WSJT-X/lib/genmsk32.f90

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Fortran
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subroutine genmsk32(msg,msgsent,ichk,itone,itype)
use hashing
character*22 msg,msgsent,hashmsg
character*4 crpt,rpt(0:31)
logical first
integer itone(144)
integer ig24(0:4096-1) !Codewords for Golay (24,12) code
integer*1 codeword(24),bitseq(32)
integer*1 s8r(8)
data s8r/1,0,1,1,0,0,0,1/
data rpt /'-04 ','-03 ','-02 ','-01 ','00 ','01 ','02 ','03 ','04 ', &
'05 ','06 ','07 ','08 ','09 ','10 ', &
'R-04','R-03','R-02','R-01','R00','R01','R02','R03','R04', &
'R05','R06','R07','R08','R09','R10', &
'RRR ','73 '/
data first/.true./
save first,ig24
if(first) then
call golay24_table(ig24) !Define the Golay(24,12) codewords
first=.false.
endif
itype=-1
msgsent='*** bad message ***'
itone=0
i1=index(msg,'>')
if(i1.lt.9) go to 900
call fmtmsg(msg,iz)
crpt=msg(i1+2:i1+5)
do i=0,31
if(crpt.eq.rpt(i)) go to 10
enddo
go to 900
10 irpt=i !Report index, 0-31
if(ichk.lt.10000) then
hashmsg=msg(2:i1-1)//' '//crpt
call hash(hashmsg,22,ihash)
ihash=iand(ihash,127) !7-bit hash
ig=32*ihash + irpt !12-bit codeword
else
ig=ichk-10000
endif
ncodeword=ig24(ig)
!write(*,*) 'codeword is: ',ncodeword,'message is: ',ig,'report index: ',irpt,'hash: ',ihash
do i=1,24
codeword(i)=iand(1,ishft(ncodeword,1-i))
enddo
bitseq(1:8)=s8r
bitseq(9:32)=codeword
bitseq=2*bitseq-1
! Map I and Q to tones.
itone=0
do i=1, 16
itone(2*i-1)=(bitseq(2*i)*bitseq(2*i-1)+1)/2;
itone(2*i)=-(bitseq(2*i)*bitseq(mod(2*i,32)+1)-1)/2;
enddo
! Flip polarity
itone=-itone+1
msgsent=msg
itype=7
900 return
end subroutine genmsk32