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fixed does not currently work for radix 3
This commit is contained in:
Mark Borgerding 2003-10-17 01:26:14 +00:00
parent 317f11e66e
commit 73744b908c
1 changed files with 39 additions and 26 deletions
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65
kiss_fft.c
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@ -169,37 +169,50 @@ void bfly3(
int m int m
) )
{ {
const int p=3; kiss_fft_cpx *Fout0,*Fout1,*Fout2;
int u,k,q1,q;
int u;
kiss_fft_cpx * scratch = st->scratch; kiss_fft_cpx * scratch = st->scratch;
kiss_fft_cpx * twiddles = st->twiddles; kiss_fft_cpx * twiddles = st->twiddles;
kiss_fft_cpx t; kiss_fft_cpx t[6];
//kiss_fft_cpx epi3 = twiddles[fstride*m];
kiss_fft_cpx epi3 = { -0.500000000000000 , -0.866025403784439 };
kiss_fft_cpx nepi3 = { -0.500000000000000 , 0.866025403784439 };
if ( st->inverse){
epi3.i *=-1;
nepi3.i *=-1;
}
//printf("epi3=%e,%ei\n",epi3.r,epi3.i);
for ( u=0; u<m; ++u ) { for ( u=0; u<m; ++u ) {
k=u;
for ( q1=0 ; q1<p ; ++q1 ) {
scratch[q1] = Fout[ k ];
#ifdef FIXED_POINT
scratch[q1].r /= p;
scratch[q1].i /= p;
#endif
k += m;
}
k=u; Fout0=Fout++;
for ( q1=0 ; q1<p ; ++q1 ) { Fout1=Fout0+m;
int twidx=0; Fout2=Fout0+2*m;
Fout[ k ] = scratch[0]; scratch[0] = *Fout0;
for (q=1;q<p;++q ) { scratch[1] = *Fout1;
int Norig = st->nfft; scratch[2] = *Fout2;
twidx += fstride * k;
if (twidx>=Norig) twidx-=Norig; // st->nfft = 3*m*fstride
C_MUL(t,scratch[q] , twiddles[twidx] ); // u < m
Fout[ k ].r += t.r; C_MUL(t[0],scratch[1] , twiddles[fstride*u ] );
Fout[ k ].i += t.i; //C_MUL(t[2],scratch[1] , twiddles[fstride*u+fstride*m] );
} C_MUL(t[2],t[0] , epi3 );
k += m; //C_MUL(t[4],scratch[1] , twiddles[fstride*u+2*fstride*m] );
} C_MUL(t[4],t[2] , epi3);
C_MUL(t[1],scratch[2] , twiddles[fstride*u*2] );
//C_MUL(t[3],scratch[2] , twiddles[(fstride*(u+m)*2)%st->nfft] );
C_MUL(t[3],t[1] , nepi3);
//C_MUL(t[5],scratch[2] , twiddles[(fstride*(u+2*m)*2)%st->nfft] );
C_MUL(t[5],t[3] , nepi3);
Fout0->r = scratch[0].r + t[0].r + t[1].r;
Fout0->i = scratch[0].i + t[0].i + t[1].i;
Fout1->r = scratch[0].r + t[2].r + t[3].r;
Fout1->i = scratch[0].i + t[2].i + t[3].i;
Fout2->r = scratch[0].r + t[4].r + t[5].r;
Fout2->i = scratch[0].i + t[4].i + t[5].i;
} }
} }