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real fwd and rev fft works

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This commit is contained in:
Mark Borgerding
2003-12-09 04:10:50 +00:00
parent 14e9b0dce4
commit b737756abb
4 changed files with 98 additions and 36 deletions
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53
kiss_fftr.c
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@ -48,6 +48,8 @@ void * kiss_fftr_alloc(int nfft,int inverse_fft)
for (i=0;i<nfft;++i) {
double phase = -3.14159265358979323846264338327 * ( (double)i / nfft + .5);
if (inverse_fft)
phase *= -1;
st->super_twiddles[i] = kf_cexp( phase );
}
return st;
@ -58,13 +60,13 @@ static void pcpx( kiss_fft_cpx * c)
printf("%g + %gi\n",c->r,c->i);
}
void kiss_fftr(const void * cfg,const kiss_fft_scalar *fin,kiss_fft_cpx *fout)
void kiss_fftr(const void * cfg,const kiss_fft_scalar *timedata,kiss_fft_cpx *freqdata)
{
/* input buffer fin is stored row-wise */
/* input buffer timedata is stored row-wise */
kiss_fftr_state *st = ( kiss_fftr_state *)cfg;
int k,N;
if (st->minus3 != -3 || st->substate->inverse ) {
if ( st->minus3 != -3 || st->substate->inverse) {
fprintf(stderr,"kiss fft usage error: improper alloc\n");
exit(1);
}
@ -72,10 +74,10 @@ void kiss_fftr(const void * cfg,const kiss_fft_scalar *fin,kiss_fft_cpx *fout)
N = st->substate->nfft;
/*perform the parallel fft of two real signals packed in real,imag*/
kiss_fft( st->substate , (const kiss_fft_cpx*)fin, st->tmpbuf );
kiss_fft( st->substate , (const kiss_fft_cpx*)timedata, st->tmpbuf );
fout[0].r = st->tmpbuf[0].r + st->tmpbuf[0].i;
fout[0].i = 0;
freqdata[0].r = st->tmpbuf[0].r + st->tmpbuf[0].i;
freqdata[0].i = 0;
for (k=1;k<N;++k) {
kiss_fft_cpx fpnk,fpk,f1k;
@ -86,12 +88,43 @@ void kiss_fftr(const void * cfg,const kiss_fft_scalar *fin,kiss_fft_cpx *fout)
C_ADD( f1k, fpk , fpnk );
C_SUBFROM( fpk , fpnk );
C_MUL( fout[k], fpk , st->super_twiddles[k] );
C_ADDTO(fout[k],f1k);
C_MUL( freqdata[k], fpk , st->super_twiddles[k] );
C_ADDTO(freqdata[k],f1k);
fout[k].r /= 2;
fout[k].i /= 2;
freqdata[k].r /= 2;
freqdata[k].i /= 2;
}
freqdata[N].r = st->tmpbuf[0].r - st->tmpbuf[0].i;
freqdata[N].i = 0;
}
void kiss_fftri(const void * cfg,const kiss_fft_cpx *freqdata,kiss_fft_scalar *timedata)
{
/* input buffer timedata is stored row-wise */
kiss_fftr_state *st = (kiss_fftr_state *) cfg;
int k, N;
if (st->minus3 != -3 || st->substate->inverse == 0) {
fprintf (stderr, "kiss fft usage error: improper alloc\n");
exit (1);
}
N = st->substate->nfft;
st->tmpbuf[0].r = freqdata[0].r + freqdata[N].r;
st->tmpbuf[0].i = freqdata[0].r - freqdata[N].r;
for (k = 1; k <= N / 2; ++k) {
kiss_fft_cpx fk, fnkc, fek, fok, tmpbuf;
fk = freqdata[k];
fnkc.r = freqdata[N - k].r;
fnkc.i = -freqdata[N - k].i;
C_ADD (fek, fk, fnkc);
C_SUB (tmpbuf, fk, fnkc);
C_MUL (fok, tmpbuf, st->super_twiddles[k]);
C_ADD (st->tmpbuf[k], fek, fok);
C_SUB (st->tmpbuf[N - k], fek, fok);
st->tmpbuf[N - k].i *= -1;
}
kiss_fft (st->substate, st->tmpbuf, (kiss_fft_cpx *) timedata);
}