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split out tmpbuf and scratchbuf, since they are only used in certain cases

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This commit is contained in:
Mark Borgerding 2004-04-03 02:59:20 +00:00
parent 835c16c582
commit 1bbb274965
2 changed files with 36 additions and 25 deletions
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13
_kiss_fft_guts.h
View File

@ -18,13 +18,18 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
typedef struct { kiss_fft_scalar r; kiss_fft_scalar i; }kiss_fft_cpx; */
#include "kiss_fft.h"
#define MAXFACTORS 32
/* e.g. an fft of length 128 has 4 factors
as far as kissfft is concerned
4*4*4*2
*/
struct kiss_fft_state{
int nfft;
int inverse;
int *factors;
kiss_fft_cpx * twiddles;
kiss_fft_cpx * tmpbuf;
kiss_fft_cpx * scratch;
int factors[2*MAXFACTORS];
kiss_fft_cpx twiddles[1];
};
/*

48
kiss_fft.c
View File

@ -18,11 +18,19 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
fixed or floating point complex numbers. It also delares the kf_ internal functions.
*/
/* the max length of the sequence of factors of nfft ,
MAXFACTORS==32 this should be good up to more 1e15 samples
( 2 * 3**31 )
*/
#define MAXFACTORS 32
static kiss_fft_cpx *scratchbuf=NULL;
static size_t nscratchbuf=0;
static kiss_fft_cpx *tmpbuf=NULL;
static size_t ntmpbuf=0;
#define CHECKBUF(buf,nbuf,n) \
do { \
if ( nbuf < (size_t)(n) ) {\
buf = (kiss_fft_cpx*)realloc(buf,sizeof(kiss_fft_cpx)*(n)); \
nbuf = (size_t)(n); \
} \
}while(0)
static void kf_bfly2(
kiss_fft_cpx * Fout,
@ -209,27 +217,28 @@ static void kf_bfly_generic(
)
{
int u,k,q1,q;
kiss_fft_cpx * scratch = st->scratch;
kiss_fft_cpx * twiddles = st->twiddles;
kiss_fft_cpx t;
int Norig = st->nfft;
CHECKBUF(scratchbuf,nscratchbuf,p);
for ( u=0; u<m; ++u ) {
k=u;
for ( q1=0 ; q1<p ; ++q1 ) {
scratch[q1] = Fout[ k ];
C_FIXDIV(scratch[q1],p);
scratchbuf[q1] = Fout[ k ];
C_FIXDIV(scratchbuf[q1],p);
k += m;
}
k=u;
for ( q1=0 ; q1<p ; ++q1 ) {
int twidx=0;
Fout[ k ] = scratch[0];
Fout[ k ] = scratchbuf[0];
for (q=1;q<p;++q ) {
twidx += fstride * k;
if (twidx>=Norig) twidx-=Norig;
C_MUL(t,scratch[q] , twiddles[twidx] );
C_MUL(t,scratchbuf[q] , twiddles[twidx] );
C_ADDTO( Fout[ k ] ,t);
}
k += m;
@ -305,7 +314,7 @@ void kf_factor(int n,int * facbuf)
/*
*
* User-callable function to allocate all necessary scratch space for the fft.
* User-callable function to allocate all necessary storage space for the fft.
*
* The return value is a contiguous block of memory, allocated with malloc. As such,
* It can be freed with free(), rather than a kiss_fft-specific function.
@ -314,10 +323,7 @@ kiss_fft_cfg kiss_fft_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem
{
kiss_fft_cfg st=NULL;
size_t memneeded = sizeof(struct kiss_fft_state)
+ sizeof(kiss_fft_cpx)*nfft /* twiddle factors*/
+ sizeof(kiss_fft_cpx)*nfft /* tmpbuf*/
+ sizeof(int)*2*MAXFACTORS /* factors*/
+ sizeof(kiss_fft_cpx)*nfft; /* scratch*/
+ sizeof(kiss_fft_cpx)*(nfft-1); /* twiddle factors*/
if ( lenmem==NULL ) {
st = ( kiss_fft_cfg)malloc( memneeded );
@ -330,10 +336,6 @@ kiss_fft_cfg kiss_fft_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem
int i;
st->nfft=nfft;
st->inverse = inverse_fft;
st->twiddles = (kiss_fft_cpx*)(st+1); /* just beyond struct*/
st->tmpbuf = (kiss_fft_cpx*)(st->twiddles + nfft);/* just after twiddles*/
st->scratch = (kiss_fft_cpx*)(st->tmpbuf + nfft);
st->factors = (int*)(st->scratch + nfft);
for (i=0;i<nfft;++i) {
const double pi=3.14159265358979323846264338327;
@ -348,11 +350,15 @@ kiss_fft_cfg kiss_fft_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem
return st;
}
void kiss_fft_stride(kiss_fft_cfg st,const kiss_fft_cpx *fin,kiss_fft_cpx *fout,int in_stride)
{
if (fin == fout) {
kf_work(st->tmpbuf,fin,1,in_stride, st->factors,st);
memcpy(fout,st->tmpbuf,sizeof(kiss_fft_cpx)*st->nfft);
CHECKBUF(tmpbuf,ntmpbuf,st->nfft);
kf_work(tmpbuf,fin,1,in_stride, st->factors,st);
memcpy(fout,tmpbuf,sizeof(kiss_fft_cpx)*st->nfft);
}else{
kf_work( fout, fin, 1,in_stride, st->factors,st );
}