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about to start working on real inverse fft optimzation

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Mark Borgerding
2003-12-09 01:51:29 +00:00
parent 008d7fd4ea
commit 14e9b0dce4
1 changed files with 6 additions and 11 deletions
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15
kiss_fftr.c
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@ -47,7 +47,7 @@ void * kiss_fftr_alloc(int nfft,int inverse_fft)
kf_init_state (st->substate, nfft, inverse_fft); kf_init_state (st->substate, nfft, inverse_fft);
for (i=0;i<nfft;++i) { for (i=0;i<nfft;++i) {
double phase = -3.14159265358979323846264338327 * i / nfft; double phase = -3.14159265358979323846264338327 * ( (double)i / nfft + .5);
st->super_twiddles[i] = kf_cexp( phase ); st->super_twiddles[i] = kf_cexp( phase );
} }
return st; return st;
@ -78,25 +78,20 @@ void kiss_fftr(const void * cfg,const kiss_fft_scalar *fin,kiss_fft_cpx *fout)
fout[0].i = 0; fout[0].i = 0;
for (k=1;k<N;++k) { for (k=1;k<N;++k) {
kiss_fft_cpx fpnk,fpk,f1k,f2k,scr[2]; kiss_fft_cpx fpnk,fpk,f1k;
fpk = st->tmpbuf[k]; fpk = st->tmpbuf[k];
fpnk.r = st->tmpbuf[N-k].r; fpnk.r = st->tmpbuf[N-k].r;
fpnk.i = -st->tmpbuf[N-k].i; fpnk.i = -st->tmpbuf[N-k].i;
C_ADD( f1k, fpk , fpnk ); C_ADD( f1k, fpk , fpnk );
C_SUBFROM( fpk , fpnk ); C_SUBFROM( fpk , fpnk );
C_MUL( fout[k], fpk , st->super_twiddles[k] );
f2k.r = fpk.i; C_ADDTO(fout[k],f1k);
f2k.i = -fpk.r;
C_MUL( scr[1], f2k , st->super_twiddles[k] );
C_ADD(fout[k],f1k,scr[1]);
fout[k].r /= 2; fout[k].r /= 2;
fout[k].i /= 2; fout[k].i /= 2;
} }
} }