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This commit is contained in:
Mark Borgerding 2003-11-07 03:04:52 +00:00
parent e9095a161c
commit 1486d89291
1 changed files with 39 additions and 21 deletions
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60
kiss_fft.c
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@ -287,45 +287,63 @@ void bfly_generic(
int p int p
) )
{ {
int u,q,d; int u,q,d,fsm,halfp,mp;
kiss_fft_cpx * scratch = st->scratch; kiss_fft_cpx * scratch = st->scratch;
kiss_fft_cpx * scratch2 = scratch + p;
kiss_fft_cpx * tw = st->twiddles; kiss_fft_cpx * tw = st->twiddles;
kiss_fft_cpx tlo,t1,t2,t3,t4; 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;
}
}
for ( u=0; u<m; ++u ) { for ( u=0; u<m; ++u ) {
scratch[0] = Fout[u]; scratch[0] = Fout[0];
scratch2 = scratch + p;
for ( q=1 ; q<p ; ++q ) { for ( q=1 ; q<p ; ++q ) {
C_MUL( scratch[q] , Fout[ m*q + u] , tw[u*fstride*q] ); C_MUL( scratch[q] , Fout[ m*q ] , tw[u*fstride*q] );
Fout[ m*q + u] = scratch[0]; Fout[ m*q ] = scratch[0];
C_ADDTO(Fout[u] , scratch[q] ); C_ADDTO(*Fout , scratch[q] );
} }
for ( q=1; q<p ; ++q ) { for ( q=1; q<p ; ++q ) {
int twidx = q*fstride * m; int twidx = q*fsm;
for ( d=1; d<=p/2;++d) {
tlo = tw[ twidx]; Foutlo=Fout;
twidx += d*fstride*m; Fouthi=Fout + mp;
if (twidx >= st->nfft) for ( d=1; d<=halfp;++d) {
twidx -= st->nfft; Foutlo += m;
Fouthi -= m;
tlo = *scratch2++;
t3.r = scratch[q].r * tlo.r; t3.r = scratch[q].r * tlo.r;
t3.i = scratch[q].r * tlo.i; t3.i = scratch[q].r * tlo.i;
t4.r = scratch[q].i * tlo.i; t4.r = scratch[q].i * tlo.i;
t4.i = - scratch[q].i * tlo.r; t4.i = - scratch[q].i * tlo.r;
t1.r = t3.r - t4.r; Foutlo->r += t3.r - t4.r;
t1.i = t3.i - t4.i; Fouthi->r += t3.r + t4.r;
Foutlo->i += t3.i - t4.i;
t2.r = t3.r + t4.r; Fouthi->i -= t3.i + t4.i;
t2.i = - (t3.i + t4.i);
C_ADDTO( Fout[ m*d+u ] ,t1);
C_ADDTO( Fout[ m*(p-d)+u ] ,t2);
} }
} }
++Fout;
} }
} }
@ -351,7 +369,7 @@ void fft_work(
switch (p) { switch (p) {
case 2: bfly2(Fout,fstride,st,m); break; case 2: bfly2(Fout,fstride,st,m); break;
#if 0 #if 0
case 3: bfly3(Fout,fstride,st,m); break; case 3: bfly3(Fout,fstride,st,m); break;
#endif #endif
case 4: bfly4(Fout,fstride,st,m); break; case 4: bfly4(Fout,fstride,st,m); break;