/***************************  Fraunhofer IIS FDK Tools  **********************

                        (C) Copyright Fraunhofer IIS (2003)
                               All Rights Reserved

    Please be advised that this software and/or program delivery is
    Confidential Information of Fraunhofer and subject to and covered by the

    Fraunhofer IIS Software Evaluation Agreement
    between Google Inc. and  Fraunhofer
    effective and in full force since March 1, 2012.

    You may use this software and/or program only under the terms and
    conditions described in the above mentioned Fraunhofer IIS Software
    Evaluation Agreement. Any other and/or further use requires a separate agreement.


   $Id$
   Author(s):   M. Lohwasser, M. Gayer
   Description:

   This software and/or program is protected by copyright law and international
   treaties. Any reproduction or distribution of this software and/or program,
   or any portion of it, may result in severe civil and criminal penalties, and
   will be prosecuted to the maximum extent possible under law.

******************************************************************************/

#include "fft_rad2.h"

#include "scramble.h"

#define __FFT_RAD2_CPP__

#if defined(__arm__)	/* cppp replaced: elif */
#include "arm/fft_rad2_arm.cpp"

#elif defined(__GNUC__) && defined(__mips__) && defined(__mips_dsp)	/* cppp replaced: elif */
#include "mips/fft_rad2_mips.cpp"

#endif



/*****************************************************************************

    functionname: dit_fft (analysis)
    description:  dit-tukey-algorithm
                  scrambles data at entry
                  i.e. loop is made with scrambled data
    returns:
    input:
    output:

*****************************************************************************/

#ifndef FUNCTION_dit_fft

void dit_fft(FIXP_DBL *x, const INT ldn, const FIXP_STP *trigdata, const INT trigDataSize)
{
    const INT n=1<<ldn;
    INT trigstep,i,ldm;

    scramble(x,n);
    /*
     * 1+2 stage radix 4
     */

    for (i=0;i<n*2;i+=8)
    {
      FIXP_DBL a00, a10, a20, a30;
      a00 = (x[i + 0] + x[i + 2])>>1;  /* Re A + Re B */
      a10 = (x[i + 4] + x[i + 6])>>1;  /* Re C + Re D */
      a20 = (x[i + 1] + x[i + 3])>>1;  /* Im A + Im B */
      a30 = (x[i + 5] + x[i + 7])>>1;  /* Im C + Im D */

      x[i + 0] = a00 + a10;       /* Re A' = Re A + Re B + Re C + Re D */
      x[i + 4] = a00 - a10;       /* Re C' = Re A + Re B - Re C - Re D */
      x[i + 1] = a20 + a30;       /* Im A' = Im A + Im B + Im C + Im D */
      x[i + 5] = a20 - a30;       /* Im C' = Im A + Im B - Im C - Im D */

      a00 = a00 - x[i + 2];       /* Re A - Re B */
      a10 = a10 - x[i + 6];       /* Re C - Re D */
      a20 = a20 - x[i + 3];       /* Im A - Im B */
      a30 = a30 - x[i + 7];       /* Im C - Im D */

      x[i + 2] = a00 + a30;       /* Re B' = Re A - Re B + Im C - Im D */
      x[i + 6] = a00 - a30;       /* Re D' = Re A - Re B - Im C + Im D */
      x[i + 3] = a20 - a10;       /* Im B' = Im A - Im B - Re C + Re D */
      x[i + 7] = a20 + a10;       /* Im D' = Im A - Im B + Re C - Re D */
    }

    for(ldm=3; ldm<=ldn; ++ldm)
    {
        INT m=(1<<ldm);
        INT mh=(m>>1);
        INT j,r;

        trigstep=((trigDataSize << 2)>>ldm);

        FDK_ASSERT(trigstep > 0);

        /* Do first iteration with c=1.0 and s=0.0 separately to avoid loosing to much precision.
           Beware: The impact on the overal FFT precision is rather large. */
        {
            j = 0;

            for(r=0; r<n; r+=m)
            {
                INT t1 = (r+j)<<1;
                INT t2 = t1 + (mh<<1);
                FIXP_DBL vr,vi,ur,ui;

