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Fixed point works

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'make test' output:

### testing SNR for  1024 point FFTs
#### DOUBLE
snr_t2f = 296.51
snr_f2t = 315.25
#### FLOAT
snr_t2f = 146.39
snr_f2t = 142.86
#### SHORT
snr_t2f = 58.077
snr_f2t = 27.897

#### timing 10000 x 1024 point FFTs
#### DOUBLE
Elapsed:0:01.53 user:1.06 sys:0.26
#### FLOAT
Elapsed:0:01.29 user:0.98 sys:0.12
#### SHORT
Elapsed:0:02.08 user:1.65 sys:0.03
This commit is contained in:
Mark Borgerding 2003-10-14 01:09:33 +00:00
parent 8460f1f8f5
commit 6b76490456
1 changed files with 29 additions and 15 deletions
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44
kiss_fft.c
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@ -37,6 +37,10 @@ typedef struct {
}kiss_fft_state;
#ifdef FIXED_POINT
#define C_SUB( res, a,b)\
do { (res).r=((a).r-b.r+1)>>1; (res).i=((a).i-b.i+1)>>1; }while(0)
#define C_ADDTO( res , a)\
do { (res).r=((res).r+(a).r+1)>>1; (res).i=((res).i+(a).i+1)>>1; }while(0)
/* We don't have to worry about overflow from multiplying by twiddle factors since they
* all have unity magnitude. Still need to shift away fractional bits after adding 1/2 for
* rounding. */
@ -45,6 +49,11 @@ typedef struct {
(m).i = ( ( (a).r*(b).i + (a).i*(b).r) + (1<<14) ) >> 15;\
}while(0)
#else // not FIXED_POINT
#define C_SUB( res, a,b)\
do { (res).r=(a).r-(b).r; (res).i=(a).i-(b).i; }while(0)
#define C_ADDTO( res , a)\
do { (res).r += (a).r; (res).i += (a).i; }while(0)
#define C_MUL(m,a,b) \
do{ (m).r = (a).r*(b).r - (a).i*(b).i;\
(m).i = (a).r*(b).i + (a).i*(b).r; }while(0)
@ -80,17 +89,21 @@ void fft2work(
const kiss_fft_cpx * f,
int fstride,
int * factors,
const kiss_fft_state * st,
int m
const kiss_fft_state * st
)
{
int u;
kiss_fft_cpx * Fout2;
int u,m;
kiss_fft_cpx t;
//kiss_fft_cpx * scratch = st->scratch;
kiss_fft_cpx * twiddles = st->twiddles;
//int Norig = st->nfft;
if (m==1) {
factors++;// p==2
m=*factors++;
if (*factors == 2){
fft2work(Fout,f,fstride*2,factors,st);
fft2work(Fout+m,f+fstride,fstride*2,factors,st);
}else if (m==1) {
Fout[0] = f[0];
Fout[1] = f[fstride];
} else {
@ -98,12 +111,14 @@ void fft2work(
fft_work( Fout + m, f+fstride, fstride*2,factors,st);
}
Fout2 = Fout + m;
for ( u=0; u<m; ++u ) {
C_MUL (t, Fout[ u +m ] , twiddles[fstride * u]);
Fout[u+m].r = Fout[u].r - t.r;
Fout[u+m].i = Fout[u].i - t.i;
Fout[u].r += t.r;
Fout[u].i += t.i;
C_MUL (t, *Fout2 , *twiddles);
twiddles += fstride;
C_SUB( *Fout2 , *Fout , t );
C_ADDTO( *Fout , t );
++Fout2;
++Fout;
}
}
@ -122,18 +137,17 @@ void fft_work(
kiss_fft_cpx * twiddles = st->twiddles;
int Norig = st->nfft;
p=*factors++;
m=*factors++;
#if 1
switch (*factors) {
case 2:
fft2work(Fout,f,fstride,factors,st,m);
fft2work(Fout,f,fstride,factors,st);
return;
default:
break;
}
#endif
p=*factors++;
m=*factors++;
for (q=0;q<p;++q) {
if (m==1)