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Fixed generic mixed radix butterfly

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'make test' output:
### testing SNR for  1024 point FFTs
#### DOUBLE
snr_t2f = 296.95
snr_f2t = 317.25
#### FLOAT
snr_t2f = 147.96
snr_f2t = 145.14
#### SHORT
snr_t2f = 52.414
snr_f2t = 22.438

#### timing 10000 x 1024 point FFTs
#### DOUBLE
Elapsed:0:03.56 user:2.63 sys:0.19
#### FLOAT
Elapsed:0:01.35 user:1.07 sys:0.10
#### SHORT
Elapsed:0:01.70 user:1.37 sys:0.06
This commit is contained in:
Mark Borgerding 2003-10-15 02:52:34 +00:00
parent 0424734e9d
commit 9504aa79c1
1 changed files with 6 additions and 43 deletions
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49
kiss_fft.c
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@ -37,14 +37,6 @@ 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)
#define C_SUBFROM( 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. */
@ -84,32 +76,6 @@ void printcpx(const char * desc,kiss_fft_cpx c)
{
printf("%s = (%e,%e)\n",desc,(double)c.r,(double)c.i);
}
static
inline
kiss_fft_cpx crot(kiss_fft_cpx c, int numquads)
{
kiss_fft_cpx out;
switch (numquads&3) {
case 0:
out.r = c.r;
out.i = c.i;
break;
case 1:
out.r = c.i;
out.i = -c.r;
break;
case 2:
out.r = -c.r;
out.i = -c.i;
break;
case 3:
out.r = -c.i;
out.i = c.r;
break;
}
return out;
}
#define C_ROTADDTO(sum,c,q) \
do{\
@ -133,7 +99,6 @@ kiss_fft_cpx crot(kiss_fft_cpx c, int numquads)
}\
}while(0)
static
void fft_work(
kiss_fft_cpx * Fout,
@ -278,13 +243,11 @@ void fft_work(
kiss_fft_cpx t;
kiss_fft_cpx * scratch = st->scratch;
kiss_fft_cpx * twiddles = st->twiddles;
#if 1
#if 1
switch (*factors) {
case 4: fft4work(Fout,f,fstride,factors,st); return;
case 2: fft2work(Fout,f,fstride,factors,st); return;
default:
break;
default: break;
}
#endif
p=*factors++;
@ -295,7 +258,7 @@ void fft_work(
Fout[q] = *f;
else
fft_work( Fout + m*q, f, fstride*p,factors,st);
f+= fstride;
f += fstride;
}
for ( u=0; u<m; ++u ) {
@ -303,15 +266,15 @@ void fft_work(
for ( q1=0 ; q1<p ; ++q1 ) {
scratch[q1] = Fout[ k ];
#ifdef FIXED_POINT
scratch[q1].r >>= 1;
scratch[q1].i >>= 1;
scratch[q1].r /= p;
scratch[q1].i /= p;
#endif
k += m;
}
k=u;
for ( q1=0 ; q1<p ; ++q1 ) {
int twidx=3;
int twidx=0;
Fout[ k ] = scratch[0];
for (q=1;q<p;++q ) {
int Norig = st->nfft;