kf_work()

static void kf_work ( kiss_fft_cpx * Fout, const kiss_fft_cpx * f, const size_t fstride, int in_stride, int * factors, const kiss_fft_cfg st )

static

Definition at line 240 of file kiss_fft.cpp.hpp.

{
    kiss_fft_cpx * Fout_beg=Fout;
    const int p=*factors++; /* the radix  */
    const int m=*factors++; /* stage's fft length/p */
    const kiss_fft_cpx * Fout_end = Fout + p*m;
 
#ifdef _OPENMP
    // use openmp extensions at the 
    // top-level (not recursive)
    if (fstride==1 && p<=5)
    {
        int k;
 
        // execute the p different work units in different threads
#       pragma omp parallel for
        for (k=0;k<p;++k) 
            kf_work( Fout +k*m, f+ fstride*in_stride*k,fstride*p,in_stride,factors,st);
        // all threads have joined by this point
 
        switch (p) {
            case 2: kf_bfly2(Fout,fstride,st,m); break;
            case 3: kf_bfly3(Fout,fstride,st,m); break; 
            case 4: kf_bfly4(Fout,fstride,st,m); break;
            case 5: kf_bfly5(Fout,fstride,st,m); break; 
            default: kf_bfly_generic(Fout,fstride,st,m,p); break;
        }
        return;
    }
#endif
 
    if (m==1) {
        do{
            *Fout = *f;
            f += fstride*in_stride;
        }while(++Fout != Fout_end );
    }else{
        do{
            // recursive call:
            // DFT of size m*p performed by doing
            // p instances of smaller DFTs of size m, 
            // each one takes every mth sample
            // so0, s1, s2 become
            // so, sm, s2m, s3m, ...
            // s1, s(1+m), s(1+2m), ...
            // s2, s(2+m), s(2+2m), ...
            // etc.
            kf_work( Fout , f, fstride*p, in_stride, factors,st);
            f += fstride*in_stride;
        }while( (Fout += m) != Fout_end );
    }
 
    Fout=Fout_beg;
 
    // recombine the p smaller DFTs 
    switch (p) {
        case 2: kf_bfly2(Fout,fstride,st,m); break;
        case 3: kf_bfly3(Fout,fstride,st,m); break;
        case 4: kf_bfly4(Fout,fstride,st,m); break;
        case 5: kf_bfly5(Fout,fstride,st,m); break;
        default: kf_bfly_generic(Fout,fstride,st,m,p); break;
    }
}

References FL_NOEXCEPT, kf_bfly2(), kf_bfly3(), kf_bfly4(), kf_bfly5(), kf_bfly_generic(), and kf_work().

Referenced by kf_work(), and kiss_fft_stride().

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