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/*
* Copyright (c) 2003-2004, Mark Borgerding. All rights reserved.
* This file is part of KISS FFT - https://github.com/mborgerding/kissfft
*
* SPDX-License-Identifier: BSD-3-Clause
* See COPYING file for more information.
*/
#include "kiss_fftndr.h"
#include "_kiss_fft_guts.h"
#define MAX(x,y) ( ( (x)<(y) )?(y):(x) )
struct kiss_fftndr_state
{
int dimReal;
int dimOther;
kiss_fftr_cfg cfg_r;
kiss_fftnd_cfg cfg_nd;
void * tmpbuf;
};
static int prod(const int *dims, int ndims)
{
int x=1;
while (ndims--)
x *= *dims++;
return x;
}
kiss_fftndr_cfg kiss_fftndr_alloc(const int *dims,int ndims,int inverse_fft,void*mem,size_t*lenmem)
{
kiss_fftndr_cfg st = NULL;
size_t nr=0 , nd=0,ntmp=0;
int dimReal = dims[ndims-1];
int dimOther = prod(dims,ndims-1);
size_t memneeded;
(void)kiss_fftr_alloc(dimReal,inverse_fft,NULL,&nr);
(void)kiss_fftnd_alloc(dims,ndims-1,inverse_fft,NULL,&nd);
ntmp =
MAX( 2*dimOther , dimReal+2) * sizeof(kiss_fft_scalar) // freq buffer for one pass
+ dimOther*(dimReal+2) * sizeof(kiss_fft_scalar); // large enough to hold entire input in case of in-place
memneeded = sizeof( struct kiss_fftndr_state ) + nr + nd + ntmp;
if (lenmem==NULL) {
st = (kiss_fftndr_cfg) malloc(memneeded);
}else{
if (*lenmem >= memneeded)
st = (kiss_fftndr_cfg)mem;
*lenmem = memneeded;
}
if (st==NULL)
return NULL;
memset( st , 0 , memneeded);
st->dimReal = dimReal;
st->dimOther = dimOther;
st->cfg_r = kiss_fftr_alloc( dimReal,inverse_fft,st+1,&nr);
st->cfg_nd = kiss_fftnd_alloc(dims,ndims-1,inverse_fft, ((char*) st->cfg_r)+nr,&nd);
st->tmpbuf = (char*)st->cfg_nd + nd;
return st;
}
void kiss_fftndr(kiss_fftndr_cfg st,const kiss_fft_scalar *timedata,kiss_fft_cpx *freqdata)
{
int k1,k2;
int dimReal = st->dimReal;
int dimOther = st->dimOther;
int nrbins = dimReal/2+1;
kiss_fft_cpx * tmp1 = (kiss_fft_cpx*)st->tmpbuf;
kiss_fft_cpx * tmp2 = tmp1 + MAX(nrbins,dimOther);
// timedata is N0 x N1 x ... x Nk real
// take a real chunk of data, fft it and place the output at correct intervals
for (k1=0;k1<dimOther;++k1) {
kiss_fftr( st->cfg_r, timedata + k1*dimReal , tmp1 ); // tmp1 now holds nrbins complex points
for (k2=0;k2<nrbins;++k2)
tmp2[ k2*dimOther+k1 ] = tmp1[k2];
}
for (k2=0;k2<nrbins;++k2) {
kiss_fftnd(st->cfg_nd, tmp2+k2*dimOther, tmp1); // tmp1 now holds dimOther complex points
for (k1=0;k1<dimOther;++k1)
freqdata[ k1*(nrbins) + k2] = tmp1[k1];
}
}
void kiss_fftndri(kiss_fftndr_cfg st,const kiss_fft_cpx *freqdata,kiss_fft_scalar *timedata)
{
int k1,k2;
int dimReal = st->dimReal;
int dimOther = st->dimOther;
int nrbins = dimReal/2+1;
kiss_fft_cpx * tmp1 = (kiss_fft_cpx*)st->tmpbuf;
kiss_fft_cpx * tmp2 = tmp1 + MAX(nrbins,dimOther);
for (k2=0;k2<nrbins;++k2) {
for (k1=0;k1<dimOther;++k1)
tmp1[k1] = freqdata[ k1*(nrbins) + k2 ];
kiss_fftnd(st->cfg_nd, tmp1, tmp2+k2*dimOther);
}
for (k1=0;k1<dimOther;++k1) {
for (k2=0;k2<nrbins;++k2)
tmp1[k2] = tmp2[ k2*dimOther+k1 ];
kiss_fftri( st->cfg_r,tmp1,timedata + k1*dimReal);
}
}
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