ft8d/chkcall.f90

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Fortran
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2018-12-15 07:25:41 -05:00
subroutine chkcall(w,bc,cok)
! Check "w" to see if it could be a valid standard callsign or a valid
! compound callsign.
! Return base call "bc" and a logical "cok" indicator.
character w*13 !A putative callsign
character bc*6 !Base call (tentative)
character c*1
logical cok,isdigit,isletter
isdigit(c)=(ichar(c).ge.ichar('0')) .and. (ichar(c).le.ichar('9'))
isletter(c)=(ichar(c).ge.ichar('A')) .and. (ichar(c).le.ichar('Z'))
cok=.true.
bc=w(1:6)
n1=len_trim(w)
if(n1.gt.11) go to 100
if(index(w,'.').ge.1) go to 100
if(index(w,'+').ge.1) go to 100
if(index(w,'-').ge.1) go to 100
if(index(w,'?').ge.1) go to 100
if(n1.gt.6 .and. index(w,'/').le.0) go to 100
i0=index(w,'/')
if(max(i0-1,n1-i0).gt.6) go to 100 !Base call must be < 7 characters
if(i0.ge.2 .and. i0.le.n1-1) then !Extract base call from compound call
if(i0-1.le.n1-i0) bc=w(i0+1:n1)//' '
if(i0-1.gt.n1-i0) bc=w(1:i0-1)//' '
endif
nbc=len_trim(bc)
if(nbc.gt.6) go to 100 !Base call should have no more than 6 characters
! One of first two characters (c1 or c2) must be a letter
if((.not.isletter(bc(1:1))) .and. (.not.isletter(bc(2:2)))) go to 100
if(bc(1:1).eq.'Q') go to 100 !Calls don't start with Q
! Must have a digit in 2nd or 3rd position
i1=0
if(isdigit(bc(2:2))) i1=2
if(isdigit(bc(3:3))) i1=3
if(i1.eq.0) go to 100
! Callsign must have a suffix of 1-3 letters
if(i1.eq.nbc) go to 100
n=0
do i=i1+1,nbc
j=ichar(bc(i:i))
if(j.lt.ichar('A') .or. j.gt.ichar('Z')) go to 100
n=n+1
enddo
if(n.ge.1 .and. n.le.3) go to 200
100 cok=.false.
200 return
end subroutine chkcall