subroutine genmsk(msg0,ichk,msgsent,i4tone,itype) ! Encode a JTMSK message ! Input: ! - msg0 requested message to be transmitted ! - ichk if ichk=1, return only msgsent ! if ichk.ge.10000, set imsg=ichk-10000 for short msg ! - msgsent message as it will be decoded ! - i4tone array of audio tone values, 0 or 1 ! - itype message type ! 1 = standard message "Call_1 Call_2 Grid/Rpt" ! 2 = type 1 prefix ! 3 = type 1 suffix ! 4 = type 2 prefix ! 5 = type 2 suffix ! 6 = free text (up to 13 characters) ! 7 = short message " Rpt" use iso_c_binding, only: c_loc,c_size_t use packjt use hashing character*22 msg0 character*22 message !Message to be generated character*22 msgsent !Message as it will be received integer*4 i4Msg6BitWords(13) !72-bit message as 6-bit words integer*1, target:: i1Msg8BitBytes(13) !72 bits and zero tail as 8-bit bytes integer*1 e1(198) !Encoded bits before re-ordering integer*1 i1EncodedBits(198) !Encoded information-carrying bits integer i4tone(234) !Tone #s, data and sync (values 0-1) integer*1 i1hash(4) integer b11(11) data b11/1,1,1,0,0,0,1,0,0,1,0/ !Barker 11 code equivalence (ihash,i1hash) save if(msg0(1:1).eq.'@') then !Generate a fixed tone read(msg0(2:5),*,end=1,err=1) nfreq !at specified frequency go to 2 1 nfreq=1000 2 i4tone(1)=nfreq else message=msg0 do i=1,22 if(ichar(message(i:i)).eq.0) then message(i:)=' ' exit endif enddo do i=1,22 !Strip leading blanks if(message(1:1).ne.' ') exit message=message(i+1:) enddo if(message(1:1).eq.'<') then call genmsk_short(message,msgsent,ichk,i4tone,itype) if(itype.lt.0) go to 999 i4tone(36)=-35 go to 999 endif call packmsg(message,i4Msg6BitWords,itype) !Pack into 12 6-bit bytes call unpackmsg(i4Msg6BitWords,msgsent) !Unpack to get msgsent if(ichk.eq.1) go to 999 call entail(i4Msg6BitWords,i1Msg8BitBytes) !Add tail, make 8-bit bytes ihash=nhash(c_loc(i1Msg8BitBytes),int(9,c_size_t),146) ihash=2*iand(ihash,32767) !Generate the CRC i1Msg8BitBytes(10)=i1hash(2) !CRC to bytes 10 and 11 i1Msg8BitBytes(11)=i1hash(1) nsym=198 !(72+12+15)*2 = 198 kc=13 nc=2 nbits=87 call enc213(i1Msg8BitBytes,nbits,e1,nsym,kc,nc) !Encode the message j=0 do i=1,nsym/2 !Reorder the encoded bits j=j+1 i1EncodedBits(j)=e1(2*i-1) i1EncodedBits(j+99)=e1(2*i) enddo ! Insert three Barker 11 codes and three "even-f0-parity" bits i4tone=0 !Start with all 0's n1=35 n2=69 n3=94 i4tone(1:11)=b11 !11 sync bits i4tone(11+1:11+n1)=i1EncodedBits(1:n1) !n1 data bits nn1=count(i4tone(11+1:11+n1).eq.0) !Count the 0's if(mod(nn1,2).eq.0) i4tone(12+n1)=1 !1 parity bit i4tone(13+n1:23+n1)=b11 !11 sync bits i4tone(23+n1+1:23+n1+n2)=i1EncodedBits(n1+1:n1+n2) !n2 data bits nn2=count(i4tone(23+n1+1:23+n1+n2).eq.0) !Count the 0's if(mod(nn2,2).eq.0) i4tone(24+n1+n2)=1 !1 parity bit i4tone(25+n1+n2:35+n1+n2)=b11 !11 sync bits i4tone(35+n1+n2+1:35+n1+n2+n3)=i1EncodedBits(n1+n2+1:n1+n2+n3)!n3 data bits nn3=count(i4tone(35+n1+n2+1:35+n1+n2+n3).eq.0) !Count the 0's if(mod(nn3,2).eq.0) i4tone(36+n1+n2+n3)=1 !1 parity bit endif n=count(i4tone.eq.0) if(mod(n,2).ne.0) stop 'Parity error in genmsk.' 999 return end subroutine genmsk