mirror/kissfft
1
0
Fork 0
mirror of https://github.com/mborgerding/kissfft.git synced 2025-07-18 21:14:24 -04:00
Code Issues Packages Projects Releases Wiki Activity

very minor tweaks to radix 3 code

Browse Source
This commit is contained in:
Mark Borgerding
2004-02-24 02:21:03 +00:00
parent ac2eb527b7
commit 71bf5965b8
4 changed files with 39 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
kiss_fft.c
View File

@ -26,7 +26,7 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
static void kf_bfly2(
kiss_fft_cpx * Fout,
const int fstride,
const size_t fstride,
const kiss_fft_cfg st,
int m
)
@ -49,7 +49,7 @@ static void kf_bfly2(
static void kf_bfly4(
kiss_fft_cpx * Fout,
const int fstride,
const size_t fstride,
const kiss_fft_cfg st,
const size_t m
)
@ -96,53 +96,51 @@ static void kf_bfly4(
static void kf_bfly3(
kiss_fft_cpx * Fout,
const int fstride,
const size_t fstride,
const kiss_fft_cfg st,
int m
size_t m
)
{
kiss_fft_cpx *Fout0,*Fout1,*Fout2;
size_t k=m;
const size_t m2 = 2*m;
kiss_fft_cpx *tw1,*tw2;
kiss_fft_cpx scratch[5];
kiss_fft_cpx epi3;
epi3 = st->twiddles[fstride*m];
Fout0=Fout;
Fout1=Fout0+m;
Fout2=Fout0+2*m;
tw1=tw2=st->twiddles;
do{
C_FIXDIV(*Fout0,3); C_FIXDIV(*Fout1,3); C_FIXDIV(*Fout2,3);
C_FIXDIV(*Fout,3); C_FIXDIV(Fout[m],3); C_FIXDIV(Fout[m2],3);
C_MUL(scratch[1],*Fout1 , *tw1);
C_MUL(scratch[2],*Fout2 , *tw2);
C_MUL(scratch[1],Fout[m] , *tw1);
C_MUL(scratch[2],Fout[m2] , *tw2);
C_ADD(scratch[3],scratch[1],scratch[2]);
C_SUB(scratch[0],scratch[1],scratch[2]);
tw1 += fstride;
tw2 += fstride*2;
Fout1->r = Fout0->r - scratch[3].r/2;
Fout1->i = Fout0->i - scratch[3].i/2;
Fout[m].r = Fout->r - scratch[3].r/2;
Fout[m].i = Fout->i - scratch[3].i/2;
C_MULBYSCALAR( scratch[0] , epi3.i );
C_ADDTO(*Fout0,scratch[3]);
C_ADDTO(*Fout,scratch[3]);
Fout2->r = Fout1->r + scratch[0].i;
Fout2->i = Fout1->i - scratch[0].r;
Fout[m2].r = Fout[m].r + scratch[0].i;
Fout[m2].i = Fout[m].i - scratch[0].r;
Fout1->r -= scratch[0].i;
Fout1->i += scratch[0].r;
Fout[m].r -= scratch[0].i;
Fout[m].i += scratch[0].r;
++Fout0;++Fout1;++Fout2;
tw1 += fstride;
tw2 += fstride*2;
}while(--m);
++Fout;
}while(--k);
}
static void kf_bfly5(
kiss_fft_cpx * Fout,
const int fstride,
const size_t fstride,
const kiss_fft_cfg st,
int m
)
@ -204,7 +202,7 @@ static void kf_bfly5(
/* perform the butterfly for one stage of a mixed radix FFT */
static void kf_bfly_generic(
kiss_fft_cpx * Fout,
const int fstride,
const size_t fstride,
const kiss_fft_cfg st,
int m,
int p
@ -243,7 +241,7 @@ static
void kf_work(
kiss_fft_cpx * Fout,
const kiss_fft_cpx * f,
const int fstride,
const size_t fstride,
int in_stride,
int * factors,
const kiss_fft_cfg st