         scratch[11].r = ADD32_ovflw(scratch[0].r, ADD32_ovflw(S_MUL(scratch[7].r,yb.r), S_MUL(scratch[8].r,ya.r)));

         scratch[11].i = ADD32_ovflw(scratch[0].i, ADD32_ovflw(S_MUL(scratch[7].i,yb.r), S_MUL(scratch[8].i,ya.r)));

         scratch[12].r = SUB32_ovflw(S_MUL(scratch[9].i,ya.i), S_MUL(scratch[10].i,yb.i));

         scratch[12].i = SUB32_ovflw(S_MUL(scratch[10].r,yb.i), S_MUL(scratch[9].r,ya.i));

         C_ADD(*Fout2,scratch[11],scratch[12]);

         C_SUB(*Fout3,scratch[11],scratch[12]);

         ++Fout0;++Fout1;++Fout2;++Fout3;++Fout4;

      }

   }

}

#endif /* OVERRIDE_kf_bfly5 */

#endif

#ifdef CUSTOM_MODES

static

void compute_bitrev_table(

         int Fout,

         opus_int16 *f,

         const size_t fstride,

         int in_stride,

         opus_int16 * factors,

         const kiss_fft_state *st

            )

{

   const int p=*factors++; /* the radix  */

   const int m=*factors++; /* stage's fft length/p */

    /*printf ("fft %d %d %d %d %d %d\n", p*m, m, p, s2, fstride*in_stride, N);*/

   if (m==1)

   {

      int j;

      for (j=0;j<p;j++)

      {

         *f = Fout+j;

         f += fstride*in_stride;

      }

   } else {

      int j;

      for (j=0;j<p;j++)

      {

         compute_bitrev_table( Fout , f, fstride*p, in_stride, factors,st);

         f += fstride*in_stride;

         Fout += m;

      }

   }

}

/*  facbuf is populated by p1,m1,p2,m2, ...

    where

    p[i] * m[i] = m[i-1]

    m0 = n                  */

static

int kf_factor(int n,opus_int16 * facbuf)

{

    int p=4;

    int i;

    int stages=0;

    int nbak = n;

    /*factor out powers of 4, powers of 2, then any remaining primes */

    do {

        while (n % p) {

            switch (p) {

                case 4: p = 2; break;

                case 2: p = 3; break;

                default: p += 2; break;

            }

            if (p>32000 || (opus_int32)p*(opus_int32)p > n)

                p = n;          /* no more factors, skip to end */

        }

        n /= p;

#ifdef RADIX_TWO_ONLY

        if (p!=2 && p != 4)

#else

        if (p>5)

#endif

        {

           return 0;

        }

        facbuf[2*stages] = p;

        if (p==2 && stages > 1)

        {

           facbuf[2*stages] = 4;

           facbuf[2] = 2;

        }

        stages++;

    } while (n > 1);

    n = nbak;

    /* Reverse the order to get the radix 4 at the end, so we can use the

       fast degenerate case. It turns out that reversing the order also

       improves the noise behaviour. */

    for (i=0;i<stages/2;i++)

    {

       int tmp;

       tmp = facbuf[2*i];

       facbuf[2*i] = facbuf[2*(stages-i-1)];

       facbuf[2*(stages-i-1)] = tmp;

    }

    for (i=0;i<stages;i++)

    {

        n /= facbuf[2*i];

        facbuf[2*i+1] = n;

    }

    return 1;

}

static void compute_twiddles(kiss_twiddle_cpx *twiddles, int nfft)

{

   int i;

#ifdef FIXED_POINT

   for (i=0;i<nfft;++i) {

      opus_val32 phase = -i;

#ifdef ENABLE_QEXT

      twiddles[i].r = (int)MIN32(2147483647, floor(.5+2147483648*cos((2*M_PI/nfft)*phase)));

      twiddles[i].i = (int)MIN32(2147483647, floor(.5+2147483648*sin((2*M_PI/nfft)*phase)));

#else

      kf_cexp2(twiddles+i, DIV32(SHL32(phase,17),nfft));

#endif

   }

#else

   for (i=0;i<nfft;++i) {

      const double pi=3.14159265358979323846264338327;

      double phase = ( -2*pi /nfft ) * i;

      kf_cexp(twiddles+i, phase );

   }

#endif

}

int opus_fft_alloc_arch_c(kiss_fft_state *st) {

   (void)st;

   return 0;

}

/*

 *

 * Allocates all necessary storage space for the fft and ifft.

 * The return value is a contiguous block of memory.  As such,

 * It can be freed with free().

