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the path I was taking would only work for prime numbers (Galois fields)

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Mark Borgerding 2003-11-08 01:42:15 +00:00
parent e98f9ff29a
commit bd23fe8d23
1 changed files with 20 additions and 53 deletions
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73
kiss_fft.c
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@ -287,63 +287,32 @@ void bfly_generic(
int p
)
{
int u,q,d,fsm,halfp,mp,uf;
int u,k,q1,q;
kiss_fft_cpx * scratch = st->scratch;
kiss_fft_cpx * scratch2 = scratch + p;
kiss_fft_cpx * tw = st->twiddles;
kiss_fft_cpx tlo,t3,t4;
kiss_fft_cpx *Foutlo,*Fouthi;
fsm = fstride*m;
halfp=p/2;
mp=m*p;
for ( q=1; q<p ; ++q ) {
int twidx = q*fsm;
for ( d=1; d<=halfp;++d) {
tlo = tw[ twidx];
twidx += d*fsm;
if (twidx >= st->nfft)
twidx -= st->nfft;
*scratch2++ = tlo;
}
}
kiss_fft_cpx * twiddles = st->twiddles;
kiss_fft_cpx t;
int Norig = st->nfft;
for ( u=0; u<m; ++u ) {
scratch[0] = Fout[0];
scratch2 = scratch + p;
uf=u*fstride;
Foutlo=Fout;
for ( q=1 ; q<p ; ++q ) {
Foutlo += m;
C_MUL( scratch[q] , *Foutlo , tw[uf*q] );
*Foutlo = scratch[0];
k=u;
for ( q1=0 ; q1<p ; ++q1 ) {
scratch[q1] = Fout[ k ];
C_FIXDIV(scratch[q1],p);
k += m;
}
for ( q=1; q<p ; ++q ) {
C_ADDTO(*Fout , scratch[q] );
Foutlo=Fout+m;
Fouthi=Fout+mp;
do{
tlo = *scratch2++;
t3.r = scratch[q].r * tlo.r;
t3.i = scratch[q].r * tlo.i;
t4.r = scratch[q].i * tlo.i;
t4.i = - scratch[q].i * tlo.r;
Fouthi -= m;
Foutlo->r += t3.r - t4.r;
Foutlo->i += t3.i - t4.i;
Fouthi->r += t3.r + t4.r;
Fouthi->i -= t3.i + t4.i;
}while( (Foutlo += m) < Fouthi );
k=u;
for ( q1=0 ; q1<p ; ++q1 ) {
int twidx=0;
Fout[ k ] = scratch[0];
for (q=1;q<p;++q ) {
twidx += fstride * k;
if (twidx>=Norig) twidx-=Norig;
C_MUL(t,scratch[q] , twiddles[twidx] );
C_ADDTO( Fout[ k ] ,t);
}
k += m;
}
++Fout;
}
}
@ -369,9 +338,7 @@ void fft_work(
switch (p) {
case 2: bfly2(Fout,fstride,st,m); break;
#if 1
case 3: bfly3(Fout,fstride,st,m); break;
#endif
case 4: bfly4(Fout,fstride,st,m); break;
case 5: bfly5(Fout,fstride,st,m); break;
default: bfly_generic(Fout,fstride,st,m,p); break;