WSJT-X/lib/genjt9.f90

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Fortran
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subroutine genjt9(msg0,msgsent,i4tone)
! Encodes a JT9 message and returns msgsent, the message as it will
! be decoded, and an integer array i4tone(85) of 9-FSK tone values
! in the range 0-8.
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 i1Msg8BitBytes(13) !72 bits and zero tail as 8-bit bytes
integer*1 i1EncodedBits(207) !Encoded information-carrying bits
integer*1 i1ScrambledBits(207) !Encoded bits after interleaving
integer*4 i4DataSymbols(69) !Data symbols (values 0-7)
integer*4 i4GrayCodedSymbols(69) !Gray-coded symbols (values 0-7)
integer*4 i4tone(85) !Tone #s, data and sync (values 0-8)
include 'jt9sync.f90'
save
message=msg0
do i=1,22
if(ichar(message(i:i)).eq.0) then
message(i:)=' '
exit
endif
enddo
do i=1,22 !Omit leading blanks
if(message(1:1).ne.' ') exit
message=message(i+1:)
enddo
call packmsg(message,i4Msg6BitWords) !Pack message into 12 6-bit bytes
call unpackmsg(i4Msg6BitWords,msgsent) !Unpack to get msgsent
if(i4tone(1).eq.-99) go to 999
call entail(i4Msg6BitWords,i1Msg8BitBytes) !Add tail, convert to 8-bit bytes
nsym2=206
call encode232(i1Msg8BitBytes,nsym2,i1EncodedBits) !Encode K=32, r=1/2
call interleave9(i1EncodedBits,1,i1ScrambledBits) !Interleave the bits
call packbits(i1ScrambledBits,nsym2,3,i4DataSymbols) !Pack 3-bits into words
call graycode(i4DataSymbols,69,1,i4GrayCodedSymbols) !Apply Gray code
! Insert sync symbols at ntone=0 and add 1 to the data-tone numbers.
j=0
do i=1,85
if(isync(i).eq.1) then
i4tone(i)=0
else
j=j+1
i4tone(i)=i4GrayCodedSymbols(j)+1
endif
enddo
999 return
end subroutine genjt9