WSJT-X/lib/downsam9.f90
Bill Somerville 8d8d64c07c Thread safety enhancements to jt9
Serialize thread unsafe FFTW3 calls

Serialize FFTW3 plan initializations in four2a

Serialize decoder results output to file/console

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4928 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2015-02-04 01:41:26 +00:00

93 lines
2.4 KiB
Fortran

subroutine downsam9(id2,npts8,nsps8,newdat,nspsd,fpk,c2,nz2)
!Downsample from id2() into c2() so as to yield nspsd samples per symbol,
!mixing from fpk down to zero frequency. The downsample factor is 432.
use, intrinsic :: iso_c_binding
use FFTW3
include 'constants.f90'
! parameter (NMAX1=1024*1920)
parameter (NMAX1=884736)
type(C_PTR) :: plan !Pointers plan for big FFT
integer*2 id2(0:8*npts8-1)
real*4 x1(0:NMAX1-1)
complex c1(0:NMAX1/2)
complex c2(0:1440-1)
real s(5000)
logical first
common/patience/npatience,nthreads
data first/.true./
save plan,first
nfft1=604800 !Forward FFT length
df1=12000.0/nfft1
npts=8*npts8
if(newdat.eq.1) then
fac=6.963e-6 !Why this weird constant?
do i=0,npts-1
x1(i)=fac*id2(i)
enddo
x1(npts:nfft1-1)=0. !Zero the rest of x1
endif
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 FFTs just once
!$omp critical(fftw) ! serialize non thread-safe FFTW3 calls
plan=fftwf_plan_dft_r2c_1d(nfft1,x1,c1,nflags)
!$omp end critical(fftw)
first=.false.
endif
if(newdat.eq.1) then
fac=6.963e-6 !Why this weird constant?
do i=0,npts-1
x1(i)=fac*id2(i)
enddo
x1(npts:nfft1-1)=0. !Zero the rest of x1
call timer('FFTbig9 ',0)
call fftwf_execute_dft_r2c(plan,x1,c1)
call timer('FFTbig9 ',1)
nadd=int(1.0/df1)
s=0.
do i=1,5000
j=int((i-1)/df1)
do n=1,nadd
j=j+1
s(i)=s(i)+real(c1(j))**2 + aimag(c1(j))**2
enddo
enddo
endif
ndown=8*nsps8/nspsd !Downsample factor
nfft2=nfft1/ndown !Backward FFT length
nh2=nfft2/2
nf=nint(fpk)
i0=int(fpk/df1)
nw=100
ia=max(1,nf-nw)
ib=min(5000,nf+nw)
call pctile(s(ia),ib-ia+1,40,avenoise)
fac=sqrt(1.0/avenoise)
do i=0,nfft2-1
j=i0+i
if(i.gt.nh2) j=j-nfft2
c2(i)=fac*c1(j)
enddo
call four2a(c2,nfft2,1,1,1) !FFT back to time domain
nz2=8*npts8/ndown
return
end subroutine downsam9