WSJT-X/qmap/libqmap/fftbig.f90

57 lines
1.3 KiB
Fortran

subroutine fftbig(dd,nmax)
! Do the full length FFT of complex data stored in array dd(2,nmax).
use, intrinsic :: iso_c_binding
use FFTW3
use timer_module, only: timer
parameter (MAXFFT1=5376000)
real*4 dd(2,nmax) !Input data
complex ca(MAXFFT1) !FFT of input
real*8 df
type(C_PTR) :: plan1 !Pointer to FFTW plan
logical first
common/cacb/ca
equivalence (rfilt,cfilt)
data first/.true./,npatience/0/
save
if(nmax.lt.0) go to 900
nfft1=MAXFFT1
if(first) then
nflags=FFTW_ESTIMATE
if(npatience.eq.1) nflags=FFTW_ESTIMATE_PATIENT
if(npatience.eq.2) nflags=FFTW_MEASURE
if(npatience.eq.3) nflags=FFTW_PATIENT
if(npatience.eq.4) nflags=FFTW_EXHAUSTIVE
! Plan the big FFT just once
call timer('FFTplan ',0)
plan1=fftwf_plan_dft_1d(nfft1,ca,ca,+1,nflags)
call timer('FFTplan ',1)
df=96000.d0/nfft1
first=.false.
endif
nz=min(nmax,nfft1)
do i=1,nz
ca(i)=cmplx(dd(1,i),dd(2,i))
enddo
if(nmax.lt.nfft1) then
do i=nmax+1,nfft1
ca(i)=0.
enddo
endif
call timer('FFTbig ',0)
call fftwf_execute_dft(plan1,ca,ca)
call timer('FFTbig ',1)
go to 999
900 call fftwf_destroy_plan(plan1)
999 return
end subroutine fftbig