lasp/beamforming/c/fft.c

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// fft.cpp
//
// Author: J.A. de Jong -ASCEE
//
// Description:
//
//////////////////////////////////////////////////////////////////////
#define TRACERPLUS (-5)
#include "ascee_tracer.h"
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#include "fft.h"
#include "types.h"
#include "fftpack.h"
typedef struct Fft_s {
us nfft;
us nchannels;
vd fft_work;
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} Fft;
Fft* Fft_alloc(const us nfft,const us nchannels) {
fsTRACE(15);
if(nchannels > ASCEE_MAX_NUM_CHANNELS) {
WARN("Too high number of channels! Please increase the "
"ASCEE_MAX_NUM_CHANNELS compilation flag");
return NULL;
}
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Fft* fft = a_malloc(sizeof(Fft));
if(fft==NULL) {
WARN("Fft allocation failed");
return NULL;
}
fft->nfft = nfft;
fft->nchannels = nchannels;
/* Initialize foreign fft lib */
fft->fft_work = vd_alloc(2*nfft+15);
npy_rffti(nfft,fft->fft_work.ptr);
check_overflow_vx(fft->fft_work);
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/* print_vd(&fft->fft_work); */
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feTRACE(15);
return fft;
}
void Fft_free(Fft* fft) {
fsTRACE(15);
dbgassert(fft,NULLPTRDEREF);
vd_free(&fft->fft_work);
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a_free(fft);
feTRACE(15);
}
us Fft_nchannels(const Fft* fft) {return fft->nchannels;}
us Fft_nfft(const Fft* fft) {return fft->nfft;}
void Fft_fft(const Fft* fft,const dmat* timedata,cmat* result) {
fsTRACE(15);
dbgassert(fft && timedata && result,NULLPTRDEREF);
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dbgassert(timedata->n_rows == fft->nfft,"Invalid size for time data rows."
" Should be equal to nfft");
dbgassert(timedata->n_cols == fft->nchannels,"Invalid size for time data cols."
" Should be equal to nchannels");
const us nfft = fft->nfft;
vd fft_result = vd_alloc(fft->nfft);
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for(us col=0;col<fft->nchannels;col++) {
vd timedata_col = dmat_column((dmat*) timedata,col);
vd_copy(&fft_result,&timedata_col);
vd_free(&timedata_col);
npy_rfftf(fft->nfft,fft_result.ptr,fft->fft_work.ptr);
/* Fftpack stores the data a bit strange, the resulting array
* has the DC value at 0,the first cosine at 1, the first sine
* at 2 etc. This needs to be shifted properly in the
* resulting matrix, as for the complex data, the imaginary
* part of the DC component equals zero. */
check_overflow_vx(fft_result);
check_overflow_vx(fft->fft_work);
vc resultcol = cmat_column(result,col);
*getvcval(&resultcol,0) = *getvdval(&fft_result,0);
memcpy((void*) getvcval(&resultcol,1),
(void*) getvdval(&fft_result,1),
(nfft-1)*sizeof(d));
/* Set imaginary part of Nyquist frequency to zero */
((d*) getvcval(&resultcol,nfft/2))[1] = 0;
check_overflow_xmat(*timedata);
/* Free up storage of the result column */
vc_free(&resultcol);
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}
/* print_vd(&fft->fft_work); */
vd_free(&fft_result);
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feTRACE(15);
}
//////////////////////////////////////////////////////////////////////