                //cplxMultDiv2(&vi, &vr, x[t2+1], x[t2], (FIXP_SGL)1.0, (FIXP_SGL)0.0);
                vi = x[t2+1]>>1;
                vr = x[t2]>>1;

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui-vi;

                t1 += mh;
                t2 = t1+(mh<<1);

                //cplxMultDiv2(&vr, &vi, x[t2+1], x[t2], (FIXP_SGL)1.0, (FIXP_SGL)0.0);
                vr = x[t2+1]>>1;
                vi = x[t2]>>1;

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui-vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui+vi;
            }
        }
        for(j=1; j<mh/4; ++j)
        {
            FIXP_STP cs;

            cs = trigdata[j*trigstep];

            for(r=0; r<n; r+=m)
            {
                INT t1 = (r+j)<<1;
                INT t2 = t1 + (mh<<1);
                FIXP_DBL vr,vi,ur,ui;

                cplxMultDiv2(&vi, &vr, x[t2+1], x[t2], cs);

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui-vi;

                t1 += mh;
                t2 = t1+(mh<<1);

                cplxMultDiv2(&vr, &vi, x[t2+1], x[t2], cs);

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui-vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui+vi;

                /* Same as above but for t1,t2 with j>mh/4 and thus cs swapped */
                t1 = (r+mh/2-j)<<1;
                t2 = t1 + (mh<<1);

                cplxMultDiv2(&vi, &vr, x[t2], x[t2+1], cs);

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui-vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui+vi;

                t1 += mh;
                t2 = t1+(mh<<1);

                cplxMultDiv2(&vr, &vi, x[t2], x[t2+1], cs);

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur-vr;
                x[t1+1] = ui-vi;

                x[t2]   = ur+vr;
                x[t2+1] = ui+vi;
            }
        }
        {
            j = mh/4;

            for(r=0; r<n; r+=m)
            {
                INT t1 = (r+j)<<1;
                INT t2 = t1 + (mh<<1);
                FIXP_DBL vr,vi,ur,ui;

                cplxMultDiv2(&vi, &vr, x[t2+1], x[t2], STC(0x5a82799a), STC(0x5a82799a));

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui-vi;

                t1 += mh;
                t2 = t1+(mh<<1);

                cplxMultDiv2(&vr, &vi, x[t2+1], x[t2], STC(0x5a82799a), STC(0x5a82799a));

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui-vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui+vi;
            }
        }
    }
}
#endif


/*****************************************************************************

    functionname: dit_ifft (synthesis)
    description:  dit-tukey-algorithm
                  scrambles data at entry
                  i.e. loop is made with scrambled data
    returns:
    input:
    output:

*****************************************************************************/

#if !defined(FUNCTION_dit_ifft)
void dit_ifft(FIXP_DBL *x, const INT ldn, const FIXP_STP *trigdata, const INT trigDataSize)
{
    const INT n=1<<ldn;
    INT trigstep,i,ldm;

    scramble(x,n);

    /*
      1+2 stage radix 4
    */

    for (i=0;i<n*2;i+=8)
    {
      FIXP_DBL a0, a1, a2, a3, a00, a10, a20, a30;

      a00 = (x[i + 0] + x[i + 2])>>1;   /* Re A + Re B */
      a10 = (x[i + 4] + x[i + 6])>>1;   /* Re C + Re D */
      a20 = (x[i + 1] + x[i + 3])>>1;   /* Im A + Im B */
      a30 = (x[i + 5] + x[i + 7])>>1;   /* Im C + Im D */
      a0  = (x[i + 0] - x[i + 2])>>1;   /* Re A - Re B */
      a2  = (x[i + 4] - x[i + 6])>>1;   /* Re C - Re D */
      a3  = (x[i + 1] - x[i + 3])>>1;   /* Im A - Im B */
      a1  = (x[i + 5] - x[i + 7])>>1;   /* Im C - Im D */

