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broken

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working towards mixed radix
decomposition seems to work (for 2)
indices scrambled
This commit is contained in:
Mark Borgerding 2003-08-16 23:40:14 +00:00
parent c9ff98b2c9
commit 502211bc6a
3 changed files with 97 additions and 47 deletions
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2
Makefile
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@ -2,7 +2,7 @@ message:
@echo "Nothing to make here. Move on down to sample_code for ... you guessed it! Sample Code!" @echo "Nothing to make here. Move on down to sample_code for ... you guessed it! Sample Code!"
tarball: clean tarball: clean
tar -czf kiss_fft.tar.gz . tar --exclude CVS -czf kiss_fft.tar.gz .
clean: clean:
cd sample_code && make clean cd sample_code && make clean

126
kiss_fft.c
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@ -13,6 +13,7 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
*/ */
#include <stdlib.h> #include <stdlib.h>
#include <stdio.h>
#include <math.h> #include <math.h>
#include "kiss_fft.h" #include "kiss_fft.h"
/* /*
@ -26,10 +27,19 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
*/ */
typedef struct { typedef struct {
int nfft; int nr; // N remaining
kiss_fft_cpx* twiddle; int radix; // radix of the stage
int * swap_indices; kiss_fft_cpx * twiddle;
int nswap; }kiss_fft_stage;
#define MAX_STAGES 20
typedef struct {
int nstages;
int allocsize;
kiss_fft_stage stages[MAX_STAGES];
int * unscramble_indices;
}kiss_fft_state; }kiss_fft_state;
#ifdef FIXED_POINT #ifdef FIXED_POINT
@ -73,20 +83,15 @@ typedef struct {
// create the twiddle factors // create the twiddle factors
static static
void make_twiddles(kiss_fft_cpx * twiddle,int nfft,int inverse_fft) void make_twiddles(kiss_fft_cpx * twiddle,int ntwid,int symmetry,int inverse_fft)
{ {
const double pi=3.14159265358979323846264338327; const double pi=3.14159265358979323846264338327;
int n; int n;
for (n=0;n< (nfft>>1);++n) { int denom = ntwid*symmetry;
#ifdef FIXED_POINT
// TODO: find another way to calculate these without so much floating point math for (n=0;n<ntwid;++n) {
twiddle[n].r = (kiss_fft_scalar)(TWIDDLE_RANGE*cos(2*pi*n/nfft)+.5); twiddle[n].r = cos(2*pi*n/denom);
twiddle[n].i = -(kiss_fft_scalar)(TWIDDLE_RANGE*sin(2*pi*n/nfft)+.5); twiddle[n].i = -sin(2*pi*n/denom);
#else
twiddle[n].r = cos(2*pi*n/nfft);
twiddle[n].i = -sin(2*pi*n/nfft);
#endif
// inverse fft uses complex conjugate twiddle factors // inverse fft uses complex conjugate twiddle factors
if (inverse_fft) if (inverse_fft)
twiddle[n].i *= -1; twiddle[n].i *= -1;
@ -141,32 +146,59 @@ void undo_bit_rev( kiss_fft_cpx * f, const int * swap_indices,int nswap)
// the heart of the fft // the heart of the fft
static static
void fft_work(int N,kiss_fft_cpx *f,const kiss_fft_cpx * twid,int twid_step) void fft_work( kiss_fft_cpx * f,const kiss_fft_stage * stage , int nstages )
{ {
N >>= 1; int n;
// only works for 2s
{ // declare automatic variables in here to reduce stack usage { // declare automatic variables in here to reduce stack usage
int n;
kiss_fft_cpx csum,cdiff; kiss_fft_cpx csum,cdiff;
const kiss_fft_cpx * cur_twid = twid;
kiss_fft_cpx *f1 = f; kiss_fft_cpx *f1 = f;
kiss_fft_cpx *f2 = f+N; kiss_fft_cpx *f2 = f+ stage->nr;
for (n=0;n<N;++n) const kiss_fft_cpx * twid = stage->twiddle;
for ( n = 0 ; n < stage->nr ; ++n )
{ {
C_ADD( csum, *f1 , *f2 ); C_ADD( csum, *f1 , *f2 );
C_SUB( cdiff, *f1 , *f2 ); C_SUB( cdiff, *f1 , *f2 );
*f1++ = csum; *f1++ = csum;
C_MUL(*f2, cdiff, *cur_twid); C_MUL(*f2, cdiff, *twid);
++f2; ++f2;
cur_twid += twid_step; ++twid;
} }
} }
if (N==1) return; if ( nstages == 1 )
//twid_step *= 2; return;
fft_work(N,f+N,twid,twid_step*2);
fft_work(N,f,twid,twid_step*2); for (n=0;n<stage->radix;++n)
fft_work( f + n * stage->nr ,stage+1,nstages-1);
} }
static
kiss_fft_state * decompose( kiss_fft_state * st, int * pnfft,int radix,int inverse_fft)
{
int nfft = *pnfft;
while (nfft>1 && (nfft%radix)==0) {
int newsize;
int nstages=st->nstages;
nfft /= radix;
fprintf(stderr,"%d ",radix);
newsize = st->allocsize + nfft * sizeof(kiss_fft_cpx);
st=(kiss_fft_state*)realloc(st,newsize);
st->stages[nstages].radix=radix;
st->stages[nstages].nr=nfft;
st->stages[nstages].twiddle = (kiss_fft_cpx*)((char*)st + st->allocsize);
make_twiddles( st->stages[nstages].twiddle,nfft,radix,inverse_fft );
st->allocsize = newsize;
st->nstages = nstages+1;
}
*pnfft = nfft;
return st;
}
/* /*
* void * kiss_fft_alloc(int nfft,int inverse_fft) * void * kiss_fft_alloc(int nfft,int inverse_fft)
@ -179,26 +211,36 @@ void fft_work(int N,kiss_fft_cpx *f,const kiss_fft_cpx * twid,int twid_step)
void * kiss_fft_alloc(int nfft,int inverse_fft) void * kiss_fft_alloc(int nfft,int inverse_fft)
{ {
kiss_fft_state * st=NULL; kiss_fft_state * st=NULL;
// allocate one large buffer to hold the state, twiddle buffers, and bit-rev indices int tmp;
int size = sizeof(kiss_fft_state) + (nfft>>1)*sizeof(kiss_fft_cpx) + nfft*sizeof(int); int i;
int allocsize=sizeof(kiss_fft_state) + nfft*sizeof(int);
st = ( kiss_fft_state *)malloc(size); st = ( kiss_fft_state *)malloc( allocsize );
if (st) { st->nstages=0;
st->twiddle = (kiss_fft_cpx*)(st+1); // pointer just beyond the kiss_fft_state struct st->allocsize=allocsize;
st->swap_indices = (int*)( st->twiddle + (nfft>>1) );// pointer just beyond the twiddle buffer st->unscramble_indices = (int*)(st+1);// just past end of buffer
st->nfft = nfft;
// initialize the twiddle factors for (i=0;i<nfft;++i)
make_twiddles(st->twiddle,nfft,inverse_fft); st->unscramble_indices[i] = i;
// create list of index-swaps
st->nswap = make_bit_reverse_indices(st->swap_indices,nfft); fprintf(stderr,"factoring %d: ",nfft);
tmp=nfft;
st = decompose( st,&tmp,2,inverse_fft);
fprintf(stderr,"\n");
// TODO factor 3,5,7,11 ???
if ( tmp > 1 ) {
fprintf(stderr,"%d not factorable by 2,3 (%d remaining)\n",nfft,tmp);
free(st);
return NULL;
} }
return st; return st;
} }
void kiss_fft(const void * cfg,kiss_fft_cpx *f) void kiss_fft(const void * cfg,kiss_fft_cpx *f)
{ {
const kiss_fft_state * st = cfg; const kiss_fft_state * st = cfg;
fft_work(st->nfft, f, st->twiddle , 1 ); fft_work( f, st->stages , st->nstages );
undo_bit_rev(f,st->swap_indices,st->nswap);
} }

