mirror of
https://github.com/mborgerding/kissfft.git
synced 2025-07-23 07:24:33 -04:00
better, reduced mutliply in real fft
This commit is contained in:
17
kiss_fftr.c
17
kiss_fftr.c
@ -79,25 +79,30 @@ void kiss_fftr(const void * cfg,const kiss_fft_scalar *timedata,kiss_fft_cpx *fr
|
||||
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;
|
||||
for (k=1;k <= N/2 ; ++k ) {
|
||||
kiss_fft_cpx fpnk,fpk,f1k,f2k,tw;
|
||||
|
||||
fpk = st->tmpbuf[k];
|
||||
fpnk.r = st->tmpbuf[N-k].r;
|
||||
fpnk.i = -st->tmpbuf[N-k].i;
|
||||
|
||||
C_ADD( f1k, fpk , fpnk );
|
||||
C_SUBFROM( fpk , fpnk );
|
||||
C_MUL( freqdata[k], fpk , st->super_twiddles[k] );
|
||||
C_ADDTO(freqdata[k],f1k);
|
||||
C_SUB( f2k, fpk , fpnk );
|
||||
C_MUL( tw , f2k , st->super_twiddles[k]);
|
||||
|
||||
C_ADD( freqdata[k] , f1k ,tw);
|
||||
freqdata[k].r /= 2;
|
||||
freqdata[k].i /= 2;
|
||||
|
||||
freqdata[N-k].r = f1k.r - tw.r;
|
||||
freqdata[N-k].i = - (f1k.i - tw.i);
|
||||
freqdata[N-k].r /= 2;
|
||||
freqdata[N-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 */
|
||||
|
Reference in New Issue
Block a user