 * */

kiss_fft_state *opus_fft_alloc_twiddles(int nfft,void * mem,size_t * lenmem,

                                        const kiss_fft_state *base, int arch)

{

    kiss_fft_state *st=NULL;

    size_t memneeded = sizeof(struct kiss_fft_state); /* twiddle factors*/

    if ( lenmem==NULL ) {

        st = ( kiss_fft_state*)KISS_FFT_MALLOC( memneeded );

    }else{

        if (mem != NULL && *lenmem >= memneeded)

            st = (kiss_fft_state*)mem;

        *lenmem = memneeded;

    }

    if (st) {

        opus_int16 *bitrev;

        kiss_twiddle_cpx *twiddles;

        st->nfft=nfft;

#ifdef FIXED_POINT

        st->scale_shift = celt_ilog2(st->nfft);

# ifdef ENABLE_QEXT

        if (st->nfft == 1<<st->scale_shift)

           st->scale = QCONST32(1.0f, 30);

        else

           st->scale = (((opus_int64)1073741824<<st->scale_shift)+st->nfft/2)/st->nfft;

# else

        if (st->nfft == 1<<st->scale_shift)

           st->scale = Q15ONE;

        else

           st->scale = (1073741824+st->nfft/2)/st->nfft>>(15-st->scale_shift);

# endif

#else

        st->scale = 1.f/nfft;

#endif

#if defined(ENABLE_PFA)

        if (nfft == 60 || nfft == 120 || nfft == 240 || nfft == 480

#if defined(ENABLE_QEXT)

            || nfft == 960

#endif

           )

        {

           st->twiddles = NULL;

           st->shift = -1;

           st->bitrev = NULL;

        } else

#endif

        {

           if (base != NULL && base->twiddles != NULL)

           {

              st->twiddles = base->twiddles;

              st->shift = 0;

              while (st->shift < 32 && nfft<<st->shift != base->nfft)

                 st->shift++;

              if (st->shift>=32)

                 goto fail;

           } else {

              st->twiddles = twiddles = (kiss_twiddle_cpx*)KISS_FFT_MALLOC(sizeof(kiss_twiddle_cpx)*nfft);

              compute_twiddles(twiddles, nfft);

              st->shift = -1;

           }

           if (!kf_factor(nfft,st->factors))

           {

              goto fail;

           }

           /* bitrev */

           st->bitrev = bitrev = (opus_int16*)KISS_FFT_MALLOC(sizeof(opus_int16)*nfft);

           if (st->bitrev==NULL)

               goto fail;

           compute_bitrev_table(0, bitrev, 1,1, st->factors,st);

        }

        /* Initialize architecture specific fft parameters */

        if (opus_fft_alloc_arch(st, arch))

            goto fail;

    }

    return st;

fail:

    opus_fft_free(st, arch);

    return NULL;

}

kiss_fft_state *opus_fft_alloc(int nfft,void * mem,size_t * lenmem, int arch)

{

   return opus_fft_alloc_twiddles(nfft, mem, lenmem, NULL, arch);

}

void opus_fft_free_arch_c(kiss_fft_state *st) {

   (void)st;

}

void opus_fft_free(const kiss_fft_state *cfg, int arch)

{

   if (cfg)

   {

      opus_fft_free_arch((kiss_fft_state *)cfg, arch);

      opus_free((opus_int16*)cfg->bitrev);

      if (cfg->shift < 0)

         opus_free((kiss_twiddle_cpx*)cfg->twiddles);

      opus_free((kiss_fft_state*)cfg);

   }

}

#endif /* CUSTOM_MODES */

#if !defined(ENABLE_PFA) || defined(OPUS_CUSTOM) || defined(ENABLE_DEEP_PLC)

#ifdef FIXED_POINT

#ifndef OVERRIDE_fft_downshift

static void fft_downshift(kiss_fft_cpx *x, int N, int *total, int step) {

   int shift;

   shift = IMIN(step, *total);

   *total -= shift;

   if (shift == 1) {

      int i;

      for (i=0;i<N;i++) {

         x[i].r = SHR32(x[i].r, 1);

         x[i].i = SHR32(x[i].i, 1);

      }

   } else if (shift>0) {

      int i;

      for (i=0;i<N;i++) {

         x[i].r = PSHR32(x[i].r, shift);

         x[i].i = PSHR32(x[i].i, shift);

      }

   }

}

#endif /* OVERRIDE_fft_downshift */

#else

#define fft_downshift(x, N, total, step)

#endif

void opus_fft_impl(const kiss_fft_state *st,kiss_fft_cpx *fout ARG_FIXED(int downshift))

{

    int m2, m;

    int p;

    int L;

    int fstride[MAXFACTORS];

    int i;

    int shift;

    /* st->shift can be -1 */

    shift = st->shift>0 ? st->shift : 0;

    fstride[0] = 1;

    L=0;

    do {

       p = st->factors[2*L];

       m = st->factors[2*L+1];

       fstride[L+1] = fstride[L]*p;