      x[i + 0] = a00 + a10;    /* Re A' = Re A + Re B + Re C + Re D */
      x[i + 4] = a00 - a10;    /* Re C' = Re A + Re B - Re C - Re D */
      x[i + 1] = a20 + a30;    /* Im A' = Im A + Im B + Im C + Im D */
      x[i + 5] = a20 - a30;    /* Im C' = Im A + Im B - Im C - Im D */
      x[i + 2] = a0 - a1;      /* Re B' = Re A - Re B - Im C + Im D */
      x[i + 6] = a0 + a1;      /* Re D' = Re A - Re B + Im C - Im D */
      x[i + 3] = a3 + a2;      /* Im B' = Im A - Im B + Re C - Re D */
      x[i + 7] = a3 - a2;      /* Im D' = Im A - Im B - Re C + Re D */
    }

    for(ldm=3; ldm<=ldn; ++ldm)
    {
        const INT m=(1<<ldm);
        const INT mh=(m>>1);

        INT j,r;

        trigstep=((trigDataSize << 2)>>ldm);

        {
            j = 0;

            for(r=0; r<n; r+=m)
            {
                INT t1 = (r+j)<<1;
                INT t2 = t1 + (mh<<1);
                FIXP_DBL vr,vi,ur,ui;

                //cplxMultDiv2(&vr, &vi, x[t2], x[t2+1], FL2FXCONST_SGL(1.0), (FIXP_SGL)0.0);
                vi = x[t2+1]>>1;
                vr = x[t2]>>1;

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui-vi;

                t1 += mh;
                t2 = t1+(mh<<1);

                //cplxMultDiv2(&vi, &vr, x[t2], x[t2+1], FL2FXCONST_SGL(1.0), FL2FXCONST_SGL(0.0));
                vr = x[t2+1]>>1;
                vi = x[t2]>>1;

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur-vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur+vr;
                x[t2+1] = ui-vi;
            }
        }
        for(j=1; j<mh/4; ++j)
        {
            FIXP_STP cs;

            cs = trigdata[j*trigstep];

            for(r=0; r<n; r+=m)
            {
                INT t1 = (r+j)<<1;
                INT t2 = t1 + (mh<<1);
                FIXP_DBL vr,vi,ur,ui;

                cplxMultDiv2(&vr, &vi, x[t2], x[t2+1], cs);

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui-vi;

                t1 += mh;
                t2 = t1+(mh<<1);

                cplxMultDiv2(&vi, &vr, x[t2], x[t2+1], cs);

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur-vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur+vr;
                x[t2+1] = ui-vi;

                /* Same as above but for t1,t2 with j>mh/4 and thus cs swapped */
                t1 = (r+mh/2-j)<<1;
                t2 = t1 + (mh<<1);

                cplxMultDiv2(&vr, &vi, x[t2+1], x[t2], cs);

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur-vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur+vr;
                x[t2+1] = ui-vi;

                t1 += mh;
                t2 = t1+(mh<<1);

                cplxMultDiv2(&vi, &vr, x[t2+1], x[t2], cs);

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur-vr;
                x[t1+1] = ui-vi;

                x[t2]   = ur+vr;
                x[t2+1] = ui+vi;
            }
        }
        {
            j = mh/4;
            for(r=0; r<n; r+=m)
            {
                INT t1 = (r+mh/2-j)<<1;
                INT t2 = t1 + (mh<<1);
                FIXP_DBL vr,vi,ur,ui;

                cplxMultDiv2(&vr, &vi, x[t2], x[t2+1], STC(0x5a82799a), STC(0x5a82799a));

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur+vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur-vr;
                x[t2+1] = ui-vi;

                t1 += mh;
                t2 = t1+(mh<<1);

                cplxMultDiv2(&vi, &vr, x[t2], x[t2+1], STC(0x5a82799a), STC(0x5a82799a));

                ur = x[t1]>>1;
                ui = x[t1+1]>>1;

                x[t1]   = ur-vr;
                x[t1+1] = ui+vi;

                x[t2]   = ur+vr;
                x[t2+1] = ui-vi;
            }
        }
    }
}
#endif