fft_rad2_arm.cpp - Android社区 - https://www.androidos.net.cn/

/* -----------------------------------------------------------------------------------------------------------
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Fraunhofer Institute for Integrated Circuits IIS
Attention: Audio and Multimedia Departments - FDK AAC LL
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----------------------------------------------------------------------------------------------------------- */

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

Author(s):
   Description: dit_fft ARM assembler replacements.

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

/* NEON optimized FFT currently builds only with RVCT toolchain */

#ifndef FUNCTION_dit_fft

/* If dit_fft was not yet defined by ARM-Cortex ... */

#if defined(SINETABLE_16BIT)

#define FUNCTION_dit_fft

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

date:   28.07.2005   srl

Contents/description: dit-tukey-FFT-algorithm

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

#if defined(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 i;

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 */
    }

INT mh = 1 << 1;
    INT ldm = ldn - 2;
    INT trigstep = trigDataSize;

do
    {
        const FIXP_STP *pTrigData = trigdata;
        INT j;

mh <<= 1;
        trigstep >>= 1;

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. */
        {
            FIXP_DBL *xt1 = x;
            int r = n;

do {
                FIXP_DBL *xt2 = xt1 + (mh<<1);
                /*
                FIXP_DBL *xt1 = x+ ((r)<<1);
                FIXP_DBL *xt2 = xt1 + (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 = xt2[1]>>1;
                vr = xt2[0]>>1;

ur = xt1[0]>>1;
                ui = xt1[1]>>1;

xt1[0] = ur+vr;
                xt1[1] = ui+vi;

xt2[0] = ur-vr;
                xt2[1] = ui-vi;

xt1 += mh;
                xt2 += mh;

//cplxMultDiv2(&vr, &vi, x[t2+1], x[t2], (FIXP_SGL)1.0, (FIXP_SGL)0.0);
                vr = xt2[1]>>1;
                vi = xt2[0]>>1;

ur = xt1[0]>>1;
                ui = xt1[1]>>1;

xt1[0] = ur+vr;
                xt1[1] = ui-vi;

xt2[0] = ur-vr;
                xt2[1] = ui+vi;

xt1 = xt2 + mh;
            } while ((r=r-(mh<<1)) != 0);
        }
        for(j=4; j<mh; j+=4)
        {
            FIXP_DBL *xt1 = x + (j>>1);
            FIXP_SPK cs;
            int r = n;

pTrigData += trigstep;
            cs = *pTrigData;

do
            {
                FIXP_DBL *xt2 = xt1 + (mh<<1);
                FIXP_DBL vr,vi,ur,ui;

cplxMultDiv2(&vi, &vr, xt2[1], xt2[0], cs);

ur = xt1[0]>>1;
                ui = xt1[1]>>1;

xt1[0] = ur+vr;
                xt1[1] = ui+vi;

xt2[0] = ur-vr;
                xt2[1] = ui-vi;

xt1 += mh;
                xt2 += mh;

cplxMultDiv2(&vr, &vi, xt2[1], xt2[0], cs);

ur = xt1[0]>>1;
                ui = xt1[1]>>1;

xt1[0] = ur+vr;
                xt1[1] = ui-vi;

xt2[0] = ur-vr;
                xt2[1] = ui+vi;

/* Same as above but for t1,t2 with j>mh/4 and thus cs swapped */
                xt1 = xt1 - (j);
                xt2 = xt1 + (mh<<1);

cplxMultDiv2(&vi, &vr, xt2[0], xt2[1], cs);

ur = xt1[0]>>1;
                ui = xt1[1]>>1;

xt1[0] = ur+vr;
                xt1[1] = ui-vi;

xt2[0] = ur-vr;
                xt2[1] = ui+vi;

xt1 += mh;
                xt2 += mh;

cplxMultDiv2(&vr, &vi, xt2[0], xt2[1], cs);

ur = xt1[0]>>1;
                ui = xt1[1]>>1;

xt1[0] = ur-vr;
                xt1[1] = ui-vi;

xt2[0] = ur+vr;
                xt2[1] = ui+vi;

xt1 = xt2 + (j);
            }  while ((r=r-(mh<<1)) != 0);
        }
        {
            FIXP_DBL *xt1 = x + (mh>>1);
            int r = n;

do
            {
                FIXP_DBL *xt2 = xt1 + (mh<<1);
                FIXP_DBL vr,vi,ur,ui;

cplxMultDiv2(&vi, &vr, xt2[1], xt2[0], STC(0x5a82799a), STC(0x5a82799a));

ur = xt1[0]>>1;
                ui = xt1[1]>>1;

xt1[0] = ur+vr;
                xt1[1] = ui+vi;

xt2[0] = ur-vr;
                xt2[1] = ui-vi;

xt1 += mh;
                xt2 += mh;

cplxMultDiv2(&vr, &vi, xt2[1], xt2[0], STC(0x5a82799a), STC(0x5a82799a));

ur = xt1[0]>>1;
                ui = xt1[1]>>1;

xt1[0] = ur+vr;
                xt1[1] = ui-vi;

xt2[0] = ur-vr;
                xt2[1] = ui+vi;

xt1 = xt2 + mh;
            }  while ((r=r-(mh<<1)) != 0);
        }
    } while (--ldm != 0);
}

#endif /* if defined(FUNCTION_dit_fft)  */

#endif /* if defined(SINETABLE_16BIT) */

#endif /* ifndef FUNCTION_dit_fft */

C++程序 | 322行 | 10.7 KB

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