       L++;

    } while(m!=1);

    m = st->factors[2*L-1];

    for (i=L-1;i>=0;i--)

    {

       if (i!=0)

          m2 = st->factors[2*i-1];

       else

          m2 = 1;

       switch (st->factors[2*i])

       {

       case 2:

          fft_downshift(fout, st->nfft, &downshift, 1);

          kf_bfly2(fout, m, fstride[i]);

          break;

       case 4:

          fft_downshift(fout, st->nfft, &downshift, 2);

          kf_bfly4(fout,fstride[i]<<shift,st,m, fstride[i], m2);

          break;

 #ifndef RADIX_TWO_ONLY

       case 3:

          fft_downshift(fout, st->nfft, &downshift, 2);

          kf_bfly3(fout,fstride[i]<<shift,st,m, fstride[i], m2);

          break;

       case 5:

          fft_downshift(fout, st->nfft, &downshift, 3);

          kf_bfly5(fout,fstride[i]<<shift,st,m, fstride[i], m2);

          break;

 #endif

       }

       m = m2;

    }

    fft_downshift(fout, st->nfft, &downshift, downshift);

}

#endif /* !ENABLE_PFA || OPUS_CUSTOM || ENABLE_DEEP_PLC */

#endif

void opus_fft_c(const kiss_fft_state *st,const kiss_fft_cpx *fin,kiss_fft_cpx *fout)

{

#if defined(ENABLE_PFA)

   if (st->nfft == 60 || st->nfft == 120 || st->nfft == 240 || st->nfft == 480

#if defined(ENABLE_QEXT)

       || st->nfft == 960

#endif

      )

   {

      int i;

      celt_coef scale = st->scale;

      VARDECL(kiss_fft_cpx, tmp);

      SAVE_STACK;

      ALLOC(tmp, st->nfft, kiss_fft_cpx);

      for (i = 0; i < st->nfft; i++) {

#ifndef FIXED_POINT

         tmp[i].r = fin[i].r * scale;

         tmp[i].i = fin[i].i * scale;

#else

         tmp[i].r = S_MUL2(fin[i].r, scale);

         tmp[i].i = S_MUL2(fin[i].i, scale);

#endif

      }

      opus_fft_pfa_c(st, tmp, fout ARG_FIXED(st->scale_shift - 1));

      RESTORE_STACK;

      return;

   }

#if !defined(OPUS_CUSTOM) && !defined(ENABLE_DEEP_PLC)

   celt_assert2(0, "PFA FFT called with unsupported size in non-custom mode");

#endif

#endif

#if !defined(ENABLE_PFA) || defined(OPUS_CUSTOM) || defined(ENABLE_DEEP_PLC)

   int i;

   celt_coef scale;

#ifdef FIXED_POINT

   /* Allows us to scale with MULT16_32_Q16(), which is faster than

      MULT16_32_Q15() on ARM. */

   int scale_shift = st->scale_shift-1;

#endif

   scale = st->scale;

   celt_assert2 (fin != fout, "In-place FFT not supported");

   /* Bit-reverse the input */

   for (i=0;i<st->nfft;i++)

   {

      kiss_fft_cpx x = fin[i];

      fout[st->bitrev[i]].r = S_MUL2(x.r, scale);

      fout[st->bitrev[i]].i = S_MUL2(x.i, scale);

   }

   opus_fft_impl(st, fout ARG_FIXED(scale_shift));

#endif

}

void opus_ifft_c(const kiss_fft_state *st,const kiss_fft_cpx *fin,kiss_fft_cpx *fout)

{

#if defined(ENABLE_PFA)

   if (st->nfft == 60 || st->nfft == 120 || st->nfft == 240 || st->nfft == 480

#if defined(ENABLE_QEXT)

       || st->nfft == 960

#endif

      )

   {

      opus_ifft_pfa_c(st, fin, fout ARG_FIXED(0));

      return;

   }

#if !defined(OPUS_CUSTOM) && !defined(ENABLE_DEEP_PLC)

   celt_assert2(0, "PFA IFFT called with unsupported size in non-custom mode");

#endif

#endif

#if !defined(ENABLE_PFA) || defined(OPUS_CUSTOM) || defined(ENABLE_DEEP_PLC)

   int i;

   celt_assert2 (fin != fout, "In-place FFT not supported");

   /* Bit-reverse the input */

   for (i=0;i<st->nfft;i++)

      fout[st->bitrev[i]] = fin[i];

   for (i=0;i<st->nfft;i++)

      fout[i].i = -fout[i].i;

   opus_fft_impl(st, fout ARG_FIXED(0));

   for (i=0;i<st->nfft;i++)

      fout[i].i = -fout[i].i;

#endif

}