46 lines
752 B
Fortran
46 lines
752 B
Fortran
subroutine inter_wspr(id,ndir)
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! Interleave (ndir=1) or de-interleave (ndir=-1) the array id.
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integer*1 id(0:161),itmp(0:161)
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integer j0(0:161)
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logical first
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data first/.true./
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save
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if(first) then
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! Compute the interleave table using bit reversal.
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k=-1
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do i=0,255
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n=0
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ii=i
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do j=0,7
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n=n+n
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if(iand(ii,1).ne.0) n=n+1
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ii=ii/2
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enddo
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if(n.le.161) then
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k=k+1
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j0(k)=n
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endif
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enddo
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first=.false.
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endif
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if(ndir.eq.1) then
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do i=0,161
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itmp(j0(i))=id(i)
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enddo
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else
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do i=0,161
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itmp(i)=id(j0(i))
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enddo
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endif
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do i=0,161
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id(i)=itmp(i)
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enddo
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return
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end subroutine inter_wspr
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