16
tools/fftutil.c
View File

@ -26,7 +26,7 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
void fft_file(FILE * fin,FILE * fout,int nfft,int isinverse) void fft_file(FILE * fin,FILE * fout,int nfft,int isinverse,int useascii)
{ {
void *st; void *st;
kiss_fft_cpx * buf; kiss_fft_cpx * buf;
@ -36,7 +36,13 @@ void fft_file(FILE * fin,FILE * fout,int nfft,int isinverse)
while ( fread( buf , sizeof(kiss_fft_cpx) * nfft ,1, fin ) > 0 ) { while ( fread( buf , sizeof(kiss_fft_cpx) * nfft ,1, fin ) > 0 ) {
kiss_fft( st , buf ); kiss_fft( st , buf );
fwrite( buf , sizeof(kiss_fft_cpx) , nfft , fout ); if (useascii) {
int i;
for (i=0;i<nfft;++i)
fprintf(fout, "(%g,%g) ", (double)buf[i].r,(double)buf[i].i);
}else{
fwrite( buf , sizeof(kiss_fft_cpx) , nfft , fout );
}
} }
free(st); free(st);
free(buf); free(buf);
@ -48,11 +54,13 @@ int main(int argc,char ** argv)
int isinverse=0; int isinverse=0;
FILE *fin=stdin; FILE *fin=stdin;
FILE *fout=stdout; FILE *fout=stdout;
int useascii=0;
while (1) { while (1) {
int c=getopt(argc,argv,"n:i"); int c=getopt(argc,argv,"n:ia");
if (c==-1) break; if (c==-1) break;
switch (c) { switch (c) {
case 'a':useascii=1;break;
case 'n':nfft = atoi(optarg);break; case 'n':nfft = atoi(optarg);break;
case 'i':isinverse=1;break; case 'i':isinverse=1;break;
} }
@ -70,7 +78,7 @@ int main(int argc,char ** argv)
++optind; ++optind;
} }
fft_file(fin,fout,nfft,isinverse); fft_file(fin,fout,nfft,isinverse,useascii);
if (fout!=stdout) fclose(fout); if (fout!=stdout) fclose(fout);
if (fin!=stdin) fclose(fin); if (fin!=stdin) fclose(fin);